JP4890176B2 - Satellite signal judging device - Google Patents

Description

  The present invention relates to a satellite signal determination device and a positioning device.

  GPS (Global Positioning System) simultaneously receives signals transmitted from 29 satellites (as of June 1, 2006) orbiting about 20,000 km at the receiver, and satellite orbit information and time information This is a system that makes it possible to calculate the current position of the receiver by acquiring navigation data including.

  In this case, the satellite uses a pseudo-random code called a unique PN (Pseudo Noise) code and transmits a signal that is phase-modulated by a spread spectrum system. Since the receiver is provided with a PN code generator corresponding to the satellite, when a signal from the satellite is received, a correlation value between the PN code received from the satellite and the PN code generated by the receiver is obtained. Thus, it is determined whether or not the receiver is receiving a transmission signal of a desired satellite. Here, the correlation value of the PN code shows a peak when the PN code of the received signal and the PN code of the receiver are in the same phase, and when the phase difference is 1 chip or more, or cross-correlate with other satellites. If it is, it will be a small value. Here, “Chip” means the length of time required to transfer either 1 or 0 in binary.

  Here, in order to receive the transmission signal of the satellite, first, a correlation value between the PN code received from each satellite and the PN code generated by the receiver is obtained. When a peak of a certain value or more is detected in the correlation value, it is determined that a transmission signal from a desired satellite is received, and thereafter navigation data of each satellite is collected while capturing the signal. The navigation data is transmitted as a subframe of 6 seconds (300 bits) at 50 bps. The subframes are divided into five categories, subframe 1 is the correction value of each satellite's clock, health status, etc., and subframes 2 and 3 are ephemeris data including the orbit parameters of each satellite. , 5 are rough orbit information (almanac data) and ionospheric delay correction coefficients for all satellites. These subframes 1 to 5 are transmitted in order, and the subframes 1 to 5 are collected to form one frame. This one frame requires 30 seconds (1500 bits) to broadcast. Furthermore, the frame is divided into 25 types. By receiving these 25 frames for 12.5 minutes (1500 × 25 bits), all information can be collected.

  In order for the receiver to calculate the current position of the receiver, it is necessary to simultaneously receive at least three or more satellites and acquire ephemeris data. The ephemeris data is detailed orbit information of the transmitting satellite itself. Since the ephemeris data cannot be acquired unless the transmission signal of the transmitting satellite white is received, the ephemeris data must also be acquired by at least three or more satellites. . From the acquired ephemeris data, the position of the satellite is calculated, the distance from the receiver to the satellite is obtained from the propagation time, and the positioning result can be obtained by solving a predetermined simultaneous equation.

  In an actual receiver, a transmission signal of a satellite is received, and a process for specifying which satellite the received signal belongs to is performed. The particular method is by calculating the correlation value between the PN code of the received signal and the PN code of the desired satellite of the receiver and determining whether the peak has exceeded a certain threshold. If the peak exceeds the threshold, it is determined that the PN code of the desired satellite has been received, tracking processing is performed, and navigation data sent from the satellite is received.

  Here, FIG. 5 is an example of a graph in which the horizontal axis represents the phase shift amount between the PN code of the received signal and the PN code of the desired satellite in the receiver, and the vertical axis represents the correlation value. In the example shown in the figure, since autocorrelation occurs and a peak appears in the desired satellite, it can be understood that the transmission signal of the desired satellite is received.

  Next, in this case, let us consider a case where the threshold is lowered and the sensitivity is increased as shown in FIG. Here, the desired satellite is satellite A, and the visible satellite other than the desired satellite is satellite B. When the correlation value peak exceeds the threshold value between the PN code received from satellite B by cross-correlation and the PN code of satellite A generated by the receiver, the receiver tracks as satellite A. The satellite B is tracked by mistake. Then, by continuing the tracking as it is, the ephemeris data of the satellite B is received as the ephemeris data of the satellite A. That is, the satellite position calculated from the received ephemeris data is that of satellite B instead of that of satellite A. Further, since the transmission time of the signal from the satellite is calculated from the peak obtained by the cross-correlation, it is not meaningful. Therefore, there arises a problem that this result appears as a positioning error.

  Therefore, Patent Document 1 discloses a technique for preventing a determination that a desired satellite signal is being received even though another wrong satellite transmission signal is received. .

  As measures for preventing such erroneous determination, Patent Document 1 discloses the following four means of checks 1 to 4.

(1) Check 1
There is known a technique for improving accuracy by correcting an error in the distance between the reference station and all visible satellites using radio waves transmitted from a reference station whose position is known. Here, the reference station transmits information on the distance between the reference station and all visible satellites obtained by reception as auxiliary data to the receiver. Therefore, the satellite number of the visible satellite can be known from the auxiliary data, so the satellite number of the visible satellite transmitted by the auxiliary data is compared with the satellite number of the visible satellite transmitted by the auxiliary data, and the satellite number of the visible satellite transmitted by the auxiliary data. If there is no satellite number received by the receiver, it is determined that it has not been received from the desired satellite, and the ephemeris data received from the satellite is invalidated and not used for positioning calculation.

(2) Check 2
The transmission signal of the desired satellite is received by the receiver, and the Doppler frequency A acquired from the carrier frequency and the Doppler frequency B predicted from the ephemeris data acquired from the desired satellite are acquired. Then, the absolute value of the difference between the Doppler frequency A and the Doppler frequency B is calculated. If the absolute value of the difference is equal to or greater than a predetermined threshold, it is determined that the satellite from which the Doppler frequency A is acquired is different from the satellite from which the Doppler frequency B is acquired, and the ephemeris data received from the desired satellite is invalidated for positioning calculation. Do not use for.

(3) Check 3
Measure the distance from the approximate position of the previous receiver to the desired satellite and the distance from the approximate position of the current receiver to the desired satellite, and calculate the amount of change in distance from the difference between the previous distance and the current distance. Measure actual values. Further, a predicted value of the amount of change in the distance between the desired satellite and the receiver predicted from the ephemeris data acquired from the desired satellite is calculated, and the absolute value of the difference between the actually measured value and the predicted value is calculated. If the absolute value of the difference is greater than or equal to a predetermined threshold, it is determined that the satellite that measured the actual value and the satellite that measured the predicted value are different, and the ephemeris data received from the desired satellite is invalid and is not used for positioning calculation. Like that.

(4) Check 4
Of the visible satellites, satellite C is considered as a desired satellite, and satellite D is considered as a satellite other than satellite C. A difference A between the distance from the approximate position of the receiver to the satellite C and the distance from the approximate position of the receiver to the satellite D is calculated. Further, the difference B between the transmission time of the transmission signal of the satellite C and the transmission time of the transmission signal of the satellite D is calculated. Then, the absolute value of the difference between the difference A and the difference B is calculated, and when the absolute value of the difference is equal to or greater than a predetermined threshold, it is determined that one of the satellites C and D is not correct. The ephemeris data received from C and the ephemeris data received from satellite D are made invalid and are not used for positioning calculation.
Japanese Patent Laid-Open No. 2003-21672 JJSPILKER, Jr., “GPS Signal Structure and Performance Characteristics”, GLOBAL POSITIONING SYSTEMPapers published in NAVIGATION VOLUME 1, THE INSTITUTE OF NAVIGATION, 1980, p46Table2-6

  Here, in the next-generation GNSS (Global Navigation Satellite System), signals transmitted from satellites include conventional L1 signals and L2 signals that can be used by the private sector. The L1 signal and the L2 signal include the same information output from the same satellite at the same time, but are different in frequency band (L1 signal is 1575.42 MHz, L2 signal is 1272.70 MHz). .

  The techniques of checks 1 to 4 described above can be applied not only to the L1 signal but also to the L2 signal.

  However, the above-described techniques 1 through 4 have the following problems.

  The technique of Check 1 requires a separate line for transmission from the reference station, which is complicated.

  In the check 2 technique, when the satellite E is considered as a visible satellite other than the desired satellite, the peak of the correlation value is a threshold value between the PN code received from the satellite E by cross-correlation and the PN code of the desired satellite generated by the receiver. In this case, the Doppler frequency that can be acquired from the carrier frequency of the transmission signal is the Doppler frequency C of the satellite E, and the ephemeris data used for the prediction of the Doppler frequency is also that of the satellite E. The frequency is the Doppler frequency C of satellite E. Accordingly, since the Doppler frequencies of the same satellite are used, there is a problem that no difference is produced and the ephemeris data cannot be excluded.

