Language selection

Search

Patent 2242193 Summary

Third-party information liability

Some of the information on this Web page has been provided by external sources. The Government of Canada is not responsible for the accuracy, reliability or currency of the information supplied by external sources. Users wishing to rely upon this information should consult directly with the source of the information. Content provided by external sources is not subject to official languages, privacy and accessibility requirements.

Claims and Abstract availability

Any discrepancies in the text and image of the Claims and Abstract are due to differing posting times. Text of the Claims and Abstract are posted:

  • At the time the application is open to public inspection;
  • At the time of issue of the patent (grant).
(12) Patent Application: (11) CA 2242193
(54) English Title: RADIO NAVIGATION SYSTEM USING OUT-OF-BAND PSEUDOLITES
(54) French Title: SYSTEME DE RADIONAVIGATION UTILISANT DES PSEUDOLITES HORS BANDE
Status: Deemed Abandoned and Beyond the Period of Reinstatement - Pending Response to Notice of Disregarded Communication
Bibliographic Data
(51) International Patent Classification (IPC):
  • G01S 5/14 (2006.01)
(72) Inventors :
  • HOLDEN, THOMAS (United States of America)
  • HANSON, PETER (United States of America)
(73) Owners :
  • STANFORD TELECOMMUNICATIONS, INC.
(71) Applicants :
  • STANFORD TELECOMMUNICATIONS, INC. (United States of America)
(74) Agent:
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 1997-01-31
(87) Open to Public Inspection: 1997-08-07
Examination requested: 2002-01-25
Availability of licence: N/A
Dedicated to the Public: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US1997/001238
(87) International Publication Number: WO 1997028455
(85) National Entry: 1998-07-03

(30) Application Priority Data:
Application No. Country/Territory Date
08/595,137 (United States of America) 1996-02-01

Abstracts

English Abstract


A system of stationary pseudolite navigation transmitters for broadcasting a
GPS-like signal at a frequency F1, a non-GPS carrier frequency, is provided in
the environment of GPS spread spectrum navigation signals at a radio frequency
L1. A plurality of pseudolite stations (PL) broadcast a plurality of spread
spectrum pseudolite navigation signals at a radio frequency F1 which are at a
different frequency than the frequency L1. According to the invention, at
least one reference station (REF) is provided for receiving the GPS navigation
and the pseudolite navigation signals and deriving navigation correction data
(Differential GPS, kinematic observations data) signals. At least one of the
pseudolite stations serves as a master station (PL1) in association with each
reference station. A communication link provides differential GPS and
observation data signals from each reference receiver to its master pseudolite
station(s) which modulate(s) the reference station observations and integrity
data for broadcasting to a plurality of mobile receivers (NRX) which receive
the pseudolite and GPS navigation signals including the navigation correction
signals from the master pseudolite stations and produce accurate navigation
information therefrom in the presence or absence of useful GPS navigation
signals.


French Abstract

La présente invention concerne un système d'émetteurs stationnaires de navigation par pseudolites permettant d'émettre, en environnement de signaux de navigation GPS large spectre utilisant une fréquence radio L1, un signal de type GPS utilisant une fréquence F1 autre qu'une fréquence de porteuse GPS. Une pluralité de stations pseudolites (PL) émet une pluralité de signaux de navigation GPS large spectre utilisant une fréquence radio F1, les fréquences de ces signaux étant différentes de la fréquence L1. L'invention comporte au moins une station de référence (REF) conçue pour recevoir les signaux de navigation GPS ainsi que les signaux de navigation pseudolites, et pour en dériver les signaux des données de correction de navigation (GPS Différentiel, données d'observations cinématiques). L'une au moins des stations pseudolites sert de station maîtresse (PL1) en association avec chacune des stations de référence. Une liaison de télécommunications assure le transfert des signaux du GPS Différentiel et des données d'observation depuis chaque récepteur de référence vers l'une au moins de ses stations pseudolites modulant les données d'observation et d'intégrité de la station de référence pour émettre, à destination d'une pluralité de récepteurs mobiles (NRX), des signaux de navigation pseudolites et GPS, y compris les signaux de correction de navigation en provenance des stations pseudolites maîtresses, et produire, à partir de ces signaux, des informations de navigation précises en présence ou en l'absence de signaux de navigation GPS utiles.

