JPH1010224A - Method and system for integrating loran-c and satellite navigation system (sns) in order to enhance accuracy, availability and integrity of system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the system accuracy by timing a loran-C signal and providing positional information additionally to a navigation signal and smoothing a user position and a speed data between supplementary data messages or between addition and deletion of satellites available for determination of user position and speed. SOLUTION: In order to use a loran-C navigation signal received through a local loran-C receiver 5' as a communication signal and an auxiliary navigation signal, received supplementary satellite navigation signal and message are integrated with the loran-C signal. More specifically, the loran-C signal is timed and received by a satellite navigation system(SNS) receiver 3'. Positional information is then provided additionally to the positional information of a satellite navigation signal subjected to differential correction through a DSNS receiver 4' in order to make smooth a user position and a speed data between supplementary data messages of satellite signal and between satellites to be added and deleted which are available for determining the position of a user receiver and the speed. According to the arrangement, system accuracy can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio navigation system, and more particularly to an improvement of radio navigation information from a satellite navigation system (SNS).
Timed to provide additional position information and between augmented data messages and between adding the satellite contribution signal to the user position and velocity equation and removing or subtracting the satellite contribution signal from that equation. By using the Laurent C navigation system to provide communication signals and supplemental navigation signals used to smooth user position and velocity data, the United States Global Positioning System, or GPS, The format is currently exclusively available.

[0002]

BACKGROUND OF THE INVENTION Satellite navigation systems offer very attractive services in terms of their coverage and accuracy, but the accuracy is limited to ships in port environments and aircraft in approach and landing. Is not sufficient for the safety of conventional applications. Position accuracy is limited by the satellite's ability to provide accurate and timely information about satellite clock offsets, orbit parameters, and propagation conditions. In addition, satellites are not continuously monitored and are not in the range of their ground control centers, and thus do not provide sufficient integrity to notify users of a failure in a timely manner. Other limitations of concern are the availability of the minimum number of satellites required for confirmation,
Geometric dilution (GD) of satellite orientation and resulting accuracy
OP), and the tracked satellite is in the user's view,
And the discontinuities associated with those changes as they exit.

[0003] Accordingly, GPS augments have been proposed to provide data communication to provide GPS users with a communication channel to improve GPS accuracy and integrity, and to provide timing in the communication channel. Through the relationship, supplemental navigation services that improve availability and reduce discontinuities can also be included. Augmentation systems for providing data that improve accuracy and completeness
It is simply called differential GPS (DGPS).

[0004] Two general methods of such augmentation have been proposed and demonstrated in the literature (see, for example, the following paper: Johnson, G., "Multisite Reference Station Difference GPS Results, And Performance (Results and Perf
ormance of Multi-Site Reference Station Differenti
al GPS) "by Radice, JT and Wilson, R." Standard for Offshore DGPS Reference and Integrity Monitoring "
s For Maritime DGPSReference Stations and Integrit
y Monitors) "by Barboux, Jean-Pierre," Evaluation of differential GPS performance for separation of user criteria (An Asses
sment of Differential GPS Performance With Respect
To User-Reference Separation) "
93 GPS Conference (minutes from September 22-24, 1994) and Alsip, Douglas H. CDR et al., "The Coast Guard's Differential G Plan.
PS Program) ”(The 48th Annual Meeting of the Navigation Association (199
Minutes of June 29-July 1, 4))).

[0005] (1) "Wide-area augmentation" provides users with data on clock offsets, orbit parameters, and propagation conditions of each satellite. This technique uses a specialized communication system to send data from a number of remote GPS monitor receivers to a central data processing facility. The central facility is
For each satellite in view, determine all of the various corrections,
The resulting message is then sent via the specialized communication system to an additional communication facility for transmission to the user (offering a satellite link). The central facility also monitors the remote monitoring site for proper operation. That is,
(2) A "local augmentation" is provided to the user for each satellite in view of each of the multiple remote GPS monitor receiver sites,
Provide data regarding the pseudorange correction and then communicate directly to the user from the monitor receiver site (or a nearby communication site). Pseudo-range correction combines all correction factors in a single period. The monitoring site is monitored by both internal checks and central facilities for proper operation.

[0006] In any of the above methods, about 5 meters,
Or better accuracy, but
Due to the large number of steps required for communication, longer delays in a wide-area augmentation system providing a complete message and a lower communication reliability of about 500
There may be degradation with local augmentation above nm.

[0007]

A greatly improved technique according to the present invention is to use Loran-C technology to augment SNS, or GPS. Laurent C augmented GPS can also be either local or global. In either case, the Laurent C signal is timed to provide additional location information,
Used as communication and supplemental navigation signals used to smooth user position and velocity data between augmented data messages and between addition and deletion of satellites available for user position and velocity equations. You. A GPS monitor receiver is intended, but not required, to be located at Laurent C station.

[0008] Accordingly, it is an object of the present invention to improve the accuracy, availability, and integrity of the system by modifying the Roland C.
And new and improved methods and apparatus for integrating satellite navigation system technology with satellites.

[0009] Other and further objects are described below and are more particularly set forth in the appended claims.

[0010]

SUMMARY OF THE INVENTION In summary, however, from one of the broad aspects of the present invention, the present invention comprises a plurality of satellites for transmitting navigation signals to a terrestrial user receiver,
Also, to improve the accuracy and completeness of the navigation signal,
In a satellite navigation system communicating an augmented data message, at each terrestrial receiver also receiving a Laurent C navigation signal, and receiving the received Laurent C signal as a communication signal and as a supplementary navigation signal. Integrating the augmented satellite navigation signals and messages with the received Laurent C signal, i.e., providing additional location information to the location information of the satellite navigation signals, between the satellite signal augmented data messages and at the user Timing the Laurent C signal to smooth the user position and velocity data between the added and deleted satellite communications available for position and velocity determination. I do.

A preferred and best mode technique, device design, and configuration are presented below.

The present invention will now be described with reference to the accompanying drawings.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a hybrid global system, cooperation between the use of satellite navigation and Roland C navigation has been described, for example, by the 1993 GPS Conference of the Navigation Association (September 22-2, 1994).
D, entitled "Eurofix", found in the minutes of the 4th)
The much closer integration and interaction, especially with satellite augmentation techniques, proposed in the article by r. Duck van Willingen and LJ Beckhus, underlies the method of the present invention.

In FIG. 1, the Laurent C transmitter 1 is corrected by differential GPS data at 4 (DGPS) under the atomic clock (cesium) timing synchronization at 2 as shown in the figure. Controlled by a satellite (GPS) reference signal at 3 received locally at the Loran-C transmitter station. Suitable transmitters are, for example, U.S. Patent Nos. 3,711,725, 3,889,263, and
Nos. 4,001,598, 4,151,528, and 4,423,419.

[0015] The Laurent C station is particularly suitable for differential GPS monitor receiver sites. The station is designed with very high reliability power system requirements to ensure reliable operation as a radio navigation transmitter site.
Further, navigation system techniques, such as power plants, are directed and assigned to respond quickly to equipment power demands. Thus, a relatively small increase in Laurent C's on-site power load and workload does not substantially affect site staffing and operational costs and provide the best reliability possible.

In addition to the site's technical capabilities, the presence of a triple recombination cesium frequency standard at the station provides additional synergies in its use as a differential GPS monitor receiver site. The cesium standard allows for accurate and fast determination of GPS integrity and ensures that the differential GPS base station clock offset remains constant over a relatively long (several thousand seconds) time period. this is,
Next, the DG using asynchronous transfer of corrected data, enabling the use of differential GPS corrections, measured at different times,
Substantially improve the performance of the PS system. This also improves system performance when data bit errors occur or when the communication channel is slow.

At the user's terrestrial (or other) receiver terminal, the "Eurofix" Loran C transmission at 5 is located from the local GPS receiver 6 connected by the DGPS data carried in the Laurent C transmission. Receive calibration. This results in DGPS position and velocity output of the receiver 6 and raw or calibrated Laurent C position data from the Laurent C receiver 5. Suitable receivers are described, for example, in U.S. Patent Nos. 3,736,590, 3,774,210, 3,92
Nos. 1,076, 4,392,138, and 4,482,896.

