U.S. patent application number 14/843391 was filed with the patent office on 2016-07-07 for communication method and system that uses low latency/low data bandwidth and high latency/high data bandwidth pathways.
This patent application is currently assigned to TESLA WIRELESS COMPANY LLC. The applicant listed for this patent is Tesla Wireless Company LLC. Invention is credited to Kevin Babich.
Application Number | 20160197669 14/843391 |
Document ID | / |
Family ID | 56108053 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160197669 |
Kind Code |
A1 |
Babich; Kevin |
July 7, 2016 |
COMMUNICATION METHOD AND SYSTEM THAT USES LOW LATENCY/LOW DATA
BANDWIDTH AND HIGH LATENCY/HIGH DATA BANDWIDTH PATHWAYS
Abstract
A communication system uses multiple communications links,
preferably links that use different communications media. The
multiple communications links may include a high latency/high
bandwidth link using a fiber-optic cable configured to carry large
volumes of data but having a high latency. The communications links
may also include a low latency/low bandwidth link implemented using
skywave propagation of radio waves and configured to carry smaller
volumes of data with a lower latency across a substantial portion
of the earth's surface. The two communications links may be used
together to coordinate various activities such as the buying and
selling of financial instruments.
Inventors: |
Babich; Kevin; (Valparaiso,
IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tesla Wireless Company LLC |
Valparaiso |
IN |
US |
|
|
Assignee: |
TESLA WIRELESS COMPANY LLC
Valparaiso
IN
|
Family ID: |
56108053 |
Appl. No.: |
14/843391 |
Filed: |
September 2, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14566851 |
Dec 11, 2014 |
9136938 |
|
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14843391 |
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Current U.S.
Class: |
370/315 |
Current CPC
Class: |
H04B 7/22 20130101; H04W
28/20 20130101; H04B 7/145 20130101; H04B 7/18504 20130101; H04B
10/25 20130101 |
International
Class: |
H04B 7/22 20060101
H04B007/22; H04W 28/20 20060101 H04W028/20; H04B 7/145 20060101
H04B007/145 |
Claims
1. A method, comprising: transmitting command data from a
transmission station via a first communication link, wherein the
command data defines one or more commands; transmitting triggering
data from the transmission station via a second communication link,
wherein the triggering data includes an identifier identifying at
least one of the one or more commands; wherein the second
communication link transmits the triggering data using
electromagnetic waves transmitted via skywave propagation; and
wherein the first communication link has greater latency than the
second communication link.
2. The method of claim 1, wherein the first communication link has
larger data bandwidth than the second communication link.
3. A method, comprising: transmitting command data from a
transmission station via a first communication link, wherein the
command data defines one or more commands; transmitting triggering
data from the transmission station via a second communication link,
wherein the triggering data includes an identifier identifying at
least one of the one or more commands; and wherein the first and
second communication links transmit the triggering data using
electromagnetic waves transmitted via skywave propagation.
4. The method of claim 1, further comprising: determining a maximum
usable frequency for skywave propagation over the second
communication link; and transmitting the triggering data over the
second communication link at a frequency that is less than or equal
to the maximum usable frequency.
5. The method of claim 1, further comprising: determining a minimum
usable frequency for skywave propagation over the second
communication link; and transmitting the triggering data over the
second communication link at a frequency that is greater than or
equal to the minimum usable frequency.
6. The method of claim 1, wherein said transmitting the triggering
data includes transmitting the electromagnetic waves below the
critical angle.
7. The method of claim 1, further comprising: receiving the command
data at a receiving station remote from the transmission station;
and receiving the triggering data at the receiving station.
8. The method of claim 7, further comprising: transmitting the
command data on both the first communication link and the second
communication link.
9. The method of claim 8, wherein said receiving the command data
includes receiving the command data via the first communication
link before receiving the command data via the second communication
link.
10. The method of claim 8, wherein said receiving the command data
includes receiving the command data via the second communication
link before receiving the command data via the first communication
link.
11. The method of claim 7, further comprising: transmitting the
triggering data on both the first communication link and the second
communication link.
12. The method of claim 11, wherein said receiving the triggering
data includes receiving the triggering data via the first
communication link before receiving the triggering data via the
second communication link.
13. The method of claim 11, wherein said receiving the triggering
data includes receiving the triggering data via the second
communication link before receiving the triggering data via the
first communication link.
14. The method of claim 7, further comprising: executing at least
one of the one or more commands identified in the triggering data
in response to said receiving the triggering data, the at least one
command executed using a processor at the receiving station.
15. The method of claim 14, wherein said executing occurs on or
after both the command data and triggering data is fully received
at the receiving station.
16. A method, comprising: receiving command data at a receiving
station via a first communication link, wherein the command data
defines one or more commands; receiving triggering data at a
receiving station via a second communication link, wherein the
triggering data includes an identifier identifying at least one of
the one or more commands; wherein the triggering data passes over
the second communication link to the receiving station using
electromagnetic waves received via skywave propagation; and wherein
the command data passes over the first communication link to the
receiving station without using skywave propagation.
17. The method of claim 16, wherein the first communication link
has larger data bandwidth than the second communication link.
18. The method of claim 16, further comprising: executing at least
one of the one or more commands identified in the triggering data
in response to said receiving the triggering data, the at least one
command executed using a processor at the receiving station.
19. The method of claim 1, wherein the command data is defined by a
collection of data with a first size, and the triggering data is
defined by a collection of data with a second size, and the first
size is greater than or equal to the second size.
20. The method of claim 1, wherein the one or more commands include
instructions to buy and/or sell one or more financial
instruments.
21. The method of claim 1, wherein the first communication link
includes an optical fiber.
22. The method of claim 1, further comprising: retransmitting the
electromagnetic waves via one or more repeaters.
23. The method of claim 1, wherein the second communication link
transmits the triggering data using multiple frequencies.
24. The method of claim 23, wherein: the second communication link
transmits on a first frequency for a first period of time, and on a
second frequency for the first period of time; and the first
frequency and the second frequency are different frequencies.
25. The method of claim 1, wherein the skywave propagation includes
refracting the electromagnetic waves from the ionosphere.
26. The method of claim 1, wherein there is at least one skip zone
between the transmitting and receiving stations.
27. The method of claim 1, wherein the distance between the
transmitting and receiving stations is greater than the radio
horizon.
28. The method of claim 1, wherein the first communication link,
and the second communication link are the same communication
link.
29. The method of claim 1, wherein the first communication link,
and the second communication link are separate communication
links.
30. A system, comprising: a processor coupled to a memory; a first
network interface responsive to the processor and coupled to a
communication network, wherein the network interface is configured
to send command data defining one or more commands using the
communication network; a second network interface responsive to the
processor and coupled to a radio-frequency communication interface;
an antenna system coupled to the radio-frequency communications
interface; wherein the radio-frequency communication interface is
configured to send triggering data using electromagnetic waves
broadcast from the antenna system; wherein the antenna system and
radio-frequency interface are configured to transmit the
electromagnetic waves via skywave propagation; and wherein the
triggering data includes an identifier identifying at least one of
the one or more commands.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/566,851, filed Dec. 11, 2014, which is
hereby incorporated by reference.
BACKGROUND
[0002] Recent technological improvements have dramatically improved
the ability to communicate across vast distances. Extensive fiber
optic and satellite networks now allow remote parts of the world to
communicate with one another. However, by spanning across these
great distances, such as across the Atlantic or Pacific Oceans,
fiber optic cables can incur a round-trip latency or time lag of
about 60 msec or more. Satellite communications can experience even
greater lag times. In many cases, this high latency cannot be
overcome because it is inherent in the communications medium and
equipment. For example, light may traverse an optical fiber 30-40%
more slowly than a radio wave traveling the same distance through
free space. Fiber optic networks typically require multiple
repeaters that further increase latency. While generally not
problematic in a number of circumstances, this high latency can
cause unacceptable delays in the execution of time sensitive
activities, especially time sensitive activities that require
complex logic and/or are dependent on conditions that rapidly
change. These latency issues can for example create problems for a
whole host of activities, such as in the operation and/or
synchronization of distributed computer systems, scientific
experiments with geographically large sensor arrays, and
telemedicine/diagnostic activities, to name just a few. In one
particular example, orders to buy and sell securities or other
financial instruments in world markets typically rely on
communications links that carry data and instructions over systems
using fiber optic lines, coaxial cables, or microwave communication
links. Any delays in executing an order, such as caused by the high
latency across fiber optic lines, can lead to significant financial
losses.
SUMMARY
[0003] A unique communication system and method has been developed
to address the above-mentioned latency issues as well as other
issues. In the communication system, command data is transmitted so
as to be received at a receiving station before (or at the same
time) triggering data is received. The command data includes one or
more directives, instructions, algorithms, and/or rules for
controlling a machine, such as a computer and/or mechanical device,
to take one or more actions. For example, the command data in one
form includes a program for buying and/or selling particular
options or stocks at certain price levels, ranges, and/or based on
other conditions. Command data is typically (but not in all
circumstances) larger in size than the triggering data such that
the command data takes longer than the triggering data to transmit
over communication links having the same data bandwidth. The
triggering data includes information identifying one or more
commands in the command data to execute. For example, the
triggering data can identify one or more particular options in the
command data that identifies the particular stock (or multiple
stocks) to purchase at a particular price (or prices). In one
example, the command data is transmitted over a communication link
that has high bandwidth and high latency, such as over a fiber
optic cable, and the triggering data is transmitted over a
communication link that has low bandwidth and low latency, such as
through sky-wave propagation by refracting and/or scattering radio
waves from the ionosphere. The relatively small-sized triggering
data is then able to be more quickly received at a receiving
station than if the triggering data was transmitted over the high
bandwidth and high latency communication link provided by fiber
optic cable. This communication system and method dramatically
reduces the time to execute complex time-sensitive actions, such as
financial transactions, over large distances at remote locations.
In one form, this technique is used to remotely perform actions
past the radio horizon, such as for transatlantic communications.
This technique can be adapted for one-way type communications or
even two-way type communications.
[0004] This unique communication system and method in one example
uses multiple communications links. In one form, the communication
links use different communications media. Such a system might be
used, for example, to transmit a large collection of preprogrammed
commands or rules over a high latency/high bandwidth link in
advance of a triggering event which may be a market event, news
report, a predetermined date and time, and the like. This set of
rules or preprogrammed actions may be sent as a software update to
an executable program, or as a firmware upgrade for a Field
Programmable Gate Array (FPGA). When a triggering event occurs,
triggering data can be sent over a low latency/low bandwidth link
alone, or over both links, causing the preprogrammed commands to be
executed as planned.
