JP2010145179A - Gnss receiving device and positioning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an influence of multipath, and to improve positioning accuracy. <P>SOLUTION: This GNSS (Global Navigation Satellite System) receiving device for performing positioning operation, based on a positioning signal transmitted from a GNSS satellite has: a pseudo distance operation part for determining a pseudo distance between the GNSS satellite and the GNSS receiving device by using a cord included in the positioning signal; a route difference changing rate estimation part for estimating a changing rate of a route difference between a direct wave and a reflected wave from the GNSS satellite; a time constant setting part for determining a time constant of a filter corresponding to the changing rate of the route difference estimated by the route difference changing rate estimation part, and setting the time constant; and a noise removal part for filtering the pseudo distance determined by the pseudo distance operation part with a phase variation of a carrier wave, by the time constant set by the time constant setting part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a GNSS receiver and a positioning method for receiving a signal from a GNSS orbiting satellite and measuring the position and velocity.

  The Global Navigation Satellite System (GNSS) is a system that obtains the distance from each GNSS satellite by capturing three navigation satellites (GNSS orbiting satellites) (hereinafter referred to as GNSS satellites) from the aircraft, It is a navigation system that can obtain the flight position in three dimensions of the aircraft by adjusting the time with the signal from the eye navigation satellite. Satellite navigation includes the Global Positioning System (GPS), Galileo, and others.

For example, a GNSS receiver is mounted on a moving body and measures the position and speed of the moving body. For example, the GNSS receiver receives radio waves from a plurality of GNSS satellites to measure the distances (pseudo distances) from the plurality of GNSS satellites to the GNSS receiver, and receives the GNSS reception based on the measured values. Measures the moving object equipped with the device. The signal emitted by the GNSS satellite arrives at the GNSS receiver with a delay in the distance between the GNSS satellite and the GNSS receiver by the time the radio wave propagates. Therefore, if the time required for radio wave propagation is obtained for a plurality of GNSS satellites, the position of the GNSS receiver can be obtained by positioning calculation. For example, for radio waves emitted by a plurality of GNSS satellites, the distance from each GNSS satellite to the GNSS receiver is determined in the refusal section of the GNSS receiver. Then, the positioning calculation unit obtains the position of the GNSS receiver based on the distance obtained by the measurement rejection unit.
JP-A-5-19036

  For example, in a GPS receiver, a correlation between a received signal from a GPS satellite and a replica signal of the received signal is obtained, and a pseudo distance is obtained from the position of the correlation peak. The pseudorange is affected by multipath and noise. The noise includes noise caused by thermal noise of an electronic circuit that constitutes the GPS receiver. In order to reduce noise, a process called carrier smoothing is performed in which filtering using a carrier phase is performed on a pseudorange including noise.

  FIG. 1 (a) shows an example of a GPS receiver. The GPS receiving device 10 includes a satellite capturing / tracking processing unit 2 and a noise removing unit 6. The satellite acquisition / tracking processing unit 2 includes a correlator 4. The satellite capture / tracking processing unit 2 captures and tracks a GPS satellite. The correlator 4 obtains a correlation value by correlating the received signal from the GPS satellite and the C / A code replica signal. For example, as shown in FIG. 1 (b), the correlator 4 obtains correlation values at three points of E / P / L, and adjusts the phase of the replica signal so that P is maximized, whereby a correlation peak is obtained. Is detected. The phase delay amount of the correlation peak indicates a pseudo distance between the GPS satellite and the GPS receiver. However, the pseudo distance by the C / A code obtained by the correlator 4 includes a large error variation due to thermal noise. For this reason, noise due to thermal noise is removed by the noise removal unit 6 by carrier smoothing processing in which the pseudorange is filtered by the phase change amount of the carrier wave. For example, as shown in FIG. 1C, the pseudo distance A output from the correlator 4 is subjected to carrier smoothing processing and output from the noise removing unit 6 as a highly accurate pseudo distance B.

  In addition, when the radio wave from the GPS satellite is affected by multipath, the GPS receiver simultaneously receives the direct wave directly received from the GPS satellite and the reflected wave reflected from the building. . For example, as shown in FIG. 2 (a), a GPS receiver mounted on a moving body receives a direct wave and a reflected wave. When a direct wave and a reflected wave are received simultaneously, the received wave becomes a combined waveform of the direct wave and the reflected wave, and the correlation waveform is obtained by obtaining a correlation between the combined wave and a C / A code replica signal. . When the direct wave and the reflected wave are received in the same phase, an error occurs in the direction in which the code phase is delayed, as shown in FIG. That is, it is preferable to recognize the peak position of the direct wave as a pseudorange, but the peak position of the synthesized wave is recognized as a pseudorange. Therefore, an error occurs in the direction in which the phase difference between the peak position of the direct wave and the peak position of the synthesized wave and the code phase are delayed. An error occurs in the direction in which the code phase is delayed, so that the pseudorange looks long.