  In the technique of Check 3, a desired satellite is a satellite F, and a visible satellite other than the satellite F is a satellite G. When the peak of the correlation value between the PN code received from the satellite G and the PN code of the satellite F generated by the receiver exceeds the threshold value due to the cross-correlation, the receiver tracks as the satellite F. Will be tracked. In this case, the distance between the satellite and the receiver is the distance between the satellite F and the receiver as described above, and the transmission time is calculated from the peak obtained by the cross-correlation, which is not meaningful. Therefore, the current positioning result calculated at this time is meaningless. However, the next positioning result is not as meaningful as the current positioning result, but the change amount A from the current positioning result, which is the difference between the current positioning result and the next positioning result, is attributed to the satellite G. . Therefore, the amount of change A is that of satellite G. In addition, since the ephemeris data used for the predicted value of the change in the distance between the satellite and the receiver is also the ephemeris data received from the satellite G, the predicted value of the change in the distance between the satellite and the receiver is It becomes that of satellite G. Therefore, since the change amount A and the predicted value are the change amount of the same satellite, there is a problem that no difference is generated and the ephemeris data cannot be excluded.

  In the technique of Check 4, as described above, it is possible to determine that one of the satellites C and D is different, but it is not possible to specify which of the satellites C and D is different. Therefore, it is necessary to invalidate the ephemeris data received from the satellite C and the ephemeris data received from the satellite D so as not to be used for the positioning calculation, which is inefficient.

  As described above, the techniques disclosed in Checks 1 to 4 have a problem that correct satellite determination cannot be performed accurately, simply, and efficiently.

  Further, in the next-generation GNSS system, as shown in the example of FIG. 7, two frequency signals of the L1 signal 111 and the L2 signal 112 are simultaneously transmitted from the satellites 101, 102, and 103 and can be received by the antenna 121 of the receiver. .

  In this case, when the above-described checks 1 to 4 are extended to the determination of the two-frequency signal, there is a problem that the number of checks increases and the processing load becomes heavy.

  Therefore, the determination of the L1 signal is performed accurately, simply and efficiently, and the determination result is used to efficiently determine the L2 signal. I want to make sure that satellites are emitted accurately, easily, and efficiently.

  Accordingly, an object of the present invention is to accurately determine from which satellite the two-frequency signal is emitted when two-frequency signals each containing the same information are simultaneously output from the same satellite in the satellite navigation system. It is simple and efficient.

  (1) The present invention relates to a receiving device that receives a first signal and a second signal transmitted at the same time from different satellites as received signals from different satellites, a PN code of the first signal, and a PN of a desired satellite A first determination means for calculating a correlation value with the code, and determining whether the first signal belongs to a desired satellite based on whether the peak of the correlation value exceeds a first threshold; When the first determination unit determines that the first signal belongs to the desired satellite, the difference between the carrier frequency received from the desired satellite and the carrier frequency received from a satellite other than the desired satellite is greater than the second threshold value. The first determination unit receives the first signal from the desired satellite and the non-desired satellite depending on whether the signal is large, and determines whether the cross-correlation is performed. Received from the desired satellite When the difference between the carrier frequency and the carrier frequency received from the non-desired satellite is equal to or less than the second threshold value, the signal level of the received signal from the desired satellite and the signal of the received signal from the non-desired satellite Third determination means for determining whether or not the first signal is received from the desired satellite and a satellite other than the desired satellite based on whether or not the difference from the level is smaller than a third threshold; and And when the third determination means determines that the first signal is received from the desired satellite and the non-desired satellite, the transmission time of the first signal of the determined satellite and the first Whether to receive the second signal from the satellite that is determined to receive the first signal based on whether the difference between the transmission time of the two signals is smaller than a fourth threshold value or not. A satellite signal having a determination means A determination device.

  (2) In another aspect of the present invention, a plurality of satellites corresponding to each of the satellites from different satellites using the first signal and the second signal transmitted at the same time and having undergone phase modulation by the spread spectrum method as reception signals. A receiving device for receiving on each channel, and positioning means for performing positioning calculation based on orbit information of the satellite included in each received signal of each satellite received on each channel, and for each channel, the first The correlation value between the PN code of the signal and the PN code of the desired satellite in the channel is calculated, and the first signal of the satellite desired in the channel is determined by whether or not the peak of the correlation value exceeds the first threshold. If the first determination means determines whether the first signal is that of the desired satellite in the channel, the first determination means for determining whether or not Depending on whether or not the difference between the carrier frequency received from the satellite desired by the channel and the carrier frequency received from a satellite other than the channel desired is larger than the second threshold, it is not desired by the satellite desired by the channel and the channel. Second determination means for receiving the first signal from a satellite and determining whether or not there is a cross-correlation for all combinations of a satellite desired in the channel and a satellite other than desired in the channel; If the difference between the carrier frequency received from the desired satellite on the channel by the second determination means and the carrier frequency received from a satellite other than the desired on the channel is equal to or less than the second threshold, the desired frequency on the channel The signal level of the received signal from the satellite and the received signal from the satellite other than desired on the channel Third determination for determining whether or not the first signal is received from a satellite desired by the channel and a satellite other than the desired by the channel depending on whether or not the difference from the signal level is smaller than a third threshold. When the difference between the signal level of the received signal from the satellite desired by the channel and the signal level of the received signal from a satellite other than the desired by the channel is larger than the third threshold by the means and the third determining means, Removing means for removing the received signal from the satellite having the lower signal level from the satellite desired by the channel and the satellite other than desired by the channel from the object of the positioning calculation by the positioning means; And when it is determined by the third determination means that the first signal is received from a desired satellite on the channel and a satellite other than the desired on the channel. Is determined to be receiving the first signal based on whether or not the difference between the transmission time of the first signal and the transmission time of the second signal of the determined satellite is smaller than a fourth threshold value. And a fourth determination means for determining whether or not the second signal is also received from the satellite.

  According to the present invention, the first determination means generates the PN code of the desired satellite (in each channel of the receiving device) to identify the desired satellite. Then, the second determination means and the third determination means determine whether or not the first signal of the satellite is that of the desired satellite. In the second determination means, using the fact that the Doppler frequency on the carrier frequency is different for each satellite, if the carrier frequency is similar between the desired satellite and the non-desired satellite, both satellites are the same satellite, It is determined that one of the satellites is likely to be received in error. In this case, the third determination means determines which satellite is erroneously received by comparing the signal level. Therefore, the correctness of the satellite can be accurately determined by the second determination means and the third determination means. In addition, since a separate line for transmission from the reference station is unnecessary, it is possible to easily determine whether the satellite is correct or incorrect. Further, since neither satellite makes an error in the third determining means, the correctness of the satellite can be determined efficiently.

  Next, since the first signal and the second signal are simultaneously transmitted from the same satellite on the assumption that the correctness of the satellite can be accurately, easily and efficiently performed with respect to the first signal, Utilizing the fact that only the error range occurs at the transmission time, it is possible to accurately, simply and efficiently perform the correctness of the satellite on the second signal by the fourth determination means.

  Therefore, the determination as to which satellite the two-frequency signal received from the satellite is generated can be performed accurately, simply and efficiently as a whole.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of electrical connection of the positioning device 1 according to the present embodiment. This positioning device 1 performs various calculations and centrally controls each part of the positioning device 1, a ROM 3 that stores various programs executed by the CPU 2 and fixed data, and a RAM 4 that is a work area of the CPU 2. 5 is connected. The bus 5 is connected to a receiving device 6 for receiving a satellite signal modulated by the spread spectrum method.

  FIG. 2 is a functional block diagram illustrating processing executed by the CPU 2 based on a program stored in the ROM 3.

  First, a transmission signal from all visible satellites is received by an antenna 7 connected to the receiving device 6. The receiving device 6 acquires the carrier frequency and code phase of the received transmission signals (L1 signal and L2 signal), specifies the transmission satellite, and acquires navigation data. Then, ephemeris data is acquired from the acquired navigation data. From the carrier frequency and code phase, the signal level, propagation time, and transmission time of the received signal can be calculated. The ephemeris data is detailed orbit information of the transmitting satellite itself in navigation data including satellite orbit information and time information.

  The receiving device 6 includes a plurality of channels (here, the number of channels is n) corresponding to each satellite. In the receiving device 6, the L1 signal and the L2 signal that are identified as belonging to the satellite that is the target channel of each channel are obtained. Here, as described above, the L1 signal and the L2 signal are signals including the same information transmitted from the same satellite at the same time, but have different frequency bands.

  As described above, the transmission satellite in each channel of the receiving device 6 is identified by calculating the correlation value between the PN code of the L1 signal that is the received signal and the PN code of the satellite targeted by the receiving device 6 and calculating the peak value. This is done by determining whether or not a certain threshold value has been exceeded. If the peak exceeds the threshold, it is determined that the PN code of the desired satellite has been received, tracking processing is performed, and navigation data sent from the satellite is received.

  And in the positioning apparatus 1 of this Embodiment, it is determined whether the L1 signal and L2 signal which were received by each channel have been received from the desired satellite.

  First, the L1 signal determination unit 11 determines whether or not the L1 signal can be received from a desired satellite in each channel. The L1 signal determination unit 11 includes a carrier frequency comparison unit 12 and a signal level comparison unit 13 which will be described later.

  Further, the L2 signal determination unit 21 determines whether or not the L2 signal can be received from a desired satellite in each channel. The L2 signal determination unit 21 includes a transmission time comparison unit 22 described later.

  The positioning unit 31 performs positioning calculation based on the signals of the satellites correctly received on each channel by the determinations in the L1 signal determination unit 11 and the L2 signal determination unit 21.

  First, the process (L1 determination) performed by the L1 signal determination unit 11 will be described. FIG. 3 is a flowchart of processing performed by the L1 signal determination unit 11.

  First, the code phase and carrier frequency of the L1 signal of all visible satellites are acquired from the receiving device 6 (step S1).

  As described above, each channel of the receiving device 6 generates a PN code of a satellite desired by the channel and searches for the desired satellite. Here, among a plurality of channels, a desired satellite in one channel is a satellite K, and a desired satellite in any other channel is a satellite L. The carrier frequency of the satellite K and the carrier frequency of the satellite L are compared from the carrier frequency acquired by the receiving device 6. Since the Doppler frequency riding on the carrier frequency is different for each satellite, the carrier frequency shows a different value for each satellite. That is, the carrier frequency comparison unit 12 calculates the absolute value of the difference between the carrier frequency of the satellite K and the carrier frequency of the satellite L by the carrier frequency comparison unit 22 (step S2), and compares the result A with a predetermined threshold a. (Step S3).

  Here, the threshold value a is set to an appropriate value that can distinguish whether the carrier frequency of the satellite K and the carrier frequency of the satellite L are similar or different. If the result A is larger than the threshold value a (Y in step S3), it is determined that the satellite K and the satellite L are received from the satellite K and the satellite L, respectively (step S4), and the L1 signal is measured by the positioning unit 31. Used for calculation.

  If the result A is equal to or less than the threshold value a (N in step S3), it is determined that there is a high possibility that the satellite K and the satellite L are the same satellite, and one of the satellites is erroneously received, and the signal The level comparison unit 13 determines the following signal levels. That is, the signal level comparison unit 13 determines which satellite is received by the satellite K or the satellite L by comparing the signal levels.

  According to Non-Patent Document 1, which is one of the GPS standard papers, the signal level in the case of cross-correlation is theoretically lower by about 23.8 dB than the signal level in the case of self-phase. . From this result, the threshold value is set as b, and a signal level difference value for determining whether the correlation is autocorrelation or cross-correlation is set. Assume that the signal level of the satellite K is high and the signal level of the satellite L is low. The absolute value of the difference between the signal level of the satellite K and the signal level of the satellite L is calculated (step S5), and the result B is compared with the threshold value b (step S6).

  If the value of the result B is smaller than the threshold value b (Y in step S6), since the carrier frequencies of the satellite K and the satellite L are similar in the result A, the satellite K and the satellite L are the same satellite and one of the satellites. However, it is determined that satellites K and L can be received from satellites K and L, respectively, assuming that the satellites coincided by the same Doppler frequency. (Step S4), the L1 signal is used for positioning calculation in the positioning unit 31.

  If the result B is equal to or greater than the threshold value b (N in step S6), it is determined that the satellite K has received from the satellite K (step S7), and the satellite L has received from a satellite other than the satellite L. The ephemeris data received as the satellite L is invalidated and is not used for positioning calculation (step S8).

  The determinations in steps S2 to S8 described above are performed by combining the satellites K and L in each channel (steps S9 to S12), and the L1 signal can be received from the desired satellite in each channel. Make sure. That is, there are four desired satellites S1, S2, S3, and S4, the receiving device 6 has four channels corresponding to these four satellites, and all of the satellites S1 to S4 are currently visible satellites. Since there are six combinations of two satellites S1 to S4, the above-described determination is performed on each channel with respect to these six sets.