[0005] In one example of the system, the low latency/low bandwidth
communications link uses radio waves to transmit data in concert
with the higher latency/high bandwidth communications link which
may be a packet switched network operating over fiber optic cables.
Such a combination may include various combinations with widely
varying differentials between the high and low latency links. The
low latency link may use high frequency (HF) radio waves to
transmit over a propagation path between North America and Europe.
Radio waves may transmit, for example, with a one-way latency of 20
to 25 ms or less (40 to 50 ms round trip). A higher latency link
may carry data over a different propagation path, or perhaps
through a different medium between the same two continents that,
for example, may have a latency of about 30 ms or more one-way, or
60 ms or more both ways.
[0006] The system may also constantly monitor and use different HF
bands to maintain the highest available signal strength between
remote locations depending on solar and atmospheric conditions.
This monitoring may include accessing third-party data, analyzing
results obtained by experimentation, and/or using software
modeling. These conditions can be particularly important in the low
latency link which may use skywave propagation to relay HF
transmissions over long distances. This skywave propagation may be
augmented by repeater stations on the ground or possibly in the
air.
[0007] In another aspect, overall security of the system may be
enhanced by sending a continual stream of actions and/or triggering
messages over the separate communications links to confuse
malicious third parties and discourage attempts to intercept and
decipher future transmissions. These messages may be very short, or
intermingled with various other transmissions which may go on
continuously, or for only short periods of time on a predetermined
schedule. In a related aspect, security may be enhanced by sending
short messages over skywave propagation on one or more frequencies,
or by sending small parts of a message on several frequencies at
the same time. Various additional techniques may also be employed
to enhance security such as encryption, two-way hashing, and the
like, which may incur additional latency in both links.
[0008] So as to aid in appreciating the unique features of this
communication system and method, the communication system and
method will be described with reference to executing trades of
stocks, bonds, futures, or other financial instruments, but it
should be recognized that this system and method can be used in a
large number of other fields where latency is a concern, such as
for distributed computing, scientific analysis, telemedicine,
military operations, etc.
[0009] Further forms, objects, features, aspects, benefits,
advantages, and embodiments of the present invention will become
apparent from a detailed description and drawings provided
herewith.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic diagram of a system for transmitting
data over separate communication links, one of which uses skywave
propagation.
[0011] FIG. 2 is a schematic diagram further illustrating the
skywave propagation of FIG. 1
[0012] FIG. 3 is a schematic diagram illustrating the use of
ground-based repeaters in the skywave propagation of FIG. 1.
[0013] FIG. 4 is a student schematic diagram illustrating the use
of airborne repeaters in the skywave propagation of FIG. 1.
[0014] FIG. 5 is a schematic diagram illustrating additional layers
of the atmosphere including the ionized layer shown in FIG. 1.
[0015] FIG. 6 is a schematic diagram illustrating various ionized
layers of the atmosphere shown in FIG. 5.
[0016] FIG. 7 is a schematic diagram illustrating additional
details of skywave propagation generally illustrated in FIGS.
1-6.
[0017] FIG. 8 is a schematic diagram illustrating additional detail
for the communication nodes of FIG. 1.
[0018] FIG. 9 is a schematic diagram illustrating additional detail
for the RF communication interface in FIG. 8.
[0019] FIGS. 10-13 are timing diagrams illustrating the coordinated
use of multiple communication links like those illustrated in FIGS.
1-9.
[0020] FIG. 14 is a flowchart generally illustrating actions taken
by the system of FIGS. 1-13.
[0021] FIG. 15-18 are flowcharts illustrating additional detail for
actions illustrated in FIG. 14.
DETAILED DESCRIPTION
[0022] For the purpose of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is thereby
intended. Any alterations and further modifications in the
described embodiments, and any further applications of the
principles of the invention as described herein are contemplated as
would normally occur to one skilled in the art to which the
invention relates. One embodiment of the invention is shown in
great detail, although it will be apparent to those skilled in the
relevant art that some features that are not relevant to the
present invention may not be shown for the sake of clarity.
[0023] FIG. 1 illustrates at 100 one example of a system configured
to transfer data via a low latency, low bandwidth communication
link 104, and separate data via a high latency, high bandwidth
communication link 108. Communication links 104 and 108 provide
separate connections between a first communication node 112 and a
second communication node 116. Low latency connection 104 may be
configured to transmit data using electromagnetic waves 124 passing
through free space via skywave propagation. Electromagnetic waves
124 may be generated by a transmitter in first communication node
112, passed along a transmission line 136 to an antenna 128. Waves
124 may be radiated by antenna 128 encountering an ionized portion
of the atmosphere 120. This radiated electromagnetic energy may
then be refracted by the ionized portion of the atmosphere 120
causing waves 124 to redirect toward earth. Waves 124 may be
received by a receiving antenna 132 coupled to second
communications node 116 by transmission line 140. As illustrated in
FIG. 1, a transmitting communication node may use skywave
propagation to transmit electromagnetic energy long distances
across the earth surface without the need of one or more
transmission lines to carry the electromagnetic energy.
[0024] Data may also be transmitted between communications nodes
112 and 116 using a high latency communication link 108. As
illustrated in FIG. 1, high latency communication link 108 may be
implemented using a transmission line 144 passing through the
earth, which may include passing under or through an ocean or other
body of water. As shown in FIG. 1, the high latency communication
link may include repeaters 152. FIG. 1 illustrates four repeaters
152 along transmission line 144 although any suitable number of
repeaters 152 may be used. Transmission line 144 may also have no
repeaters at all. Although FIG. 1 illustrates communication link
104 transmitting information from first communication node 112 to
second communication node 116, the data transmitted may pass along
communication links 104, 108 in the both directions.
[0025] The configuration shown in FIG. 1 is further illustrated in
FIG. 2 where first communication node 112 and second communication
node 116 are geographically remote from one another separated by a
substantial portion of the surface of the earth (156). This portion
of the earth's surface may include one or more continents, oceans,
mountain ranges, or other geographic areas. For example, the
distance spanned in FIGS. 1-7 may cover a single continent,
multiple continents, an ocean, and the like. In one example, node
112 is in Chicago, Ill. in the United States of America, and node
116 is in London, England, in the United Kingdom. In another
example, node 112 is in New York City, N.Y., and node 116 is in Los
Angeles, Calif., both cities being in North America. Any suitable
combination of distance, communication nodes, and communications
links is envisioned that can provide satisfactory latency and
bandwidth.
[0026] FIG. 2 illustrates that skywave propagation allows
electromagnetic energy to traverse long distances. Using skywave
propagation, low latency communication link 104 transmits
electromagnetic waves 124 into a portion of the atmosphere 120 that
is sufficiently ionized to refract electromagnetic waves 124 toward
the earth. The waves may then be reflected by the surface of the
earth and returned to the ionized portion of the upper atmosphere
120 where they may be refracted toward earth again. Thus
electromagnetic energy may "skip" repeatedly allowing the low
latency, low bandwidth signals 124 to cover distances substantially
greater than those which may be covered by non-skywave
propagation.
[0027] Another example of the system illustrated in FIG. 1 appears
in FIG. 3 where the skywave propagation discussed with respect to
FIGS. 1 and 2 may be enhanced using repeaters 302 and 306. In this
example, first repeater 302 may receive the low latency
communication signals emanating from antenna 128. The signals may
be refracted by the ionized region 120 and returned to earth where
they may be received by repeater 302 and retransmitted via skywave
propagation. The refracted signal may be received by repeater 306
and retransmitted using skywave propagation to second
communications node 116 via antenna 132. Although two repeating
stations are illustrated in FIG. 3, any suitable number,
configuration, or positioning of ground repeating stations 302 is
considered. Increasing the number of repeaters 302, 306 may provide
for the opportunity to transmit low latency signals over greater
distances in a wider array of atmospheric missions, however, the
physical limitations of the repeater circuitry that receives and
retransmits the signal may add additional latency to low latency
communication link 104.
[0028] FIG. 4 illustrates another example of the system illustrated
in FIG. 1 where one or more repeaters along the first
communications link are airborne, such as in an aircraft,
dirigible, balloon, or other device 410 configured to maintain the
repeater aloft in the atmosphere. In this example, signals
transmitted from first communications node 112 via antenna 128 may
be received by an airborne repeater 414 either as line of sight
communication 402, or by skywave propagation as described herein
elsewhere. The signals may be received by airborne repeater 414 and
retransmitted as line of sight communication 406, or by skywave
propagation to the second communications node 116 along the low
latency link 104.
[0029] Additional details regarding skywave propagation are
illustrated in FIGS. 5-7. The relation to the system disclosed and
various layers of the upper atmosphere is illustrated in FIG. 5.
For purposes of radio transmission, the layers of the upper
atmosphere may be divided as shown into successively higher layers
such as the troposphere 504, the stratosphere 508, and the
ionosphere 512.
[0030] The ionosphere is named as such because it includes a high
concentration of ionized particles. The density of these particles
in the ionosphere furthest from earth is very low and becomes
progressively higher in the areas of the ionosphere closer to
earth. The upper region of the ionosphere is energized by powerful
electromagnetic radiation from the sun which includes high-energy
ultraviolet radiation. This solar radiation causes ionization of
the air into free electrons, positive ions, and negative ions. Even
though the density of the air molecules in the upper ionosphere is
low, the radiation particles from space are of such high energy
that they cause extensive ionization of the relatively few air
molecules that are present. The ionization extends down through the
ionosphere with diminishing intensity as air becomes denser with
the highest degree of ionization thus occurring at the upper
extremities of the ionosphere, while the lowest degree occurs in
the lower portion of the ionosphere.
[0031] These differences in ionization between the upper and lower
extremities of the ionosphere 512 are further illustrated in FIG.
6. The ionosphere is illustrated in FIG. 6 with three layers
designated, respectively, from lowest level to highest level as D
layer 608, E layer 612, and F layer 604. The F layer 604 may be
further divided into two layers designated F1 (the higher layer) at
616 and F2 (the lower layer) at 620. The presence or absence of
layers 616 and 620 in the ionosphere and their height above the
earth vary with the position of the sun. At high noon, radiation
from the sun 624 passing into the ionosphere is greatest, tapering
off at sunset and at a minimum at night. When the radiation is
removed, many of the ions recombine causing the D layer 608 and the
E layer 612 to disappear, and further causing the F1 and F2 layers
616, 620 to recombine into a single F layer 604 during the night.