  When the reflected wave is received in the opposite phase to the direct wave, an error occurs in the direction in which the code phase advances as shown in FIG. That is, it is preferable to recognize the peak position of the direct wave as a pseudorange, but the peak position of the synthesized wave is recognized as a pseudorange. Therefore, an error occurs in the direction in which the phase difference between the peak position of the direct wave and the peak position of the synthesized wave and the code phase advance. An error occurs in the direction in which the code phase advances, so that the pseudorange looks short.

  In addition, when a mobile object or GPS satellite equipped with a GPS receiver moves relative to the wall, the path difference between the direct wave and the reflected wave changes over time, and the direct wave and the reflected wave As the path difference between the two changes, the phase of the reflected wave also changes. Therefore, when the phase of the reflected wave changes, the error included in the pseudorange also fluctuates around the true value.

  One period of the phase of the reflected wave corresponds to 20 cm. Therefore, every time the path difference becomes 20 cm shorter or longer, the correlation waveform repeats between FIG. 2 (b) and FIG. 2 (c), and the pseudorange repeats a cycle of long, short and long with respect to the true value. .

  For example, when a moving body moves vertically on a wall at a speed of 40 km / h, the speed of 40 km / h is about 11 m / s, so that the pseudo distance fluctuates 110 times per second from 11 m / 0.2 m × 2 = 110.

  At the output stage of the GPS receiver, noise is removed by the filter described above. As shown in FIG. 2 (d), when the moving speed of the moving body is sufficiently high, the fluctuation of the pseudo distance due to the multipath is averaged to some extent by the filter. However, fluctuations in pseudorange with a long period when the moving speed is slow or stopped are hardly averaged. This is because a filter with a short time constant is mainly used to remove noise due to thermal noise.

  Therefore, when the speed of the moving body on which the GPS receiver is mounted is slow or stopped, the error due to multipath increases.

  For example, GPS positioning means for receiving a radio wave from a GPS satellite and measuring its current position; and a self-supporting positioning means for measuring its current position from azimuth data from a direction sensor and speed data from a speed sensor; And a data processing means for selectively outputting data from the GPS positioning means or data from the self-supporting positioning means. In this device, the PDOP (position dilution of precision) value is not more than a predetermined value, the speed data from the GPS positioning means is not less than the predetermined value, and the speed data from the GPS positioning means and the speed data from the self-supporting positioning means Only when the difference between them is within a predetermined value, data from the GPS positioning means is selected (see, for example, Patent Document 1).

  The present invention has been made in view of the above points, and an object of the present invention is to provide a GNSS receiver and a positioning method that can reduce the influence of multipath and improve positioning accuracy.

In order to solve the above problems, the GNSS receiver
In a GNSS receiver that performs positioning calculations based on positioning signals transmitted from GNSS satellites,
Using a code included in the positioning signal, a pseudorange calculation unit for obtaining a pseudorange between the GNSS satellite and the GNSS receiver,
A path difference change rate estimator for estimating a change rate of a path difference between the direct wave and the reflected wave from the GNSS satellite;
A time constant setting unit for obtaining a time constant of the filter corresponding to the rate of change of the path difference estimated by the path difference change rate estimation unit, and setting the time constant;
And a noise removing unit that filters the pseudo distance obtained by the pseudo distance calculating unit with the time constant set by the time constant setting unit using a phase change amount of a carrier wave.

This GNSS receiver
In a GNSS receiver that performs positioning calculations based on positioning signals transmitted from GNSS satellites,
Using a code included in the positioning signal, a pseudorange calculation unit for obtaining a pseudorange between the GNSS satellite and the GNSS receiver,
A noise removing unit that filters the pseudo distance obtained by the pseudo distance calculating unit with a plurality of different time constants by a phase change amount of a carrier wave;
A path difference change rate estimator for estimating a change rate of a path difference between the direct wave and the reflected wave from the GNSS satellite;
A selection unit that selects any one of the pseudoranges filtered by the noise removal unit with a plurality of different time constants based on the rate of change of the route difference estimated by the route difference change rate estimation unit; Have

In other examples,
The path difference change rate estimation unit estimates the path difference change rate from the moving speed of the GNSS receiver.

