JP2003018061A - Satellite navigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a satellite navigation system that supervises a maximum rate of change in an ionospheric layer in both the time and space, to reduce probability of impairing the safety of aircrafts. SOLUTION: GPS(global positioning system) 110a, 110b acquire data from the ionospheric layer and transmit a GPS signal to ground. A geostationary satellite 109 relays the data and transmits the data to ground. A plurality of SBAS(satellite based augmentation system) reference stations 102 are installed on ground to receive the GPS signal from the GPS 110a, 110b and the geostationary satellite 109. An ionospheric layer monitor device 101 receives the GPS signal and the data from the geostationary satellite 109, to monitor, the ionospheric layer. A processing station 111 receives the signal received by the SBAS reference stations 102, coming from the GPS 110a, 110b and the geostationary satellite 109 and outputs date to a ground uplink station 107. The ground uplink station 107 transmits a transmission message 108 to the geostationary satellite 109.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite navigation monitoring system, and in particular, it is a worldwide system for monitoring satellite signals such as GPS over a wide area on the ground, and as a result, generating a reinforcement message and transmitting it to an aircraft via a geostationary satellite. Satellite navigation surveillance system.

[0002]

2. Description of the Related Art Recently, satellite navigation to an aircraft by satellites in low earth orbit, middle altitude orbit, geostationary orbit, etc. has been actively performed. Wide area satellite navigation reinforcement system (Satell)
iteBased Augmentation Sys
tem: hereinafter referred to as SBAS), highly reliable information is provided in real time to an aircraft flying in the atmosphere by improving the positioning accuracy.

However, a change in the electromagnetic wave propagation delay caused by a change in the ionosphere may lower the accuracy of radio positioning, so it is necessary to obtain and notify the latest information on the ionosphere.

FIG. 3 is a system block diagram showing a conventional satellite navigation monitoring system.

Referring to FIG. 3, the GPS (Global PB) is established in each of a plurality of SBAS reference stations 401, SBAS reference stations 402, SBAS reference stations 403, and SBAS reference stations 404 installed on the ground.
Positioning System) 411, GPS
The GPS signals 405a, 405c, 405f, and 405h from 412, GPS413, and GPS414 are monitored.

These SBAS reference stations 401-4
The information monitored by 04 analyzes various error factors at processing station 410 via SBAS terrestrial network 407. For example, GPS clock error, ephemeris error, ionospheric error, and troposphere error. As a result of analyzing the error, some error factors are divided into categories, the correction value and the confidence level are calculated, and transmitted from the terrestrial uplink station 406 to the geostationary satellite 415 through the uplink line 408 and the geostationary satellite 415. To the aircraft 416 via the downlink line 409. The information transmitted by this downlink line 409 is GP
It includes provision of S signal, differential correction information, and integrity information.

In this case, the category of the variable element is divided into three types: a high-speed correction value having a relatively high-speed variable element, a long-term correction value having a relatively slow variable element, and an ionosphere correction value.

Here, the confidence level is a correction value for the calculated variable element, which is the aircraft 4 which is the user.
When 16 is used, 99.9% is the accuracy of the residual error that is overbound.

Normally, a user of an aircraft or the like cannot know the true value of his / her position during navigation. Therefore, basically, the navigation is performed based on the information from the navigation system such as the satellite navigation system. However, satellite navigation systems handle signals with errors, and at the same time, there is no guarantee that 100% of the correct information can be transmitted to the user, considering the incompleteness of the algorithm and the unpredictable situation. Therefore, the above-mentioned correction of the ionosphere and the confidence level are calculated together, and it is judged that this value should exceed the residual error with a corresponding probability.

FIG. 4 is a block diagram showing a conventional SBAS ionosphere monitoring system.

Received signals from the GPS 210a, 210b and the geostationary satellite 212 received by the SBAS reference station 202 are input to the processing station 211. Processing station 211
Then, the input data validity check unit 203 checks whether or not the data of the input received signal is valid.

GPS signals from the GPS 210a and 210b are weak radio waves and are generally affected by various noises. Further, in the receiver using the carrier phase, a phenomenon called cycle slip occurs when the satellite is unlocked, and an error corresponding to an integral multiple of the wavelength may occur. The defective data such as the multipath delay, the influence of noise, and the cycle slip are removed by the input data validity check unit 203, and are output to the statistical processing unit 204 which extracts only valid data. However, multiple error factors are related and it is difficult to completely separate them.

