U.S. patent application number 14/172453 was filed with the patent office on 2014-06-05 for apparatus and method for use in global position measurements.
This patent application is currently assigned to SiGe Semiconductor (Europe) Limited. The applicant listed for this patent is SiGe Semiconductor (Europe) Limited. Invention is credited to Stuart Walker Strickland, Ben J. Tarlow.
Application Number | 20140156179 14/172453 |
Document ID | / |
Family ID | 39135469 |
Filed Date | 2014-06-05 |
United States Patent
Application |
20140156179 |
Kind Code |
A1 |
Tarlow; Ben J. ; et
al. |
June 5, 2014 |
APPARATUS AND METHOD FOR USE IN GLOBAL POSITION MEASUREMENTS
Abstract
Embodiments of the invention involve providing assistance data
to a global position and navigation receiver, for example
topographical data, such that the receiver can decide on a specific
action depending on that data. The topographical data may include
one or both of geographical data and architectural data.
Geographical data may include information about natural formations,
such as hills, valleys, forests, etc. Architectural data may
include manmade formations, such as streets, buildings, bridges,
etc. The receiver may then interpret and decide on a course of
action for controlling the receiver base on the assistance
data.
Inventors: |
Tarlow; Ben J.; (Cottenham,
GB) ; Strickland; Stuart Walker; (Bishop's Stortford,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SiGe Semiconductor (Europe) Limited |
Hertfordshire |
|
GB |
|
|
Assignee: |
SiGe Semiconductor (Europe)
Limited
Hertfordshire
GB
|
Family ID: |
39135469 |
Appl. No.: |
14/172453 |
Filed: |
February 4, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12310552 |
Jun 7, 2010 |
8692710 |
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PCT/CA2007/001519 |
Aug 31, 2007 |
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14172453 |
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60841217 |
Aug 31, 2006 |
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Current U.S.
Class: |
701/412 |
Current CPC
Class: |
G01S 19/22 20130101;
G01C 21/00 20130101; G01C 21/30 20130101; G01S 19/25 20130101 |
Class at
Publication: |
701/412 |
International
Class: |
G01C 21/00 20060101
G01C021/00 |
Claims
1. An apparatus for a receiver having circuitry configured to
receive signals from at least one source providing global
positioning information, the apparatus comprising a receiver
controller configured to compare an estimated position of the at
least one source providing global positioning information with
topographical data to determine whether a topographical feature
defined in the topographical data would block receipt of the
signals from the at least one source by the receiver and to modify
navigational instructions provided by the receiver to a user to
guide the user on a path that is less affected by a topographical
feature that has been determined to block receipt of the
signals.
2. The apparatus of claim 1 wherein the topographical data
describes a topographical aspect of an area local to the
receiver.
3. The apparatus of claim 1 wherein the topographical data includes
at least one of data pertaining to at least one architectural
feature in an area local to the receiver and data pertaining to at
least one geographical feature in the area local to the
receiver.
4. The apparatus of claim 1 wherein the topographical data includes
for an area local to the receiver at least one of a width of at
least one street, an orientation of at least one street, a height
of at least one topographical feature, data indicative of a
property of materials of at least one topographical feature, data
indicative of a change in elevation, and altitude information.
5. The apparatus of claim 1 wherein the receiver controller is
further configured to interpret the topographical data to make a
decision to control operation of the receiver.
6. The apparatus of claim 1 wherein the receiver controller is
further configured to use the topographical data to determine
whether the at least one source providing global positioning
information, which is above a horizon, is visible to the
receiver.
7. The apparatus of claim 6 wherein when the at least one source
providing global positioning information is visible to the
receiver, the receiver controller is further configured to enable
the receiver to search for the at least one source to acquire a
signal.
8. The apparatus of claim 6 wherein when the at least one source
providing global positioning information is not visible to the
receiver, the receiver controller is further configured to stop the
receiver from searching for the at least one source to acquire a
signal.
9. A global positioning system receiver configured to receive the
signals from the at least one source providing global positioning
information comprising the apparatus of claim 1.
10. A method to use in a receiver having circuitry configured to
receive signals from at least one source providing global
positioning information, the method comprising: comparing an
estimated position of the at least one source providing global
positioning information with topographical data to determine
whether a topographical feature defined in the topographical data
would block receipt of the signals from the at least one source by
the receiver; and modifying navigational instructions provided by
the receiver to a user to guide the user on a path that is less
affected by a topographical feature that has been determined to
block receipt of the signals.
11. The method of claim 10 wherein the topographical data describes
a topographical aspect of an area local to the receiver.
12. The method of claim 10 further comprising using the
topographical data to control power consumption of the
receiver.
13. The method of claim 10 further comprising using the
topographical data to determine if the receiver is positioned in a
location that is influenced by multipath.