  Next, processing (L2 determination) performed by the L2 signal determination unit 21 will be described. FIG. 4 is a flowchart of processing performed by the L2 signal determination unit 21.

  Since the L1 signal can be received from the desired satellite by the above-described processing performed by the L1 signal determination unit 11, the L2 signal determination unit 21 determines whether or not the L2 signal can be received from the desired satellite. Judge with. First, the L2 signal determination unit 21 acquires the code phase and the carrier frequency of the satellite L2 signal determined to have been correctly received by passing the L1 determination by the L1 signal determination unit 11 from the receiving device 6 (step S21). ).

  Among these satellites, one satellite is designated as a satellite M. The transmission time comparison unit 22 calculates the transmission time of the L1 signal from the code phase of the L1 signal of the satellite M, and calculates the transmission time of the L2 signal from the code phase of the L2 signal of the satellite M (step S22).

  Then, the transmission time of the L1 signal of the satellite M and the transmission time of the L2 signal of the satellite M are compared, and it is determined whether or not the L2 signal is received from the satellite M. Since the L1 signal and the L2 signal are broadcast simultaneously from the satellite, the transmission time of the L1 signal acquired by the receiving device 6 and the transmission time of the L2 signal are basically the same time. However, since the L1 signal and the L2 signal have different carrier frequencies, various errors such as ionospheric delay and multipath are different. Therefore, there is a difference between the transmission time of the L1 signal and the transmission time of the L2 signal by an error. However, since these various errors are at most about 0.1 μs (30 m) in total, the threshold c is estimated so as not to fall within such an error range in order to judge that the difference is due to the error alone. (For example, 1 μs (300 m)) is set. Then, the absolute value of the difference between the transmission time of the L1 signal of the satellite M and the transmission time of the L2 signal of the satellite M is calculated (step S23), and the result C is compared with the threshold c (step S24).

  Accordingly, if the result C is smaller than the threshold c (Y in step S24), it is determined that the L2 signal of the satellite M is received from the satellite M (step S25), and the L2 signal is used for the positioning calculation in the positioning unit 31. To do.

  If the result C is equal to or greater than the threshold value c (N in step S24), it is determined that the L2 signal of the satellite M is received from a satellite other than the satellite M, and the L2 signal of the satellite M is not used for positioning. (Step S26).

  The processes in steps S22 to S26 described above are performed for all the satellites that have passed the L1 determination in each channel (step S27), and it is confirmed that the L2 signal can be received from the satellite desired by each channel.

  According to the positioning device 1 described above, the desired satellite is identified by generating the PN code of the desired satellite in each channel of the receiving device 6. Then, the carrier frequency comparison unit 12 and the signal level comparison unit 13 determine whether the L1 signal of the satellite is that of a desired satellite. The carrier frequency comparison unit 12 uses the fact that the Doppler frequency on the carrier frequency is different for each satellite, and if the carrier frequency is similar between the desired satellite and the non-desired satellite, both satellites are the same satellite. It is determined that there is a high possibility that one of the satellites is received in error. In this case, the signal level comparison unit 13 determines which satellite is erroneously received by comparing the signal levels. Therefore, the correctness of the satellite can be accurately determined by the carrier frequency comparison unit 12 and the signal level comparison unit 13. In addition, since a separate line for transmission from the reference station is unnecessary, it is possible to easily determine whether the satellite is correct or incorrect. Further, since neither of the satellites makes an error in the signal level comparison unit 13, the correctness of the satellites can be determined efficiently.

  Next, the L1 signal and the L2 signal are simultaneously transmitted from the same satellite on the assumption that the L1 signal can be accurately, easily and efficiently performed on the satellite, so at the transmission time of the signal of the two frequencies. Makes use of the fact that only an error range occurs, and the transmission time comparison unit 22 can accurately, simply, and efficiently perform the correctness of the satellite for the L2 signal.

  Therefore, the determination as to which satellite the two-frequency signal received from the satellite is generated can be performed accurately, simply and efficiently as a whole.

  In the above example, first, the correctness of the satellite is accurately determined for the L1 signal, and the correctness of the satellite is determined for the L2 signal on the premise of this. However, the present invention is not limited to this. Instead, the correctness of the satellite may be accurately determined for the L2 signal, and the correctness of the satellite may be determined for the L1 signal on the premise of this.