Therefore, in general, when the error factors can be accurately separated, the confidence level is high (in this case,
The value is small), and if the degree of separation of error factors is ambiguous, the confidence level is low (in this case, the value is large).

Next, the statistical processing unit 204 derives an ionospheric delay estimated value at the Pierce point based on the ionospheric measurement value at the Pierce point and the ionospheric correction value calculated at the grid point, and statistically processes them. The data is output to the statistical processing unit 205.

FIG. 5 is a diagram for explaining the pierce point and the grid point.

The Pierce Point 501 is a satellite and SBA
The S reference station is connected by a straight line and indicates the point where it intersects with the point at an altitude of 350 km. Although the influence of the ionosphere varies depending on altitude, it is said that the 350 km point is the largest,
The model represented here is generally used. FIG. 5 shows an image of this projected on the earth.

On the other hand, the grid points 502 are, in principle, the intersections when the latitude and longitude are viewed at 5 degree intervals, and S
When the BAS system transmits an ionosphere-related message to the aircraft, the data for each grid point 502 will be transmitted.

The ionosphere is a natural phenomenon that changes continuously, but since it is impossible to install an infinite number of SBAS reference stations, it must be estimated based on limited measurement data. Points 501 and grid points 502 are provided.

Since the GPS 210a and 210b move every moment, the pierce point 501 of the ionosphere also moves with time. Therefore, from a plurality of Pierce points 501 obtained by a combination of a plurality of SBAS reference stations and GPS satellites, the ionosphere at a grid point 502 located at the center of a quadrangle surrounded by a grid of latitude and longitude lines enclosing them. The correction value and confidence level will be estimated. This estimation is performed by the statistical processing unit 205.
Is processed in.

The confidence level is the probability that an error at the grid point 502 has a reasonable probability (usually 99.9).
%) Is a parameter that indicates the accuracy of the overbound error, and since it is the value corresponding to the vertical component that is transmitted to the user in particular, the value of this parameter is given as GIVE.
(Grid Ionospheric Vertica
l Error) value.

The parameters from the statistical processing unit 205 are converted into a predetermined message format by the transmission message generation unit 206, the transmission message 208 is transmitted from the terrestrial uplink station 207 to the geostationary satellite 212, and the geostationary satellite 2 is transmitted.
12 will be transmitted to the user via the data link of the downlink 209, and will be received and monitored again by the SBAS reference station 202.

As an example of such a satellite navigation reinforcement system, the "reinforcement data relay device for satellite navigation reinforcement system" described in Japanese Patent Laid-Open No. 2000-206224 is known.

In this publication, the augmentation data transmitted from the SBAS satellite is transmitted to the DGPS (Differential Global) via the SBAS augmentation data relay device.
(Positioning System) correction data, the SBAS augmented data relay device transmits the DGPS correction data to the mobile station by a beacon wave, and the mobile station based on the navigation data and the DGPS correction data transmitted from the GPS satellite. Techniques for calculating position are described.

[0024]

In the conventional satellite navigation monitoring system described above, the SBAS reference station on the ground is installed only in a limited place, and it is said that it is possible to accurately monitor all ionospheric changes. Not always, especially if the estimation on the ground side is ambiguous, and overlook it and raise the confidence level more than necessary (that is, if the GIVE value is estimated to be low),
The user has to underestimate the magnitude of the actual error, which has the drawback that the aircraft is at risk.

On the contrary, it is possible to uniformly set the GIVE value to a large value, but if the GIVE value is increased without any grounds, the aircraft side determines that the satellite navigation signal is invalid and is hidden from the user. Although it can be avoided from danger, it has a drawback that the system cannot be used.

The object of the present invention is to monitor the maximum rate of change of the ionosphere in both time and space and to accurately derive the GIVE value based on the monitoring result. It is to provide a satellite navigation monitoring system that reduces the number and improves the reliability of the entire system.