14. The method of claim 10 further comprising using the
topographical data to control selection, acquisition, and tracking
of the signals from the at least one source providing global
positioning information.
15. The method of claim 10 further comprising using the
topographical data to control position determination performed by
the receiver.
16. The method of claim 10 further comprising using altitude data
for controlling a determination of a receiver position estimate
calculated by the receiver when the topographical data includes the
altitude data for an area local to the receiver.
17. A system for a receiver having circuitry configured to receive
signals from at least one source providing global positioning
information, the system comprising: a wireless enabled device
located remotely from the receiver and configured to receive
navigational instructions provided by the receiver; and a receiver
controller configured to compare an estimated position of the at
least one source providing global positioning information with
topographical data to determine whether a topographical feature
defined in the topographical data would block receipt of the
signals from the at least one source by the receiver and to modify
the navigational instructions provided by the receiver to a user to
guide the user on a path that is less affected by a topographical
feature that has been determined to block receipt of the
signals.
18. The method of claim 17 wherein the topographical data includes
at least one of data pertaining to at least one architectural
feature in an area local to the receiver and data pertaining to at
least one geographical feature in the area local to the
receiver.
19. The method of claim 17 wherein the topographical data includes
for an area local to the receiver at least one of a width of at
least one street, an orientation of at least one street, a height
of at least one topographical feature, data indicative of a
property of materials of at least one topographical feature, data
indicative of a change in elevation, and altitude information.
20. The method of claim 17 further comprising using the
topographical data to control operation of the receiver.
Description
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS
[0001] Any and all applications for which a foreign or domestic
priority claim is identified in the Application Data Sheet as filed
with the present application are hereby incorporated by reference
under 37 CFR 1.57.
BACKGROUND
[0002] The present invention relates to apparatus and methods for
measuring global position.
[0003] The basic functionality of a Global Positioning System (GPS)
receiver is determining its position by computing time delays
between transmission and reception of signals transmitted from a
network of GPS satellites above the earth's surface, which are
received by the receiver on or near the surface of the earth. The
GPS satellites transmit to the receiver absolute time information
associated with the satellite signal. A respective time delay
resulting from signal transmission from each of the respective
satellites to the receiver is multiplied by the speed of light to
determine the distance from the receiver to each of the respective
satellites from which data is received. This distance is known as
the pseudorange. If fewer than three satellites are used to
determine a position, the distance may not be precisely
determinable due to an offset between an oscillator in the receiver
generating a clock signal for the receiver and the timing signal to
which `the satellites are synchronized. The GPS satellites also
transmit to the receivers satellite-positioning data, generally
known as ephemeris data.
[0004] The timing signal from each satellite includes a time tag
that is used by the receiver to determine when each received signal
was transmitted by each respective satellite. By knowing the exact
time of transmission of each of the signals, the receiver uses the
ephemeris data to calculate where each satellite was when it
transmitted a signal. The receiver then combines the knowledge of
respective satellite positions with the computed distances to the
satellites to determine the receiver's position.
[0005] Position calculations generated from satellite signals
require pseudorange measurements, ephemeris data, and absolute time
of transmission, from four satellites or more to determine a three
dimensional position estimate of the GPS receiver's location, which
includes latitude, longitude and altitude. Measurement information
from three satellites is needed to determine a two dimensional
position estimate of the GPS receiver's location, which includes
latitude and longitude.
[0006] Other Global Navigation Satellite Systems (GNSS) operate
using similar principles as GPS described above.
[0007] Existing standardized assistance data used in GPS signal
acquisition is described in the 3GPP ETSI Technical Specification
04.31. This assistance data may include the following: coarse time,
date; coarse position; fine time, Doppler for satellite with
respect to a stationary receiver; almanac; ephemerides; UTC model.
Some manufacturers provide their own assistance data.
SUMMARY OF THE INVENTION
[0008] The current use of assistance data is limited in its scope
in that it provides no data specific to the nature of the local
environment. This means a receiver may have no knowledge of the
environment in an area local to the receiver. As a result, the
receiver is unaware and/or incapable of determining when satellites
may be occluded from the view of the receiver. With knowledge of
the environment in an area local to the receiver, for example
topographical data, the receiver can use the topographical data to
make decisions regarding control of the receiver. Such decisions
may enable the receiver to: determine if the receiver is operating
in a location that is likely to be influenced by multipath; control
how the receiver will operate in a location that is likely to be
influenced by multipath; control power consumption of the receiver;
control at least one of selection, acquisition and tracking a
signal from at least one source providing global positioning
information; and control position determination performed by the
receiver.