Since the position of the sun varies with respect to a given point
on earth, the exact characteristics of layers 608, 612, 616, and
620 of ionosphere 512 can be extremely difficult to predict but may
be determined by experimentation.
[0032] The ability for a radio wave to reach a remote location
using skywave propagation depends on various factors such as ion
density in layers 608-620 (when they are present), the frequency of
the transmitted electromagnetic energy, and the angle of
transmission. For example, if the frequency of a radio wave is
gradually increased, a point will be reached where the wave cannot
be refracted by D layer 608 which is the least ionized layer of
ionosphere 512. The wave may continue through the D layer 608 and
into the E layer 612 where its frequency may still be too great to
refract the singles passing through this layer as well. The waves
124 may continue to the F2 layer 620 and possibly into the F1 layer
616 as well before they are bent toward earth. In some cases, the
frequency may be above a critical frequency making it impossible
for any refraction to occur causing the electromagnetic energy to
be radiated out of the earth's atmosphere (708).
[0033] Thus, above a certain frequency, electromagnetic energy
transmitted vertically continues into space and is not refracted by
ionosphere 512. However, some waves below the critical frequency
may be refracted if the angle of propagation 704 is lowered from
the vertical. Lowering the angle of propagation 704 also allows
electromagnetic waves 124 transmitted by antenna 128 to be
refracted toward Earth's surface within a skip zone 720 making it
possible to traverse a skip distance 724 and reach a remote antenna
132. Thus the opportunity for successful skywave propagation over a
certain skip distance 724 is further dependent on the angle of
transmission as well as the frequency, and therefore the maximum
usable frequency varies with the condition of the ionosphere,
desired skip distance 724, propagation angle 704. FIG. 7 also
illustrates that non-skywave propagation such as groundwave signals
and/or line of sight signals 716 are unlikely to traverse skip
distance 724.
[0034] FIG. 8 illustrates one example of additional aspects of a
communication node 800 which is like communication nodes 112 and
116. Communication node 800 can include a processor 804 for
controlling various aspects of communication node 800. The
processor may be coupled to a memory 816 useful for storing rules
or command data 820. Devices for accepting user input and providing
output (I/O) to a user (824) may also be included. These devices
may include a keyboard or keypad, a mouse, a display such as a flat
panel monitor and the like, a printer, plotter, or 3D printer, a
camera, or a microphone. Any suitable devices for user I/O may be
included. Node 800 may also include a network interface 832
responsive to the processor 804 and coupled to a communication
network 836. A security module 828 may be included as well and may
be used to reduce or eliminate the opportunity for third-parties to
intercept, jam, or change data as it passes between communications
nodes 800. In one example, communication node 800 is implemented as
a computer executing software to control the interaction of the
various aspects of node 800.
[0035] Network interface 836 may be configured to send and receive
data such as command data 820, or triggering data which may be
passed from a triggering system 840. Communication network 836 may
be coupled to a network such as the internet and configured to send
and receive data without the use of skywave propagation. For
example, communication network 836 may transmit and receive data
over optical fibers or other transmission lines running along the
earth similar to transmission lines 144 illustrated in previous
figures.
[0036] Node 800 may include a second network interface 808
responsive to processor 804 and coupled to a radio-frequency
communication interface 812. This second network interface 808 may
be used to transfer data such as command data 820 or triggering
data passed from triggering system 840. Network interface 808 may
be coupled to an antenna like antenna 128 which may include
multiple antennas or antenna elements. The radio-frequency
communication interface 808 may be configured to send and receive
data such as triggering data using electromagnetic waves
transmitted and/or received via antenna 128. As discussed above,
antenna 128 may be configured to send and receive the
electromagnetic waves via skywave propagation.
[0037] Node 800 may include additional aspects illustrated in FIG.
9. Radio-frequency communication interface 812 may include a
transmitter 904 configured to transmit electromagnetic energy using
antenna 128. Receiver 908 may optionally be included as well and
configured to receive electromagnetic waves from antenna 128.
Transmitter 904 and receiver 908 may also be coupled to a modem 912
configured to modulate signals received by interface 812 to encode
information or data from a digital stream for transmission by
transmitter 904. Modem 912 may also be configured to demodulate
signals received by receiver 908 from antenna 128 to decode the
transmitted signal into a digital data stream usable by processor
804 or that may be stored in memory 816.
[0038] FIGS. 10 through 13 illustrate examples of the disclosed
system in operation illustrating how various networks can be used
either alone, or in concert, to transmit command and triggering
data corresponding with various events. FIGS. 10-13 illustrate the
use of two separate communications links labeled "A" and "B." These
links may use any suitable communication link separately or in
tandem as shown. For example, communication link A may be a low
latency link like communication link 104, and communication link B
may be a high latency link like communication link 108. In another
example, both links A and B may be low latency communication links.
In yet another example, both communication links may be high
latency communication links. In another aspect, any combination of
data bandwidth may be used for links A and B. For example, link A
may be a low latency link with either high or low data bandwidth,
and link B may be a high latency link with either high or low data
bandwidth.
[0039] More specifically, in one example, link A is a low
latency/low bandwidth communication link carrying triggering
signals and is implemented as discussed herein using HF radio waves
propagated via skywave propagation. In this example, link B is a
high latency/high bandwidth communication link carrying command
data and is implemented as discussed herein using fiber-optic
cables, coaxial cables, or other transmission lines.
[0040] FIG. 10 illustrates such a system in operation illustrating
links A and B passing data corresponding to events 1020, 1024, and
1028 as time passes. In FIG. 10, link B is illustrated as having a
higher data bandwidth and higher latency than low latency link A.
High latency link B is utilized to transfer command data over a
period of time prior to corresponding successive events. Before
event 1020, command data 1016 may be transferred over high latency
link B taking a relatively short amount of time to transfer a large
volume of data due to the higher data bandwidth of link B. At about
the time event 1020 occurs, a triggering signal 1012 may be
transmitted over low latency link A. The triggering signal 1012 may
include an identifier identifying one or more commands to be
executed by a processor such as processor 804.
[0041] This process may be repeated multiple times were data 1017
corresponding with a subsequent event 1024 may be transferred over
high latency link B ahead of event 1024. Trigger signal 1013 may
then be sent over low latency link A using skywave propagation in
response to event 1024 resulting in the execution of various
instructions or rules in a processor of the receiving
communications node. Event 1028 may cause the system to send
trigger 1024 which may select commands sent along with data 1018 in
advance. Thus FIG. 10 illustrates a successive transfers of data
1016, 1017, and 1018 over high latency link B from one
communications node to a remote communications node. As events
1020, 1024, and 1028 occur over time, triggering signals 1012,
1013, 1014 may be triggered using low latency link A to quickly
transfer information configured to trigger the remote receiving
communications node to act on commands or other aspects of data
1016, 1017, and 1018 sent before the corresponding events take
place.
[0042] Other configurations and uses of links A and B are
envisioned as well. In another example, link A is a low latency/low
bandwidth communication link carrying both command data and
triggering signals and is implemented as discussed herein using HF
radio waves propagated via skywave propagation. In this example,
link B is a high latency/high bandwidth communication link carrying
command data and triggering data, and is implemented as discussed
herein using fiber-optic cables, coaxial cables, or other
transmission lines.
[0043] The operation of this example of the disclosed system is
illustrated in FIG. 11. In FIG. 11, data 1116, 1117, 1118 are
transmitted using both low latency link A and high latency link B.
Triggering signals 1112, 1113, and 1114 may also be transmitted
over both link A and link B as illustrated in response to events
1120, 1124, and 1128. In this configuration, the high and low
latency links A and B respectively provide redundancy so that if
triggering or command data fails to be transmitted or received,
(such as signal 1112 on link A or data 1118 and triggering signal
1114 on link B) the data may still be passed to the remote
communications node through another communications link. Signals
1112 or 1114 may not be received or sent for any number of reasons
such as equipment failures, changes in atmospheric conditions,
severed or damaged fiber-optic cables, damage to antennas or
antenna arrays, and the like.
[0044] As illustrated in FIG. 11, link A may require additional
time to transfer data 1116, 1117, 1118 where low latency link A has
a lower data bandwidth then high latency link B. In other examples,
these situations may be reversed where high latency link B takes
longer to transfer data than low latency link A, or both links A
and B may take about the same amount of time. FIG. 11 illustrates
that, for example, data 1116 may take longer to transmit on low
latency/low bandwidth link A then on high latency/high bandwidth
link B.
[0045] FIG. 12 illustrates another example of a low latency/low
bandwidth link A transferring commands and triggering data
corresponding to command and triggering data passed over a high
latency/high bandwidth link B. In this example, data 1216 is
transferred over link B ahead of an event 1220. Triggering signal
1212 is passed over link A in response to event 1220 to activate or
execute commands, rule comparisons or other instructions
corresponding with data 1216. In this example, high latency link B
transfers data 1216 as part of a steady stream of encoded data
transmissions 1240. Encoded data 1240 may include hashed,
encrypted, or otherwise obfuscated data transmissions to mask data
1216 reducing or eliminating the opportunity for unauthorized
access. This data encoding may use any suitable technique such as
public or private key encryption, one or 2-way hashing, and the
like. In this example, encoded data stream 1240 is transferred
continuously over high latency link B and includes data 1216, 1217,
and 1218, along with triggering signals 1212, 1213, and 1214. FIG.
12 also illustrates that the system may be configured to transmit
triggering signals without including them in encoded data 1240
(1212, 1213), and may optionally begin sending the encoded stream
1240 over low latency link A along with a later set of triggering
data 1214. By sending a continuous stream of data that may or may
not include command or triggering data, unauthorized access to
commands encoded in transmissions 1240 may be reduced or eliminated
altogether in advance of events 1220, 1224, and 1228.
[0046] Transmissions sent on low latency link A may also be encoded
to reduce or eliminate the opportunity for unauthorized access and
may or may not be sent in tandem with encoded data 1240. As
illustrated in FIG. 12, triggering signal 1212 may be sent without
being part of a continuous stream of encoded data while in another
example, a similar triggering signal 1214 may be sent as part of
encoded data 1240. With low latency link A, similar encoding
techniques may be used for the data such as public or private key
encryption, one-way or two-way hashing, or other suitable means of
obscuring triggering data 1214. By sending triggering data as part
of a continuous encoded data stream, unauthorized access may be
reduced or eliminated as triggering signals may be time sensitive
making it prohibitively expensive to determine the contents of the
triggering signal before it is either used or its usefulness
expires.
