JP5050584B2 - POSITIONING METHOD, POSITIONING DEVICE, AND POSITIONING PROGRAM - Google Patents

Description

  The present invention relates to a positioning method, a positioning device, and a positioning program, and in particular, calculates a multipath error of a system that performs positioning based on a signal transmitted from an artificial satellite such as a satellite navigation system and removes the multipath error. The present invention relates to a positioning method, a positioning device, and a positioning program for calculating a distance.

  FIG. 3 shows a system configuration diagram of an example of the satellite navigation system. In the figure, a GNSS (Global Navigation Satellite System) satellite 11 is represented by a global positioning system (GPS) developed in the United States and a GLONASS (Global Orbiting Navigation Satellite System) developed in Russia. It is an artificial satellite used in the satellite navigation system. An SBAS (Satellite Based Augmentation System) satellite 12 is an artificial satellite used in the GNSS navigation reinforcement system.

  This Global Positioning Satellite Navigation System (GNSS) uses the time difference (distance) of received signals obtained by receiving radio waves (GNSS signals) radiated from a plurality of GNSS satellites 11 at the same time at the same ground station and radio waves. This is a system that provides the position and time at the ground station from the position of the radiated GNSS satellite 11. A value obtained by converting this time difference into a distance is called a pseudorange, and the error is mainly caused by the clock of the GNSS satellite 11, the ionosphere, the troposphere, the multipath, the clock of the receiver, and the like. The position is calculated based on the distance from the plurality of GNSS satellites 11, and the accuracy is 10 m or less.

  Currently, a system has been developed with a view to using this GNSS up to a terminal area such as takeoff and landing of the user 13 as an aircraft, and an auxiliary system that reinforces the accuracy and reliability of the GNSS is a GNSS navigation reinforcement system. In particular, a system that uses the SBAS satellite 12 and is intended to reinforce a wide area is SBAS. The SBAS includes (1) distance correction information between the SBAS satellite 12 and the user 13, (2) reliability information, and (3) distance information between the SBAS satellite 12 and the user 13 (time difference information similar to the GNSS satellite 11). )I will provide a.

  The SBAS receives observation data received from navigation satellites such as GPS by a number of ground stations, GMS (Ground Monitoring System) 15-1 to 15-n, and receives the information as a master control station (MCS). 14 to create the above three pieces of information. These three pieces of information are provided as messages to the user 13 via the SBAS satellite 12.

  In such a satellite navigation system, it is necessary to calculate the distance correction information between the satellites 11 and 12 and the user 13 more accurately in order to improve the accuracy, and the GMS 15-1 to GMS 15-1 as the data provider for generating the correction information It is necessary to remove 15-n multipath errors.

  As a method of reducing this multipath error (position error caused by multipath), GPS multipath error is estimated, and the result is determined using a threshold value, and a satellite with multipath is not used. Thus, there are known positioning methods and positioning devices that obtain positioning results from which the effects of multipath have been removed.

  Also, the signal transmitted from the positioning satellite is received by the reference station, and the pseudo distance and the reception position of the reception position are calculated based on the received signal, resulting from the multipath obtained in advance at the reception position from the pseudo distance. A positioning method that corrects the reception position by subtracting the position error is also known (see, for example, Patent Document 1).

JP 2005-49147 A

  However, the conventional multipath error elimination method that estimates the multipath error of GPS and determines from the result using a threshold and does not use the multipath-existing satellite is a satellite that can be used for positioning. If the number of satellites is not sufficient, the number of artificial satellites may be less than 4 and positioning may become impossible.

  In addition, since the conventional positioning method described in Patent Document 1 is based on the premise that a position error due to 24-hour multipath is calculated in advance, the condition that the situation of the fixed point and the multipath is the same as that of the prior measurement is necessary. Yes, there is a limit to multipath error estimation. In addition, in the conventional positioning method described in Patent Document 1, since the ionospheric error is not considered, sufficient multipath error cannot be removed.

  The present invention has been made in view of the above points, and provides a positioning method, a positioning device, and a positioning program capable of calculating a multipath error including an ionospheric error in real time and calculating a pseudo distance from which the multipath error is removed. The purpose is to do.