[0009] According to a first aspect of the invention, there is
provided an apparatus for a receiver, the receiver having circuitry
configured to receive signals from at least one source providing
global positioning information, the apparatus comprising: an
interface configured to receive data, the data being other than a
receiver position estimate determined by the receiver, that
describes an aspect of the environment in an area local to the
receiver; and a receiver controller configured to use the data to
control operation of the receiver.
[0010] In some embodiments, the data comprises topographical data
for describing a topographical aspect of an area local to the
receiver. The topographical data may include at least one of data
pertaining to at least one architectural feature in an area local
to the receiver and data pertaining to at least one geographical
feature in an area local to the receiver. Particular examples of
the data may include: width of at least one street in an area local
to the receiver; orientation of at least one street in an area
local to the receiver; height of at least one feature in an area
local to the receiver; data indicative of one or more properties of
one or more material(s) of at least one feature in an area local to
the receiver; data indicative of at least one change in elevation
in an area local to the receiver; and altitude information in an
area local to the receiver.
[0011] In some embodiments, the receiver controller is configured
to interpret the data to make a decision to control operation of
the receiver.
[0012] In some embodiments, the receiver controller further
comprises one or more of: a multipath influence determiner
configured to use the data to determine if the receiver is
positioned in a location that is likely to be influenced by
multipath; a multipath influence controller configured to use the
data to control how operation of the receiver in a location that is
likely to be influenced by multipath; a power consumption
controller configured to use the data to control power consumption
of the receiver; a selection/acquisition/tracking controller
configured to use the data to control one or more of selection,
acquisition and tracking a signal from at least one vehicle
providing global positioning information; a position determination
controller configured to use the data to control position
determination performed by the receiver; and a navigation
controller configured to use the data to control a navigation
function of the receiver.
[0013] In some embodiments, the multipath influence determiner is
configured to perform at least one of: determine at least one
probable source of multipath; predict if at least one or a
plurality of topographical feature(s) in an area local to the
receiver will cause one or more multi-path component(s) of
signal(s); provide an indication of the presence of one or more
multi-path component(s) of signal(s); and one or more of predict,
estimate, determine and provide an indication of the magnitude of
one or more multi-path component(s) of signal(s)
[0014] In some embodiments, the receiver controller is configured
to use the data to determine whether the at least one source
providing global positioning information, which is above the
horizon, is likely to be visible to the receiver. To determine
whether the at least one source providing global positioning
information is likely to be visible to the receiver, the receiver
controller may compare an estimated position of the at least one
source with topographical data that indicates whether or not a
feature defined in the topographical data would block receipt of a
signal from the at least one satellite by the receiver.
[0015] Furthermore, in some embodiments, if the receiver controller
determines that the at least one source providing global
positioning information is visible to the receiver, the receiver
controller enables the receiver to search for the at least one
source to acquire a signal; and if the receiver controller
determines that the at least one source providing global
positioning information is not likely to be visible to the
receiver, the receiver controller stops the receiver from searching
for the at least one source to acquire a signal.
[0016] In some embodiments, the interface is configured to access a
computer readable medium for storing the data. The computer
readable medium may be collocated with the receiver. The data may
be provided and/or updated from one or more suitable sources, for
example, by connecting to a receiver including the apparatus to a
data source. The data may be provided and/or updated from one or
more source(s) located remotely from the receiver. The receiver may
be configured to request the data from the one or more source(s),
and/or the receiver may be configured to receive the data without
the need for the receiver sending a request to the one or more
source(s).
[0017] In some embodiments, the apparatus described herein may be
part of a global positioning system receiver for receiving signals
from at least one source providing global positioning information.
Such a receiver may further include: receive circuitry configured
to receive signals from at least one source providing global
positioning information; a signal processor configured to acquire
signals from the at least one source providing global positioning
information and configured to receive control information from the
receiver controller; and a position determiner configured to
determine one or more receiver position estimate(s) using the
received signals from at least one source and configured to receive
control information from the receiver controller.
[0018] According to a second embodiment of the invention, there is
provided a method for use in a receiver, the receiver having
circuitry configured to receive signals from at least one source
providing global positioning information, "the method comprising:
receiving data, the data being other than a receiver position
estimate determined by the receiver, that describes an aspect of
the environment in an area local to the receiver; and using the
data to control operation of the receiver.
[0019] In some embodiments, using the data to control operation of
the receiver comprises interpreting the data and making a decision
to control operation of the receiver.
[0020] In some embodiments, when the data includes altitude data
for an area local to" the receiver, the method further comprising
using the altitude data for controlling the determination of a
receiver position estimate calculated by the receiver. In. some
embodiments, using the altitude data for controlling the
determination of a receiver position estimate calculated by the
receiver comprises using the altitude data and signals from a
minimum of two sources providing global positioning information
when determining a two-dimensional position estimate of the current
position of the receiver. In some embodiments, using the altitude
data for controlling the determination of a receiver position
estimate calculated by the receiver comprises using the altitude
data and signals from a minimum of three sources providing global
positioning information when determining a three-dimensional
position estimate of the current position of the receiver.