[0047] Another example of the disclosed system in operation is
illustrated in FIG. 13 where triggering signals 1312, 1313, 1314
may correspond with low latency link A ceasing to send a carrier
signal or data stream 1350. The communication nodes may be
configured to receive carrier 1350 and may be triggered to accept a
triggering signal 1312, 1313, or 1314 when carrier 1350 ceases to
be sent ahead of sending the triggering signal. Carrier signal 1350
may include a continuous digital or analog signal sent by skywave
propagation, or by any other suitable means. The signal may include
a continuous analog signal at a single frequency, a signal that
varies continuously with time, or other suitable signal. Carrier
signal 1350 may also include digital data transmissions including,
for example, a repeated series of datagrams containing information
that remains the same, or changes in a predictable fashion with
time.
[0048] A dropout or change in the carrier signal, for example at
1315, may indicate a triggering signal to the receiving
communications node, or that a triggering signal is about to be
sent. This example may be characterized as a communications node
configured to trigger a response based on data 1316, 1317, 1318 on
a "signal low" condition such as when the carrier 1350 stops
transmitting at 1315 just ahead of the transmission of triggering
signal 1312, 1313, or 1314. High latency link B may be configured
similarly. The use of a carrier 1350 may be used in conjunction
with any other methods illustrated in FIGS. 10-13, or any
combination thereof, to respond to any events discussed above.
[0049] In any of the examples disclosed herein (such as in FIGS.
10-13), overall security of the system may be enhanced by sending a
continual stream of actions and/or triggering messages over the
separate communications links to confuse malicious third parties
and discourage attempts to intercept and decipher future
transmissions. The same messages may be sent over multiple links
simultaneously, over separate transmitters and receivers with
different propagation paths, or in any combination thereof. These
messages may be very short, or intermingled with other
transmissions and may be sent continuously, or for only short
periods of time on a predetermined schedule. In a related aspect,
security may be enhanced by sending short messages over skywave
propagation on one or more frequencies, or by sending small parts
of a message on several frequencies at the same time. Various
additional techniques may also be employed to enhance security such
as encryption, two-way hashing, and the like, which may incur
additional latency in both links.
[0050] No association in the time required to pass data of the same
or similar size across both links should be interpreted from FIGS.
10-13. Although FIGS. 10-13 may illustrate a relationship between
the length of time required for high latency/high bandwidth link B
to transfer data versus low latency/low bandwidth link A, FIGS.
10-13 is illustrative rather than restrictive. Link A make take
more or less time to send data of the same size as Link B and vice
versa.
[0051] In any of the communication links illustrated in FIGS.
10-13, skywave propagation may be used to transmit data. For
example, both links A and B may be low latency links using skywave
propagation as discussed herein. In this example, low latency links
A and B may both be configured for high or low data bandwidth. In
another example, both links A and B may be high latency links using
propagation techniques other than skywave propagation such as
electromagnetic waves passed through fiber-optic cables, copper
wire, and the like to name a few nonlimiting examples. High latency
links A and B may be configured for high or low data bandwidth.
[0052] Illustrated at 1400 in FIG. 14 is a general flow of actions
that may be taken by a system implementing the features discussed
above (e.g. the system illustrated in FIG. 1). Commands or command
data may be initially sent at 1404 by a transmitting communications
node such as node 112 or node 800 configured to transmit command
data. The system may wait for a triggering event (1408) and send
triggering data at 1412 when a triggering event occurs. A receiving
communications node (e.g. like nodes 116 or 800) may then execute
commands (1416) included in the command data accordingly.
[0053] Illustrated in FIG. 15 is additional detail regarding the
actions that may be taken in sending command data (1404). At 1504,
command data may be received or created. The data may be received
from a transmitting third-party, or processed by the system itself
to generate one or more commands. One example of command data is a
collection of one or more trades to be executed by financial
exchanges. The commands may include orders to automatically buy
and/or sell financial instruments based on various rules or
preconditions. These rules or preconditions may include buying or
selling if the market is at a certain price, if one or more
technical indicators signals a purchase or sale, or if certain
market data received from private or government entities contains
particular values corresponding to a predetermined level (e.g. "new
housing starts", "gross domestic product", interest rates on
government bonds, and the like).
[0054] A security protocol may optionally be applied to the command
data (1508) as discussed herein elsewhere. Such security protocols
may include encrypting the command data using public or private key
encryption techniques, applying an encoding algorithm such as
two-way hashing, and the like. Any suitable technique for securing
command data may be used to make the data unreadable or unusable by
third parties.
[0055] Command data can be transmitted (1512) from a transmitting
communication node to a receiving communications node. Any suitable
technique for communicating command data may be used such as
sending the command data as a series of signals, packets, are
datagrams of any suitable size. The transmission of either the
command data, or the triggering data (or both) may occur over a low
latency low bandwidth communication link such as communication link
104, or over a high latency high-bandwidth communication link such
as communication link 108. Command data may also be transmitted by
multiple communication links such as communication links 104 and
108 sequentially or at about the same time. The transmitted command
data may be received (1516) by a receiving communications node
using any of the communication links discussed herein. The system
may optionally check the integrity of the data received and may
optionally coordinate with a transmitting communication node to
automatically resend the data if portions of it were not received
or were corrupted in transmission.
[0056] When command data has been received at a receiving
communications node, the commands may be prepared for execution
(1520). Such preparation may include upgrading or replacing
software stored in a memory on a computer to be executed by a
processor or other circuitry when a triggering event occurs. In
another example, preparing commands for execution at 1520 may
include programming a Field Programmable Gate Array (FPGA) to
automatically perform the commands. This process may occur by any
suitable means such as by performing a firmware upgrade on a
computer that uses an FPGA or similar reprogrammable circuitry.
When the commands of been prepared for execution, the system may
then wait for a triggering event to take place (1524).
[0057] The system may execute various other activities while
waiting for a triggering event to take place, examples of which are
illustrated in FIG. 16 at 1408. If no triggering event has occurred
(1602), various actions may be taken by a communications node at
either end of a communications link, or at both ends. These actions
may be the taken continuously while waiting for a triggering event
to take place.
[0058] At 1604, the system may determine a maximum usable
frequency. This action might be taken to maintain a communication
link such as link 104 that communicates via skywave propagation.
The maximum usable frequency may be automatically determined
experimentally by using a processor like processor 804 to control
transmitter 904 to send signals over a broad range of frequencies
in the electromagnetic spectrum. The processor may also control
receiver 908 to listen for responses from other transmitting
communication nodes. The processor may then analyze the signal sent
and the responses received to determine the maximum usable
frequency that may be used to achieve communication with various
remote communications nodes.
[0059] In another example, the maximum usable frequency may be
predicted or determined by propagation data provided by third
parties such as government entities. Such third parties may
continuously monitor skywave propagation across a broad range of
frequencies and distances providing this propagation data as an aid
in calculating skip distances across a range of frequencies in the
electromagnetic spectrum. Software modeling of distances,
atmospheric conditions, and any other factors impacting propagation
may also be used to determine the maximum usable frequency.
[0060] The system may determine a minimum usable frequency at 1608.
The minimum usable frequency may be determined experimentally as
described above, or by receiving and processing updated third-party
propagation data. The maximum and minimum usable frequencies may
then be stored (1612) in a memory accessible by the processor.
[0061] When the system is waiting for an event (1602), a
communication node may transmit a steady stream of signals that may
or may not contain any useful data. The signals or data are
prepared for transmission at 1616, and as discussed above, the
transmission may or may not include meaningful command data or
triggering data. They communication node may, for example, send a
transmission at a regular interval, or with a specific sequence of
data. In this way a communication node may maintain a communication
link thereby quickly become aware when the communication link is
compromised.
[0062] Where a communication link uses skywave propagation (such as
communication link 104), the system may choose a transmission
frequency (1620) using the processor or other logic circuit.
Choosing a transmission frequency may include selecting a frequency
between the minimum and maximum usable frequencies determined at
1604 and 1608. This may be done in accordance with a "frequency
hopping" system configured to repeatedly choose a different
frequency over time for transmitting and receiving. Choosing a
transmission frequency may also include selecting a frequency from
a predetermined set or range of frequencies such as in a spread
spectrum "signal hopping" configuration. The frequency may be
determined according to any suitable technique such as by
Multiple-input/Multiple-output (MIMO) using multiple transmitters
or receivers at different frequencies. The data may then be
transmitted (1624) once the transmission frequency is
determined.
[0063] The actions illustrated in FIG. 16 may continue in parallel
while the system waits for an event to occur (1602). When a
triggering event occurs, triggering data can be sent (1412).
Additional detail of actions a system may take when triggering data
is sent are illustrated in FIG. 17 at 1412. Triggering data may be
prepared (1704) which may include extracting or receiving the
triggering data from a third-party data source and configuring it
for transmission over a communications link such as communication
link 104 or 108. A security protocol may be applied to the
triggering data (1708) to reduce or eliminate the opportunity for
third-party individuals to obtain triggering data without
authorization. Any suitable security protocol may be applied as
discussed herein elsewhere.
[0064] A transmission frequency may then be chosen (1712). Examples
include selecting a frequency between the maximum and minimum
usable frequencies as previously determined, or by selecting a
frequency from a predetermined set of frequencies such as in a
"signal hopping" configuration. In another example, the system may
transmit over multiple frequencies a the same time. The system may
then transmit the triggering data at 1716 along one or more
communications links as discussed herein elsewhere.
[0065] FIG. 18 illustrates additional detail of actions the system
may take when receiving triggering data. As illustrated at 1416, a
receiving communications node may receive triggering data at 1804.
At 1808, a security protocol may be applied to unscramble, decrypt,
decode, or otherwise remove any security measures that may have
been applied when the triggering data was sent. A processor may
then process the triggering data to identify commands to execute
(1812) based on an identifier sent in the triggering data.
Triggering data may also include multiple identifiers identifying
multiple commands to execute. The system may then execute the
commands (1816) identified in the triggering data.
GLOSSARY OF DEFINITIONS AND ALTERNATIVES
[0066] The language used in the claims and specification is to only
have its plain and ordinary meaning, except as explicitly defined
below. The words in these definitions are to only have their plain
and ordinary meaning Such plain and ordinary meaning is inclusive
of all consistent dictionary definitions from the most recently
published Webster's and Random House dictionaries. As used in the
specification and claims, the following definitions apply to the
following terms or common variations thereof (e.g., singular/plural
forms, past/present tenses, etc.):
[0067] "Antenna" or "Antenna system" generally refers to an
electrical device, or series of devices, in any suitable
configuration, that converts electric power into electromagnetic
radiation. Such radiation may be either vertically, horizontally,
or circularly polarized at any frequency along the electromagnetic
spectrum. Antennas transmitting with circular polarity may have
either right-handed or left-handed polarization.
[0068] In the case of radio waves, an antenna may transmit at
frequencies ranging along electromagnetic spectrum from extremely
low frequency (ELF) to extremely high frequency (EHF). An antenna
or antenna system designed to transmit radio waves may comprise an
arrangement of metallic conductors (elements), electrically
connected (often through a transmission line) to a receiver or
transmitter. An oscillating current of electrons forced through the
antenna by a transmitter can create an oscillating magnetic field
around the antenna elements, while the charge of the electrons also
creates an oscillating electric field along the elements. These
time-varying fields radiate away from the antenna into space as a
moving transverse electromagnetic field wave. Conversely, during
reception, the oscillating electric and magnetic fields of an
incoming electromagnetic wave exert force on the electrons in the
antenna elements, causing them to move back and forth, creating
oscillating currents in the antenna. These currents can then be
detected by receivers and processed to retrieve digital or analog
signals or data.
[0069] Antennas can be designed to transmit and receive radio waves
substantially equally in all horizontal directions (omnidirectional
antennas), or preferentially in a particular direction (directional
or high gain antennas). In the latter case, an antenna may also
include additional elements or surfaces which may or may not have
any physical electrical connection to the transmitter or receiver.
For example, parasitic elements, parabolic reflectors or horns, and
other such non-energized elements serve to direct the radio waves
into a beam or other desired radiation pattern. Thus antennas may
be configured to exhibit increased or decreased directionality or
"gain" by the placement of these various surfaces or elements. High
gain antennas can be configured to direct a substantially large
portion of the radiated electromagnetic energy in a given direction
that may be vertical horizontal or any combination thereof.
[0070] Antennas may also be configured to radiate electromagnetic
energy within a specific range of vertical angles (i.e. "takeoff
angles) relative to the earth in order to focus electromagnetic
energy toward an upper layer of the atmosphere such as the
ionosphere. By directing electromagnetic energy toward the upper
atmosphere at a specific angle, specific skip distances may be
achieved at particular times of day by transmitting electromagnetic
energy at particular frequencies.
[0071] Other examples of antennas include emitters and sensors that
convert electrical energy into pulses of electromagnetic energy in
the visible or invisible light portion of the electromagnetic
spectrum. Examples include light emitting diodes, lasers, and the
like that are configured to generate electromagnetic energy at
frequencies ranging along the electromagnetic spectrum from far
infrared to extreme ultraviolet.
[0072] "Command" or "Command Data" generally refers to one or more
directives, instructions, algorithms, or rules controlling a
machine to take one or more actions, alone or in combination. A
command may be stored, transferred, transmitted, or otherwise
processed in any suitable manner. For example, a command may be
stored in a memory or transmitted over a communication network as
electromagnetic radiation at any suitable frequency passing through
any suitable medium.
[0073] "Computer" generally refers to any computing device
configured to compute a result from any number of input values or
variables. A computer may include a processor for performing
calculations to process input or output. A computer may include a
memory for storing values to be processed by the processor, or for
storing the results of previous processing.
[0074] A computer may also be configured to accept input and output
from a wide array of input and output devices for receiving or
sending values. Such devices include other computers, keyboards,
mice, visual displays, printers, industrial equipment, and systems
or machinery of all types and sizes. For example, a computer can
control a network interface to perform various network
communications upon request. The network interface may be part of
the computer, or characterized as separate and remote from the
computer.
[0075] A computer may be a single, physical, computing device such
as a desktop computer, a laptop computer, or may be composed of
multiple devices of the same type such as a group of servers
operating as one device in a networked cluster, or a heterogeneous
combination of different computing devices operating as one
computer and linked together by a communication network. The
communication network connected to the computer may also be
connected to a wider network such as the internet. Thus computer
may include one or more physical processors or other computing
devices or circuitry, and may also include any suitable type of
memory.
[0076] A computer may also be a virtual computing platform having
an unknown or fluctuating number of physical processors and
memories or memory devices. A computer may thus be physically
located in one geographical location or physically spread across
several widely scattered locations with multiple processors linked
together by a communication network to operate as a single
computer.
[0077] The concept of "computer" and "processor" within a computer
or computing device also encompasses any such processor or
computing device serving to make calculations or comparisons as
part of disclosed system. Processing operations related to
threshold comparisons, rules comparisons, calculations, and the
like occurring in a computer may occur, for example, on separate
servers, the same server with separate processors, or on a virtual
computing environment having an unknown number of physical
processors as described above.
[0078] A computer may be optionally coupled to one or more visual
displays and/or may include an integrated visual display. Likewise,
displays may be of the same type, or a heterogeneous combination of
different visual devices. A computer may also include one or more
operator input devices such as a keyboard, mouse, touch screen,
laser or infrared pointing device, or gyroscopic pointing device to
name just a few representative examples. Also, besides a display,
one or more other output devices may be included such as a printer,
plotter, industrial manufacturing machine, 3D printer, and the
like. As such, various display, input and output device
arrangements are possible.
[0079] Multiple computers or computing devices may be configured to
communicate with one another or with other devices over wired or
wireless communication links to form a communication network.
Network communications may pass through various computers operating
as network appliances such as switches, routers, firewalls or other
network devices or interfaces before passing over other larger
computer networks such as the internet. Communications can also be
passed over the communication network as wireless data
transmissions carried over electromagnetic waves through
transmission lines or free space. Such communications include using
WiFi or other Wireless Local Area Network (WLAN) or a cellular
transmitter/receiver to transfer data. Such signals conform to any
of a number of wireless or mobile telecommunications technology
standards such as 802.11a/b/g/n, 3G, 4G, and the like.
[0080] "Communication Link" generally refers to a connection
between two or more communicating entities and may or may not
include a communications channel between the communicating
entities. The communication between the communicating entities may
occur by any suitable means. For example the connection may be
implemented as an actual physical link, an electrical link, an
electromagnetic link, a logical link, or any other suitable linkage
facilitating communication.
[0081] In the case of an actual physical link, communication may
occur by multiple components in the communication link figured to
respond to one another by physical movement of one element in
relation to another. In the case of an electrical link, the
communication link may be composed of multiple electrical
conductors electrically connected to form the communication
link.
[0082] In the case of an electromagnetic link, elements the
connection may be implemented by sending or receiving
electromagnetic energy at any suitable frequency, thus allowing
communications to pass as electromagnetic waves. These
electromagnetic waves may or may not pass through a physical medium
such as an optical fiber, or through free space, or any combination
thereof. Electromagnetic waves may be passed at any suitable
frequency including any frequency in the electromagnetic
spectrum.
[0083] In the case of a logical link, the communication link may be
a conceptual linkage between the sender and recipient such as a
transmission station in the receiving station. Logical link may
include any combination of physical, electrical, electromagnetic,
or other types of communication links.
[0084] "Communication node" generally refers to a physical or
logical connection point, redistribution point or endpoint along a
communication link. A physical network node is generally referred
to as an active electronic device attached or coupled to a
communication link, either physically, logically, or
electromagnetically. A physical node is capable of sending,
receiving, or forwarding information over a communication link. A
communication node may or may not include a computer, processor,
transmitter, receiver, repeater, and/or transmission lines, or any
combination thereof.
[0085] "Critical angle" generally refers to the highest angle with
respect to a vertical line extending to the center of the Earth at
which an electromagnetic wave at a specific frequency can be
returned to the Earth using sky-wave propagation.
[0086] "Critical Frequency" generally refers to the highest
frequency that will be returned to the Earth when transmitted
vertically under given ionospheric conditions using sky-wave
propagation.
[0087] "Data Bandwidth" generally refers to the maximum throughput
of a logical or physical communication path in a communication
system. Data bandwidth is a transfer rate that can be expressed in
units of data transferred per second. In a digital communications
network, the units of data transferred are bits and the maximum
throughput of a digital communications network is therefore
generally expressed in "bits per second" or "bit/s." By extension,
the terms "kilobit/s" or "Kbit/s", "Megabit/s" or "Mbit/s", and
"Gigabit/s" or "Gbit/s" can also be used to express the data
bandwidth of a given digital communications network. Data networks
may be rated according to their data bandwidth performance
characteristics according to specific metrics such as "peak bit
rate", "mean bit rate", "maximum sustained bit rate", "information
rate", or "physical layer useful bit rate." For example, bandwidth
tests measure the maximum throughput of a computer network. The
reason for this usage is that according to Hartley's Law, the
maximum data rate of a physical communication link is proportional
to its frequency bandwidth in hertz.
[0088] Data bandwidth may also be characterized according to the
maximum transfer rate for a particular communications network. For
example: [0089] "Low Data Bandwidth" generally refers to a
communications network with a maximum data transfer rate that is
less than or about equal to 1,000,000 units of data per second. For
example, in a digital communications network, the unit of data is a
bit. Therefore low data bandwidth digital communications networks
are networks with a maximum transfer rate that is less than or
about equal to 1,000,000 bits per second (1 Mbits/s). [0090] "High
Data Bandwidth" generally refers to a communications network with a
maximum data transfer rate that is greater than about 1,000,000
units of data per second. For example, a digital communications
network with a high data bandwidth is a digital communications
network with a maximum transfer rate that is greater than about
1,000,000 bits per second (1 Mbits/s).
[0091] "Electromagnet Radiation" generally refers to energy
radiated by electromagnetic waves. Electromagnetic radiation is
produced from other types of energy, and is converted to other
types when it is destroyed. Electromagnetic radiation carries this
energy as it travels moving away from its source at the speed of
light (in a vacuum). Electromagnetic radiation also carries both
momentum and angular momentum. These properties may all be imparted
to matter with which the electromagnetic radiation interacts as it
moves outwardly away from its source.
[0092] Electromagnetic radiation changes speed as it passes from
one medium to another. When transitioning from one media to the
next, the physical properties of the new medium can cause some or
all of the radiated energy to be reflected while the remaining
energy passes into the new medium. This occurs at every junction
between media that electromagnetic radiation encounters as it
travels.
[0093] The photon is the quantum of the electromagnetic
interaction, and is the basic constituent of all forms of
electromagnetic radiation. The quantum nature of light becomes more
apparent at high frequencies as electromagnetic radiation behaves
more like particles and less like waves as its frequency
increases.
[0094] "Electromagnetic Spectrum" generally refers to the range of
all possible frequencies of electromagnetic radiation. The
electromagnetic spectrum is generally categorized as follows, in
order of increasing frequency and energy and decreasing wavelength:
[0095] "Extremely low frequency" (ELF) generally designates a band
of frequencies from about 3 to about 30 Hz with wavelengths from
about 100,000 to 10,000 km long. [0096] "Super low frequency" (SLF)
generally designates a band of frequencies generally ranging
between about 30 Hz to about 300 Hz with wavelengths of about
10,000 to about 1000 km long. [0097] "Voice frequency" or "voice
band" generally designates electromagnetic energy that is audibles
to the human ear. Adult males generally speak in the range between
about 85 and about 180 Hz while adult females generally converse in
the range from about 165 to about 255 Hz. [0098] "Very low
frequency" (VLF) generally designates the band of frequencies from
about 3 kHz to about 30 kHz with corresponding wavelengths from
about 10 to about 100 km long. [0099] "Low-frequency" (LF)
generally designates the band of frequencies in the range of about
30 kHz to about 300 kHz with wavelengths range from about 1 to
about 10 km. [0100] "Medium frequency" (MF) generally designates
the band of frequencies from about 300 kHz to about 3 MHz with
wavelengths from about 1000 to about 100 m long. [0101] "High
frequency" (HF) generally designates the band of frequencies from
about 3 MHz to about 30 MHz having wavelengths from about 100 m to
about 10 m long. [0102] "Very high frequency" (VHF) generally
designates the band of frequencies from about 30 Hz to about 300
MHz with wavelengths from about 10 m to about 1 m long. [0103]
"Ultra high frequency" (UHF) generally designates the band of
frequencies from about 300 MHz to about 3 GHz with weight
wavelengths ranging from about 1 m to about 10 cm long. [0104]
"Super high frequency" (SHF) generally designates the band of
frequencies from about 3 GHz to about 30 GHz with wavelengths
ranging from about 10 cm to about 1 cm long. [0105] "Extremely high
frequency" (EHF) generally designates the band of frequencies from
about 30 GHz to about 300 GHz with wavelengths ranging from about 1
cm to about 1 mm long. [0106] "Far infrared" (FIR) generally
designates a band of frequencies from about 300 GHz to about 20 THz
with wavelengths ranging from about 1 mm to about 15 .mu.m long.
[0107] "Long-wavelength infrared" (LWIR) generally designates a
band of frequencies from about 20 THz to about 37 THz with
wavelengths ranging from about 15 .mu.m to about 8 .mu.m long.
[0108] "Mid infrared" (MIR) generally designates a band of
frequencies from about 37 THz to about 100 THz with wavelengths
from about 8 .mu.m to about 3 .mu.m long. [0109] "Short wavelength
infrared" (SWIR) generally designates a band of frequencies from
about 100 THz to about 214 THz with wavelengths from about 3 .mu.m
to about 1.4 .mu.m long [0110] "Near-infrared" (NIR) generally
designates a band of frequencies from about 214 THz to about 400
THz with wavelengths from about 1.4 .mu.m to about 750 nm long.
[0111] "Visible light" generally designates a band of frequencies
from about 400 THz to about 750 THz with wavelengths from about 750
nm to about 400 nm long. [0112] "Near ultraviolet" (NUV) generally
designates a band of frequencies from about 750 THz to about 1 PHz
with wavelengths from about 400 nm to about 300 nm long. [0113]
"Middle ultraviolet" (MUV) generally designates a band of
frequencies from about 1 PHz to about 1.5 PHz with wavelengths from
about 300 nm to about 200 nm long. [0114] "Far ultraviolet" (FUV)
generally designates a band of frequencies from about 1.5 PHz to
about 2.48 PHz with wavelengths from about 200 nm to about 122 nm
long. [0115] "Extreme ultraviolet" (EUV) generally designates a
band of frequencies from about 2.48 PHz to about 30 PHz with
wavelengths from about 121 nm to about 10 nm long. [0116] "Soft
x-rays" (SX) generally designates a band of frequencies from about
30 PHz to about 3 EHz with wavelengths from about 10 nm to about
100 .mu.m long. [0117] "Hard x-rays" (HX) generally designates a
band of frequencies from about 3 EHz to about 30 EHz with
wavelengths from about 100 .mu.m to about 10 .mu.m long. [0118]
"Gamma rays" generally designates a band of frequencies above about
30 EHz with wavelengths less than about 10 pm long.
[0119] "Electromagnetic Waves" generally refers to waves having a
separate electrical and a magnetic component. The electrical and
magnetic components of an electromagnetic wave oscillate in phase
and are always separated by a 90 degree angle. Electromagnetic
waves can radiate from a source to create electromagnetic radiation
capable of passing through a medium or through a vacuum.
Electromagnetic waves include waves oscillating at any frequency in
the electromagnetic spectrum including, but not limited to, radio
waves, visible and invisible light, X-rays, and gamma-rays.
[0120] "Frequency Bandwidth" or "Band" generally refers to a
contiguous range of frequencies defined by an upper and lower
frequency. Frequency bandwidth is thus typically expressed as a
number of hertz (cycles per second) representing the difference
between the upper frequency and the lower frequency of the band and
may or may not include the upper and lower frequencies themselves.
A "band" can therefore be defined by a given frequency bandwidth
for a given region and designated with generally agreed on terms.
For example, the "20 meter band" in the United States is assigned
the frequency range from 14 MHz to 14.35 MHz thus defining a
frequency bandwidth of 0.35 MHz or 350 KHz. In another example, the
International Telecommunication Union (ITU) has designated the
frequency range from 300 Mhz to 3 GHz as the "UHF band".
[0121] "Fiber-optic communication" generally refers to a method of
transmitting data from one place to another by sending pulses of
electromagnetic energy through an optical fiber. The transmitted
energy may form an electromagnetic carrier wave that can be
modulated to carry data. Fiber-optic communication lines that use
optical fiber cables to transmit data can be configured to have a
high data bandwidth. For example, fiber-optic communication lines
may have a high data bandwidth of up to about 15 Tbit/s, about 25
Tbit/s, about 100 Tbit/s, about 1 Pbit/s or more. Opto-electronic
repeaters may be used along a fiber-optic communication line to
convert the electromagnetic energy from one segment of fiber-optic
cable into an electrical signal. The repeater can retransmit the
electrical signal as electromagnetic energy along another segment
of fiber-optic cable at a higher signal strength than it was
received.
[0122] "Financial instrument" generally refers to a tradable asset
of any kind General examples include, but are not limited to, cash,
evidence of an ownership interest in an entity, or a contractual
right to receive or deliver cash or another financial instrument.
Specific examples include bonds, bills (e.g. commercial paper and
treasury bills), stock, loans, deposits, certificates of deposit,
bond futures or options on bond futures, short-term interest rate
futures, stock options, equity futures, currency futures, interest
rate swaps, interest rate caps and floors, interest rate options,
forward rate agreements, stock options, foreign-exchange options,
foreign-exchange swaps, currency swaps, or any sort of
derivative.
[0123] "Ground" is used more in an electrical/electromagnetic sense
and generally refers to the Earth's surface including land and
bodies of water, such as oceans, lakes, and rivers.
[0124] "Ground-wave propagation" generally refers to a transmission
method in which one or more electromagnetic waves are conducted via
the boundary of the ground and atmosphere to travel along ground.
The electromagnetic wave propagates by interacting with the
semi-conductive surface of the earth. In essence, the wave clings
to the surfaces so as to follow the curvature of the earth.
Typically, but not always, the electromagnetic wave is in the form
of a ground or surface wave formed by low-frequency radio
waves.
[0125] "Identifier" generally refers to a name that identifies
(that is, labels the identity of) either a unique thing or a unique
class of things, where the "object" or class may be an idea,
physical object (or class thereof), or physical substance (or class
thereof). The abbreviation "ID" often refers to identity,
identification (the process of identifying), or an identifier (that
is, an instance of identification). An identifier may or may not
include words, numbers, letters, symbols, shapes, colors, sounds,
or any combination of those.
[0126] The words, numbers, letters, or symbols may follow an
encoding system (wherein letters, digits, words, or symbols
represent ideas or longer identifiers) or they may simply be
arbitrary. When an identifier follows an encoding system, it is
often referred to as a code or ID code. Identifiers that do not
follow any encoding scheme are often said to be arbitrary IDs
because they are arbitrarily assigned without meaning in any other
context beyond identifying something.
[0127] "Ionosphere" generally refers to the layer of the Earth's
atmosphere that contains a high concentration of ions and free
electrons and is able to reflect radio waves. The ionosphere
includes the thermosphere as well as parts of the mesosphere and
exosphere. The ionosphere extends from about 25 to about 600 miles
(about 40 to 1,000 km) above the earth's surface. The ionosphere
includes a number of layers that undergo considerable variations in
altitude, density, and thickness, depending among a number of
factors including solar activity, such as sunspots. The various
layers of the ionosphere are identified below. [0128] The "D layer"
of the ionosphere is the innermost layer that ranges from about 25
miles (40 km) to about 55 miles (90 km) above the Earth's surface.