In order to achieve the above object, the positioning method of the present invention provides a ground station that receives a modulated wave signal obtained by modulating a pseudo-range frequency carrier wave with a modulation signal called a code transmitted by a plurality of artificial satellites at the same time. By calculating the distance based on the code as a pseudo-range, and calculating the distance based on the original carrier that does not depend on the code as the carrier phase ,
A detecting step of detecting a carrier phase cycle slips based on the carrier wave of the pseudo distance frequency obtained by receiving the modulated wave signal satellite sends, when the occurrence of cycle slips detecting step is not detected, the pseudo A distance difference calculation step for calculating a distance difference including at least a distance calculated from the carrier phase and an ionospheric error based on the distance frequency and the carrier phase, and a distance calculated this time by the distance difference calculation step and multipath error calculation step of calculating a past predetermined value obtained by subtracting the average value of the predetermined number of times calculated distance difference from the difference as the multipath error, multipath error calculated by the multipath error calculating step, the distance difference finally the value calculated by performing an operation to remove from the pseudo distance used when calculating the distance difference calculation step Characterized in that it comprises a pseudo-distance calculation step of calculating a pseudo-range.

In order to achieve the above object, the positioning device of the present invention receives a modulated wave signal obtained by modulating a pseudo-frequency carrier wave with a modulation signal called a code, which is transmitted by a plurality of artificial satellites at the same time . The ground station calculates the distance based on the code as the pseudorange, and calculates the distance based on the original carrier that does not depend on the code as the carrier phase, and receives the modulated wave signal transmitted by the artificial satellite. A cycle slip detecting means for detecting the cycle slip of the carrier phase based on the carrier of the pseudo distance frequency obtained in the above, and when the occurrence of the cycle slip is not detected by the cycle slip detecting means , Based on the pseudo-distance, a distance for calculating a distance difference including at least the distance calculated from the carrier phase and the ionospheric error A difference calculation means, a multipath error calculation means for calculating a value obtained by subtracting an average value of distance differences calculated a predetermined number of times in the past from the distance difference calculated this time by the distance difference calculation means; A pseudo distance that calculates a final pseudo distance by calculating a value obtained by performing an operation of removing the multi-path error calculated by the path error calculating means from the pseudo distance used when calculating the distance difference in the distance difference calculating step. And a calculating means.

In order to achieve the above object, the positioning program of the present invention receives a modulated wave signal obtained by modulating a pseudo-range frequency carrier wave with a modulation signal called a code, which is transmitted by a plurality of artificial satellites at the same time . A positioning program that allows a ground-based computer to calculate a distance based on a code as a pseudorange and a distance based on an original carrier that does not depend on the code as a carrier phase. when the detecting step satellite detects cycle slips of the carrier phase based on the carrier wave of the pseudo distance frequency obtained by receiving the modulated wave signal transmitted, the occurrence of cycle slips detecting step is not detected, pseudorange The pseudo-range based on the frequency for use and the carrier phase includes at least the distance calculated from the carrier phase and the ionospheric error. A distance difference calculating step for calculating the calculated distance difference, and a value obtained by subtracting an average value of distance differences calculated a predetermined number of times in the past from the distance difference calculated this time by the distance difference calculating step is calculated as a multipath error. The multipath error calculation step and the multipath error calculated in the multipath error calculation step are removed from the pseudo distance used when calculating the distance difference in the distance difference calculation step. And a pseudo distance calculating step for calculating as a pseudo distance .

  In the positioning method, positioning apparatus, and positioning program of the present invention, the ground station that receives signals transmitted by a plurality of artificial satellites at the same time, a pseudo distance obtained by converting the time difference between the received signals into a distance, and carrier delivery of the received signals When no cycle slip occurs, calculate the multipath error considering the ionosphere error based on the carrier phase of the received signal, and subtract the multipath error from the pseudorange calculated by the ground station. Multipath errors can be removed from

  According to the present invention, it is possible to calculate an accurate pseudorange that eliminates the multipath error in consideration of the ionospheric error, so that it is possible to calculate the finally obtained pseudorange without eliminating the artificial satellite having a large multipath error. By calculating the position using the distance, an accurate positioning result can be obtained.