[0021] According to a third aspect of the invention, there is
provided computer readable medium having stored thereon program
instructions executable by a processor of a receiver, the receiver
having circuitry configured to receive signals from at least one
source providing global positioning information, for causing the
computing device to perform: receiving data, which is independent
of receiver position data determined by the receiver, and which
defines an aspect of the environment in an area local to the
receiver; and using the data to control operation of the
receiver.
[0022] According to a fourth aspect of the invention, there is
provided a memory for storing data for access by at least one
application program being executed on receiver that receives
signals from at least one source providing global positioning
information comprising: a data structure stored in said memory, the
data structure including information resident in a database used by
said application program and including: data in the form of at
least one of: (1) at least one architectural feature in an area
local to the receiver; and (2) at least one geographical feature in
an area local to the receiver; wherein the data is used by the at
least one application program to control operation of the
receiver.
[0023] In some embodiments, the memory is a computer readable
medium that is at least one of: (1) a component collocated with the
receiver; and (2) a component of an apparatus remote from the
receiver that is accessible by the receiver.
[0024] Other aspects and features of the present invention will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments of the
invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Embodiments of the invention will now be described with
reference to the drawings in which:
[0026] FIG. 1 is a flow chart describing a method of using
assistance data for controlling a receiver according to an
embodiment of the invention;
[0027] FIGS. 2A and 2B are block diagrams of examples of receivers
configured to implement embodiments of the invention; and
[0028] FIG. 3 is a block diagram of an exemplary implementation of
a receiver controller responsive to assistance data according to an
embodiment of the invention.
DETAILED DESCRIPTION
[0029] A receiver for receiving global positioning information
described herein below may be a receiver for use in a Global
Navigation Satellite System (GNSS). Exemplary types of GNSS include
Global Positioning System (GPS), Galileo, Global Navigation
Satellite System (GLONASS), Wide Area Augmentation System (WAAS)
and European Geostationary Navigation Overlay Service (EGNOS).
Moreover, the use of global positioning information is not to be
limited to information for only GPS, but is intended to be
information generated, processed, and/or transmitted by any type of
GNSS signal source, which is used for determining a position
estimate. Similarly, a source of a signal, for example, a space
vehicle or satellite, and the signal transmitted by such a source
can be a source configured to one or more of generate, -process,
and transmit one or more signals for one or more of these types of
GNSS.
[0030] Embodiments of the invention include the provision of data
to a GNSS receiver, for example topographical data, such that the
receiver can use the data to decide on a further action to be
performed. The topographical data may include one or both of
geographical data and architectural data. Geographical data may
include information about natural formations, such as hills,
valleys, forests, etc. Architectural data may include information
about manmade formations, such as streets, buildings, bridges, etc.
The data may be generally referred to as assistance data.
[0031] A practical embodiment of the invention may include at least
some of the following:
1. A source of geographic and/or architectural information,
typically held by a mapping software application or a database and
including, for example, information about street widths and
directions of flow, building heights, building materials, elevation
changes, local height above geoid. A geoid is an equipotential
surface which approximately coincides with the mean ocean surface.
It is often referred to as a close representation or physical model
of the Earth. It is the equipotential surface which coincides on
average with mean sea level. 2. An acquisition and navigation
receiver capable of using some or all of this information to
improve performance of: signal acquisition; speed or accuracy of
position calculation; navigation capability; predicted position;
source selection (which signals to search for) and/or to reduce
power consumption. 3. An interface between the source of this
information and the receiver making use of it whether or not the
two are collocated.
[0032] In some embodiments, the assistance data is generated before
it is used and stored at a given location to be accessed and
received by functional components of the receiver that will use the
assistance data. In some embodiments, the assistance data that is
received is based on the last known position and/or direction of
the receiver. In some embodiments, the assistance data stored at
the given location may be updated, based on new information about
an aspect of the environment local to the receiver. In some
embodiments, the assistance data is used in combination with
assistance data stored at a different location. In some
embodiments, the assistance data is received on demand by the
receiver immediately before use. For example, a user of a GNSS
receiver may input a current location, e.g. street address, to the
receiver, and based on that input, the receiver may request and
receive assistance data pertaining to an aspect of the environment
local to the current location of the receiver as defined by the
user input.