  In addition, the present invention is not limited to application to GPS technology, but can also be applied to Galileo, GLONASS, and the like.

It is a block diagram of the electrical connection of the positioning apparatus which is one Embodiment of this invention. It is a functional block diagram of the process which a positioning apparatus performs. It is a flowchart of the process performed in a L1 signal determination part. It is a flowchart of the process performed by the L2 signal determination part. It is a graph explaining the subject of this invention. It is a graph explaining the subject of this invention. It is a graph explaining transmission of L1 signal and L2 signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positioning device 6 Receiving device 11 L1 signal determination part 12 Carrier frequency comparison part 13 Signal level comparison part 21 L2 signal determination part 22 Transmission time comparison part 31 Positioning part

Claims (2)

A receiving device that receives a first signal and a second signal, which are different in bandwidth from each other and transmitted at the same time and phase-modulated by a spread spectrum method, from each satellite as received signals;
A correlation value between PN code of the first signal PN code as desired satellite is calculated and determined that when the peak of the correlation value exceeds the first threshold value is one the first signal is a desired satellite First determining means for
When the first determination means determines that the first signal belongs to the desired satellite, the difference between the carrier frequency received from the desired satellite and the carrier frequency received from a satellite other than the desired satellite is the second. It determines that when the threshold value or less are cross correlation without receiving the first signal from the said desired satellite and the desired non-satellite, is greater than the second threshold value is the desired satellite and the desired other a second judging means for judging that no cross-correlation to receive the first signal from a satellite,
When the difference between the carrier frequency received from the desired satellite by the second determination means and the carrier frequency received from a satellite other than the desired satellite is equal to or less than the second threshold value, the signal of the received signal from the desired satellite the determining the difference between the signal level of the received signal from the level and the desired other satellites third time smaller than the threshold is receiving the first signal from the said desired satellite and the desired non-satellite 3 determination means;
When it is determined by the second and third determination means that the first signal is received from the desired satellite and the non-desired satellite, the transmission time of the first signal of the determined satellite fourth determining means determines that the difference between the transmission time of the second signal is the fourth time threshold smaller also receives the second signal from the determined satellite that receives the first signal and When,
A satellite signal determination device. A receiving device for receiving the first signal and the second signal, which are different in bandwidth from each other and phase-modulated by a spread spectrum method, from each satellite through a plurality of channels corresponding to the respective satellites;
Positioning means for performing positioning calculation based on orbit information of the satellite included in each received signal of each satellite received by each channel;
With
For each channel,
Wherein the correlation value of the PN code of the desired satellite PN code and the channel of the first signal to calculate a satellite to which the first signal when the peak of the correlation value exceeds the first threshold value is desired in the channel a first judging means for judging to be of,
When the first determining means determines that the first signal is that of the desired satellite on the channel, the carrier frequency received from the desired satellite on the channel and the carrier received from a satellite other than the desired channel determining the difference between the frequency is the cross correlation without receiving the first signal from a satellite other than when the following second threshold value to the desired satellite and the channel to be desired in the channel, than the second threshold value When it is larger, it is determined that the first signal is received from the desired satellite and the non-desired satellite and it is determined that there is no cross-correlation. Second determination means for performing a combination of
If the difference between the carrier frequency received from the desired satellite on the channel by the second determination means and the carrier frequency received from a satellite other than the desired on the channel is equal to or less than the second threshold, the desired frequency on the channel When the difference between the signal level of the received signal from the satellite and the signal level of the received signal from a satellite other than that desired by the channel is smaller than the third threshold, the satellite desired by the channel and the satellite other than the desired by the channel third determining means for determining that receives the first signal and a,
When the difference between the signal level of the received signal from the desired satellite on the channel and the signal level of the received signal from a satellite other than the desired channel on the channel is greater than the third threshold by the third determining means, A removing means for removing the received signal from a satellite having a lower signal level from a desired satellite and a satellite other than the desired satellite in the channel from the object of positioning calculation by the positioning means;
When it is determined by the second and third determination means that the first signal is received from a satellite desired by the channel and a satellite other than the desired by the channel, the first of the satellites for which the determination has been made determining the difference between the transmission time of the transmission time of the first signal a second signal is the fourth time threshold smaller also receives the second signal from the determined satellite that receives the first signal Fourth determining means for
With
Positioning device.

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