  FIG. 1 shows a block diagram of an embodiment of a positioning apparatus according to the present invention. As shown in the figure, the positioning device of the present embodiment is provided in the master control station (MCS) 14 in the satellite navigation system shown in FIG. 3, and is transmitted from, for example, the GNSS satellite 11 in FIG. A cycle slip detecting means 100 for detecting a cycle slip of a carrier phase of a signal carrying information for calculating a pseudorange; a multipath error calculating means 110 for calculating a multipath error from the pseudorange and the carrier phase; A pseudo distance calculating unit 120 that calculates a pseudo distance from which a path error is removed is configured. In the present embodiment, it is also possible to detect the cycle slip of the carrier phase of the signal carrying the information for calculating the pseudorange transmitted from the SBAS satellite 12 of FIG.

  Each of these means 100, 110 and 120 generally operates as follows. The cycle slip detection means 100 determines the presence or absence of continuity of the carrier phase value of the signal transmitted from the GNSS satellite 11 or the SBAS satellite 12, and detects that a cycle slip has occurred when there is no continuity. The cycle slip information necessary for calculating the error is supplied to the multipath error calculation means 110.

  Here, the signal transmitted from the GNSS satellite 11 or the SBAS satellite 12 is a modulated wave signal obtained by modulating a carrier wave having an L1 pseudorange frequency and an L2 pseudorange frequency with a modulation signal called a code. A distance based on a modulation signal called a code is called a pseudo distance, and a distance obtained from an original carrier wave (radio wave signal) independent of the code is called a carrier wave phase. The pseudorange and the carrier wave phase are obtained based on the same radio wave signal, for example, in the receivers provided in each of the GMS 15-1 to 15-n in FIG. 3, but have different characteristics.

  Generally, the code is output from the receiver in units of meters, but the carrier phase is output in units of cycles. The code has a long repetition unit of 1 ms and one repetition is about 300 km multiplied by the speed of light, which is the speed of radio waves, whereas the carrier wave phase is one repetition of the wavelength of the radio wave, so the frequency of the L1 pseudorange frequency In this case, it becomes about 19 cm. The distance is obtained by specifying the ratio of one wavelength of the currently received signal. For example, a value of 153 wavelengths + 0.1 wavelength is measured and converted to the distance by multiplying the wavelength. A pseudorange with a long wavelength can easily obtain a 153 wavelength portion, but a carrier phase with a short wavelength is difficult to obtain a 153 wavelength portion.

  The carrier wave phase is data indicating the distance to the satellite as well as the pseudorange, but since the wavelength is as short as about 19 cm as described above, it is uncertain what wavelength is indicated. Normally, the receivers provided in each of the GMSs 15-1 to 15-n in FIG. 3 output the carrier phase as the number of cycles while including the uncertainty. When there is an event such as satellite acquisition being interrupted, there is a phenomenon in which the number of cycles flies over many wavelengths, and this phenomenon is called cycle slip. In order to calculate an accurate multipath error, it is necessary to accurately detect a cycle slip and calculate a carrier phase whose uncertainty does not change.

  When the cycle slip detection information indicating that a cycle slip has occurred is not input from the cycle slip detection unit 100, in other words, the multipath error calculation unit 110 receives detection information indicating that no cycle slip has occurred. Sometimes, the multipath error is calculated by taking the distance difference between the pseudorange and the carrier phase and removing the influence of the ionosphere. The pseudo distance calculating unit 120 calculates a pseudo distance obtained by subtracting the multi path error calculated by the multi path error calculating unit 110 from the pseudo distance and removing the multi path error.

  Next, the positioning method of the present invention will be described. FIG. 2 shows a flowchart of an embodiment of the positioning method according to the present invention. The positioning method of this embodiment is a positioning method by the positioning device of FIG. 1. First, the cycle slip detection means 100 uses the L1 pseudorange frequency (for example, 1575.42 MHz) and the L2 pseudorange frequency (for example, for example). 1227.6 MHz) is detected (step S 1), and the obtained cycle slip detection information is supplied to the multipath error calculation means 110.