[0033] In operation, the receiver may use information provided by
or found in an assistance data database to determine which
satellites are likely to be visible over or around one or more
geographic feature(s) or one or architectural feature (s) that
block (s) (occludes) a signal transmitted by one or more
satellite(s) The receiver may use this information to determine
probable sources of multipath and/or to calculate or estimate such
effects. The receiver may use this information to determine the
likely effects of combined or reflected signals on the dynamic
range of received signals, or one or more other factors, that would
or could impact the search for, or acquisition of, satellite
signals and/or the calculation of the position of the receiver. The
receiver may predict multipath using data such as a street's width
and/or direction, which side of the street the receiver is on
and/or the height of one or more nearby building(s). The expression
"multipath" in this context refers to a phenomenon in which a
transmitted signal is reflected by intervening objects such as
mountains, buildings or other structures one or more times before
it reaches the GNSS receiver. The reflection(s) cause the path
length of the signal to increase in comparison with a direct path,
thereby increasing the measured pseudorange. The reflected signal
may interfere destructively with the direct path signal, reducing
its strength.
[0034] In some embodiments, methods and apparatus configured to
implement the methods use information from the database to predict
or select times when specific satellites are known to come into
view of the receiver in order to control power consumption (e.g.
reduce or optimize) or aid in selection of satellites to acquire
and/or track.
[0035] Some embodiments of the invention allow the receiver to make
use of specific information about the environment in an area local
to the receiver that has not previously been an element or
ingredient of assistance data. A receiver may use this data to
improve its performance in any of a number of ways. In particular,
one advantage that cannot be achieved with conventional receivers
is to decide when it is worthwhile searching for a particular
satellite according to the likelihood that its signal is above the
horizon.about.but occluded from view of the receiver, by a
geographical or architectural feature between the particular
satellite and the receiver.
[0036] In some embodiments of the invention, the methods described
herein aid in controlling power consumption at the receiver. This
may result in improved battery life performance. For instance, if
the assistance data indicates that a satellite signal is likely to
be very difficult to detect, the receiver need not spend long
periods of time performing a power intensive search. Conversely,
the assistance data may indicate when this satellite signal is
likely to be relatively easy to detect, for example, possibly after
a period of occlusion.
[0037] Another benefit arising from the assistance data is the
provision of altitude data. A good estimate of altitude in an area
local to the receiver, which can be provided in the assistance
data, allows the receiver to calculate a two-dimensional position
from measured pseudoranges using a minimum of signals from at least
two sources. A three-dimensional position may be determined using a
minimum of signals from at least three sources. In either of the
two or three-dimensional cases, having more than two or three
signals respectively, may enable the position estimate to be more
accurate. The accuracy of the position estimate may be improved in
such cases due to having a larger number of known values than
unknown values when determining the receiver position, resulting in
what can be referred to as an over-determined solution.
[0038] As described above, the magnitude of the multipath component
of one or more signals may be predicted, making the at least one
signal easier to detect, and the effect of the multipath component
may be ameliorated. By performing at least one of predicting and
detecting the magnitude of multipath, a millisecond ambiguity
occurring in a receiver position calculation, which may be
indicated in a clock offset between the receiver clock and a
satellite clock, may be resolved. See applicant's co-pending
application no. PCT/CA2007/001520, published as Publication No. WO
2008/025151, titled "APPARATUS AND METHOD FOR USE IN GLOBAL
POSITION MEASUREMENTS" for examples of how multipath may be
predicted and how the millisecond ambiguity occurring in the
position calculation can be determined and/or compensated.
[0039] The methods described herein include obtaining the data,
from/with a database collocated with the receiver and/or accessed
by the receiver from a source at a location remote from the
receiver. In some embodiments, the source at the location remote
from the receiver may be a server, optionally dedicated to provide
such information. More generally, the assistance data source may be
a multipurpose server, one purpose of which is to provide such
information. In some embodiments, the source may be another
wireless device having an assistance data database.
[0040] In some embodiments, the receiver may be a GNSS receiver
that is collocated with a mobile or other radio receiver through
which the assistance data is communicated. When the receiver
includes a database that is collocated with the receiver, the
database may be enabled to be populated with new or updated
assistance data from time to time, when requested by the receiver,
or received unsolicited by the receiver. The new or updated
assistance data received by the receiver may be generated for that
particular receiver individually or may be generated for all
receivers in a given region and broadcast. to all receivers in that
region.
[0041] When the receiver accesses a database remote from the
receiver for assistance data, the assistance data received by the
receiver may be generated for that particular receiver individually
or may be generated for any receiver in a given region and
broadcast to all receivers in that region.
[0042] An example of a method using data to control a receiver will
now be described with reference to the flow chart of FIG. 1.
[0043] A first step 200 of the method involves receiving data, the
data being other than a receiver position estimate determined by
the receiver, that describes an aspect of the environment in an
area local to the receiver. A second step 210 of the method
involves using the data to control operation of the receiver.
