U.S. patent application number 15/782225 was filed with the patent office on 2018-02-01 for transmit noise and impedance change mitigation in wired communication system.
The applicant listed for this patent is Entropic Communications, LLC. Invention is credited to Payman Hosseinzadeh-Shanjani, Branislav Petrovic.
Application Number | 20180034488 15/782225 |
Document ID | / |
Family ID | 52809654 |
Filed Date | 2018-02-01 |
United States Patent
Application |
20180034488 |
Kind Code |
A1 |
Hosseinzadeh-Shanjani; Payman ;
et al. |
February 1, 2018 |
TRANSMIT NOISE AND IMPEDANCE CHANGE MITIGATION IN WIRED
COMMUNICATION SYSTEM
Abstract
A method, system and circuit for providing for part or all of a
transmitter, when it is in mute mode (not actively transmitting),
to be turned off, removed, decoupled or modified in general in
order to reduce the total noise submitted by the transmitter to the
wired network into network controller. In parallel, an auxiliary
circuit or impedance is added or coupled to the transmitter in
order to mitigate the total return loss change of the transmitter.
When in active transmitter mode, this auxiliary circuit or
impedance will be removed or decoupled from the transmitter and
transmitter will transmit in normal mode.
Inventors: |
Hosseinzadeh-Shanjani; Payman;
(San Diego, CA) ; Petrovic; Branislav; (La Jolla,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Entropic Communications, LLC |
Carlsbad |
CA |
US |
|
|
Family ID: |
52809654 |
Appl. No.: |
15/782225 |
Filed: |
October 12, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15452121 |
Mar 7, 2017 |
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15782225 |
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14810781 |
Jul 28, 2015 |
9590666 |
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15452121 |
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14052399 |
Oct 11, 2013 |
9094068 |
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14810781 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H03F 3/24 20130101; H04B
3/04 20130101; H04B 1/0475 20130101; H04B 2001/0408 20130101; H03K
19/0005 20130101 |
International
Class: |
H04B 1/04 20060101
H04B001/04; H04B 3/04 20060101 H04B003/04 |
Claims
1. A method of mitigating transmit noise in a transmission system,
comprising: in an active mode: coupling a first stage output to a
second stage input; and decoupling an auxiliary circuit from the
second stage input to ground; and in a mute mode: decoupling an
output of the first stage to the second stage input; and coupling
the auxiliary circuit from the second stage input to ground.
2. The method of claim 1 wherein coupling and decoupling comprises
using a member from the group consisting of hardware, software, and
firmware.
3. The method of claim 1 further comprising operating the auxiliary
circuit to mimic an impedance of a first amplifier of the first
stage.
4. The method of claim 1 further comprising configuring the
auxiliary circuit to comprise at least one member from the group
consisting of a resistive component, a capacitive component and a
reactive component.
5. The method of claim 1 further comprising selecting the auxiliary
circuit based on a frequency range.
6. The method of claim 1 further comprising selecting the auxiliary
circuit by circuit simulation or by measurement.
7. The method of claim 1 further comprising synthesizing the
auxiliary circuit to achieve a small mismatching error.
8. The method of claim 1 further comprising operating a plurality
of active and mute transmitters.
9. A method of mitigating effects of an impedance change in a
transmission system, comprising: in an active mode: coupling a
first stage output to a second stage input; and decoupling a
compensation impedance from the second stage input to ground; and
in a mute mode: decoupling an output of the first stage to the
second stage input; and coupling the compensation impedance from
the second stage input to ground.
10. The method of claim 9 wherein the coupling and decoupling
comprise coupling and decoupling a member from the group consisting
of hardware, software, and firmware.
11. The method of claim 9 further comprising operating the
compensation impedance to mimic an impedance of a first amplifier
of the first stage.
12. The method of claim 9 further comprising configuring the
compensation impedance to comprise at least one member from the
group consisting of a resistive component, a capacitive component,
and a reactive component.
13. The method of claim 9 further comprising selecting the
compensation impedance based on a frequency range.
14. The method of claim 9 further comprising selecting the
compensation impedance by circuit simulation or by measurement.
15. The method of claim 9 further comprising synthesizing the
compensation impedance to achieve a small mismatching error.
16. The method of claim 9 further comprising operating a plurality
of active and mute transmitters.
17. A circuit for mitigating transmit noise in a transmission
system, comprising: first and second switches and an auxiliary
circuit, the first switch coupling a first stage output to a second
stage input and the second switch decoupling the auxiliary circuit
from the second stage input and ground, for operation in an active
mode; and the first switch decoupling an output of the first stage
to the second stage input, and the second switch coupling the
auxiliary circuit from the second stage input to ground, for
operation in a mute mode.