[0027]

The satellite navigation monitoring system of the present invention is a wide area augmentation system for providing services to a wide area of the world in the satellite navigation system, and a plurality of monitoring stations installed on the ground. SBAS (Satelli
te Based Augmentation Sys
tem: hereinafter referred to as SBAS) Reference station and GP
S (Global Positioning System)
em), a processing station that generates a message, a data link that transmits the message from a terrestrial uplink station to an aircraft via a geostationary satellite, and the delay of radio waves by the ionosphere can be maximized as the sun moves. Equipped with multiple ionospheric monitoring devices installed on the route projected on the earth, based on the observation results of these ionospheric monitoring devices, while dynamically calculating the threshold for accurately determining the validity of the data , Reflecting the ionospheric correction value in the confidence level calculation and transmitting the message reflecting the ionospheric correction value to the aircraft via the processing station and the data link when an unexpected ionospheric fluctuation occurs. It has a feature.

A plurality of SBAS reference stations installed on the ground; an SBAS ground network of a wide area reinforcement system connected to these SBAS reference stations; and this SB
A ground uplink station connected to an AS ground network and transmitting augmented data; a geostationary satellite relaying the augmented data; a GPS transmitting GPS data; an augmented data from the geostationary satellite and the GPS data And the aircraft that is the user who receives the data; the data from the SBAS reference station is monitored, and the ionosphere prediction data is obtained by the built-in ionosphere time change rate monitoring function, ionosphere space change rate monitoring function, and ionosphere maximum change rate prediction function in the service airspace. A plurality of ionospheric monitoring devices for processing; receiving the ionospheric prediction data, and GIVE (Grid Ionospheric Ve) by the plurality of ionospheric monitoring devices;
and a processing station for calculating an ionosphere-corrected GIVE value and transmitting the reinforced data to the SBAS ground network.

Corresponding to the plurality of SBAS reference stations provided on the ground projection plane of the magnetic equator on the earth, the plurality of ionosphere monitoring devices, which are ground stations dedicated to ionosphere monitoring, are scattered all over the earth, The feature is that the monitoring data is always acquired in the region where the maximum change of the ionosphere is predicted.

Each of the plurality of SBAS reference stations monitors signals from the GPS, and analyzes various error factors in the ionosphere monitoring device based on information obtained by monitoring the magnetic equator. There is.

A GPS that acquires data from the ionosphere and transmits a GPS signal to the ground; a geostationary satellite that relays the data and transmits it to the ground; a plurality of GPSs installed on the ground.
An SBAS reference station for receiving GPS signals from the GPS and data from the geostationary satellites;
A plurality of ionospheric monitoring devices that receive S signals and data from the geostationary satellites and monitor the ionosphere; and input received signals from the GPS and geostationary satellites received at the SBAS reference station, and process data on the ground. A processing station for outputting to an uplink station; and a terrestrial uplink station for transmitting a transmission message to the geostationary satellite.

The processing station has an input data validity check unit for checking whether the data of the received signal inputted is valid; and the input data validity check unit for multipath delay, influence of noise, and cycle slip. Pear point based on the ionosphere correction value calculated at the grid point which is the intersection of the ionosphere measurement value at the ground monitoring point Pierce point and the latitude line and longitude line after the defective data is removed and only valid data is input. A first statistical processing unit for deriving ionospheric delay estimation values in, and statistically processing them; and since the GPS moves every moment, the pierce point of the ionosphere also moves with time, and the plurality of SBs
From a plurality of Pierce points obtained by a combination of an AS reference station and the GPS, ionospheric correction values and confidence levels at the grid points located at the center of a quadrangle surrounded by a grid of latitude and longitude lines encompassing them A second statistical processing unit for estimating
And a transmission message generation unit for converting the parameters from the statistical processing unit into a predetermined message format and outputting the converted message format to the terrestrial uplink station.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall conceptual view showing the arrangement of the satellite navigation monitoring system of the present invention.

Referring to FIG. 1, a plurality of SBAS reference stations 308a, SBAS reference stations 308b, SBAS reference stations 308c installed on the ground, an SBAS ground network 306 of a wide area reinforcement system connected to these SBAS reference stations, and this SBAS.
A terrestrial uplink station 307 that connects to the terrestrial network 306 and transmits data exchanged, a geostationary satellite 312 that relays data, and a GPS that transmits GPS data.
313, an aircraft 311 which is a user receiving data from the geostationary satellite 312 and GPS data, and SBAS
A plurality of ionospheres that monitor the data from the reference stations 308a to 308c and process the ionosphere prediction data by the built-in ionosphere time change rate monitoring function 302, ionosphere space change rate monitoring function 303, and ionosphere maximum change rate prediction function 304 in the service airspace. The GI by the monitoring device 301 and the ionosphere monitoring device 301 after receiving this ionosphere prediction data
Has an upward correction function for VE value prediction, and ionosphere-corrected GIVE
It comprises a processing station 305 for calculating values and transmitting the augmented data to the SBAS ground network 306.

Referring to FIG. 1, a data link for transmitting data from a terrestrial uplink station 307 to a geostationary satellite 312 via an uplink line and transmitting a message from the geostationary satellite 312 to an aircraft 311 via a downlink line. It has a function.

SBAS reference stations 308a-308
The signal from GPS313 is monitored in each of c. on the other hand,
Various error factors are analyzed by the ionosphere monitoring device 301 based on the information obtained by monitoring the magnetic equator 310. The error factors include, for example, a GPS 313 clock error, an ephemeris error, an ionosphere error, and a troposphere error. As a result of analyzing the error, the correction value and the confidence level are divided into categories of some error factors, and the ionosphere monitoring device 30
1 has a built-in ionosphere time change rate monitoring function 302, an ionosphere space change rate monitoring function 303, and an ionosphere maximum change rate prediction function 304 in the service airspace, which is transmitted to the processing station 305, and the processing station 305 outputs an ionosphere correction GIVE value. Calculate and transmit these data from the terrestrial uplink station 307 to the geostationary satellite 312 via the uplink line,
Aircraft 3 from geostationary satellite 312 via downlink line
11 will be transmitted.

That is, the SBAS reference stations 308a to 308a arranged on the ground projection plane of the magnetic equator 310 on the earth.
Corresponding to 308c, a plurality of ionosphere monitoring devices 301, which are ground stations dedicated to ionosphere monitoring, are scattered on the entire earth so that monitoring data can be always acquired in an area where the maximum change in the ionosphere is predicted.

It is generally known that the influence of the ionosphere changes along the magnetic equator 310. The magnetic equator deviates from the equator on the map to the north and south by about ± 10 to ± 15 degrees and surrounds the earth while meandering. The influence of this ionosphere is TEC (Total Ele) in a certain time zone.
ctron Content: proportional to the amount of ionospheric delay). It is known that in the Americas, it shifts toward South America, and conversely in the vicinity of Japan, it shifts toward the northern hemisphere, that is, toward Japan.

Further, it is known that the influence of the ionosphere coincides with the cycle of solar activity and changes in a cycle of about 11 years. Therefore, the ionospheric monitoring algorithm developed based on the measured data when the solar activity is inactive does not always function properly even when the solar activity becomes active.

Therefore, it is necessary to have a function capable of dynamically monitoring the activity of the ionosphere temporally and spatially and dynamically changing the operation of the algorithm depending on the monitoring result.

FIG. 2 is a block diagram showing one embodiment of the satellite navigation monitoring system of the present invention.

Referring to FIG. 2, GPS 110a, 1 for acquiring data from the ionosphere and transmitting GPS signals to the ground.
10b and a geostationary satellite 10 that relays data and transmits it to the ground
9 and a plurality of GPS 110a, 110b installed on the ground
A plurality of SBAS reference stations 102 for receiving GPS signals from the satellite and data from geostationary satellites 109;
A plurality of ionosphere monitoring devices 101 that receive GPS signals from S110a and 110b and data from a geostationary satellite 109 to monitor the ionosphere, and GPS 110a and 110b received by a plurality of SBAS reference stations 102 and reception from geostationary satellite 109. A processing station 111 that inputs a signal and outputs processed data to the terrestrial uplink station 107;
It is composed of a terrestrial uplink station 107 which transmits a transmission message 108 to a geostationary satellite 109.

In the processing station 111, the input data validity check unit 1 checks whether the data of the input received signal is valid.
Check with 03.

GPS signals from the GPS 110a and 110b are weak radio waves and are generally affected by various noises. Further, in the receiver using the carrier phase, a phenomenon called cycle slip occurs when the satellite is unlocked, and an error corresponding to an integral multiple of the wavelength may occur. The defective data such as the multipath delay, the influence of noise, and the cycle slip are removed by the input data validity check unit 103, and are output to the statistical processing unit 104 which extracts only valid data. However, multiple error factors are related and it is difficult to completely separate them.

Therefore, in general, when the error factors can be accurately separated, the confidence level is high (in this case,
If the degree of separation is ambiguous, the confidence level will be low (in this case, the value will be high).