Since the multipath error calculation means 110 requires that the cycle slip does not occur as described above in order to accurately calculate the multipath error, the cycle slip is generated based on the above cycle slip detection information. (Step S2), if it is determined that a cycle slip has occurred, the process returns to step S1 and the process is restarted from the beginning. On the other hand, if it is determined that no cycle slip has occurred, i is added and L1 distance difference CCDIF _L1 and L2 distance difference CCDIF _L2 are calculated by the following equations using L1 pseudo distance ρ _L1 , L2 pseudo distance ρ _L2 , L1 carrier phase Φ _L1 , L2 carrier phase Φ _L2. (Step S3) .

CCDIF _L1 (ti) = ρ _L1 (ti) − [(1 + 2k) λ _L1 Φ _L1 (ti) −2kλ _L2 Φ _L2 (ti)] (1)
CCDIF _L2 (ti) ＝ ρ _L2 (ti) − [(2 + 2k) λ _L1 Φ _L1 (ti) − (1 + 2k) λ _L2 Φ _L2 (ti)] (2)
However, in the equations (1) and (2), the constant k is expressed by the following equation from the L1 pseudorange frequency _fL1 and the L2 pseudorange frequency _fL2 . Further, the L1 pseudo distance ρ _L1 and the L2 pseudo distance ρ _L2 are calculated in the GMS as described above, and are input to the MCS 14.

k = f _L2 ² / (f _L1 ² −f _L2 ² ) (3)
Note that the second term and the third term on the right side of the equations (1) and (2) indicate values obtained by combining the distance calculated from the carrier phase, the bias (fixed error), and the ionospheric error.

When calculating the distance differences CCDIF _L1 and CCDIF _L2 , it is necessary to remove the influence of the ionosphere, so the calculation methods differ between the distance differences CCDIF _L1 and CCDIF _L2 . At this time, the distance differences CCDIF _L1 and CCDIF _L2 include multipath error, noise, and bias deviation. The bias deviation is the above-described uncertainty, and is a constant value as long as no cycle slip occurs. Further, since the noise value is smaller than the multipath error, the multipath error is calculated when the bias deviation is excluded from the distance differences CCDIF _L1 and CCDIF _L2 .

Therefore, the multipath error calculation means 110 calculates the multipath errors μ _L1 and μ _L2 by subtracting the bias deviation from the distance differences CCDIF _L1 and CCDIF _L2 calculated by the expressions (1) and (2) by the following expression. (Step S4).

ここで、（４）式及び（５）式中、右辺第２項は過去に予め定めた一定回数計算したＣＣＤＩＦの平均値であり、これは上記のバイアス偏差に相当する。

Here, in the equations (4) and (5), the second term on the right-hand side is the average value of CCDIF calculated a predetermined number of times in the past, and this corresponds to the above-described bias deviation.

Finally, the pseudo distance calculation means 120 subtracts the multipath error calculated by the above equations (4) and (5) from the L1 pseudo distance ρ _L1 and the L2 pseudo distance ρ _L2 by the following equations. The pseudo distances ρ _L1MT and ρ _{L2MT excluding} the path error are calculated (step S5).

ρ _L1MT (ti) = ρ _L1 (ti) −μ _L1 (ti) (6)
ρ _L2MT (ti) = ρ _L2 (ti) −μ _L2 (ti) (7)
The above steps S1 to S5 are repeatedly calculated until the program ends (step S6). Thereby, according to this Embodiment, the multipath error also including an ionosphere error can be calculated in real time, and the pseudo distance which removed the multipath error can be calculated.

  Note that the present invention is not limited to the above-described embodiment. For example, in the case of calculating a multipath error after storing data in advance instead of real-time processing, the continuation in calculating the average is continued. If the number of times i is changed to the maximum number of times n, a more accurate multipath error can be calculated.