18. The circuit of claim 17 wherein the first and second switch for
coupling and decoupling comprise a member from the group consisting
of hardware, software and firmware.
19. The circuit of claim 17 wherein the auxiliary circuit mimics an
impedance of a first amplifier of the first stage.
20. The circuit of claim 17 wherein the auxiliary circuit comprises
at least one member from the group consisting of a resistive
component, a capacitive component and a reactive component.
21. The circuit of claim 17 further comprising a plurality of
active and mute transmitters.
22. A circuit for mitigating effects of an impedance change in a
transmission system, comprising: first and second switches and an
auxiliary circuit; the first switch coupling a first stage output
to a second stage input and the second switch decoupling the
auxiliary circuit from the second stage input and ground, for
operation in an active mode; the first switch decoupling an output
of the first stage to the second stage input, and the second switch
coupling the auxiliary circuit from the second stage input to
ground, for operation in a mute mode.
23. The circuit of claim 22 wherein the first and second switches
are selected from the group consisting of hardware, software and
firmware.
24. The circuit of claim 22 wherein the auxiliary circuit mimics an
impedance of a first amplifier of the first stage.
25. The circuit of claim 22 wherein the auxiliary circuit comprises
at least one member from the group consisting of a resistive
component, a capacitive component and a reactive component.
26. The circuit of claim 22 further comprising a plurality of
active and mute transmitters.
Description
BACKGROUND
[0001] In a network, impedance change or Return Loss (RL) change of
one or more nodes while another node is transmitting or receiving
may cause interference. This is because a signal propagating
through the network is a composite of all reflections of all nodes.
Therefore, if any reflected signal component changes, the composite
will also change, affecting reception or transmission. This is
shown in FIG. 1, which depicts multiple Customer Premises Equipment
(CPEs), or nodes 10, 10', 10'', in a network (of coaxial cables 16
and taps 15, 15' and 15'' connecting CPE units and Network
Controller (NC 14)). Single port taps are shown for simplicity, but
often multiport taps are used in a typical CATV plant showing the
effects of adjacent nodes return loss change. As shown in Fig.1,
the signal propagating to network controller (NC) 14 includes
direct path data signal 12 and reflections 18 from nodes 10' and
10''. If the impedance of any of the nodes 10' or 10'' changes, the
reflections will change and consequently the received signal at NC
14 will change. Depending on isolation of nodes and the amount of
RL change, the effect can degrade the link, cause packet errors,
and in some cases may disable communications.
[0002] For the above reasons, as taught in the prior art, all the
nodes are always kept in the same state (in the transmit mode with
unchanged output impedance) all the time, no matter if they are
actively transmitting or not. When not transmitting any data or
intended content, but ready to transmit data at any moment, this is
referred to as a "transmit-ready" or "mute" state.
[0003] However, aggregate noise power of all the mute nodes while
another node is transmitting will degrade the sensitivity of the
receiver or NC 14 to the actively transmitting node. Alternatively,
in the prior art an opposite choice is made by turning the
transmitters off, so that noise is eliminated, but at the expense
of significant impedance/return loss changes, and increased delay
in turning the transmitters back on.
[0004] Clearly, achieving both low noise and unchanged impedance is
advantageous, and that is the objective of the claimed
embodiments.
SUMMARY
[0005] In the claimed embodiments, part or all of a transmitter,
when it is in mute mode (not actively transmitting), will be turned
off, removed or modified in general in order to reduce the total
noise submitted by the transmitter to the transmission line. In
parallel, an auxiliary circuit or impedance will be added to the
transmitter in order to mitigate the total return loss change of
the transmitter. When in active transmitter mode, this auxiliary
circuit or impedance will be removed from the transmitter, and
transmitter will transmit in normal mode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The disclosed method, system, and apparatus, in accordance
with one or more various embodiments, are described with reference
to the following figures. The drawings are provided for purposes of
illustration only and merely depict examples of some embodiments of
the disclosed method and apparatus. These drawings are provided to
facilitate the reader's understanding of the disclosed method and
apparatus. They should not be considered to limit the breadth,
scope, or applicability of the claimed invention. It should be
noted that for clarity and ease of illustration these drawings are
not necessarily made to scale.
[0007] FIG. 1 is an illustration of the effects of adjacent nodes
return loss changes.
[0008] FIG. 2 illustrates an active transmitter and a mute
transmitter containing the preferred embodiment
[0009] FIG. 3 illustrates the preferred embodiment on a single
transmitter in the active and mute state.