Claims

Note: Claims are shown in the official language in which they were submitted.


11
CLAIMS
1. A navigation system in an environment of GPS
spread spectrum navigation signals at a radio frequency
L1 comprising,
a plurality of pseudolite stations for broadcasting
a plurality of spread spectrum pseudolite navigation
signals at a radio frequency F1 which are at a different
frequency greater than 5% of said frequency L1, at least
one of said pseudolite stations comprising a master
pseudolite station for each reference receiver,
at least one reference station for receiving said
GPS navigation and said pseudolite navigation signals and
deriving correction data (differential GPS, kinematic
observations data) signals,
a communication link forming means for providing
differential GPS and observation data signals from each
of said reference receiver station to at least one of
said master pseudolite stations,
a plurality of mobile receivers for receiving said
pseudolite and GPS navigation signals including said
navigation correction signals from said master pseudolite
station and producing accurate navigation information
therefrom in the presence or absence of useful GPS
navigation signals.
2. A navigation system as defined in claim 1
wherein all pseudolites transmit one of a 1) GPS-like
signal or 2) non-GPS code modulation to further reduce
interference with GPS and improve the quality rate of the
observations at the plurality of user receivers,
respectively.
3. A navigation system as defined in claim 1
wherein said pseudolite stations are not synchronized
with said reference receivers.

12
4. A navigation system as defined in claim 1
wherein said pseudolite transmissions are pulsed so as to
improve the near far problem encountered in continuous RF
transmission code division multiple access systems.
5. A navigation system as defined in claim 1
wherein said mobile receivers combine L1 and F1
observations into a single solution, including code
differential GPS solutions, carrier-phase smoothed
differential GPS solutions, and kinematic differential
GPS solutions.
6. A navigation system as defined in claim 1
wherein the frequency offset of the pseudolite
transmissions at F1 provides interference protection from
signal jammers in the L1 frequency region and in a region
with a plurality of pseudolite transmissions allows the
system to continue to function and provide navigation
solution based upon the number of pseudolite signals that
each of the plurality of mobile receivers can track in
its receiver, respectively.

Description

Note: Descriptions are shown in the official language in which they were submitted.


CA 02242193 1998-07-03
W O 97/28455 ~CTrUS97/01238
l~ADIO NAVIGATION SYST~:M USING OUT-OF-BAND PSEUDOLITFS
1~
The present invention relates to a radio navigation system using out-of-
band pseudolites in an environment of the Global Position System (GPS)
navigation system.
In the GPS navigation system a plurality of satellite vehicles orbiting the
earth broadcast direct sequence spread spectrum signals at a ~requency L1 and byreceiving a plurality of GPS satellite vehicles very accurate location or navigation
infolmation can be derived at almost any position on earth that is visible (in aradio sense) to the satellites. Stationary ground reference stations are used toprovide differential correction signals to mobile navigation receivers so that the
position signals are extremely accurate and can be used for land surveys, for
example. However there can be locations and times when there are insufficient
GPS satellite vehicles visible.
The obJective of the present invention is to provide a navigation system
that is available at all times in a given area and to provide a navigation system
wherein if no GPS satellites are visible, or an insufficient number of GPS
satellites are available, a system of pseudolites, including a reference station and a
master pseudolite station, are aYailable for providing pseudolite navigation
signals for extremely accurate navigation signals to the remote mobile receiversn a glven area.
SUMM~RY OF THF INVENTION
The invention overlays a system of stationary pseudolite navigation