Next, in the statistical processing unit 104, the ionosphere at the pierce point based on the ionosphere correction value calculated at the grid point, which is the intersection of the ionosphere measurement value at the ground monitoring point, the pierce point, and the latitude line and the longitude line. The delay estimates are derived and statistically processed.

As already described with reference to FIG. 5, the pierce point 501 indicates a point connecting the satellite and the reference station with a straight line and intersecting with a point at an altitude of 350 km. The impact of the ionosphere varies depending on altitude, but 350k
The m point is considered to be the largest, and the model represented here is generally used. The grid points 502 are, in principle, intersections when the latitude / longitude are viewed at intervals of 5 degrees, and when SBAS transmits an ionosphere-related message to an aircraft, data for each grid point is transmitted.

The ionosphere is a natural phenomenon that changes continuously, but since it is impossible to install an infinite number of SBAS reference stations, it must be estimated based on limited measurement data. It has points and grid points.

Since the GPS 110a and 110b move from moment to moment, the pierce point 501 of the ionosphere also moves with time. Therefore, from a plurality of Pierce points 501 obtained by a combination of a plurality of SBAS reference stations and GPS satellites, the ionosphere at a grid point 502 located at the center of a quadrangle surrounded by a grid of latitude and longitude lines enclosing them. The correction value and confidence level will be estimated. This estimation is performed by the statistical processing unit 105.
Is processed in.

Note that this confidence level has a corresponding probability (normally 9
9.9%) is a parameter indicating the accuracy of the overbound error, and a parameter that is transmitted to the user is a value corresponding to the vertical component, which is called a GIVE value. Parameters are converted into a predetermined message format by the transmission message generation unit 106, and the transmission message 108 is transmitted from the terrestrial uplink station 107 to the geostationary satellite 109.
09 to the user via the downlink data link and again to the SBAS reference station 10
2 will be received and monitored.

On the other hand, the plurality of ionosphere monitoring devices 101 derive the maximum rate of change predicted within the service coverage area from the temporal change and spatial change of the ionosphere. This result is used for the validity check shown in the input data validity check unit 103 and for the derivation of the GIVE value by the statistical processing unit 105. The GIVE value accurately calculated by the transmission message generation unit 106 is transmitted as a message in a predetermined format to the aircraft as the user and the SBAS reference station 102 via the terrestrial uplink station 107 and the geostationary satellite 109.

As described above, the signals from the GPS 110a and 110b are weak radio waves and are easily affected by noise, multipath, cycle slip, and the like. However, most of these have a local effect, that is, even if a cycle slip occurs in one reference station, it does not always occur in another station.

Further, since the same influence is not always received by the aircraft, which is the user located at a different place, the error caused by the ground measurement system is removed as much as possible, and only normal data is used by the user. It is desirable to generate augmentation data for In the extreme case, if the removal is impossible, the system can be removed without using the data of the site. Therefore, focusing only on this point, eliminating the suspicious data as much as possible increases the operating rate of the system.

However, this is not always the case for the ionosphere. In other words, the influence of the ionosphere changes over a fairly wide range and over time, so if a large fluctuation of the ionosphere that exceeds the predictable range occurs,
If this is judged to be equivalent to local noise, incorrect information will be conveyed to the user. That is, the GIVE value is underestimated, which puts the user at risk.

This is because the ionosphere affects users even in the coverage area where there is no SBAS reference station on the ground. Therefore, based on the data collected by the ionosphere monitoring device 101 on the route projected on the earth where the ionosphere changes maximally, the input data validity checking unit 103 uses the statistical value of the estimated rate of change to determine the validity judgment threshold. It will change the level. By this operation, the data that has been inappropriately excluded in the past becomes valid, and the monitoring result is reflected in the GIVE value in the GIVE value estimation function in the statistical processing unit 105.

Since the correction value of the ionosphere can be implemented by using the receiver compatible with two frequencies, the receiver of the aircraft which is the user is compatible with two frequencies. This can be realized if there is an algorithm that allows the user to bounce the residual error with a predetermined probability, but currently there are the following problems.

At present, of the GPS frequencies, only one wave in the L1 band is protected internationally as a navigation band. Both frequencies are expected to be protected as navigation bands in the future, but the development of next-generation GPS satellites must be awaited. Further, even if the satellite side supports, not all user receivers simultaneously support two frequencies, and it is essential to consider the monitoring system on the ground side.