[0010] The figures are not intended to be exhaustive or to limit
the claimed invention to the precise form disclosed. It should be
understood that the disclosed method and apparatus can be practiced
with modification and alteration, and that the invention should be
limited only by the claims and the equivalents thereof.
DETAILED DESCRIPTION
[0011] The claimed embodiments herein solve the problems stated
above. In the claimed method, system, and circuit, part or all of
the transmitter, when it's in mute mode (not actively
transmitting), will be turned off, removed or modified in general
in order to reduce the total noise submitted by the transmitter to
the transmission line.
[0012] In parallel, an auxiliary circuit or impedance will be added
to the transmitter in order to mitigate the total return loss
change of the transmitter. The term impedance is defined as having
a resistive component, and/or a capacitive component, and/or an
inductive component, and/or a reactive component.
[0013] When in active transmit mode, this auxiliary circuit or
impedance will be removed from the transmitter and transmitter will
transmit in normal mode. Muting of the non-active transmitter and
the addition or removal of the impedance component can be achieved
by hardware switches, software, and firmware or by any other method
well known in the art. The preferred embodiments are shown in FIGS.
2 and 3. FIG. 2 shows two nodes, active transmitter 24 and mute
transmitter 32. Although the figure shows two transmitters, this
disclosure is intended to include any number of transmitters with
each transmitter in one of the two modes. First node 24, in this
figure the active transmitter, has at least two stages, stage 1 26
comprising a first stage amplifier 28 and stage 2 52 comprising
second stage amplifier 30. Second node 32, in this figure mute
transmitter, has at least two stages, stage 1 34 comprising first
stage amplifier 36 and stage 2 64 comprising second stage amplifier
38. Again, although two stages are shown, this disclosure is
intended to include any number of stages as required by the
intended use. As shown in the figure, active transmitter 24 (in an
active state) is coupled by switch 42 between first stage amplifier
28 and second stage amplifier 30. As previously indicated the
coupling can be provided in any manner well known in the art. This
provides for a clear path over wired network 70 to network
controller (NC) 44. Simultaneously, compensation impedance 46 via
an auxiliary circuit, or the like is decoupled by the switch 48
from connecting line 54 between first stage amplifier 28 and second
stage amplifier 30 with the second end of compensation impedance 46
coupled to ground 68.
[0014] Mute transmitter 32 functions similarly to active
transmitter; however, in an opposite state. Second node, in this
figure mute transmitter 32, has at least two stages, stage 1 34
comprising a first stage amplifier 36 and stage 2 64 comprising
second stage amplifier 38. Again, although two stages are shown,
this disclosure is intended to include any number of stages as
required by the intended use. As shown in the figure, mute
transmitter 32 (in an inactive state) is decoupled by the switch 56
between first stage amplifier 36 and second stage amplifier 38. As
previously indicated, the coupling can be provided in any manner
well known in the art. This provides for a decoupled path to
Network Controller (NC) 44. Simultaneously, compensation impedance
46' is coupled by switch 60 to connecting line 62 between first
stage amplifier 36 and second stage amplifier 38. The other end of
compensation impedance 46' is coupled to ground 68.
[0015] With the disclosed method, the noise injected into the line
when transmitter is in the mute mode will be reduced approximately
by the gain of the first amplifier G1. The output noise with the
traditional solution is approximately NF1+G1+G2-output loss,
whereas with the present method it is only NF2+G2-output loss. For
example, if NF1=NF2=5 dB, G1=20 dB, G2=10 dB, output loss=3 dB,
then, with traditional solution, Output noise=5+20+10-3=32 dB
(above thermal noise floor). However, with the present method,
Output noise=5+10-3=12 dB, i.e. a 20 dB improvement.
[0016] FIG. 3 shows a similar embodiment of FIG. 2; however, this
embodiment shows a same transmitter, first in a mute mode 32 and a
transition of the transmitter to an active mode 24. In FIG. 3,
impedance Z 46 is passive in a preferred embodiment to minimize
noise contributions. Impedance Z 46 is designed to mimic (and
substitute for) the output impedance of the first amplifier (G1) as
close as possible in the frequency range of interest. The goal is
to minimize the impedance change upon switchover from the amplifier
to Z, thus, minimizing the change of output 66. While in the mute
mode, the first amplifier can be powered off if it is desirable to
save the power, but it must be turned on in time to settle and be
ready for next transmission. The switchover time of the switches
should be fast so that any transient while the switch changes its
impedance from short to open and vice versa is out of band, and
does not cause any perceivable glitch. Typically the switchover
time is in the sub-nanosecond range, fast enough so the transient
is well out of band. The output impedance of the first amplifier
can be determined by circuit simulation, or measurement if
feasible. This impedance is then the target for mimicking (over
frequency of interest) by impedance Z 46, which is synthesized by
passive components, in general, a combination of resistor(s),
capacitor(s), and inductor(s). In some embodiments, active circuits
may be added to facilitate the approximation, provided their noise
contribution is low enough to be acceptable.