CA 02242193 1998-07-03
W O 97/284S5 PCTrUS97/01238
transmitters for broadcasting a GPS like signal at a frequency Fl, a non-GPS
carrier fi-equency, in tlle environment of GPS spread spectrum navigation signals
at a radio frequency L1. A plurality of pseudolite stations broadcast a plurality of
spread spectrum pseudolite navigation signals at a radio frequency Fl which are
at a different frequency than the frequency Ll. According to the invention, at
least one reference station is provided for receiving the GPS navigation and thepseudolite navigation signals and deriving navigation correction data (differential
GPS, kinematic observations data) signals. At least one of the pseudolite stations
serves as a master station in association with each reference station. A
communication link provides differential GPS and observation data signals from
each reference receiver to its master pseudolite stations which modulate the
reference station observations and integrity data for broadcasting to a plurality of
mobile receivers which receive the pseudolite and GPS navigation signals
including the navigation correction signals from the master pseudolite stations
and produce accurate navigation information therefrom in the presence or absenceof useful GPS navigation signals.
The present invention differs with respect to in-band pseudolites in the
following particulars:
1. Non-GPS Fl frequencies are available to wider range of potential
customers without danger of interfering with existing GPS facilities.
2. Prior art includes use of near GPS frequencies- e.g., within about 1-10

CA 02242193 1998-07-03
W O 97/284~5 PCTrUS97/01238
C/A code nulls (approximately l0 MHZ) of Ll (See B. D. Elrod and A. J. Van
Dierendonck, "Testing and Evaluation of GPS Augrne~nted with Pseudolites for
Precision Landing Applications," Proceedings of DSNS '93, Amsterdam, The
Netherlands, 31 March 1993.), WAAS testing within about 2.5% of nominal GPS
L1 fi~equencies, and the technique up to 3.5~o different from nominal GPS
described in Brown US patent number 5,311,194.
3. In these cases, only trivial modifications are required to receive the
signals- the signals are "in-band" as far as the receiver architectures are
concerned. In addition, tl1e detailed signal paths within the receiver can be made
to be identical, further simplifying the modeling task.
4 The present invention relaxes the range of Fl to be almost a~ ,y.
n~ e frequencies in the USA at this time appear to be 1.9 GHz and 2.4 GHz,
for example.
5. Non-GPS frequencies Fl observations can be combined with GPS
observations to jointly form both carrier-smoothed DGPS and/or kinematic
solutions as shown herein
6~ The present invention does not assume pseudolite broadcasts are
synchronize(l, neither with one another, nor with GPS.
The present invention differs with respect to conventional GPS in the
following particulars:
1. The present invention employs pseudolites to augment GPS range
observations. (Conventional DGPS provides no additional range observations).
2. Pseudolites may employ pulsing to mitigate near/far limitations.
3. At least one pseudolite broadcasts DGPS reference information, in
additiol1 to range observations. (DGPS uses separate commnnication resource).
4. GPS augmentalion may radically collapse time to achieve On-the-Fly
-

CA 02242193 1998-07-03
W O 97/284S5 PCT~US97/01238
(OTF) kinelllatic solutioll.
l)ESCl~II'TION OF TIIE l)R~WINGS
The above and othcl- objects, advantages and features of the invention will
bccome mole appalcllt ~vhell con.sideled with the following specificat;on and
accompanyillg drawillg~s whcreill:
Fig. 1 is a schelnatic illustration of a GPS-pseudolite navigation system
incorporatillg the invelllioll,
Fig. 2 is a block diagram Or a master pseudolite incorporateLI in the
invcntion,
Fig. 3 is a block diagram of a receiver incorporated in the invention, (the
REF anLI MRX receivers being preferably, identical except with respect to the
uses of their outputs), and
Fig. 4 is a block diagr;~ of all auxilialy pseudolite refelence station as
used in the invelltioll.
DE~TAILED DESCRIr'l'lON OF THE INVENTION
Referrillg to Fig. I, a constellatioll Or GPS satellite.s GPS- 1, GPS-
2.. GPS-N proviLIe basic service to most areas including the area to be served by
lhe ~syslem of pseudolilc~ l'L- 1, I'L-2....PL-N. The area to be served may haveany numbel or plurality of mobile receivers MRX-1, MRX-2.. MRX-N. One or
mole of the referellce receivcl-s REF~ are provided and are capable of receivillg the
GPS sigll.lls .-l frcclucl)cy Ll .IIld al.so lhe GPS-like ~signals rroln tlle pseuLlolilc

