JPH1183978A - Gsp receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a GSP receiver which can continue highly accurate positioning when an abnormal data is mixed into the positioning operation due to abnormality of a satellite by detecting the abnormal data on the stage of pseudo distance and removing only the abnormal data from the positioning operation to continue normal operation and removing an abnormal satellite from the receiving satellites when it is not reset immediately and replacing the abnormal satellite with a normal one. SOLUTION: The GAPS receiver comprises a pseudo distance residue comparing section 8, and an abnormal data control section 9 wherein a previous measurement of pseudo distance is subtracted from a current measurement of pseudo distance for each receiving satellite to determine a pseudo distance residue which is then compared between respective satellites to determine the difference of pseudo distance residue. An abnormal data is specified by making a decision whether the difference of pseudo distance residue exceeds a predetermined threshold or not thus removing the abnormal data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS receiver that receives a signal from a GPS satellite and measures the current position.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing the configuration of a conventional GPS receiver of this type. In the figure, 1 is GPS
An antenna, 2 is a GPS receiving unit, 3 is a GPS almanac memory, 4 is a satellite selecting unit, 5 is a pseudorange measuring unit, 6 is an orbit data demodulating unit, and 7 is a positioning calculating unit. This kind of GP
As is well known, the S receiver has a plurality of receiving satellites (for example, 8 satellites) that receive signals based on almanac data.
Radio signals from these satellites are received and demodulated by the GPS receiver, the pseudoranges of the respective satellites are calculated by using the pseudorange measuring unit 5, and the satellites are transmitted by using the orbit data demodulator 6. Obtain the orbit data and obtain the position information of the satellite. Then, using the obtained position information of each satellite and the pseudo distance,
The positioning calculation unit measures its own position (user position) and outputs positioning information (latitude, longitude, and altitude data).

[0003] However, if an error occurs in the pseudo-range or demodulated orbit data measured due to, for example, a satellite error, not only will incorrect positioning data be output, but also abnormal pseudo-range or orbit data. Is continuously received and used as it is, so that normal recovery may be difficult. It should be noted that some conventional GPS receivers are configured to delete the positioning data and restart the positioning when, for example, an unexpected position jump or the like occurs in the output positioning data.

[0004]

As described above, the conventional G
Some PS receivers are configured to delete the positioning data and restart the positioning when an error occurs in the positioning data. However, when an error occurs in the positioning data due to a satellite error, etc. In such a case, there is a problem that the same abnormal data is output even if the positioning is redone, and it is difficult to return to the normal state.

The present invention has been made to solve such a problem. When abnormal data is mixed in positioning calculation due to a satellite abnormality or the like, the abnormal data is detected at a pseudo-range stage to perform positioning. Exclude only the abnormal data from the calculation and continue normal positioning.If the satellite does not recover immediately, remove the abnormal satellite from the receiving satellite and replace it with another normal satellite for high-precision positioning. G that can continue
It aims to provide a PS receiver.

[0006]

SUMMARY OF THE INVENTION A GPS receiver according to the present invention selects a plurality of receiving satellites for receiving radio waves, and measures a pseudo distance to each of the receiving satellites based on data received from each of the selected receiving satellites. In the GPS receiver that performs positioning, a value (referred to as pseudo-range residual) obtained by subtracting the pseudo-range measured last time from the pseudo-range measured this time is obtained for each receiving satellite. The difference (absolute value) of the pseudorange residual is obtained by comparing each satellite, and abnormal data is transmitted by determining whether or not the difference between these pseudorange residuals exceeds a predetermined threshold level. There is provided a means for specifying a receiving satellite, removing a pseudorange from the receiving satellite transmitting the specified abnormal data, and removing the abnormal data at a pseudorange stage to perform positioning calculation. Since the data from the abnormal satellite can be removed at the pseudo-range stage, incorrect positioning data is not output, and it is possible to prevent a phenomenon that it is difficult to return to normal due to the incorrect positioning data.

The pseudorange residual (RHO) is given by: RHO = UT-TSV-R / C-DUT (1) where UT: user time, TSV: GPS of the satellite
Signal transmission time, R: distance between the user and the satellite obtained in the previous positioning, C: speed of light, DUT: offset amount of user clock, obtained in units of time, and the threshold level is specified in units of time. It is characterized by the following.

[0008] Further, for the receiving satellite transmitting the specified abnormal data, the data is received again and the pseudorange is measured again. If the pseudorange measured again is not abnormal data, positioning is performed including the pseudorange. The calculation is performed.

[0009] Further, when the pseudo data is measured again and the pseudo data is measured again, if the measured pseudo data is specified as abnormal data, another satellite is used as a receiving satellite in place of the satellite. It is characterized by the following.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the GPS receiver of the present invention. In the figure, 1 is a GPS antenna, 2 is a GPS receiver, 3 is a GPS almanac memory, 4 is a satellite selector, 5 is a pseudorange measuring unit,
Reference numeral 6 denotes a trajectory data demodulation unit, 7 denotes a positioning operation unit, 8 denotes a pseudorange residual comparison unit, and 9 denotes an abnormal data control unit.

Next, the operation will be described. Satellite selector 4
Then, a plurality of (for example, eight) receiving satellites for receiving a signal are selected based on the GPS almanac data, a GPS receiver 2 receives and demodulates radio waves from these satellites, and uses a pseudo distance measuring unit 5. In addition to obtaining the pseudo distance from each satellite, the orbit data demodulator 6 obtains the position information of each satellite from the orbit data of the satellite. The pseudo-range of each satellite obtained by the pseudo-range measuring unit 5 is input to a pseudo-range residual comparing unit 8 to calculate the pseudo-range residual of each satellite, and these pseudo-range residuals are compared for each satellite. Then, a difference between the pseudorange residuals is obtained, and it is determined whether or not the difference between the pseudorange residuals is larger than a predetermined threshold level.