The layer has the ability to refract signals of low frequencies,
but it allows high frequency radio signals to pass through with
some attenuation. The D layer normally, but not in all instances,
disappears rapidly after sunset due to rapid recombination of its
ions. [0129] The "E layer" of the ionosphere is the middle layer
that ranges from about 55 miles (90 km) to about 90 miles (145 km)
above the Earth's surface. The E layer typically has the ability to
refract signals with frequencies higher than the D layer. Depending
on the conditions, the E layer can normally refract frequencies up
to 20 MHz. The rate of ionic recombination in the E layer is
somewhat rapid such that after sunset it almost completely
disappears by midnight. The E layer can further include what is
termed an "E.sub.s''layer" or "sporadic E layer" that is formed by
small, thin clouds of intense ionization. The sporadic E layer can
reflect radio waves, even frequencies up to 225 MHz, although
rarely. Sporadic E layers most often form during summer months, and
it has skip distances of around 1,020 miles (1,640 km). With the
sporadic E layer, one hop propagation can be about 560 miles (900
km) to up to 1,600 miles (2,500 km), and double hop propagation can
be over 2,200 miles (3,500 km). [0130] The "F layer" of the
ionosphere is the top layer that ranges from about 90 (145 km) to
310 miles (500 km) or more above the Earth's surface. The
ionization in the F layer is typically quite high and varies widely
during the day, with the highest ionization occurring usually
around noon. During daylight, the F layer separates into two
layers, the F.sub.1 layer and the F.sub.2 layer. The F.sub.2 layer
is outermost layer and, as such, is located higher than the F.sub.1
layer. Given the atmosphere is rarified at these altitudes, the
recombination of ions occur slowly such that F layer remains
constantly ionized, either day or night such that most (but not
all) skywave propagation of radio waves occur in the F layer,
thereby facilitating high frequency (HF) or short wave
communication over long distances. For example, the F layers are
able to refract high frequency, long distance transmissions for
frequencies up to 30 MHz.
[0131] "Latency" generally refers to the time interval between a
cause and an effect in a system. Latency is physically a
consequence of the limited velocity with which any physical
interaction can propagate throughout a system. Latency is
physically a consequence of the limited velocity with which any
physical interaction can propagate. The speed at which an effect
can propagate through a system is always lower than or equal to the
speed of light. Therefore every physical system that includes some
distance between the cause and the effect will experience some kind
of latency. For example, in a communication link or communications
network, latency generally refers to the minimum time it takes for
data to pass from one point to another. Latency with respect to
communications networks may also be characterized as the time it
takes energy to move from one point along the network to another.
With respect to delays caused by the propagation of electromagnetic
energy following a particular propagation path, latency can be
categorized as follows: [0132] "Low Latency" generally refers to a
period of time that is less than or about equal to a propagation
time that is 10% greater than the time required for light to travel
a given propagation path in a vacuum. Expressed as a formula, low
latency is defined as follows:
[0132] latency low .ltoreq. d c k ( Equation 1 ) ##EQU00001##
[0133] where: [0134] d=distance (miles) [0135] c=the speed of light
in a vacuum (186,000 miles/sec) [0136] k=a scalar constant of 1.1
[0137] For example, light can travel 25,000 miles through a vacuum
in about 0.1344 seconds. A "low latency" communication link
carrying data over this 25,000 mile propagation path would
therefore be capable of passing at least some portion of the data
over the link in about 0.14784 seconds or less. [0138] "High
Latency" generally refers to a period of time that is over 10%
greater than the time required for light to travel a given
propagation path in a vacuum. Expressed as a formula, high latency
is defined as follows:
[0138] latency high > d c k ( Equation 2 ) ##EQU00002## [0139]
where: [0140] d=distance (miles) [0141] c=the speed of light in a
vacuum (186,000 miles/sec) [0142] k=a scalar constant of 1.1 [0143]
For example, light can travel 8,000 miles through a vacuum in about
0.04301 seconds. A "high latency" communication link carrying data
over this transmission path would therefore be capable of passing
at least some portion of the data over the link in about 0.04731
seconds or more.
[0144] The "high" and "low" latency of a network may be independent
of the data bandwidth. Some "high" latency networks may have a high
transfer rate that is higher than a "low" latency network, but this
may not always be the case. Some "low" latency networks may have a
data bandwidth that exceeds the bandwidth of a "high" latency
network.
[0145] "Maximum Usable Frequency (MUF)" generally refers to the
highest frequency that is returned to the Earth using sky-wave
propagation.
[0146] "Memory" generally refers to any storage system or device
configured to retain data or information. Each memory may include
one or more types of solid-state electronic memory, magnetic
memory, or optical memory, just to name a few. By way of
non-limiting example, each memory may include solid-state
electronic Random Access Memory (RAM), Sequentially Accessible
Memory (SAM) (such as the First-In, First-Out (FIFO) variety or the
Last-In-First-Out (LIFO) variety), Programmable Read Only Memory
(PROM), Electronically Programmable Read Only Memory (EPROM), or
Electrically Erasable Programmable Read Only Memory (EEPROM); an
optical disc memory (such as a DVD or CD ROM); a magnetically
encoded hard disc, floppy disc, tape, or cartridge media; or a
combination of any of these memory types. Also, each memory may be
volatile, nonvolatile, or a hybrid combination of volatile and
nonvolatile varieties.
[0147] "Non-sky-wave propagation" generally refers to all forms of
transmission, wired and/or wireless, in which the information is
not transmitted by reflecting an electromagnetic wave from the
ionosphere.
[0148] "Optimum Working Frequency" generally refers to the
frequency that provides the most consistent communication path via
sky-wave propagation. It can vary over time depending on number of
factors, such as ionospheric conditions and time of day. For
transmissions using the F.sub.2 layer of the ionosphere the working
frequency is generally around 85% of the MUF, and for the E layer,
the optimum working frequency will generally be near the MUF.
[0149] "Optical Fiber" generally refers to an electromagnetic
waveguide having an elongate conduit that includes a substantially
transparent medium through which electromagnetic energy travels as
it traverses the long axis of the conduit. Electromagnetic
radiation may be maintained within the conduit by total internal
reflection of the electromagnetic radiation as it traverses the
conduit. Total internal reflection is generally achieved using
optical fibers that include a substantially transparent core
surrounded by a second substantially transparent cladding material
with a lower index of refraction than the core.
[0150] Optical fibers are generally constructed of dielectric
material that is not electrically conductive but is substantially
transparent. Such materials may or may not include any combination
of extruded glass such as silica, fluoride glass, phosphate glass,
Chalcogenide glass, or polymeric material such as various types of
plastic, or other suitable material and may be configured with any
suitable cross-sectional shape, length, or dimension. Examples of
electromagnetic energy that may be successfully passed through
optical fibers include electromagnetic waves in the near-infrared,
mid-infrared, and visible light portion of the electromagnetic
spectrum, although electromagnetic energy of any suitable frequency
may be used.
[0151] "Polarization" generally refers to the orientation of the
electric field ("E-plane") of a radiated electromagnetic energy
wave with respect to the Earth's surface and is determined by the
physical structure and orientation of the radiating antenna.
Polarization can be considered separately from an antenna's
directionality. Thus, a simple straight wire antenna may have one
polarization when mounted abstention the vertically, and a
different polarization when mounted substantially horizontally. As
a transverse wave, the magnetic field of a radio wave is at right
angles to that of the electric field, but by convention, talk of an
antenna's "polarization" is understood to refer to the direction of
the electric field.
[0152] Reflections generally affect polarization. For radio waves,
one important reflector is the ionosphere which can change the
wave's polarization. Thus for signals received via reflection by
the ionosphere (a skywave), a consistent polarization cannot be
expected. For line-of-sight communications or ground wave
propagation, horizontally or vertically polarized transmissions
generally remain in about the same polarization state at the
receiving location. Matching the receiving antenna's polarization
to that of the transmitter may be especially important in ground
wave or line of sight propagation but may be less important in
skywave propagation.
[0153] An antenna's linear polarization is generally along the
direction (as viewed from the receiving location) of the antenna's
currents when such a direction can be defined. For instance, a
vertical whip antenna or Wi-Fi antenna vertically oriented will
transmit and receive in the vertical polarization. Antennas with
horizontal elements, such as most rooftop TV antennas, are
generally horizontally polarized (because broadcast TV usually uses
horizontal polarization). Even when the antenna system has a
vertical orientation, such as an array of horizontal dipole
antennas, the polarization is in the horizontal direction
corresponding to the current flow.
[0154] Polarization is the sum of the E-plane orientations over
time projected onto an imaginary plane perpendicular to the
direction of motion of the radio wave. In the most general case,
polarization is elliptical, meaning that the polarization of the
radio waves varies over time. Two special cases are linear
polarization (the ellipse collapses into a line) as we have
discussed above, and circular polarization (in which the two axes
of the ellipse are equal). In linear polarization the electric
field of the radio wave oscillates back and forth along one
direction; this can be affected by the mounting of the antenna but
usually the desired direction is either horizontal or vertical
polarization. In circular polarization, the electric field (and
magnetic field) of the radio wave rotates At the radio frequency
circularly around the axis of propagation.
[0155] "Processor" generally refers to one or more electronic
components configured to operate as a single unit configured or
programmed to process input to generate an output. Alternatively,
when of a multi-component form, a processor may have one or more
components located remotely relative to the others. One or more
components of each processor may be of the electronic variety
defining digital circuitry, analog circuitry, or both. In one
example, each processor is of a conventional, integrated circuit
microprocessor arrangement, such as one or more PENTIUM, i3, i5 or
i7 processors supplied by INTEL Corporation of 2200 Mission College
Boulevard, Santa Clara, Calif. 95052, USA.
[0156] Another example of a processor is an Application-Specific
Integrated Circuit (ASIC). An ASIC is an Integrated Circuit (IC)
customized to perform a specific series of logical operations is
controlling the computer to perform specific tasks or functions. An
ASIC is an example of a processor for a special purpose computer,
rather than a processor configured for general-purpose use. An
application-specific integrated circuit generally is not
reprogrammable to perform other functions and may be programmed
once when it is manufactured.
[0157] In another example, a processor may be of the "field
programmable" type. Such processors may be programmed multiple
times "in the field" to perform various specialized or general
functions after they are manufactured. A field-programmable
processor may include a Field-Programmable Gate Array (FPGA) in an
integrated circuit in the processor. FPGA may be programmed to
perform a specific series of instructions which may be retained in
nonvolatile memory cells in the FPGA. The FPGA may be configured by
a customer or a designer using a hardware description language
(HDL). In FPGA may be reprogrammed using another computer to
reconfigure the FPGA to implement a new set of commands or
operating instructions. Such an operation may be executed in any
suitable means such as by a firmware upgrade to the processor
circuitry.
[0158] Just as the concept of a computer is not limited to a single
physical device in a single location, so also the concept of a
"processor" is not limited to a single physical logic circuit or
package of circuits but includes one or more such circuits or
circuit packages possibly contained within or across multiple
computers in numerous physical locations. In a virtual computing
environment, an unknown number of physical processors may be
actively processing data, the unknown number may automatically
change over time as well.
[0159] The concept of a "processor" includes a device configured or
programmed to make threshold comparisons, rules comparisons,
calculations, or perform logical operations applying a rule to data
yielding a logical result (e.g. "true" or "false"). Processing
activities may occur in multiple single processors on separate
servers, on multiple processors in a single server with separate
processors, or on multiple processors physically remote from one
another in separate computing devices.
[0160] "Radio" generally refers to electromagnetic radiation in the
frequencies that occupy the range from 3 kHz to 300 GHz.
[0161] "Radio horizon" generally refers the locus of points at
which direct rays from an antenna are tangential to the ground. The
radio horizon can be approximated by the following equation:
d.apprxeq. {square root over (2h.sub.t)}+ {square root over
(2h.sub.r)} (Equation 3) [0162] where: [0163] d=radio horizon
(miles) [0164] h.sub.t=transmitting antenna height (feet) [0165]
h.sub.r=receiving antenna height (feet).
[0166] "Remote" generally refers to any physical, logical, or other
separation between two things. The separation may be relatively
large, such as thousands or millions of miles or kilometers, or
small such as nanometers or millionths of an inch. Two things
"remote" from one another may also be logically or physically
coupled or connected together.
[0167] "Receive" generally refers to accepting something
transferred, communicated, conveyed, relayed, dispatched, or
forwarded. The concept may or may not include the act of listening
or waiting for something to arrive from a transmitting entity. For
example, a transmission may be received without knowledge as to who
or what transmitted it. Likewise the transmission may be sent with
or without knowledge of who or what is receiving it. To "receive"
may include, but is not limited to, the act of capturing or
obtaining electromagnetic energy at any suitable frequency in the
electromagnetic spectrum. Receiving may occur by sensing
electromagnetic radiation. Sensing electromagnetic radiation may
involve detecting energy waves moving through or from a medium such
as a wire or optical fiber. Receiving includes receiving digital
signals which may define various types of analog or binary data
such as signals, datagrams, packets and the like.
[0168] "Receiving Station" generally refers to a receiving device,
or to a location facility having multiple devices configured to
receive electromagnetic energy. A receiving station may be
configured to receive from a particular transmitting entity, or
from any transmitting entity regardless of whether the transmitting
entity is identifiable in advance of receiving the
transmission.
[0169] "Skip distance" generally refers to the minimum distance
from a transmitter to where a wave from sky-wave propagation can be
returned to the Earth. To put it another way, the skip distance is
the minimum distance that occurs at the critical angle for sky-wave
propagation.
[0170] "Skip zone" or "quiet zone" generally refers to is an area
between the location where a ground wave from ground wave
propagation is completely dissipated and the location where the
first sky wave returns using sky wave propagation. In the skip
zone, no signal for a given transmission can be received.
[0171] "Satellite communication" or "satellite propagation"
generally refers to transmitting one or more electromagnetic
signals to a satellite which in turn reflects and/or retransmits
the signal to another satellite or station.
[0172] "Size" generally refers to the extent of something; a
thing's overall dimensions or magnitude; how big something is. For
physical objects, size may be used to describe relative terms such
as large or larger, high or higher, low or lower, small or smaller,
and the like. Size of physical objects may also be given in fixed
units such as a specific width, length, height, distance, volume,
and the like expressed in any suitable units.
[0173] For data transfer, size may be used to indicate a relative
or fixed quantity of data being manipulated, addressed,
transmitted, received, or processed as a logical or physical unit.
Size may be used in conjunction with the amount of data in a data
collection, data set, data file, or other such logical unit. For
example, a data collection or data file may be characterized as
having a "size" of 35 Mbytes, or a communication link may be
characterized as having a data bandwidth with a "size" of 1000 bits
per second.
[0174] "Sky-wave propagation" refers generally to a transmission
method in which one or more electromagnetic-waves radiated from an
antenna are refracted from the ionosphere back to the ground.
Sky-wave propagation further includes tropospheric scatter
transmissions. In one form, a skipping method can be used in which
the waves refracted from the ionosphere are reflected by the ground
back up to the ionosphere. This skipping can occur more than
once.
[0175] "Space-wave propagation" or sometimes referred to as "direct
wave propagation" or "line-of-sight propagation" generally refers
to a transmission method in which one or more electromagnetic waves
are transmitted between antennas that are generally visible to one
another. The transmission can occur via direct and/or ground
reflected space waves. Generally speaking, the antenna height and
curvature of the earth are limiting factors for the transmission
distances for space-wave propagation. The actual radio horizon for
a direct line of sight is larger than the visible or geometric line
of sight due to diffraction effects; that is, the radio horizon is
about 4/5 greater than the geometric line of sight.
[0176] "Spread spectrum" generally refers to a transmission method
that includes sending a portion of a transmitted signal over
multiple frequencies. The transmission over multiple frequencies
may occur simultaneously by sending a portion of the signal on
various frequencies. In this example, a receiver must listen to all
frequencies simultaneously in order to reassemble the transmitted
signal. The transmission may also be spread over multiple
frequencies by "hopping" signals. A signal hopping scenario
includes transmitting the signal for some period of time over a
first frequency, switching to transmit the signal over a second
frequency for a second period of time, before switching to a third
frequency for a third period of time, and so forth. The receiver
and transmitter must be synchronized in order to switch frequencies
together. This process of "hopping" frequencies may be implemented
in a frequency-hopping pattern that may change over time (e.g.
every hour, every 24 hours, and the like).
[0177] "Stratosphere" generally refers to a layer of the Earth's
atmosphere extending from the troposphere to about 25 to 35 miles
above the earth surface.
[0178] "Transfer Rate" generally refers to the rate at which a
something is moved from one physical or logical location to
another. In the case of a communication link or communication
network, a transfer rate may be characterized as the rate of data
transfer over the link or network. Such a transfer rate may be
expressed in "bits per second" and may be limited by the maximum
data bandwidth for a given network or communication link used to
carry out a transfer of data.
[0179] "Transmission line" generally refers to a specialized
physical structure or series of structures designed to carry
electromagnetic energy from one location to another, usually
without radiating the electromagnetic energy through free space. A
transmission line operates to retain and transfer electromagnetic
energy from one location to another while minimizing latency and
power losses incurred as the electromagnetic energy passes through
the structures in the transmission line.
[0180] Examples of transmission lines that may be used in
communicating radio waves include twin lead, coaxial cable,
microstrip, strip line, twisted-pair, star quad, lecher lines,
various types of waveguide, or a simple single wire line. Other
types of transmission lines such as optical fibers may be used for
carrying higher frequency electromagnetic radiation such as visible
or invisible light.
[0181] "Transmission Path" or "Propagation Path" generally refers
to path taken by electromagnetic energy passing through space or
through a medium. This can include transmissions through a
transmission line. In this case, the transmission path is defined
by, follows, is contained within, passes through, or generally
includes the transmission line. A transmission or propagation path
need not be defined by a transmission line. A propagation or
transmission path can be defined by electromagnetic energy moving
through free space or through the atmosphere such as in skywave,
ground wave, line-of-site, or other forms of propagation. In that
case, the transmission path can be characterized as any path along
which the electromagnetic energy passes as it is moves from the
transmitter to the receiver, including any skip, bounce, scatter,
or other variations in the direction of the transmitted energy.
[0182] "Transmission Station" generally refers to a transmitting
device, or to a location or facility having multiple devices
configured to transmit electromagnetic energy. A transmission
station may be configured to transmit to a particular receiving
entity, to any entity configured to receive transmission, or any
combination thereof.
[0183] "Transmit" generally refers to causing something to be
transferred, communicated, conveyed, relayed, dispatched, or
forwarded. The concept may or may not include the act of conveying
something from a transmitting entity to a receiving entity. For
example, a transmission may be received without knowledge as to who
or what transmitted it. Likewise the transmission may be sent with
or without knowledge of who or what is receiving it. To "transmit"
may include, but is not limited to, the act of sending or
broadcasting electromagnetic energy at any suitable frequency in
the electromagnetic spectrum. Transmissions may include digital
signals which may define various types of binary data such as
datagrams, packets and the like. A transmission may also include
analog signals.
[0184] "Triggering Data" generally refers to data that includes
triggering information identifying one or more commands to execute.
The triggering data and the command data may occur together in a
single transmission or may be transmitted separately along a single
or multiple communication links.
[0185] "Troposphere" generally refers to the lowest portion of the
Earth's atmosphere. The troposphere extends about 11 miles above
the surface of the earth in the mid-latitudes, up to 12 miles in
the tropics, and about 4.3 miles in winter at the poles.
[0186] "Tropospheric scatter transmission" generally refers to a
form of sky-wave propagation in which one or more electromagnetic
waves, such as radio waves, are aimed at the troposphere. While not
certain as to its cause, a small amount of energy of the waves is
scattered forwards to a receiving antenna. Due to severe fading
problems, diversity reception techniques (e.g., space, frequency,
and/or angle diversity) are typically used.
[0187] "Wave Guide" generally refers to a transmission line
configured to guides waves such as electromagnetic waves occurring
at any frequency along the electromagnetic spectrum. Examples
include any arrangement of conductive or insulative material
configured to transfer lower frequency electromagnetic radiation
ranging along the electromagnetic spectrum from extremely low
frequency to extremely high frequency waves. Others specific
examples include optical fibers guiding high-frequency light or
hollow conductive metal pipe used to carry high-frequency radio
waves, particularly microwaves.
[0188] It should be noted that the singular forms "a", "an", "the",
and the like as used in the description and/or the claims include
the plural forms unless expressly discussed otherwise. For example,
if the specification and/or claims refer to "a device" or "the
device", it includes one or more of such devices.
[0189] It should be noted that directional terms, such as "up",
"down", "top" "bottom", "fore", "aft", "lateral", "longitudinal",
"radial", "circumferential", etc., are used herein solely for the
convenience of the reader in order to aid in the reader's
understanding of the illustrated embodiments, and it is not the
intent that the use of these directional terms in any manner limit
the described, illustrated, and/or claimed features to a specific
direction and/or orientation.
[0190] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiment has been shown
and described and that all changes, equivalents, and modifications
that come within the spirit of the inventions defined by following
claims are desired to be protected. All publications, patents, and
patent applications cited in this specification are herein
incorporated by reference as if each individual publication,
patent, or patent application were specifically and individually
indicated to be incorporated by reference and set forth in its
entirety herein.
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