[0044] The data may be topographical data for describing a
topographical aspect of an area local to the receiver. The
topographical data may include data pertaining to at least one
architectural feature in an area local to the receiver and/or data
pertaining to at least one geographical feature in an area local to
the receiver. The data may in particular include one, some or all
of: width of at least one street in an area local to the receiver;
directional orientation of at least one street in an area local to
the receiver; height of at least one feature in an area local to
the receiver; data indicative of one or more properties of one or
more material(s) of at least one feature in an area local to the
receiver; data indicative of at least one change in elevation in an
area local to the receiver; and altitude information in an area
local to the receiver. A "feature" may be a manmade structure such
as buildings, bridges, etc. or natural formations such as trees,
hills, etc.
[0045] Using the data to control operation of the receiver may
involve interpreting the data and making a decision to control a
particular one or more operation(s) of the receiver.
[0046] Controlling the operation of the receiver may include
performing one or more of: (1) using the data to determine if the
receiver is positioned in a location that is likely to be
influenced by multipath; (2) using the data to control operation of
the receiver in a location that is likely to be influenced by
multipath; (3) using the data to control power consumption of the
receiver; (4) using the data to control one or more of selection,
acquisition and tracking a signal from at least one source
providing global positioning information; (5) using the data to
control position determination performed by the receiver; and (6)
using the data to control a navigation function of the
receiver.
[0047] In some embodiments, when the data includes altitude data
for an area local to the receiver, the method may further include
using the altitude data for controlling the determination of a
receiver position estimate calculated by the receiver. For example,
the altitude data may be used in combination with signals from a
minimum of two sources providing global positioning information
when determining a two-dimensional position estimate of the current
position of the receiver.
[0048] In another embodiment, altitude data may be used in
combination with signals from a minimum of three sources providing
global positioning information when determining a three-dimensional
position estimate of the current position of the receiver.
[0049] An example of a receiver according to an embodiment of the
invention will now be described with reference to FIG. 2A. FIG. 2A
illustrates a receiver 100 in communication with three satellites,
Space Vehicle 150, Space Vehicle 160 and Space Vehicle 170. While
only three satellites are shown in communication with the receiver,
it is to be understood that the receiver may be in contact with
one, two, or greater than three satellites at any given point in
time. Also illustrated in FIG. 2A is a wireless enabled device 140,
located remotely from the receiver, which in some embodiments, is
configured to provide assistance data to the receiver 100.
[0050] In the illustrated example, the receiver 100 includes an
antenna 110 for receiving signals from the one or more satellites.
Only a single antenna is indicated in FIG. 2A, but multiple
antennas could be used for receiving signals from one or more
satellites. The antenna 110 is shown to receive data from wireless
device 140. However, it is to be understood that a separate at
least one antenna, independent from the antenna used to receive
signals from the satellites, could be used to receive assistance
data from the wireless device 140.
[0051] In the illustrated example, the receiver 100 includes
receiver circuitry 115, a receiver controller 120, a data storage
medium 134, and an assistance data interface 136. The receiver
controller 120 as described herein is intended to be a receiver
controller responsive to the assistance data, not to be confused
with a primary receiver controller which controls all aspects of
the receiver's operation, although the receiver controller may be
incorporated in the primary receiver controller or may be separate
therefrom. In some embodiments, this receiver controller may
provide such a primary receiver controller with information to
allow the primary receiver controller to control operation of the
receiver more efficiently or with improved performance, as
described herein. In some embodiments, a single processor may be
used to implement both the receiver controller and the primary
receiver controller. The receiver controller 120 is shown to
include a multipath influence determiner 122, a multipath influence
controller 124, a power consumption controller 126, a
selection/acquisition/tracking controller 128, a position
determination controller 130, and a navigation controller 132.
These are particular examples of components for using assistance
data to control the receiver. The components are represented in
FIG. 2A as separate functional blocks, but it is to be understood
that depending on a given implementation, i.e. software, hardware,
firmware, or some combination of those three, multiple functional
blocks may be combined in one or more multi-component functional
block(s), each containing one or more of the above described
functional blocks. Not all of these components are necessarily
included in all embodiments of implementations of the invention.
Other embodiments may comprise anyone of these components.
Furthermore, other and/or additional components for using data to
control other functions of the receiver in accordance with to the
intended scope of the invention are contemplated.
[0052] In operation, the receiver circuitry 115 is configured to
receive signals from the antenna 110 from at least one source that
is providing global positioning information. In some embodiments,
the received signals are passed to other components of the receiver
100, for example, hardware and/or software for determining position
estimates based on received satellite information, which determine
one or more parameters associated with the receiver. In some
embodiments, the received signals are passed to the receiver
controller 120.
[0053] The receiver circuitry 115 may be configured to receive
assistance data from the wireless device 140 via the antenna 110.
In some embodiments, the assistance data is passed to the receiver
controller 120. The assistance data may be provided to any of the
various components 122,124,126,128,130,132 described above for use
by those respective components.