Focusing on the preferred receiver terminal embodiment of the present invention, a separate satellite navigation signal and a Laurent C navigation signal fixed point provide a new level of integration and accuracy in the embodiment of the present invention shown in FIG. Can be used for The satellite navigation system SNS receiver 3 ', such as a GPS receiver, includes:
As shown, a differential correction is provided from a data receiver 4 'of the differential satellite navigation system, for example, as described in a DGPS article cited earlier. The local Laurent C receiver 5 'provides its independent position, course, speed, and integrity, which are well known and described in the above-referenced patents and, for example, "CNSS Monitoring Site" by Gunther, GT. Of the Laurent C station as a candidate (The Potential
of Loran-C Station As CNSS Monitoring Sites) "
(International Technical Conference of the Navigation Association (January 20-22, 1993)
Day) minutes). A particularly suitable Laurent C receiver is of the Applicant's type "Acufix".
This Laurent C information, as shown, is applied to a data analysis computer, as described in the cited example above, and is of the type described in the article cited above, GP
S, or other SNS receiver 3 'independently combined with desired position, course, speed, and integrity data. Optimal position, course and speed information is generated from computer C for display to a ground (or other) user at D.

This so-called Type I configuration of FIG. 3, with augmentation by Laurent C, provides the most useful supplementary navigation signal. The Laurent C grid is known to have an offset associated with the uncertainty of LF propagation over land. This uncertainty is derived from the Laurent C signal,
It degrades the geographic accuracy of horizontal position data. However, the Laurent C gradient, which is useful in determining local area velocity, ie, change in position, is extremely stable over a relatively short period of time (several hours). Thus, changes in position can be measured very accurately. The augmentation of GPS by Laurent C is therefore by Laurent C at 5 '
It is possible to calibrate very fine position changes, ie velocity determination and, as previously explained, the Laurent C grid, 3 ′
With the very precise accuracy of GPS at
By using Laurent C between DGPS fixed points (or, more generally, DSNS fixed points), it is more likely to receive differential correction signals, possibly due to data bit errors or slow communication channels. Long delays are tolerated, and users may be responsible for faulty satellites, interference, or the lack of sufficient satellites with proper geometry,
You will be able to get in during the period of GPS suspension.

In the operation mode of the present invention shown in FIG. 4 (Type II), the differential GPS (or SNS) receiver 4 ′
Separately, the previously described pseudorange, pseudorange rate, derived by signal processing of the SNS received signal at 7;
And satellite speed (SV) data, and Roland C receiver 5 '
Analysis computer C with time difference from
Input the signal.

In the "Type III" mode of the present invention in FIG. 5, the Laurent C receiver outputs time difference and integrity data, and the SNS pseudorange is combined with the Laurent C time difference.

With respect to augmenting the communication channel using the Laurent C navigation signal, the use of the Laurent C navigation signal to provide the communication channel has already been achieved using pulse position modulation in the transmitter 1 of FIG. For example, U.S. Pat.Nos. 4,821,038 and 4,800,
As described in Issue 391, the data bits are represented,
The navigation service has no visible deterioration. Theoretically, this modulation could result in a 1.75 db noise reduction in the signal-to-noise ratio of the Laurent C system. However, in a Laurent C navigation system designed for a typical 30 db variation in atmospheric noise,
Noise reduction is meaningless. Elimination of the measured Laurent C carrier phase offset is accomplished by encoding the leading and lag bits to ensure an equal number of pulse positions, as described in the above patents. However, obviously, in addition to pulse position modulation, other techniques for modulating Laurent C radio frequency pulse transmission can also be used, including phase codes, alone or in combination with pulse position modulation. Flip or its presence,
Or, the lack may include other signal formats, such as adding extra pulses, that can constitute the message, but in essence, anything that does not interfere with the accuracy of the navigation signal.

The "Eurofix" / Laurent augmented GPS, with GPS differential correction and integrity message distributed to the user by modulation on the Roland C navigation signal, can be used, for example, for non-airplane flight in flight and at airports. Fine landing, ocean-
It offers the advantage of meeting the many exacting requirements of diverse user communities, including navigation between ports and on entry, or vehicle location for small portions of urban parcels. The present invention makes full use of the Laurent C system infrastructure of land, buildings, power, telecommunications, precision clocks, and personnel using the Roland C transmission station as a DGPS monitoring site. The service area is large, up to 600 km or more from any Laurent C transmitting station. All of the subsystems required to implement the present invention are now available and well-documented, so that implementation in the near future is possible, and such implementations are inexpensive for both users and service providers. It is something. No new radio spectrum allocation is required for each user community, as distinguished by the use of separate frequencies, and Laurent C / DGPS corrections and integrity messages are managed by local jurisdictions. Below. In addition, the user must
Or Laurent C, Integrated GPS / Laurent C, and DG
"Eu with integrated GPS / Laurent C with added PS correction and Laurent C calibrated by corrected GPS"
It has a high level of security, with many levels of capabilities, called rofix.

Further modifications will occur to those skilled in the art and such modifications are deemed to fall within the spirit and scope of the invention as defined in the appended claims.

[0025]

According to the present invention, as described above, SNS or G
In order to augment PS, Laurent C technology is used. In either case of local or wide area augmentation, the Laurent C signal is timed to provide additional position information, and the addition of satellites available between augmented data messages and for user position and velocity equations. During the removal,
Used as communication signals and supplemental navigation signals used to smooth user position and velocity data.
The differential GPS monitor receiver is located at the Laurent C station, which ensures reliable operation, so that the Laurent C
Relatively small increases in intra-office power loads and workloads do not substantially affect site staffing and operational costs and provide the best reliability possible.

In addition to the site's technical capabilities, the triple recombination cesium frequency standard at the station allows for accurate and fast determination of GPS integrity, and the clock offset of the differential GPS base station can be relatively small. Ensure that it remains constant over long (several thousand seconds) time periods. this is,
Next, the DG using asynchronous transfer of corrected data, enabling the use of differential GPS corrections, measured at different times,
Substantially improve the performance of the PS system. This also improves system performance when data bit errors occur or when the communication channel is slow.

Also, the LF over the land of the Laurent C grid
The propagation uncertainty degrades the geographic accuracy of the horizontal position data derived from the Laurent C signal. However, since the Laurent C gradient, which is useful in determining local area velocity, ie, change in position, is extremely stable over a relatively short period of time (several hours), the change in position is
It can be measured very accurately.

Furthermore, all of the subsystems required to implement the invention are now available and well documented, so that implementations in the near future are possible, and such implementations
It is inexpensive for both users and service providers. No new radio spectrum allocation is required for each user community, as distinguished by the use of separate frequencies, and the Laurent C / DGPS correction,
And integrity messages are under the control of local jurisdiction.

[Brief description of the drawings]

FIG. 1 is a block diagram of a Laurent C transmitter station interacting with local GPS receiver information for the “Eurofix” system.

FIG. 2 is a similar block diagram of a terrestrial or other user receiver device for the Laurent C transmission of FIG.

FIG. 3 is a block diagram of an integrated Laurent C and satellite navigation receive signal according to a separate fixed point mode of operation of the present invention.

FIG. 4 is a block diagram of SNS pseudorange and Laurent C time difference integration under the principles of the present invention.

FIG. 5 is a block diagram of SNS pseudorange and Laurent C arrival time (pseudorange) integration under the principles of the present invention.

[Explanation of symbols]

 3 'satellite navigation system (SNS) receiver 4' differential satellite navigation system (DSSNS) receiver 5 'local Laurent C receiver 7 SNS signal processor C analysis computer D navigation display

Claims (15)