On the other hand, RAIM (Receiver Auto) is used as a function of ensuring the safety of the aircraft receiver alone.
nomous Integrity Monitori
ng) function is known, but the performance often deteriorates due to satellite arrangement, etc., and in terms of reliability, the function of the SBAS reference station must be relied upon.

As described above, a plurality of ionosphere monitoring devices 101 are provided on the ground projection plane corresponding to the magnetic equator 310, which is the path through which the ionosphere fluctuates greatly, and the time of ionospheric fluctuations
GIV is a parameter that protects the user with respect to ionospheric error by adding a function to more accurately judge the validity of GPS data by statistically processing spatial changes.
The E value is set to an accurate value regardless of the state of the ionosphere.

That is, the current SBAS reference station 10
The reference station on the ground in 2 is installed only in a limited place, and not all ionospheric changes can be monitored accurately, so even if the ionospheric estimation on the ground side is ambiguous, I overlooked it,
If one underestimates the GIVE value of the ionosphere, the user will underestimate the magnitude of the actual error, and the aircraft will be at risk. Therefore, a function that can accurately derive the GIVE value is required.

In response to this, the fluctuation of the ionosphere causes the magnetic equator 3 to change.
Focusing on moving on the earth along 10, the ionosphere monitoring device 101 is provided on or near the magnetic equator, and statistical processing is performed based on the function of monitoring the maximum rate of change of the ionosphere both in time and space and the monitoring result. By adding the function to select the input data accurately, even if the ionospheric fluctuations that cannot be predicted at the time of system development are large, the GI is accurate.
The VE value can be derived to protect the user.

A function of promoting the dynamic change of the threshold level of the data validity check based on the monitoring of the maximum temporal / spatial change rate of the ionosphere and the result, and a function of accurately reflecting it on the GIVE value based on its statistical processing. By having the above, the safety of the aircraft user is enhanced.

[0064]

As described above, the satellite navigation monitoring system of the present invention monitors the maximum temporal / spatial change rate of the ionosphere, and dynamically changes the threshold level of data validity check based on the result and statistical processing. Based on GIVE
Since it can be accurately reflected in the value, even if there is an unpredictable fluctuation in the ionosphere, it reacts accurately and has the effect of guaranteeing the safety of the user.

[Brief description of drawings]

FIG. 1 is an overall conceptual diagram showing an arrangement of a satellite navigation monitoring system.

FIG. 2 is a block diagram showing one embodiment of the satellite navigation monitoring system of the present invention.

FIG. 3 is a system block diagram showing a conventional satellite navigation monitoring system.

FIG. 4 is a block diagram showing a conventional SBAS ionosphere monitoring system.

FIG. 5 is a diagram illustrating a pierce point and a grid point.

[Explanation of symbols]

101 ionosphere monitoring device 102 SBAS reference station 103 input data validity check unit 104 statistical processing unit 105 statistical processing unit 106 transmission message generation unit 107 ground uplink station 108 transmission message 109 geostationary satellites 110a, 110b GPS 111 processing station 202 SBAS reference station 203 Input data validity check unit 204 Statistical processing unit 205 Statistical processing unit 206 Transmission message generation unit 207 Ground uplink station 208 Transmission message 209 Downlink 210a, 210b GPS 211 Processing station 212 Geostationary satellite 301 Ionosphere monitoring device 302 Ionosphere time change rate Monitoring function 303 Ionospheric space change rate monitoring function 304 Ionospheric maximum change rate prediction function 305 Processing station 306 SBAS ground network 307 Ground uplink station 308a , 308b, 308c SBAS Reference Station 310 Magnetic Equator 311 Aircraft 312 Geostationary Satellite 313 GPS 401, 402, 403, 404 SBAS Reference Stations 405a, 405b, 405c, 405d, 405e,
405f, 405g, 405h GPS signal 406 Terrestrial uplink station 407 SBAS Terrestrial network 408 Uplink line 409 Downlink line 410 Processing station 411, 412, 413, 414 GPS 415 Geostationary satellite 416 Aircraft 501 Pierce point 502 Grid point