[0054] In some embodiments, the multipath influence determiner 122
is configured to use the data to determine if the receiver is
operating in a location that is likely to be influenced by
multipath. The multipath influence determiner 122 is configured to
perform one or more of: (1) determining probable sources of
multipath; (2) predicting if at least one or a plurality of
topographical feature(s) in an area local to the receiver will
cause one or more multi-path component(s) of signal(s); (3)
providing an indication of the presence of one or more multi-path
component(s) of signal(s); and (4) one or more of predicting,
estimating, determining and providing an indication of the
magnitude of one or more multi-path component(s) of signal(s).
[0055] In some embodiments, the multipath influence controller 124
is configured to use the data to control how the receiver will
operate in a location that is likely to be influenced by
multipath.
[0056] In some embodiments, the power consumption controller 126 is
configured to use the data to control power consumption of the
receiver. For example, the power consumption controller 126 may use
assistance data to perform one or more of reducing and optimizing
power consumption in the receiver.
[0057] In some embodiments, the selection/acquisition/tracking
controller 128 is configured to use the data to control one or more
of selection, acquisition and tracking a signal from at least one
source providing global positioning information. For example, the
selection/acquisition/tracking controller 128 may determine one or
more likely effect(s) of combined or reflected signals on the
dynamic range of at least one received signal, or of one or more
other factor(s), on the dynamic range of at least one received
signal, that may affect how the search, acquisition and/or tracking
of signals may be performed by the receiver.
[0058] In some embodiments, the position determination controller
130 is configured to use the data to control position determination
performed by the receiver 100. For example, the position
determination controller 130 may determine one or more likely
effect(s) of combined or reflected signals on the dynamic range of
at least one received signal, or of one or more other factor(s), on
the dynamic range of at least one received signal, that may affect
how position determination may be performed by the receiver
100.
[0059] In some embodiments, the receiver controller 120 is
configured to use the data to determine whether at least one
vehicle 150,160,170 providing global positioning information, which
is above the horizon, is likely to be visible to the receiver 100.
For example, the receiver controller 120 may determine whether the
at least one source 150,160,170 providing global positioning
information is likely to be visible to the receiver 100 by
comparing an estimated position of the at least one source with
topographical data that indicates whether or not a feature defined
in the topographical data would block receipt of a signal from the
at least one satellite by the receiver 100. In some embodiments, if
the receiver controller 120 determines that the at least one source
providing global positioning information is visible to the
receiver, the receiver controller 120 enables the receiver 100 to
search for the at least one source so as to acquire a signal. If
the receiver controller 120 determines that the at least one source
providing global positioning information is not likely to be
visible to the receiver 100, the receiver controller 120 may stop
the receiver 100 from searching for the at least one source to
acquire a signal. Either one of or both of the
selection/acquisition/tracking controller 128 and the power
consumption optimizer 126 may perform a method as described above
to control selection and acquisition of satellites. In so doing,
the receiver controller 120 may optimize the power consumption of
the receiver 100.
[0060] In some embodiments, the navigation controller 132 is
configured to use the data to control a navigation function of the
receiver. For example, if the receiver provides navigation
instructions to a user, the data may be used to modify navigation
instructions provided by a functional element of the receiver to
guide a user on a path that will be less affected by topographical
features that could in some manner effect how accurately position
estimates are calculated.
[0061] In the illustrated example, the receiver 100 includes the
data storage medium 134 (e.g. a memory), for storing information
that may be used by the receiver controller. This may include, for
example, temporary storage of assistance data, or storage of
information predicted, estimated, determined, or calculated by any
of the various components 122,124,126,128,130,132 described above,
which may be used to control operation of the receiver.
[0062] In some embodiments, the receiver controller 120 can be
physically implemented using software, hardware, firmware or any
combination thereof. As particular examples not meant to limit the
invention, a hardware implementation may include using application
specific integrated circuits (ASIC) or field programmable gate
arrays (FPGA). To implement the functional components in software,
in some embodiments a microprocessor capable of performing basic
digital signal processing operations is utilized. Embodiments of
the invention may be carried out in a processing chip in the GNSS
receiver.
[0063] In some embodiments, the assistance data interface 136 is
configured for enabling access between assistance data 144 located
in the wireless device 140 and the receiver controller 120. The
assistance data interface 136 may be a physical connection, for
example electrical couplers or a bus controlled by hardware or
software or a logical interface, for example, implemented in
software.
[0064] An example of a receiver 105 according to another embodiment
of the invention will now be described with reference to FIG. 2B.
The receiver of FIG. 2B is similar to the receiver of FIG. 2A,
except that the receiver of FIG. 10 2B includes a database for
storing assistance data at the receiver 105. In this embodiment, an
assistance data database 138 is part of the receiver 105. The
assistance data interface 136 is used by the receiver 105 to access
the assistance data database 138 when the receiver controller 120
needs information about the environment local to the receiver 105,
which is stored in the assistance data database 138.
[0065] The assistance data database 138 includes for example
architectural environment information and/or geographical
environment information. Information regarding an aspect of an area
local to the receiver can be determined from the assistance data
database 138. The assistance data database 138 may be stored on a
computer readable medium and be accessible by other hardware and/or
software components of the receiver 105. Examples of such other
hardware and/or software components may include a component that is
responsible for one or more of selecting, acquiring and tracking
satellites or a component that is responsible for determining
receiver position.
[0066] In FIG. 2B wireless device 140 may be accessed by the
receiver controller via the interface 136. The wireless device 142
may contain new or updated assistance data 146 that can be used in
combination with assistance data stored in assistance data database
138 or may be used to replace assistance data stored in assistance
data database 138.
[0067] In addition to the particular components described above as
components in the receivers 100, 105 that are related to the
invention, the receivers 100,105 are considered to have other
components related to the normal operation of the receiver, for
example transmit circuitry, hardware and/or software for acquiring
and tracking satellites, and hardware and/or software for
determining position estimates based on received satellite
information. The other components may be configured to receive
information from the functional blocks that have used the
assistance data, which allows the other components to be controlled
by the receiver controller. Hardware and/or software for acquiring
and tracking satellites may include a signal processor configured
to acquire signals from the at least one source providing global
positioning information. The signal processor may include a
correlating engine used to correlate one or more received signal(s)
from one or more source(s) to determine which source the one or
more received signal(s) is from.
[0068] FIG. 3 shows a more detailed example of how the receiver
controller, responsive to the assistance data, may interact with
other components in the receiver. FIG. 3 illustrates a receiver
controller 300 in two way communication with an assistance data
interface 310. The assistance data interface 310 is shown to be in
two way communication with the assistance data 320. As described
above, the assistance data may be; for example, in a database that
is either collocated with the receiver or that is located remotely
from the receiver. The receiver controller 300 is also shown
providing outputs to a position determiner module 330, a power
controller module 340 and a selection/acquisition/tracking module
350.
[0069] The receiver controller 300 uses the assistance data to
interpret the assistance data and make a decision to control one or
more operations of the receiver. For instance, the assistance data
may be interpreted and a decision made pertaining to selection of a
satellite. For example, a particular satellite is determined to be
occluded by a building whose location and height is described in
the assistance data and is therefore not likely to be visible to
the receiver. The receiver controller 300 is capable of determining
this based on the assistance data and sends a message or some other
form of output to the selection/acquisition/tracking module 350,
which is responsible for selecting, acquiring and/or tracking
satellites. With such a message or output from the receiver
controller 300, the selection/acquisition/tracking module 350 can
ultimately decide not to try to acquire the satellite.
Alternatively, the receiver controller 300 may provide a similar
message or output to the power controller module 340. The power
controller module 340 may use the message or output to ensure that
the receiver does not perform a search for the satellite, and by
doing so mitigates wasting power on a search that would at that
point in time most likely prove to be ineffective. In another
example, the assistance data 320 may include altitude data and this
altitude data could be provided to the position determiner module
330, which is responsible for using at least one signal from one or
more satellites to determine a position estimate for the receiver.
With the altitude information provided by the receiver controller
300, the position determiner module 330 can calculate the position
estimate with fewer signals than typically necessary, or possibly
improve the accuracy of the position estimate with the number of
signals that are typically necessary, i.e. a minimum of three
signals for two dimensional position estimate and a minimum or four
signals for three dimensional position estimate. These are three
examples of how the receiver controller 300 may provide output
information to one or more particular component(s) of a receiver
illustrating how the assistance data 320 can be used to control the
receiver. The receiver controller 300 may be used to control other
components in the receiver that are not specifically described
herein, but which could be positively affected by the use of
assistance data.
[0070] Using assistance data may be helpful in determining
strategies for controlling, e.g. reducing or optimizing, processor
power in a GNSS receiver. Strategies for reducing processor power
for a GNSS receiver in a device that shares processing power with
other elements in the device may be particularly useful. For
example, a cellular telephone that is GPS enabled, may also have an
MP3 music player and/or the ability to play video. Any means to
mitigate the amount of processing power used for determining a
position estimate may be advantageous to avoid the processing power
used to determine a position estimate disrupting the processing
power needed to play music or video on the cellular telephone.
[0071] In some embodiments, the assistance data may be used by the
receiver to control functional elements of the receiver in a
proactive manner. For example, this may include using the data in
an attempt to ensure that the receiver navigates a path that will
allow it to receive information from a sufficient number of sources
substantially at all times to maintain accurate position
determination.
[0072] Numerous modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
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