In other examples,
The path difference change rate estimation unit estimates the rate of change of the path difference by obtaining a distance between the GNSS receiver and a reflector located in the path of the reflected wave.

In other examples,
Map DB that stores map information
Have
The path difference change rate estimation unit obtains the position of the GNSS satellite and the position of the GNSS receiver according to the pseudorange obtained by the pseudorange calculation unit when there are a plurality of reflector candidates,
Based on the position of the GNSS satellite and the position of the GNSS receiver and the map information stored in the map DB, the path of the reflected wave having the greatest influence on the GNSS receiver is selected,
Based on the path of the reflected wave, the rate of change of the path difference is estimated.

This positioning method is
A positioning method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
Using a code included in the positioning signal, a pseudorange calculation step for obtaining a pseudorange between the GNSS satellite and the GNSS receiver,
A path difference change rate estimation step for estimating a change rate of a path difference between a direct wave and a reflected wave from the GNSS satellite;
A time constant setting step for obtaining a time constant of the filter corresponding to the change rate of the path difference estimated by the path difference change rate estimation step, and setting the time constant;
Using the time constant set by the time constant setting step, a noise removal step of filtering the pseudo distance obtained by the pseudo distance calculation step by a phase change amount of a carrier wave, and using the pseudo distance filtered by the noise removal step And a positioning calculation step for performing positioning.

This positioning method is
A positioning method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
Using a code included in the positioning signal, a pseudorange calculation step for obtaining a pseudorange between the GNSS satellite and the GNSS receiver,
A noise removal step of filtering the pseudorange obtained by the pseudorange calculation step with a plurality of different time constants by a phase change amount of the carrier wave;
A path difference change rate estimation step for estimating a change rate of a path difference between a direct wave and a reflected wave from the GNSS satellite;
A selection step of selecting any one of pseudoranges filtered with a plurality of different time constants by the noise removal step based on the change rate of the route difference estimated by the route difference change rate estimation step; ,
A positioning calculation step of performing positioning using the pseudo distance selected in the selection step.

  According to the disclosed GNSS receiver and positioning method, it is possible to reduce the influence of multipath and improve positioning accuracy.

  Next, the best mode for carrying out the present invention will be described based on the following embodiments with reference to the drawings.

  In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

(First embodiment)
A GNSS (Global Navigation Satellite System) according to this embodiment includes a GNSS satellite that orbits the earth and a GNSS receiver 100 that is located on the earth and can move on the earth. In this embodiment, GPS will be described as an example of GNSS.

  GNSS satellites always broadcast navigation messages (satellite signals) to the earth. The navigation message includes satellite orbit information (ephemeris and almanac) for the corresponding GNSS satellite, clock correction values, and ionospheric correction coefficients. The navigation message is spread by the C / A code and carried on the L1 wave (frequency: 1575.42 MHz), and is constantly broadcast toward the earth. The L1 wave is a combined wave of a Sin wave modulated with a C / A code and a Cos wave modulated with a P code (Precision Code), and is orthogonally modulated. The C / A code and the P code are pseudo noise codes, and are code strings in which -1 and 1 are arranged irregularly and periodically.

  Currently, about 30 GNSS satellites orbit the earth at an altitude of about 20,000 km, and there are 6 earth-orbiting planes tilted by 55 degrees, each with 4 or more GNSS satellites. Are evenly arranged. Therefore, at least 5 or more GNSS satellites can be observed at any time anywhere on the earth as long as the sky is open.

  The GNSS receiver 100 is mounted on a mobile object, for example. The mobile body includes an information terminal such as a mobile terminal that moves as a person moves, such as a vehicle, a motorcycle, a train, a ship, an aircraft, and a robot.

  The GNSS receiver 100 estimates the rate of change of the path difference between the direct wave and the reflected wave from the GNSS satellite from the moving speed of the GNSS receiver 100. The moving speed of the GNSS receiving apparatus 100 may be the moving speed of a moving body on which the GNSS receiving apparatus 100 is mounted. The GNSS receiver 100 dynamically changes the time constant in the case where the carrier smoothing process is performed on the pseudo distance according to the change rate of the path difference. For example, a short (small) time constant is selected when the moving speed of the moving body is fast, and a long (large) time constant is selected when the moving speed of the moving body is slow. By selecting the time constant according to the rate of change of the path difference, it is possible to reduce the influence of multipath at low speed. Further, by selecting the time constant according to the rate of change of the path difference, the accuracy of the pseudo distance can be improved following the movement of the GNSS receiver 100.

  The GNSS receiver 100 includes a satellite acquisition / tracking processing unit 102, a noise removal unit 106, and a path difference change estimation unit 108, as shown in FIG. The satellite acquisition / tracking processing unit 102 includes a correlator 104.

  The GNSS receiver 100 receives a satellite signal transmitted from a GNSS satellite via an antenna. The satellite capture / tracking processing unit 102 captures the GNSS satellite and tracks the supplemented GNSS satellite.

  The correlator 104 generates a C / A code replica signal (also referred to as a replica C / A code) and uses the replica C / A code to synchronize with the C / A code to extract a navigation message. For example, the correlator 104 uses DDL (Delay-Locked Loop) to extract a navigation message by tracking the code phase at which the correlation value of the replica C / A code with respect to the received C / A code becomes a peak. The correlator 104 obtains three correlation values of E / P / L, and detects the peak of the correlation value by adjusting the phase of the replica signal so that P becomes maximum. Further, the correlator 104 obtains a pseudo distance between the GNSS satellite and the GNSS receiver 100. The phase delay amount at the peak of the correlation value indicates the pseudo distance between the GNSS satellite and the GNSS receiver 100. Unlike the true distance between a GNSS satellite and the GNSS receiver 100, the pseudorange includes errors due to changes in radio wave propagation speed such as a clock error (clock bias) and an ionospheric delay error. Further, the correlator 104 obtains the carrier wave phase in the satellite signal from the GNSS satellite. The correlator 104 inputs the pseudorange and the carrier wave phase to the noise removing unit 106.

  The moving speed of the GNSS receiver 100 is input to the route difference change estimation unit 108. The moving speed (vehicle speed) of the moving body on which the GNSS receiver 100 is mounted may be used. The moving speed may be recognized based on a vehicle speed pulse of a moving body on which the GNSS receiver 100 is mounted, or may be calculated based on an acceleration detected by an acceleration sensor. Alternatively, it may be calculated based on a time change of the positioning position. The path difference change estimation unit 108 estimates the change rate of the path difference between the direct wave and the reflected wave from the GNSS satellite received by the GNSS receiver 100 from the input moving speed. When the path difference fluctuates at a predetermined cycle, the pseudo distance also fluctuates around a true value at a predetermined cycle. On the other hand, the number of fluctuations of the pseudo distance in a predetermined time can be obtained from the moving speed. When the pseudo distance is fluctuating, it is assumed that the path difference is also fluctuating. Therefore, by dividing the length corresponding to one period of the path difference by the number of fluctuations, the path difference is calculated from the moving speed. The rate of change (variation rate) can be estimated. The route difference change estimation unit 108 inputs the estimated change rate of the route difference to the noise removal unit 106.

  The noise removing unit 106 smoothes the pseudo distance input by the correlator 104 using the change amount of the carrier phase. When performing the smoothing, the noise removing unit 106 sets a smoothing time constant according to the path difference change rate input by the path difference change estimating unit 108. For example, when the path difference change rate is equal to or greater than a certain threshold, a small time constant is set, and when the path difference change rate is less than a certain threshold, a large value time constant is set. The time constant is determined so that fluctuations in pseudorange due to multipath are averaged to some extent. You may make it prepare a time constant in steps according to a path | route difference change rate. By setting a large time constant, the effect of multipath can be reduced even when the GNSS receiver 100 is moving at a low speed. The noise removing unit 106 outputs the smoothed pseudo distance. The GNSS receiver 100 performs a positioning calculation using the smoothed pseudo distance output by the noise removing unit 106.

  Next, a positioning method in the GNSS receiver 100 according to the present embodiment will be described with reference to FIG.

  The GNSS receiver 100 obtains a pseudo distance based on the positioning signal from the GNSS satellite (step S402). For example, the correlator 104 obtains three correlation values of E / P / L by tracking the code phase at which the correlation value of the replica C / A code with respect to the received C / A code peaks, and P is the maximum. The peak of the correlation value is detected by adjusting the phase of the replica signal so that Then, the correlator 104 calculates a pseudo distance from the peak phase of the correlation value and the reception time, and outputs it.

  The GNSS receiver 100 obtains the rate of change of the path difference between the direct wave and the reflected wave from the GNSS satellite (step S404). For example, the path difference change estimation unit 108 estimates the change rate of the path difference between the direct wave and the reflected wave from the GNSS satellite received by the GNSS receiver 100 from the moving speed of the GNSS receiver 100.

  The GNSS receiver 100 determines a time constant in carrier smoothing (step S406). The noise removing unit 106 sets a smoothing time constant based on the path difference change rate input by the path difference change estimating unit 108.

  The GNSS receiver 100 performs smoothing by using the carrier phase for the pseudorange (step S408). In this case, smoothing is performed with the set time constant.

  The GNSS receiver 100 performs a positioning calculation using the pseudorange smoothed in step S410 (step S410).

  According to the present embodiment, it is possible to select a small time constant when the moving speed of the GNSS receiver 100 is fast, and a large time constant when the moving speed is slow. By selecting a time constant in carrier smoothing, it is possible to eliminate the influence of multipath when moving at a low speed, and to calculate the pseudo distance by following the movement of the GNSS receiver. In addition, the accuracy in calculating the pseudo distance can be improved.

  In this embodiment, as shown in FIG. 5, a speed-time constant conversion unit 109 may be provided instead of the path difference change estimation unit 108. In the speed-time constant conversion unit 109, the moving speed of the GNSS receiving apparatus 100 and the time constant in carrier smoothing performed by the noise removal 106 are associated and stored. FIG. 6 shows an example of correspondence between speed and time constant. For example, the time constant is a when the moving speed (own vehicle speed) is near 0 (zero), and decreases from a to 0.1 / moving speed (m / s) as the moving speed increases. For example, a value of 10 to 80 seconds may be applied as the value of a. The speed-time constant conversion unit 109 obtains a time constant corresponding to the moving speed from the input moving speed. Then, the speed-time constant conversion unit 109 sets the time constant in the noise removal unit 106. The noise removing unit 106 performs carrier smoothing with the time constant set by the speed-time constant converting unit 109. By storing the moving speed of the GNSS receiver 100 and the time constant in carrier smoothing performed by the noise removal 106 in association with each other in advance, the processing load for obtaining the path difference change rate can be reduced. Further, since it is not necessary to obtain the path difference change rate, the processing time can be shortened.

(Second embodiment)
A GNSS receiver according to the present embodiment will be described with reference to FIG.

  The GNSS receiver 100 converges the pseudorange in advance using a plurality of filters having different time constants. Then, the GNSS receiving apparatus 100 performs positioning calculation using any one of the pseudoranges converged in advance according to the path difference change rate. When carrier smoothing is performed using a filter with a large time constant, it takes time until the pseudorange converges. By performing the carrier smoothing of the pseudo distance in advance, the processing time can be shortened compared with the case where the carrier smoothing is performed after the time constant is determined.

  The GNSS receiver 100 according to the present embodiment is the GNSS receiver described with reference to FIG. 3, and the noise removing unit 106 has a plurality of LPFs (Low Pass Filters). The LPF may be a carrier smoothing filter (CSF). Further, the GNSS receiving apparatus 100 includes a switching unit 110. In the present embodiment, a case where two types of LPFs (first LPF 1062 and second LPF 1064) are provided will be described as an example. You may make it have 3 or more types of LPF. The first LPF 1062 has a small value smoothing time constant, and the second LPF 1064 has a large value smoothing time constant.

  The first LPF 1062 smoothes the pseudorange input by the correlator 104 by the change amount of the carrier phase. When performing the smoothing, the first LPF 1062 performs a smoothing process using the smoothing time constant of the first LPF 1062 (hereinafter referred to as the first time constant). The first LPF 1062 inputs the smoothed pseudo distance (hereinafter referred to as the first pseudo distance) to the switching unit 110.

  Similarly to the first LPF 1062, the second LPF 1064 smoothes the pseudorange input by the correlator 104 using the change amount of the carrier phase. When performing the smoothing, the second LPF 1064 performs a smoothing process using the smoothing time constant of the second LPF 1064 (hereinafter referred to as a second time constant). The second LPF 1064 inputs the smoothed pseudo distance (hereinafter, the second pseudo distance) to the switching unit 110.

  Based on the path difference change rate input by the path difference change estimation unit 108, the switching unit 110 determines whether to use any one of the first pseudo distance and the second pseudo distance for the positioning calculation. decide. Then, the switching unit 110 performs switching so as to output the determined pseudo distance.

  Next, a positioning method in the GNSS receiver 100 according to the present embodiment will be described with reference to FIG.

  The GNSS receiver 100 obtains a pseudo distance based on the positioning signal from the GNSS satellite (step S802). For example, the correlator 104 obtains three correlation values of E / P / L by tracking the code phase at which the correlation value of the replica C / A code with respect to the received C / A code peaks, and P is the maximum. The peak of the correlation value is detected by adjusting the phase of the replica signal so that Then, the correlator 104 calculates a pseudo distance from the peak phase of the correlation value and the reception time, and outputs it.

  The GNSS receiver 100 obtains the rate of change of the path difference between the direct wave and the reflected wave from the GNSS satellite (step S804). For example, the path difference change estimation unit 108 estimates the change rate of the path difference between the direct wave and the reflected wave from the GNSS satellite received by the GNSS receiver 100 from the moving speed of the GNSS receiver 100.

  The GNSS receiver 100 performs carrier smoothing with the first time constant (step S806). The first LPF 1062 performs carrier smoothing with the first time constant on the pseudo distance input by the correlator 104 based on the carrier phase, and obtains the first pseudo distance.

  The GNSS receiver 100 performs carrier smoothing with the second time constant (step S808). The second LPF 1064 performs carrier smoothing on the pseudorange input by the correlator 104 with the second time constant based on the carrier phase to obtain the second pseudorange.

  Step S806 and step S808 may be performed simultaneously.

  The GNSS receiver 100 selects one of the first pseudo distance and the second pseudo distance based on the path difference change rate (step S810). Based on the path difference change rate input by the path difference change estimation unit 108, the switching unit 110 switches so as to output any one of the first pseudo distance and the second pseudo distance. For example, if the change rate of the path difference is greater than or equal to a threshold value, the first pseudo distance is switched, and if the change rate of the path difference is less than the threshold value, the second pseudo distance is output. Switch as follows.

  The GNSS receiver 100 performs positioning calculation using the pseudo distance selected in step S810 (step S812).

  According to the present embodiment, even when carrier smoothing is performed using a filter having a large time constant, carrier smoothing is performed in parallel with the process of determining the time constant. Compared with the case where smoothing is performed, the waiting time can be shortened. In particular, after a sufficient time has elapsed after the start of measurement, an optimal pseudorange can be output without waiting for the filter to reconverge.

  In this embodiment, as shown in FIG. 9, a speed comparison unit 111 may be provided instead of the path difference change estimation unit 108. The speed comparison unit 111 compares the moving speed of the GNSS receiver 100 with a threshold value. The speed comparison unit 111 inputs the comparison result to the switching unit 110. The switching unit 110 performs switching so as to output one of the output signals of the first LPF 1062 and the second LPF 1064 based on the input comparison result. Further, for example, the speed comparison unit 111 may input the comparison result to the switching unit 110 only when the moving speed is equal to or higher than a threshold value. In this case, when the comparison result is input, the switching unit 110 determines that the moving speed of the GNSS receiver 100 is fast, and switches the output signal from the first LPF 1062 to be output. By switching to one of the output signals of the first LPF 1062 and the second LPF 1064 according to the comparison result between the moving speed of the GNSS receiver 100 and the threshold, the processing load for obtaining the path difference change rate can be reduced. . Further, since it is not necessary to obtain the path difference change rate, the processing time can be shortened.

(Third embodiment)
A GNSS receiver according to the present embodiment will be described with reference to FIG.

  In the embodiment described above, the GNSS receiver 100 reflects the radio waves from the GNSS receiver 100 and the GNSS satellite without estimating from the moving speed of the GNSS receiver 100 when estimating the path difference change rate. Then, the distance to the assumed reflector is obtained and estimated from the distance. By obtaining the distance between the GNSS receiver 100 and the reflector, the path difference change rate can be estimated even when the GNSS receiver 100 moves in parallel with the reflector. For example, as shown in FIG. 11 (a), when a wall exists in parallel with the traveling direction of the vehicle on which the GNSS receiver is mounted, and a multipath occurs due to the wall, When the GNSS satellite movement is not considered, the change rate of the path difference is a value close to zero regardless of the moving speed of the vehicle. Therefore, when a wall exists in parallel with the traveling direction of the vehicle on which the GNSS receiver is mounted, and a multipath occurs due to the wall, the rate of change of the route difference cannot be predicted.

  The GNSS receiving apparatus 100 includes a path difference detecting unit 113 in place of the path difference change estimating unit 108 in the GNSS receiving apparatus described with reference to FIG.