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5J062 AA08 BB03 CC07 DD12 EE02                       EE04                 5K067 BB21 DD51 EE07 FF02 GG01                       GG11 HH22 LL01 LL05 LL11                 5K072 AA02 AA24 BB02 BB13 BB18                       BB22 DD02 GG08 HH01 HH08

Claims (6)

[Claims] 1. A satellite navigation system is a wide area augmentation system that provides services to a wide area worldwide, and is a plurality of surveillance stations installed on the ground, SBAS (Sat).
ellite Based Augmentation
System: hereinafter referred to as SBAS) Reference station and GPS (Global Positioning)
The processing station that generates the message to supplement the system), the data link that transmits the message from the terrestrial uplink station to the aircraft via the geostationary satellite, and the delay of the radio waves by the ionosphere with the movement of the sun can be maximized. Equipped with multiple ionospheric monitoring devices installed on the route projected on the earth, based on the observation results of these ionospheric monitoring devices, while dynamically calculating the threshold for accurately determining the validity of the data , Reflecting the ionospheric correction value in the confidence level calculation and transmitting the message reflecting the ionospheric correction value to the aircraft via the processing station and the data link when an unexpected ionospheric fluctuation occurs. Characteristic satellite navigation monitoring system. 2. A plurality of SBAS reference stations installed on the ground; an SBAS terrestrial network of a wide area reinforcement system connected to these SBAS reference stations;
A terrestrial uplink station that is connected to the BAS terrestrial network and transmits augmented data; a geostationary satellite that relays the augmented data; a GPS that transmits GPS data;
An aircraft that is a user who receives the augmented data from the geostationary satellite and the GPS data; and a built-in ionosphere time change rate monitoring function, ionosphere space change rate monitoring function, and service airspace that monitors data from the SBAS reference station. A plurality of ionosphere monitoring devices that process the ionosphere prediction data by the ionosphere maximum change rate prediction function; and a GIVE (Grid Ionospheric V) by the plurality of ionosphere monitoring devices that receives the ionosphere prediction data.
a satellite navigation monitoring system having an upward correction function for the prediction of an optical error, calculating a ionosphere-corrected GIVE value, and transmitting the reinforced data to the SBAS ground network; . 3. Corresponding to the plurality of SBAS reference stations provided on the ground projection plane of the magnetic equator on the earth,
The satellite according to claim 2, wherein the plurality of ionospheric monitoring devices, which are ground stations dedicated to ionospheric monitoring, are scattered all over the earth, and the monitoring data is always acquired in an area where the maximum change in the ionosphere is predicted. Navigation monitoring system. 4. Each of the plurality of SBAS reference stations monitors signals from the GPS, and analyzes various error factors in the ionosphere monitoring device based on the information obtained by monitoring the magnetic equator. The satellite navigation monitoring system according to claim 2, which is characterized in that. 5. A GPS that acquires data from the ionosphere and transmits a GPS signal to the ground; a geostationary satellite that relays the data and transmits the data to the ground; a plurality of GPSs installed on the ground.
An SBAS reference station for receiving GPS signals from S and data from the geostationary satellites; G from the GPS
A plurality of ionospheric monitoring devices that receive PS signals and data from the geostationary satellites and monitor the ionosphere; and input received signals from the GPS and geostationary satellites received by the SBAS reference station, and process data on the ground. A satellite navigation monitoring system comprising: a processing station for outputting to an uplink station; and a terrestrial uplink station for transmitting a transmission message to the geostationary satellite. 6. The processing station includes an input data validity check unit for checking whether or not the data of an input received signal is valid; a multipath delay, an influence of noise, and a cycle in the input data validity check unit. Slip defect data is removed, only valid data is input, and the ionosphere measurement value and latitude line at the ground monitoring point, Pierce Point,
A first statistical processing unit for deriving an ionospheric delay estimation value at a Pierce point based on an ionospheric correction value calculated at a grid point which is an intersection of longitude lines, and statistically processing these; and the GPS moves momentarily. Therefore, the pierce point of the ionosphere also moves with time, and the plurality of S
From a plurality of Pierce points obtained by the combination of the BAS reference station and the GPS, the ionosphere correction value and the confidence level at the grid point located at the center of a quadrangle surrounded by a grid of latitude and longitude lines encompassing them And a transmission message generation unit for converting the parameter from the second statistical processing unit into a predetermined message format and outputting the parameter to the terrestrial uplink station. The satellite navigation monitoring system according to claim 5, characterized in that: