NZ270606A - Differential global positioning system - Google Patents
Differential global positioning systemInfo
- Publication number
- NZ270606A NZ270606A NZ270606A NZ27060695A NZ270606A NZ 270606 A NZ270606 A NZ 270606A NZ 270606 A NZ270606 A NZ 270606A NZ 27060695 A NZ27060695 A NZ 27060695A NZ 270606 A NZ270606 A NZ 270606A
- Authority
- NZ
- New Zealand
- Prior art keywords
- range
- mobile station
- calculated
- station
- terms
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/0009—Transmission of position information to remote stations
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
- G01S19/07—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
- G01S19/071—DGPS corrections
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/40—Correcting position, velocity or attitude
- G01S19/41—Differential correction, e.g. DGPS [differential GPS]
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S11/00—Systems for determining distance or velocity not using reflection or reradiation
- G01S11/02—Systems for determining distance or velocity not using reflection or reradiation using radio waves
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- Position Fixing By Use Of Radio Waves (AREA)
Description
<div class="application article clearfix" id="description">
<p class="printTableText" lang="en">2706Q$ <br><br>
No.: Date: <br><br>
' Prioriiy Psts{3): <br><br>
Specification Filed: <br><br>
; : <br><br>
• &.G>lC«2r).fo*L <br><br>
I <br><br>
' r'v:' ic ;; ori Dato: 2LA..Efi.B.J§:&iL.... <br><br>
| P.O. Journal /Jo: <br><br>
NEW ZEALAND PATENTS ACT, 1953 <br><br>
COMPLETE SPECIFICATION DIFFERENTIAL GLOBAL POSITIONING SYSTEM <br><br>
,*7 We, COSSOR ELECTRONICS LIMITED, The Pinnacles, Harlow, Essex CM19 5BB, United Kingdom, a British company hereby declare the invention for which/<P7 we pray that a patent may be granted to jp^Vus, and the method by which it is to be performed, to be particularly described in and by the following statement: - <br><br>
- 1 - <br><br>
(followed by page la) <br><br>
270606 <br><br>
- ia- <br><br>
DIFFERENTIAL GLODAL POSITIONING OYflTBM <br><br>
The present invention relates to a global positioning system (GPS) in which radio navigation signals emitted by a number of satellite vehicles (SVs) are received by a mobile station and used to calculate the position of the mobile station. <br><br>
The United States Department of Defence provides a GPS under the name NAVSTAR which gives world wide coverage and is available to commercial as well as military users. Authorized military; users have full access to the system and thus can obtain a Precise Positioning Service (PPS). Other users have a lower level of access giving a Standard Positioning Service (SPS) with lower accuracy. To achieve this an encryption technique known as Anti-Spoofing is applied and users of the Precise Positioning Service require a decryption key. Also both the precise position code available to authorized users and the coarse acquisition code available to commercial users are degraded by the application of Selective Availability (SA) processing to the satellite signals to reduce the accuracy of the range measurements. The "dither" introduced by SA processing can be removed by authorized users of the precise positioning code. <br><br>
• A technique exists to improve the accuracy of the Standard Positioning Service, known as differential correction technique. In a differential GPS, a fixed reference station of known position compares the information provided by the GPS with the known data and generates correction terms for transmission to the mobile station, which uses them to correct the calculated position of the mobile station. Typically the messages transmitted to the mobile station by the reference station include correction terms for the range and the rate of change of range, SV constellation health data, and reference station parameters. <br><br>
If such a differential correction technique were applied to a system using the Precise Positioning <br><br>
2 <br><br>
mobile station would embody precise positioning information resulting from removal of the SA or "dither" terms at the reference station and would therefore have to be protected by further encryption. <br><br>
In accordance with the present invention there is provided a differential global positioning system in which radio navigation signals emitted by a plurality of satellite vehicles (SVs) are received by a reference station and a mobile station and error terms representing the difference between the calculated range of the reference station from an SV and the true range are applied to correct the calculated range of the mobile station from the SV, the navigation signals emitted by the SVs comprising a precise position coda, containing SA terms, and at least the mobile station having means for deriving the precise position code, free of SA terms, characterized in that range signals are calculated at the reference station without removal of SA terms and transmitted to the mobile station together with time of measurement information, and at the mobile station the SA terms for the time at which the measurements were made are removed from the range signal, the true range of the reference station is calculated using ephetneris corrected for SA and the known position of the reference station, and error terms are calculated and aprrj.'-ied to correct the; calculated range of the mobile station. <br><br>
Information as to the true position of the reference station can be stored in the mobile station or transmitted from the reference station. <br><br>
The navigation signals from the SVs will also normally comprise a coarse acquisition code for the Standard Positioning Service, also containing SA terms. The range and range rate signals calculated at the reference station can be derived from either the precise position code or the coarse acquisition code. <br><br>
Preferably the signals calculated at the reference station include the rate of change of the difference between calculated and true range and the mobile station removes the SA terms from those range <br><br>
f <br><br>
\ ' <br><br>
^ 0 6 0 b <br><br>
- 3 - <br><br>
signals before they are used in the correction of the calculated range of the mobile station. <br><br>
Preferably the transmission of signals from the reference station to the mobile station is effected by means of an HF communications link. <br><br>
The invention will now be described in more detail with the aid of an example illustrated in the accompanying drawings, in which <br><br>
Figure 1 is a block circuit diagram of equipment for the mobile station of a system in accordance with the invention, and <br><br>
Figure 2 is a block diagram of the differential correction process effected by the apparatus of Figure l. <br><br>
In the system in accordance with the invention the reference station serves as a range measurement facility, the sole function of which is to make instantaneous time-tagged measurements of range. No correction activity is made at the reference station. In the example to be described the information transmitted to the mobile station by the reference station comprises the reference station identity, the SV tracked, a pseudo range estimate, a pseudo range rate estimate and the time of measurement. The range and range rate signals are estimates because they are calculated from the radio navigation signals and do not rely on the frue position of the reference station. They are "pseudo" because they are uncorrected and include all the SA terms. The information is received at the mobile station (Figure 1) <br><br>
by an HF Communications Module 10 which comprises two HF Receiver/Demodulator units 11 and 12 operating at 1.6 MHz and 3.2 MHz respectively under the control of a communications supervisor unit 13. <br><br>
The mobile station has its own conventional GPS Antenna Sub-System 14 providing inputs Ll and L2 to a radio-frequency module 15 which in turn feeds data by way of a signal processor module IS to a control processor module 17. The processor module 17 also receives, via an interface module 18, the information from the reference station received by the communications module 10. <br><br>
i'' <br><br>
270 6 0§ <br><br>
- 4 - <br><br>
interface module 19 transmits to the processor module 17 Che crypto-variable key input from a KYK13 fill gun 20. This allows the mobile station access to PPS data and the SA correction function. <br><br>
Referring now to Figure 2, the control processor module 17 effects the successive calculations shown in this diagram. Information as to the reference station location is provided either by RTCM message type 3, which is an industry protocol for differential GPS, or from a look-up table 21, and provides the basis for the reference station almanac 22. The differential data from the reference station is used at 23 to compute the pseudo range and pseudo range rate for the reference station. These are then combined with the true position and time information to effect the reference error calculation 24. <br><br>
The mobile station, through its GPS modules, has access to all the PPS data necessary to calculate a position and a velocity and thus can effect the pseudo range and pseudo range rate measurement 25 for the mobile station. These estimates are then subjected to differential error correction 2 6 by the application of the range correction from 24. The correction is derived according to the formula <br><br>
^COR 11 ^R*r " ^RT " RRSA <br><br>
Where,* <br><br>
Ren » Reference Station Range Correction <br><br>
R„e? =« Reference Station Range Measurement <br><br>
Rrt =» Reference Station True Range <br><br>
Rrsa * Reference Station SA "dither" correction <br><br>
The true range R„ is calculated by using ephemeris received by the mobile station and corrected for SA in order to give the true position of the SV. The Rrsa term is given by the SA correction 28 for the time at which the reference station measurements were made. This allows for the delay in the measurement, computation and transmission o;. the reference information to the mobile station. The SA correction 28 is also applied to the <br><br>
2706 <br><br>
- 5 - <br><br>
Following the differential error correction 26 the corrected range and range rate information is processed by a Kalman filter 27 and used for determination of position, velocity etc. in the conventional manner. Specifically the information can be used for position determination of any mobile object, whether airborne, naval, space or terrestrial and for navigation including obstruction warning. <br><br></p>
</div>
Claims (5)
- <div class="application article clearfix printTableText" id="claims"> <p lang="en"> 270 6 06<br><br> WHAT/tfWE CLAIM IS:<br><br> 6<br><br> 1 .<br><br> A differential global positioning system in which radio navigation signals emitted by a plurality of satellite vehicles (SVs) are received by a reference station and a mobile station and error terms representing the difference between the calculated range of the reference station from an SV and the true range are applied to correct the calculated range of the mobile station from the SV, the navigation signals emitted by the SVs comprising a precise position code, containing SA terms, and at least the mobile station having means for deriving the precise position code, free of SA terms, characterized in that range signals are calculated at the reference station without removal of SA terms and transmitted to the mobile station together with time of measurement information, and at the mobile station the SA terms for the time at which the measurements were made are removed from the range signal, the true range of the reference station is calculated using ephemeris corrected for SA and the known position of the reference station, and error terms are calculated and applied to correct the calculated range of the mobil'e station.<br><br>
- 2. A system as claimed in claim 1 wherein the mobile station has stored information as to iue trut: location of the reference' station.<br><br>
- 3. "A system as claimed in claim 1 or 2 in which the signals calculated at the reference station include the rate of change of the difference between calculated and true range and the mobile station removes the SA terms from those range rate signals before they are used in the correction of the calculated range of the mobile station.<br><br>
- 4 . A system as claimed, in any of the preceding claims including an HF communications link for transmitting signals from the reference station to the mobile station.<br><br> r '<br><br> \ '■<br><br> 270606<br><br> 7<br><br>
- 5. A differential global positioning system substantially as hereinbefore described with reference to the accompanying drawings.<br><br> By the authorised agents A J PARK & SON<br><br> </p> </div>
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9403968A GB2287149B (en) | 1994-03-02 | 1994-03-02 | Differential global positioning system |
Publications (1)
Publication Number | Publication Date |
---|---|
NZ270606A true NZ270606A (en) | 1997-02-24 |
Family
ID=10751129
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
NZ270606A NZ270606A (en) | 1994-03-02 | 1995-03-02 | Differential global positioning system |
Country Status (4)
Country | Link |
---|---|
AU (1) | AU693135B2 (en) |
FR (1) | FR2716977B3 (en) |
GB (1) | GB2287149B (en) |
NZ (1) | NZ270606A (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0847537B1 (en) * | 1995-09-01 | 1999-04-21 | KONLE, Tilmar | System for determining the location of mobile objects |
DE19538694A1 (en) * | 1995-10-19 | 1997-04-24 | Bosch Gmbh Robert | Receiving device for evaluating location data |
AUPN896496A0 (en) * | 1996-03-27 | 1996-04-26 | Sigtec Navigation Pty Ltd | Apparatus and method for differential satellite positioning |
DE19809212A1 (en) * | 1998-03-04 | 1999-09-09 | Siemens Ag | Determining geographic position of receiver in geographic area |
EP1229343A1 (en) * | 2001-01-31 | 2002-08-07 | BRITISH TELECOMMUNICATIONS public limited company | A system and method for determining the location of a mobile |
CN102135623B (en) | 2011-03-23 | 2014-11-05 | 中兴通讯股份有限公司 | Mobile terminal and calibration method of global positioning system |
CN105182384A (en) * | 2015-08-24 | 2015-12-23 | 桂林电子科技大学 | Dual-mode real-time pseudo-range differential positioning system and pseudo-range correction data generation method |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4751512A (en) * | 1986-01-21 | 1988-06-14 | Oceanonics, Inc. | Differential navigation system for remote mobile users |
JPH05232210A (en) * | 1992-02-20 | 1993-09-07 | Kokusai Denshin Denwa Co Ltd <Kdd> | Positioning method and control method of moving body utilizing gas satellite |
JPH0616888U (en) * | 1992-06-12 | 1994-03-04 | 東京コスモス電機株式会社 | Fixed station for differential GPS, GPS positioning device for mobiles, navigation device, and radio receiver for GPS positioning device |
-
1994
- 1994-03-02 GB GB9403968A patent/GB2287149B/en not_active Expired - Fee Related
-
1995
- 1995-03-02 FR FR9502434A patent/FR2716977B3/en not_active Expired - Lifetime
- 1995-03-02 AU AU13562/95A patent/AU693135B2/en not_active Ceased
- 1995-03-02 NZ NZ270606A patent/NZ270606A/en unknown
Also Published As
Publication number | Publication date |
---|---|
AU693135B2 (en) | 1998-06-25 |
GB2287149B (en) | 1998-02-25 |
FR2716977A1 (en) | 1995-09-08 |
GB9403968D0 (en) | 1994-09-21 |
AU1356295A (en) | 1995-09-07 |
GB2287149A (en) | 1995-09-06 |
FR2716977B3 (en) | 1996-05-31 |
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