  The path difference detection unit 113 receives a detection signal from a radar, an image signal from a camera, and the like. The route difference detection unit 113 estimates a route difference based on the input signal. For example, as shown in FIG. 11B, the path difference detection unit 113 obtains a distance R to the obstacle from the detection signal from the radar, and estimates the path difference based on the distance R to the obstacle. You may make it do. In this case, the object to be detected may be only an object located in a range (distance) that is assumed to be affected by multipath due to reflection of radio waves by the reflector. In a general reception correlator, since the detection area has a radius of about 150 m, only an object located in the range of the radius of about 150 m may be detected.

  Further, for example, the route difference detection unit 113 may estimate the route difference by performing image processing based on an image signal from the camera. Then, the route difference detection unit 113 obtains a route difference change rate based on the estimated route difference. If the detected reflector is large enough to generate multipath, calculate the rate of change of the distance between the reflector and the GNSS receiver, Switch filters.

  In FIG. 10, as an example, a path difference detection unit 113 is provided instead of the path difference change estimation unit 108 of the GNSS receiver described with reference to FIG. 7, and the path difference detection unit 113 detects from the radar. A signal and an image signal from a camera are shown, but a path difference detection unit 113 is provided instead of the path difference change estimation unit 108 of the GNSS receiver described with reference to FIG. A detection signal from a radar and an image signal from a camera may be input to the path difference detection unit 113.

  When estimating the path difference change rate from the moving speed of the GNSS receiver, if the GNSS receiver moves in parallel with a reflector that is expected to reflect radio waves from the GNSS satellite, the path difference change rate is It was not possible to estimate. By estimating the path difference change rate based on the distance estimated based on the detection signal from the radar and the image signal from the camera, even if the GNSS receiver moves in parallel with the reflector, The rate of change can be estimated.

(Fourth embodiment)
A GNSS receiver according to the present embodiment will be described with reference to FIG.

  In the third embodiment, the GNSS receiver 100 performs the following processing when there are a plurality of paths that are assumed to be reflected wave paths. Using the radio wave from the GNSS satellite, the position of the GNSS satellite and the position and moving direction of the GNSS receiver are roughly estimated. Then, the GNSS receiver refers to the map DB based on the position of the GNSS satellite and the position of the GNSS receiver, and as a reflected wave path from the positional relationship with the building registered on the map Choose the most likely route. Then, the GNSS receiver estimates the rate of change of the route difference from the moving direction of the GNSS receiver and the most likely route.

  As shown in FIG. 13, when there are a plurality of reflector candidates in the detection area, there are also a plurality of path difference candidates. FIG. 13 shows two reflectors as reflector candidates. In this case, it is not known which route the change rate of the route difference should be obtained. According to the present embodiment, the position of the GNSS satellite and the position and moving direction of the GNSS receiver are obtained. Then, based on the two positions and the position of the building stored in the map DB, a three-dimensional relationship is calculated to obtain an optimum reflected wave path. The rate of change of the path difference is estimated from the path of the reflected wave and the moving direction of the GNSS receiver.

  The most likely reflection path can be selected by finding the optimal reflected wave path based on the position of the GNSS satellite, the position of the GNSS receiver, and the position of the building stored in the map DB. The change rate of the path difference can be estimated from the moving direction of the GNSS receiver.

  For convenience of explanation, specific numerical examples will be described to facilitate understanding of the invention. However, unless otherwise specified, these numerical values are merely examples, and any appropriate value may be used.

  Although the present invention has been described above with reference to specific embodiments, each embodiment is merely an example, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. I will. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram, but such an apparatus may be realized by hardware, software, or a combination thereof. The present invention is not limited to the above-described embodiments, and various variations, modifications, alternatives, substitutions, and the like are included without departing from the spirit of the present invention.

It is explanatory drawing of a GNSS receiver, (a) is a functional block diagram which shows a GNSS receiver, (b) is a figure which shows a pseudorange, (c) is a figure which shows a carrier smoothing process. It is explanatory drawing which shows the influence of multipath, (a) is a figure which shows a path | route difference, (b) and (c) are figures which show a pseudo distance, (d) is a figure which shows a carrier smoothing process. It is a functional block diagram which shows the GNSS receiver which concerns on one Example. It is a flowchart which shows operation | movement of the GNSS receiver which concerns on one Example. It is a functional block diagram which shows the GNSS receiver which concerns on one Example. It is explanatory drawing of an example of the relationship between speed and a time constant. It is a functional block diagram which shows the GNSS receiver which concerns on one Example. It is a flowchart which shows operation | movement of the GNSS receiver which concerns on one Example. It is a functional block diagram which shows the GNSS receiver which concerns on one Example. It is a functional block which shows the GNSS receiver which concerns on one Example. It is explanatory drawing which shows the example of application of the GNSS receiver which concerns on one Example, (a) is a figure which shows the case where a wall exists in parallel with the advancing direction of the own vehicle, (b) is a figure which shows a detection area. . It is a functional block diagram which shows the GNSS receiver which concerns on one Example. It is explanatory drawing which shows the example of application of the GNSS receiver which concerns on one Example.

Explanation of symbols

2 Satellite acquisition / tracking processing unit 4 Correlator 6 Noise removal unit 10 GNSS receiver 100 GNSS receiver 102 Satellite acquisition / tracking processing unit 104 Correlator 106 Noise removal unit 1062 First LPF (Low Pass Filter)
1064 2nd LPF (Low Pass Filter)
108 path difference change estimation unit 109 speed-time constant conversion unit 110 switching unit 111 speed comparison unit 112 map DB
113 Path difference detection unit

Claims (7)

In a GNSS receiver that performs positioning calculations based on positioning signals transmitted from GNSS satellites,
Using a code included in the positioning signal, a pseudorange calculation unit for obtaining a pseudorange between the GNSS satellite and the GNSS receiver,
A path difference change rate estimator for estimating a change rate of a path difference between the direct wave and the reflected wave from the GNSS satellite;
A time constant setting unit for obtaining a time constant of the filter corresponding to the rate of change of the path difference estimated by the path difference change rate estimation unit, and setting the time constant;
A GNSS receiving apparatus, comprising: a noise removing unit that filters the pseudo distance obtained by the pseudo distance calculating unit with a time constant set by the time constant setting unit using a phase change amount of a carrier wave. In a GNSS receiver that performs positioning calculations based on positioning signals transmitted from GNSS satellites,
Using a code included in the positioning signal, a pseudorange calculation unit for obtaining a pseudorange between the GNSS satellite and the GNSS receiver,
A noise removing unit that filters the pseudo distance obtained by the pseudo distance calculating unit with a plurality of different time constants by a phase change amount of a carrier wave;
A path difference change rate estimator for estimating a change rate of a path difference between the direct wave and the reflected wave from the GNSS satellite;
A selection unit that selects any one of the pseudoranges filtered by the noise removal unit with a plurality of different time constants based on the rate of change of the route difference estimated by the route difference change rate estimation unit; A GNSS receiver characterized by comprising: In the GNSS receiver according to claim 1 or 2,
The route difference change rate estimation unit estimates the rate of change of the route difference from the moving speed of the GNSS receiver. In the GNSS receiver according to claim 1 or 2,
The path difference change rate estimation unit estimates the rate of change of the path difference by obtaining a distance between the GNSS receiver and a reflector located in the path of the reflected wave. In the GNSS receiver according to claim 4,
Map DB that stores map information
Have
The path difference change rate estimation unit obtains the position of the GNSS satellite and the GNSS receiver according to the pseudorange obtained by the pseudorange calculation unit when there are a plurality of reflector candidates,
Based on the position of the GNSS satellite and the GNSS receiver and the map information stored in the map DB, the path of the reflected wave having the greatest influence on the GNSS receiver is selected,
A GNSS receiver characterized by estimating a change rate of the path difference based on a path of the reflected wave. A positioning method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
Using a code included in the positioning signal, a pseudorange calculation step for obtaining a pseudorange between the GNSS satellite and the GNSS receiver,
A path difference change rate estimation step for estimating a change rate of a path difference between a direct wave and a reflected wave from the GNSS satellite;
A time constant setting step for obtaining a time constant of the filter corresponding to the change rate of the path difference estimated by the path difference change rate estimation step, and setting the time constant;
A noise removal step of filtering the pseudo distance obtained by the pseudo distance calculating step by the phase change amount of the carrier wave with the time constant set by the time constant setting step;
A positioning calculation step of performing positioning using the pseudorange filtered by the noise removing step. A positioning method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
Using a code included in the positioning signal, a pseudorange calculation step for obtaining a pseudorange between the GNSS satellite and the GNSS receiver,
A noise removal step of filtering the pseudorange obtained by the pseudorange calculation step with a plurality of different time constants by a phase change amount of the carrier wave;
A path difference change rate estimation step for estimating a change rate of a path difference between a direct wave and a reflected wave from the GNSS satellite;
A selection step of selecting any one of pseudoranges filtered with a plurality of different time constants by the noise removal step based on the change rate of the route difference estimated by the route difference change rate estimation step; ,
A positioning calculation step of performing positioning using the pseudo distance selected in the selection step.

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