[Claims] 1. A satellite navigation system comprising a plurality of satellites for transmitting a radio navigation signal to a terrestrial user receiver and communicating an augmented data message to improve the accuracy and integrity of the navigation signal. Receiving, at each terrestrial receiver, a Laurent C navigation signal; and using the received augmented satellite navigation signal and message to use the Laurent C signal as a communication signal and a supplementary navigation signal.
Integrating with the received Laurent C signal, i.e. providing additional location information to the location information of the satellite navigation signal, which can be used between any satellite signal augmented data messages and for determining the position and speed of the user receiver Timing the Laurent C signal to smooth the user position and velocity data between any added satellites and deleted satellite communications. 2. Differentially correcting the user-received satellite navigation signal to generate improved position, course, speed, and integrity information; and calculating the position, course, and speed from the Laurent C received signal. Further steps are performed, including deriving separate fixed points of the integrity information and analyzing and combining all received information to obtain optimal position, course and speed decisions. ,
The method of claim 1. 3. Differentially receiving a satellite navigation signal to generate differential correction and integrity information; and generating pseudorange, pseudorange rate, and satellite speed data information. Further steps are performed, including signal processing of the received satellite navigation signals, and analyzing and combining all received information to obtain optimal position, course and speed determinations. Item 1. The method according to Item 1. 4. Differentially receiving a satellite navigation signal to generate differential correction and integrity information; and generating pseudo-range, pseudo-range rate, and satellite velocity data information. Signal processing of the received satellite navigation signal, deriving pseudorange, pseudorange rate and integrity information upon arrival from the Roland C received signal, determining optimal position, course and speed Further analyzing and combining all received information to obtain the received information.
The method described in. 5. The satellite navigation signal with fine precision is used to calibrate the stable gradient grid of the Laurent C signal, and the location between fixed points of the satellite navigation signal and the fine definition of the Laurent C in speed determination. The method of claim 1, wherein using the change enables user reception throughout a period of satellite signal outage. 6. The Laurent C communication signal comprises:
The method according to claim 1, wherein the method is provided by a modulation based on a radio navigation signal transmission. 7. The method of claim 6, wherein the modulation is one or both of pulse position modulation and phase code flip modulation, serving as a data bit representation. 8. The method according to claim 1, wherein pulse position modulation is used.
8. The method of claim 7, wherein the measured carrier phase offset of the signal is provided by an encoding that provides an equal number of pulse positions to the leading and lagging bits. 9. An apparatus for integrating Loran C navigation and communication signals, radio navigation signals of a satellite navigation system, and augmented data message signals, for improving system accuracy, availability, and integrity. A user terrestrial receiver for receiving satellite radio navigation signals and augmenting data message signals, including one or more of satellite clock offset, orbit parameters, propagation conditions, and / or pseudorange corrections Means and, in each of such receiver means, as a communication signal and a supplementary navigation signal, Laurent C
A Roland C receiver means for receiving signals is provided between satellite signal augmented data messages, and between added satellites and deleted satellite communications available for position and velocity determination of user receiver means. , Device for smoothing user position and velocity data, in combination. 10. A means for using a fine-accuracy received satellite navigation signal to calibrate a grid of stable gradients of a received Laurent C signal; 10. The apparatus of claim 9, wherein means are provided for enabling user reception throughout the period of the satellite signal outage using fine changes in the Laurent C of the speed determination. 11. A means for differentially correcting a user-received satellite navigation signal to generate improved position, course, velocity, and integrity information, and a position, course, from a Laurent C received signal. Means for deriving a separate fixed point of the speed, speed, and integrity information, and means for analyzing and combining all the received information to obtain an optimal position, course, and speed determination, are provided. An apparatus according to claim 9. 12. A means for differentially receiving a satellite navigation signal to generate differential correction and integrity information, and for generating pseudorange, pseudorange rate, and satellite velocity data information. Wherein means are provided for signal processing the received satellite navigation signals and means for analyzing and combining all received information to obtain optimal position, course and speed determinations. Device according to claim 9. 13. Differentially receiving a satellite navigation signal to generate differential correction and integrity information;
Means for signal processing the received satellite navigation signal to generate pseudorange, pseudorange rate, and satellite velocity data information; and pseudorange, arrival pseudo, from the Laurent C received signal. 10. The method according to claim 9, wherein the steps of deriving range rate and integrity information and means for analyzing and combining all received information to obtain optimal position, course and speed decisions are provided. apparatus. 14. The apparatus of claim 9, wherein the Laurent C communication signal is provided as a modulation based on a Laurent C signal. 15. The Laurent C communication signal is provided by at least one of pulse position modulation and phase code modulation serving as a data bit representation.
An apparatus according to claim 4.