CA 02242l93 l998-07-03
W 097/284S5 PCTrUS97/01238
statiolls PL- 1, PL-2....PL-N at a frequency F1 which can be chosen over a wide
ral)ge "n~l nee~ n~L be llc,ll lllc GPS frequency Ll. A communication link CL,
wllich may be lan(l lhle, Iniclowave, fiber oplic, a short set of wires, etc. from the
rercrence rcceiver REF to one or more of llle pseudolites PL-I, PL-2...PL-N
supplies Differelllial GPS (DGPS), kinelllatic observations and integlity data to
the pseu~lolites. The pseudolites transmil GPS-like spread spectrum signals at
frequency I~l lo refcrencc ~lalioll REF and Ihe mobile receivers MRX-I, MRX-
2.. MRX-N in order to augment the GPS signals. One of the pseudolite stations
in this system (PL-I) has been ~lesignateLI a master pseudolite station. The master
p.seudolite nlod-llatcs thc obsclvation an~l integrity data received fiom the
reference station REF over communication link CL, thereby broadcasting this
inrol nla~ioll lo thc MRX population.
The mobile r eceivers MRX are capable of receiving GPS signals at
fiequency Ll and the GPS-like signals from the pseudolite stations PL-I, PL-
2...PL-N at fi-equency Fl. Receiver elements best realized as exact copy of
elemellt at tlle relel-ellce statioll REF in order for best opportunity for
implementation depelldenl errors lo cancel out. Since these are true receivers,
(i.e., they need not transmit signals), there may be any number of them in the
service area.
If no GPS satellites are vi.sible or in lille-of-sight within the service area
(e.g., al lhc referellce receivel- REE~, the system may operate willlout GPS. In that
case, it replaces GPS, rathel thall augmenting it, and the GPS time is not
available. If one GPS salellite is available within the service area, e.g., at the
refcrence rcceiver REF, tlle syslem can lransrer GPS time to lhe mobile receivers

CA 02242193 1998-07-03
W O 97/28455 PCT~US97/01238
MRX as limited by observation errors and conventional limits of the Navstar GPS
Standard Positioning Service. Carrier-smoothed code (pseudo-range, Pl~)
observations are possible with only one GPS satellite visible. The pseudolites can
auglnent this PR, but must fully replace GPS if true kinematic solutions are to be
derived. If two or more GPS satellites are available, GPS time can be transferred
and GPS observations can participate in the kinematic solution.
The reference receiver is preferably adapted to handle the observations of
the non-master pseudolite stations. The invention contemplates reducing these
PRs modulo a preset value (set at above twice the expected maximum
measurement range). The reference station observations may be coll,prt;ssed to
be suitable for broadcast. For example, the most significant bits (MSB) of rangeand rate may be infrequently broadcast, with frequent updates supplied relative to
these values, thus reducing the number of bits required. Note that the non-master
pseudolites need not be synchronized to GPS or any other pseudolite. This may
present special problems at the receivers, since the resulting PR values are farmore arbitrary than true GPS. The master pseudolite may be synchronized to
GPS (if any) by mcans of observing its own DGPS terms in the commllnic~tton
link CL between the reference station R~F and the master pseudolite station.
This is not required but may be useful if pseudolites PL can replace GPS within
part of tlle service area and when GPS time is useful.

CA 02242l93 l998-07-03
WO 97/Z8455 PCTAUS97/01238
Like the reference receiver REF, the MRX will need to handle
observations of the non-master pseudolites.
In general, there must be at least one reference station, and at least one
master pseudolite per reference station. However, there can be multiple reference
stations, and multiple master pseudolites can be connected to modulate the
observation and integrity data from any reference station. Systems may
incorporate multiple reference stations to provide the benefits of improved system
reliability and to extend the service area. Reliability improves when several
reference signals are available to the typical MRX. A larger area may be served
while m~intzl;nin~ nomhlal accuracy by spreading reference stations to cover it
evenly; i.e., so that there is a fixed upper limit to the distance from an MRX to its
closest available reference station. Accuracy at each MRX is limited by the
distance from that MRX to the reference station it is using.
This incorporation of multiple master pseudolites may be required in the
following situations. In some cases it is seen that a single master pseudolite
source may not illllmin~te the desired coverage area. These areas could include
regions near blockages, such as near bridges, large bllilflings and docks; regions
near moving blockages such as ships; or regions with highly irregular terrain,
such as canyons, mines and factories.
Referring to Fig.2 a reference frequency source such as crystal oscillator
~0 or other stab}e frequency source SFS is selected by selection switch SSw as asource for multi-synthesizer MS which generates and outputs a control signal
fconlrDI7 a carrier cos wfl(t), and fcode from one of the selected input reference