  The present invention also includes a positioning program that causes the block configuration of FIG. 1 and each step of FIG. 2 to be executed by computer software.

It is a block diagram of one embodiment of a positioning device of the present invention. It is a flowchart of one embodiment of the positioning method of the present invention. It is a system configuration diagram of an example of a satellite navigation system to which the present invention is applied.

Explanation of symbols

11 GNSS satellite 12 SBAS satellite 13 User 14 Master control station (MCS)
15-1 to 15-n GMS
100 cycle slip detection means 110 multipath error calculation means 120 pseudo distance calculation means

Claims (3)

The distance based on the code is calculated as a pseudorange by a ground station that has received a modulated wave signal modulated by a modulation signal called a code, which is transmitted by a plurality of artificial satellites at the same time, and having a pseudorange frequency carrier wave. In the positioning method for calculating the distance based on the original carrier that does not depend on the code as the carrier phase ,
A detection step of detecting a cycle slip of a carrier phase based on the carrier of the pseudo-range frequency obtained by receiving the modulated wave signal transmitted by the artificial satellite;
A distance difference including at least a distance calculated from the carrier phase and an ionospheric error in the pseudo distance based on the pseudo-range frequency and the carrier phase when the occurrence of the cycle slip is not detected in the detection step. A distance difference calculating step for calculating
A multipath error calculating step of calculating a value obtained by subtracting an average value of the distance difference calculated a predetermined number of times in the past from the distance difference calculated this time by the distance difference calculating step;
A value calculated by performing an operation of removing the multipath error calculated in the multipath error calculation step from the pseudo distance used when calculating the distance difference in the distance difference calculation step is used as a final pseudo value. And a pseudo distance calculating step for calculating as a distance . The distance based on the code is calculated as a pseudorange by a ground station that has received a modulated wave signal modulated by a modulation signal called a code, which is transmitted by a plurality of artificial satellites at the same time, and having a pseudorange frequency carrier wave. In the positioning device that calculates the distance based on the original carrier wave independent of the code as the carrier wave phase ,
Cycle slip detection means for detecting a cycle slip of a carrier phase based on the carrier of the pseudo-range frequency obtained by receiving the modulated wave signal transmitted by the artificial satellite;
When the generation of the cycle slip is not detected by the cycle slip detection means, the pseudo distance based on the pseudo distance frequency and the carrier phase includes at least a distance calculated from the carrier phase and an ionospheric error. A distance difference calculating means for calculating a distance difference;
Multipath error calculation means for calculating, as the multipath error, a value obtained by subtracting an average value of the distance difference calculated a predetermined number of times in the past from the distance difference calculated this time by the distance difference calculation means;
A value calculated by performing an operation of removing the multipath error calculated by the multipath error calculating means from the pseudo distance used when calculating the distance difference in the distance difference calculating step is used as a final pseudo value. A positioning apparatus comprising: pseudo distance calculation means for calculating as a distance. The distance based on the code is set as the pseudo distance by the computer of the ground station that has received the modulated wave signal that is modulated by the modulation signal called the code, which is transmitted by a plurality of artificial satellites at the same time. A positioning program for calculating and calculating a distance based on an original carrier that does not depend on the code as a carrier phase ;
In the computer,
A detection step of detecting a cycle slip of a carrier phase based on the carrier of the pseudo-range frequency obtained by receiving the modulated wave signal transmitted by the artificial satellite;
A distance difference including at least a distance calculated from the carrier phase and an ionospheric error in the pseudo distance based on the pseudo-range frequency and the carrier phase when the occurrence of the cycle slip is not detected in the detection step. A distance difference calculating step for calculating
A multipath error calculating step of calculating a value obtained by subtracting an average value of the distance difference calculated a predetermined number of times in the past from the distance difference calculated this time by the distance difference calculating step;
A value calculated by performing an operation of removing the multipath error calculated in the multipath error calculation step from the pseudo distance used when calculating the distance difference in the distance difference calculation step is used as a final pseudo value. A positioning program for executing a pseudo-distance calculation step for calculating as a distance .

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