[0017] In one embodiment impedance Z 46 consists of a resistor
only, providing a first-order match to the first amplifier's output
impedance. In another embodiment, a C and L are added to the
resistor, to achieve a closer approximation. In general, a higher
order circuit for impedance Z 46 can be synthesized achieving
arbitrarily small mismatching errors.
[0018] The following presents a simplified summary of one or more
embodiments in order to provide a basic understanding of some
aspects of such embodiments. This summary is not an extensive
overview of the one or more embodiments, and is intended to neither
identify key or critical elements of the embodiments nor delineate
the scope of such embodiments. Its sole purpose is to present some
concepts of the described embodiments in a simplified form as a
prelude to the more detailed description that is presented
later.
[0019] While various embodiments of the disclosed method and
apparatus have been described above, it should be understood that
they have been presented by way of example only, and should not
limit the claimed invention. Likewise, the various diagrams may
depict an example architectural or other configuration for the
disclosed method and apparatus. This is done to aid in
understanding the features and functionality that can be included
in the disclosed method and apparatus. The claimed invention is not
restricted to the illustrated example architectures or
configurations, rather the desired features can be implemented
using a variety of alternative architectures and configurations.
Indeed, it will be apparent to one of skill in the art how
alternative functional, logical or physical partitioning and
configurations can be implemented to implement the desired features
of the disclosed method and apparatus. Also, a multitude of
different constituent module names other than those depicted herein
can be applied to the various partitions. Additionally, with regard
to flow diagrams, operational descriptions and method claims, the
order in which the steps are presented herein shall not mandate
that various embodiments be implemented to perform the recited
functionality in the same order unless the context dictates
otherwise.
[0020] Although the disclosed method and apparatus is described
above in terms of various exemplary embodiments and
implementations, it should be understood that the various features,
aspects and functionality described in one or more of the
individual embodiments are not limited in their applicability to
the particular embodiment with which they are described. Thus, the
breadth and scope of the claimed invention should not be limited by
any of the above-described exemplary embodiments.
[0021] Terms and phrases used in this document, and variations
thereof, unless otherwise expressly stated, should be construed as
open ended as opposed to limiting. As examples of the foregoing:
the term "including" should be read as meaning "including, without
limitation" or the like; the term "example" is used to provide
exemplary instances of the item in discussion, not an exhaustive or
limiting list thereof; the terms "a" or "an" should be read as
meaning "at least one," "one or more" or the like; and adjectives
such as "conventional," "traditional," "normal," "standard,"
"known" and terms of similar meaning should not be construed as
limiting the item described to a given time period or to an item
available as of a given time, but instead should be read to
encompass conventional, traditional, normal, or standard
technologies that may be available or known now or at any time in
the future. Likewise, where this document refers to technologies
that would be apparent or known to one of ordinary skill in the
art, such technologies encompass those apparent or known to the
skilled artisan now or at any time in the future.
[0022] A group of items linked with the conjunction "and" should
not be read as requiring that each and every one of those items be
present in the grouping, but rather should be read as "and/or"
unless expressly stated otherwise. Similarly, a group of items
linked with the conjunction "or" should not be read as requiring
mutual exclusivity among that group, but rather should also be read
as "and/or" unless expressly stated otherwise. Furthermore,
although items, elements or components of the disclosed method and
apparatus may be described or claimed in the singular, the plural
is contemplated to be within the scope thereof unless limitation to
the singular is explicitly stated.
[0023] The presence of broadening words and phrases such as "one or
more," "at least," "but not limited to" or other like phrases in
some instances shall not be read to mean that the narrower case is
intended or required in instances where such broadening phrases may
be absent. The use of the term "module" does not imply that the
components or functionality described or claimed as part of the
module are all configured in a common package. Indeed, any or all
of the various components of a module, whether control logic or
other components, can be combined in a single package or separately
maintained and can further be distributed in multiple groupings or
packages or across multiple locations.
[0024] Additionally, the various embodiments set forth herein are
described in terms of exemplary block diagrams, flow charts and
other illustrations. As will become apparent to one of ordinary
skill in the art after reading this document, the illustrated
embodiments and their various alternatives can be implemented
without confinement to the illustrated examples. For example, block
diagrams and their accompanying description should not be construed
as mandating a particular architecture or configuration.
* * * * *