CA 02242193 1998-07-03
W O 97/28455 PCTrUS97/01238
frequencies. Oscillator CO is a crystal oscillator or better. The control unit CU
receives fcontrol and selectively uses an external interface EXT/lNT for controland/or is interfaced to a reference receiver which provides advantageously both
GPS reference observations and PL broadcast data and outputs a control signal tocode generator CG. Code generator CG generates a spread spectrum code at a
rate selected by use of tlle frequency fcode and has the ability to modulate a data
pattern on the spread spectrum code. The cos wf,(t) signal is binary phase shiftkeyed (E3PSK) in modulator or mixer M. Optionally, a pulser P controlled by an
output of control block CU C~ll be used to provide greater effective dynamic
range at the receiver and the thus forrnul~tefi signal is amplified and broadcast to
all of the mobile receivers MRX.
I~eferring to the receiver block diagram illustrated in Fig. 3, antenna and
front end A receives the L1 and F1 signals and splits the output, supplying dualGPS- like receivers Rl and R2, respectively. Receiver R1 is a traditional GPS
receiver for processing the Ll signal frequencies and receiver R2 has slight
modifications for processing thc - signal frequencies. Both receivers are lockedto frequency and timing signal inputs from frequency and timing synthesizer FTS
which is supplied with a base rrequency from source CO. Frequency and timing
synthesizer FTS generates reference and timing signals to coordinate receivers Rl
ancl ~2 and to drive control microprocessor CMP. Control microprocessor CMP
provides high level control and integrates the observations and data of receivers

CA 02242l93 l998-07-03
W O 97/28455 PCTrUS97/01238
R I and R2. Reference interface RI outputs the reference link data to
communication link CL which is connected to the master pseudolite. The
solution output interface SO provides the navigation in~ormation to the user via a
utilization device, which may be a display, a recorder or perfo~n a control or
guidance function. The following table sets out some of the parameters:
Input code data data format Examples
Freq. rate rate andcontent
1575.42 1.023 50 bps ICD-GPS-200 NovaTel RT-20
Fl fcode = fcOdc variant of GSV 1012
1.023 ~ 21000 WAAS/LAAS (modif. forFl)
(typical, fd;
others
possible)
An exemplary l~lock diagram of an auxiliary pseudolite reference REF
(Fig. l) is illustrated in Fig. 4, which parallels Fig. 2. This example assumes
BPSK modulation of frequency Fl The pulser function block P' again is optional.
It provides a way of pulsing or chopping the output signal for greater effectivedynamic range at tlle receiver. Oscillator OSC-2 is also of the quartz crystal
oscillator family or better. The auxiliary pseudolite does not require an external
time base input. As indicated the pseudolite has provision for external interface
EXT INT and control. The pseudolite optionally broadcasts its location if known.The multi-synthesizer MS' and code generator CG' are the same as described in
connection with Fig.2. The control element or microprocessor CMP' selects the
spread spectrum code and any data to be modulated on it, and generates the

CA 02242193 1998-07-03
W O 97/28455 PCT~US97/01238
pulsing element control signal and provides external interface signals. Its timing
is derived from the multi-synthesizer. The control element or microprocessor
controls the selection of the SS code, the pulsing control and services the external
interface.
While preferred embodiments of the invention have been shown and
described, it will be appreciated that various modifications and adaptations of the
invention will be obvious to those skilled in the art and it is intended that the
claims encompass such modification~ and adaptations.
WHAT IS CLAIMED IS:

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

2024-08-01:As part of the Next Generation Patents (NGP) transition, the Canadian Patents Database (CPD) now contains a more detailed Event History, which replicates the Event Log of our new back-office solution.

Please note that "Inactive:" events refers to events no longer in use in our new back-office solution.

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Event History , Maintenance Fee  and Payment History  should be consulted.

Event History

Description Date
Inactive: Office letter 2008-04-17
Inactive: Office letter 2008-04-17
Revocation of Agent Requirements Determined Compliant 2008-04-17
Revocation of Agent Request 2008-04-10
Revocation of Agent Request 2008-04-10
Time Limit for Reversal Expired 2005-01-31
Application Not Reinstated by Deadline 2005-01-31
Inactive: Abandoned - No reply to s.30(2) Rules requisition 2004-04-28
Deemed Abandoned - Failure to Respond to Maintenance Fee Notice 2004-02-02
Inactive: S.30(2) Rules - Examiner requisition 2003-10-28
Amendment Received - Voluntary Amendment 2003-09-16
Inactive: S.30(2) Rules - Examiner requisition 2003-03-28
Amendment Received - Voluntary Amendment 2002-10-24
Letter Sent 2002-02-27
Request for Examination Received 2002-01-25
Request for Examination Requirements Determined Compliant 2002-01-25
All Requirements for Examination Determined Compliant 2002-01-25
Inactive: IPC assigned 1998-09-29
Classification Modified 1998-09-29
Inactive: First IPC assigned 1998-09-29
Inactive: Single transfer 1998-09-25
Inactive: Courtesy letter - Evidence 1998-09-15
Inactive: Notice - National entry - No RFE 1998-09-14
Application Received - PCT 1998-09-09
Application Published (Open to Public Inspection) 1997-08-07

Abandonment History

Abandonment Date Reason Reinstatement Date
2004-02-02

Maintenance Fee

The last payment was received on 2002-12-23

Note : If the full payment has not been received on or before the date indicated, a further fee may be required which may be one of the following

  • the reinstatement fee;
  • the late payment fee; or
  • additional fee to reverse deemed expiry.

Please refer to the CIPO Patent Fees web page to see all current fee amounts.

Fee History

Fee Type Anniversary Year Due Date Paid Date
Basic national fee - standard 1998-07-03
Registration of a document 1998-07-03
MF (application, 2nd anniv.) - standard 02 1999-02-01 1998-12-31
MF (application, 3rd anniv.) - standard 03 2000-01-31 2000-01-26
MF (application, 4th anniv.) - standard 04 2001-01-31 2001-01-25
Request for examination - standard 2002-01-25
MF (application, 5th anniv.) - standard 05 2002-01-31 2002-01-25
MF (application, 6th anniv.) - standard 06 2003-01-31 2002-12-23
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
STANFORD TELECOMMUNICATIONS, INC.
Past Owners on Record
PETER HANSON
THOMAS HOLDEN
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

To view selected files, please enter reCAPTCHA code :



To view images, click a link in the Document Description column. To download the documents, select one or more checkboxes in the first column and then click the "Download Selected in PDF format (Zip Archive)" or the "Download Selected as Single PDF" button.

List of published and non-published patent-specific documents on the CPD .

If you have any difficulty accessing content, you can call the Client Service Centre at 1-866-997-1936 or send them an e-mail at CIPO Client Service Centre.


Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Representative drawing 1998-09-30 1 7
Claims 2003-09-16 2 71
Description 2003-09-16 11 409
Description 1998-07-03 10 349
Claims 1998-07-03 2 71
Abstract 1998-07-03 1 61
Drawings 1998-07-03 2 36
Cover Page 1998-09-30 2 83
Notice of National Entry 1998-09-14 1 209
Reminder of maintenance fee due 1998-10-01 1 110
Courtesy - Certificate of registration (related document(s)) 1998-11-18 1 114
Reminder - Request for Examination 2001-10-02 1 129
Acknowledgement of Request for Examination 2002-02-27 1 180
Courtesy - Abandonment Letter (Maintenance Fee) 2004-03-29 1 175
Courtesy - Abandonment Letter (R30(2)) 2004-07-07 1 166
PCT 1998-07-03 11 388
Correspondence 1998-09-15 1 30
Fees 2002-12-23 1 37
Fees 2000-01-26 1 33
Fees 2002-01-25 1 34
Fees 2001-01-25 1 36
Fees 1998-12-31 1 36
Correspondence 2008-04-10 1 37
Correspondence 2008-04-17 1 15
Correspondence 2008-04-17 1 22
Correspondence 2008-04-10 1 36