Here, the pseudorange residual (RHO) and its comparison will be described. The pseudorange residual (RH)
O) means, for example, RHO = UT-TSV-R / C-DUT Expression (1) where UT: user time, TSV: GPS of the satellite
The signal transmission time, R: the distance between the user and the satellite obtained in the previous positioning, C: luminous flux, DUT: offset amount of the user clock, is a measured distance difference expressed in units of time. The pseudo distance residual RHO may be a time obtained by subtracting the pseudo distance (UT-TSV) n-1 obtained last time from the pseudo distance (UT-TSV) n obtained this time.

Next, the difference (absolute value) of the pseudorange residual RHO of each satellite calculated in this manner is compared for each satellite, and it is determined whether or not the difference is larger than a predetermined threshold level. I do. | RHOi-RHOj |> threshold level For example, when there are eight receiving satellites, 28 kinds of determinations are made. This threshold level is, for example, 500 μs
When (150 km) is set, even if the GPS receiver is mounted on a moving body and moving, it is unlikely that the moving body will be displaced in this way, and the difference in the pseudorange residual RHO exceeding the threshold level is considered. Therefore, it can be seen that data from any satellite is abnormal data. Also 2
By judging the eight combinations, it is possible to determine from which satellite the data is abnormal.

When abnormal data is detected by the pseudo-range residual comparing unit 8 as described above, the pseudo-range from another receiving satellite excluding the pseudo-range from the satellite from which the abnormal data is detected is calculated by positioning. The position information of each satellite is obtained from the orbit data sent from the orbit data demodulation unit 6 to determine the self-position (user position), and the positioning information (latitude, longitude, altitude data) is output. . Further, the information on the abnormal data is input to the abnormal data
Operates to send a reset signal to the pseudo-range measuring unit 5 and the orbit data demodulating unit 6 to re-receive data from the satellite and execute the pseudo-range measurement and demodulation of the orbit data of the satellite again. Then, the pseudo distance measured by this re-execution is judged again by the pseudo distance residual comparing unit 8 as to whether or not it is abnormal data. If the pseudo distance is not abnormal data, the pseudo distance data is also sent to the positioning calculation unit 7. Then, positioning calculation is performed.
If the pseudo distance measured by the re-execution is also abnormal data, the abnormal data control unit 9 operates the satellite selection unit 4 to remove the satellite that sends the abnormal data from the receiving satellite, and replaces it with another satellite. Select the satellite as the receiving satellite.

[0015] Even when there is a satellite that operates as described above and transmits abnormal data, positioning calculation is performed using pseudorange data from a normal satellite, so that the output positioning information is correct. It becomes information, and it is possible to prevent the occurrence of a position jump or the like. Further, even in the case where the satellite abnormality does not recover immediately, the positioning is continued using the replacement satellite as the receiving satellite, so that the deterioration of the positioning accuracy can be prevented.

[0016]

As described above, the GPS receiver of the present invention compares the pseudorange residual for each satellite to determine the difference in the pseudorange residual, and compares the pseudorange residual with the threshold level. Since the positioning calculation is performed by removing the abnormal data at the distance, the output of the incorrect positioning data can be prevented even when an abnormal satellite exists, and the occurrence of position jump can be prevented. In the case where the abnormal satellite does not return immediately, the receiving satellite is replaced with another satellite and the positioning calculation is continued, so that the positioning accuracy can be prevented from deteriorating.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus configuration for explaining the present invention.

FIG. 2 is a block diagram for explaining a conventional GPS receiver of this type.

[Description of Signs] 1 GPS antenna 2 GPS receiving unit 3 GPS almanac memory 4 Satellite selecting unit 5 Pseudorange measuring unit 6 Orbit data demodulating unit 7 Positioning calculating unit 8 Pseudorange residual comparing unit 9 Abnormal data control unit

Claims (4)

[Claims] 1. A GPS for selecting a plurality of receiving satellites for receiving radio waves and measuring a pseudo distance to each of the receiving satellites based on data received from each of the selected receiving satellites for positioning.
The receiver calculates a value obtained by subtracting the pseudo distance measured last time from the pseudo distance measured this time (called pseudo distance residual) for each receiving satellite, and compares these pseudo distance residuals for each satellite. The difference (absolute value) between the pseudorange residuals is obtained, and the receiving satellite transmitting the abnormal data is identified by determining whether or not the difference between these pseudorange residuals exceeds a predetermined threshold level. Means for removing a pseudorange from a receiving satellite transmitting the specified abnormal data, and performing positioning calculation by removing the abnormal data at a pseudorange stage. 2. The pseudorange residual (RHO) is given by: RHO = UT−TSV−R / C−DUT (1) where UT: user time, TSV: GPS of the satellite
Signal transmission time, R: distance between the user and the satellite obtained in the previous positioning, C: speed of light, DUT: offset amount of the user clock, obtained in units of time, and the threshold level is specified in units of time. The GPS receiver according to claim 1, wherein: 3. The receiving satellite transmitting the specified abnormal data receives the data again and measures the pseudorange again. If the pseudorange measured again is not abnormal data, the pseudorange is included. The GPS receiver according to claim 1, wherein positioning calculation is performed. 4. A means for receiving another data and measuring the pseudo-range again, and when the measured pseudo-range is identified as abnormal data, means for using another satellite as a receiving satellite in place of the satellite. The GPS receiver according to claim 3, wherein: