JP5903906B2 - Positioning satellite signal receiver, positioning satellite signal receiver processing method, and program - Google Patents

Description

  The present invention relates to a positioning satellite signal receiver, a processing method of a positioning satellite signal receiver, and a program.

  In general, in a positioning device using GPS (Global Positioning System), when calculating the moving speed of a receiver, a total of four speed components in the X, Y, and Z directions and a clock drift amount of the receiver are defined as unknowns. It is known that it is necessary to solve the equation (see, for example, Patent Document 1).

  Problems that may occur at this time include the following cases. That is, when the above four unknown equations are solved and the moving speed of the receiver is calculated, the calculated value of this time is abruptly changed from the previous calculated value (for example, the calculated value of one second before). The actual moving speed of the receiver does not change suddenly, and the actual moving speed may not match the calculated moving speed.

  The cause of this problem is that the moving speed suddenly changes because the clock drift is not correctly obtained. In other words, in addition to the direct wave that is a positioning signal that directly arrives at the receiver from the GPS satellite, there is a multipath wave that is a positioning signal that arrives at the receiver after being reflected from the GPS satellite to the building or the like. When an equation having two unknowns is solved using the method of least squares, clock drift cannot be obtained correctly. As a result, the moving speed of the receiver cannot be obtained correctly, and the moving speed may change suddenly.

  An example of the clock used in the above-described receiver is TCXO (Temperature Compensated Crystal Oscillator). It is known that TCXO does not change the amount of clock drift abruptly.

  Therefore, the following method can be considered as a method for preventing a sudden change in the moving speed of the receiver and obtaining the correct moving speed. In other words, when a sudden change occurs in the moving speed or clock drift amount, the moving speed is calculated again using the average value of the data that has been determined that the positioning signal reception state is good in the previous calculation of the moving speed. There has been considered a method of calculating a correct moving speed while preventing a sudden change in the moving speed by calculating. Examples of the above average value include those that are calculated in advance and stored in the storage unit before a sudden change such as a moving speed occurs.

JP 2000-31163 A

  In the above method, as a technique for determining a multipath wave, when comparing a positioning signal and a replica signal of a positioning signal generated by a receiver, a C / A code phase considered to be the center on the receiver side is used. A technique is used in which a C / A code advanced by a certain amount and a C / A code delayed by a certain amount are created, the correlation between the C / A code and the received signal is obtained, and the estimated code phase is obtained so that both are equal.

  According to this technique, in the case of a mixed wave of a direct wave and a multipath wave, the multipath wave can be excluded from the mixed wave. However, when only the multipath wave is received by the receiver, there is a problem that the received positioning signal cannot be determined as a multipath wave. When only multipath waves are received in this way, there is a problem that a large error occurs in the calculated moving speed of the receiver.

  The present invention has been made to solve the above-described problem, and suppresses erroneous calculation of a moving speed or the like even in a situation where only a multipath wave from a satellite is received. An object of the present invention is to provide a positioning satellite signal receiver, a processing method of the positioning satellite signal receiver, and a program.

In order to achieve the above object, the present invention provides the following means.
A positioning satellite signal receiver according to the present invention includes at least a calculation satellite that repeatedly performs a speed calculation process for obtaining a plurality of directional velocity components and clock drifts that are unknown based on a received positioning satellite signal of a positioning satellite. The signal receiver, wherein the calculation unit is a past average value of the latest clock drift obtained by the latest speed calculation process and a plurality of clock drifts obtained by the speed calculation process performed so far. If the difference is determined to exceed the predetermined threshold, it is obtained by the speed calculation processing performed so far. and the past average value of the plurality of clock drift, adopted as the most recent clock drift, the unknowns at speed operation to reduce one, the plurality Using historical average of clock drift as a known value during speed operation, a plurality of direction velocity component obtained by the speed calculation processing for obtaining the plurality of directional velocity component, obtained by the most recent speed calculation processing Employed as a plurality of directional velocity components.

According to the positioning satellite signal receiver processing method of the present invention, a positioning satellite signal receiver that repeatedly performs speed calculation processing for obtaining a plurality of directional velocity components and clock drifts that are unknowns based on the received positioning satellite signal of the positioning satellite. A difference between a most recent clock drift obtained by the latest speed computation process and a past average value of a plurality of clock drifts obtained by the speed computation process performed so far is a processing method. When the difference is determined to exceed the predetermined threshold, the plurality of clock drifts obtained by the speed calculation processing performed so far are determined. the historical average value of adopted as the most recent clock drift, in order to reduce one unknown at the time of speed calculation, over a plurality of clock drift Using the average value as a known value during speed calculation, a plurality of direction velocity obtained a plurality of direction velocity component obtained by the speed calculation processing for obtaining the plurality of directional velocity component, by the most recent speed calculation processing It is characterized by adopting as an ingredient.

A program according to the present invention is a program for causing a computer to function as a positioning satellite signal receiver that obtains a plurality of directional velocity components and clock drifts based on a received positioning satellite signal of a positioning satellite. The speed calculation process for obtaining a plurality of directional speed components and clock drifts that are unknowns is repeated, and the latest clock drift obtained by the most recent speed calculation process and the speed calculation process performed so far are obtained. When the difference between the plurality of clock drifts and the past average value exceeds a predetermined threshold value is determined, and it is determined that the difference exceeds the predetermined threshold value, The past average value of the plurality of clock drifts obtained by the speed calculation processing is calculated as the latest clock. Adopted as a lift, in order to reduce one unknown at the time of speed calculation, using the past average value of the plurality of clock drift as a known value during speed calculation, the speed calculation processing of obtaining the plurality of directional velocity component It is made to function as a calculation means which employ | adopts the calculated | required several direction speed component as several direction speed component calculated | required by the said latest speed calculation process.

  The positioning satellite signal receiver of the present invention determines that the positioning satellite signal receiver has received a multipath wave when the difference between the latest clock drift value and the past average value exceeds a predetermined threshold, The past average value of multiple clock drifts is adopted as the most recent clock drift, and the multiple speed velocity components obtained by the velocity calculation processing for obtaining the multiple direction velocity components excluding the clock drift are used as the latest velocity calculation processing. As a plurality of directional velocity components obtained by In other words, if the calculated clock drift value suddenly changes, it is determined that the positioning satellite signal receiver has received a multipath wave, and a calculation method for obtaining a plurality of directional velocity components and clock drift is determined. Change to a calculation method that has less influence. In this way, even when the positioning satellite signal receiver receives only the multipath wave, it is possible to suppress erroneous calculation of the moving speed.

  The plurality of directional velocity components include an X-axis velocity component (X-direction velocity component), a Y-axis velocity component (Y-direction velocity component), and a Z-axis velocity component (Z Direction velocity component).

  When only multipath waves are received, the most recent clock drift values are not used, but the previous clock drift values are used as the most recent clock drift, so that multiple directional velocities caused by the multipath waves can be obtained. It is possible to suppress errors in components and clock drift values.

When the arithmetic unit determines that the difference is equal to or less than the predetermined threshold, the arithmetic unit obtains the latest average value, which is an average of the past average value of the plurality of clock drifts and the latest clock drift , when the difference is obtained. Preferably, the latest average value is stored in the past average value, and the latest average value is obtained by a weighted average calculation process in which the past average value is heavily weighted with respect to the latest clock drift.

Further, the weighting factor used in the processing of the weighted average calculation, the as the number of updating times of said plurality of clock drift, which is used to calculate the historical average value increases, the weighting of the historical average value for the most recent clock drift It is preferable to change so that becomes heavy.

  In this way, according to the size of the number of clock drifts used for the calculation of the past average value, the weight for the past average value is changed to be heavier than the weight for the latest clock drift. It is possible to suppress errors due to a plurality of directional velocity components and clock drift values. The magnitude of the number of clock drifts can also be rephrased as the number of times the past average value is calculated (in other words, the number of times the past average value is updated). In this case, the weighting coefficient is changed so that the weighting of the past average value becomes heavier according to the number of updates of the past average value.

  According to the positioning satellite signal receiver, the positioning satellite signal receiver processing method, and the program of the present invention, when the difference between the latest clock drift value and the past average value exceeds a predetermined threshold, a plurality of The past average value of clock drift is adopted as the most recent clock drift, and multiple direction speed components obtained by speed calculation processing to obtain multiple direction speed components excluding clock drift are obtained by the latest speed calculation processing. By adopting as a plurality of directional velocity components obtained, it is possible to suppress erroneous calculation of the moving velocity or the like even when a situation where only a multipath wave from a satellite is received occurs.

It is a block diagram explaining the whole structure of the GPS receiver which concerns on one Embodiment of this invention. It is a flowchart explaining the positioning calculation process in consideration of the multipath wave in the GPS receiver of FIG. 3 is a flowchart illustrating a process for calculating a clock drift average value in FIG. 2. It is a graph explaining the change of the speed calculated by the GPS receiver of FIG. 1 and the conventional GPS receiver.

  A GPS receiver (positioning satellite signal receiver) 100 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating the overall configuration of a GPS receiver according to the present embodiment.

  In the present embodiment, the GPS receiver 100 of the present invention will be described as applied to a receiver of a positioning system that uses an artificial satellite (positioning satellite) called a GPS satellite. The GPS receiver 100 of the present embodiment receives positioning signals transmitted from a plurality of artificial satellites, demodulates information included in positioning signals transmitted from the respective GPS satellites, and obtains information obtained therefrom. By analyzing, the three-dimensional position of the GPS receiver 100 is measured (3D positioning) and the moving speed (hereinafter referred to as “speed”) is measured. The GPS receiver 100 may perform 3D positioning as described above, or may perform two-dimensional positioning (2D positioning), and is not particularly limited.

  The GPS receiver 100 includes an antenna 101, a frequency converter 102, a clock oscillator 103, an analog-digital converter 104 (hereinafter referred to as “AD converter 104”), signal detection / tracking / data. A demodulation unit 105 and a calculation unit (calculation means, computer) 106 are mainly provided.

  The antenna 101 receives radio waves (positioning satellite signals) transmitted from GPS satellites and converts them into electrical signals. The frequency converter 102 converts the GPS carrier L1 = 1,575,420,000 Hz into an IF signal (for example, 4,092,000 Hz).

  The clock oscillator 103 includes a crystal resonator, and generates a signal having a predetermined frequency, for example, 16,368,000 Hz. Further, a signal used as a reference clock for the frequency conversion unit 102 and the AD conversion unit 104 is generated. The AD conversion unit 104 performs quantization and sampling of an IF (Intermediate Frequency) signal output from the frequency conversion unit 102.

  The signal detection / tracking / data demodulating unit 105 detects (searches) the satellite signal based on the input signal, performs tracking processing of the satellite signal that has been searched, and data demodulation. A plurality of signal detection / tracking / data demodulation units 105 are installed in the GPS receiver 100 and are often called channels.

  The calculation unit 106 selects which satellite is received, controls the signal detection / tracking / data demodulation unit 105, and outputs the code phase, carrier frequency, and demodulation of the satellite output from the signal detection / tracking / data demodulation unit 105. The positioning operation is performed based on the received navigation message bits. When positioning calculation is performed, it is determined whether or not there is a sudden change in the clock drift or speed calculation result due to multipath waves, and if a clock drift or a sudden change in speed is detected, the average clock drift until the previous positioning is added to the unknown clock drift term. By substituting a value, the unknown in the speed calculation is reduced by one, and the speed calculation is performed.

Next, the operation of the GPS receiver 100 will be described with reference to the flowchart shown in FIG.
First, a general positioning calculation is performed in the calculation unit 106 (S201), and a speed calculation is performed based on position information obtained by the positioning calculation (S202). The positioning calculation in S201 is started at a timing based on a predetermined cycle. After that, the calculation unit 106 determines whether or not the result of the positioning calculation in S201 is 3D positioning (S203).

  When it is determined that the positioning calculation result is 3D positioning (in the case of YES), the calculation unit 106 performs calculation processing for calculating the average value of the clock drift using the clock drift obtained in the processing of S202. Performed (S204). This is because the clock drift does not change suddenly.

Here, the details of the process of calculating the average value of the clock drift in S204 will be described with reference to the flowchart shown in FIG.
First, a calculation process of the clock drift non-update time is performed in the arithmetic unit 106 (S301). The clock drift non-update time is the time from the execution of the previous clock update process to the present.

  The obtained clock drift non-update time is used for the calculation process of the clock drift average value. Next, the difference between the most recently calculated clock drift value (hereinafter referred to as “the most recent clock drift”) and the average value (past average value) of the previous clock drift values is obtained, and this difference is obtained. Is determined by the calculation unit 106 (S302). Here, as the threshold value, 1.0 + 0.02 × clock non-update time [Hz] can be exemplified. Note that the threshold value is set in consideration of the influence of the vibration frequency of the crystal resonator provided in the clock oscillator 103.

  In the determination process of S302, when it is determined that the difference is equal to or smaller than the predetermined threshold value (in the case of YES), the number of updates (cumulative value) of the clock drift average value is equal to or smaller than the first threshold value (for example, five times). Is determined by the calculation unit 106 (S303). In the determination process of S303, when it is determined that the number of updates is equal to or less than the first threshold value (in the case of YES), the calculation unit 106 performs a clock drift average value calculation process (S304). Specifically, the clock drift average value is updated based on the following equation (1).

Here, CD _ave is the clock drift average value, N _CD is the clock drift average value update count, and CD is the latest clock drift (current clock drift) value.

  Thereafter, in the arithmetic unit 106, the update processing of the clock drift average value last change time is performed (S305), and the update processing of the clock drift average value update count is performed (S306). When the number of updates is changed, the process of calculating the average value of the clock drift ends, and the process returns to the process shown in the flowchart of FIG.

  On the other hand, in the determination process of S303, when it is determined that the number of updates exceeds the first threshold (in the case of NO), the number of updates (cumulative value) of the clock drift average value is the second threshold (for example, 10 times). Whether or not it is the following is determined by the calculation unit 106 (S307). In the determination process of S307, when it is determined that the number of updates is equal to or less than the second threshold value (in the case of YES), the calculation unit 106 updates the update weighting coefficient (hereinafter referred to as “update weighting coefficient”) of the clock drift average value. The calculation process is calculated (S308). Specifically, an update weighting coefficient calculation process is performed based on the following equation (2).

Here, the speed TDOP is a TDOP calculated in the speed calculation by the same method as the TDOP calculated in the positioning calculation.

  Thereafter, an update process of the clock drift average value is performed (S309). Specifically, the update process is performed based on the following formula (3).

  Further, in the arithmetic unit 106, a process for updating the last update time of the clock drift average value is performed (S310), and a process for updating the number of updates of the clock drift average value is performed (S311). When the number of updates is changed, the process of calculating the average value of the clock drift ends, and the process returns to the process shown in the flowchart of FIG.

  On the other hand, in the determination process of S307, when it is determined that the number of updates exceeds the second threshold value (in the case of NO), the difference between the clock drift value obtained this time and the clock drift average value is the third value. Determination processing whether or not the threshold value (for example, 1.0 [Hz]) or less is performed by the calculation unit 106 (S312). Note that the values of the first threshold value, the second threshold value, and the third threshold value described above are set in consideration of the influence of the vibration frequency of the crystal resonator provided in the clock oscillator 103.

  In the determination process of S312, when it is determined that the above difference is equal to or smaller than the third threshold value (in the case of YES), the arithmetic unit 106 updates the update weighting coefficient (hereinafter referred to as “update weighting coefficient”) of the clock drift average value. Is calculated) (S313). Specifically, an update weighting coefficient calculation process is performed based on the following equation (4).

In this embodiment, description will be made by applying to an example in which the weighting constant is set to 9.

  Thereafter, the clock drift average value update processing using the above-described equation (3) is performed by the arithmetic unit 106 (S314), and the clock drift average value final update time update processing is performed (S315). When the last update time is updated, the process of calculating the average value of the clock drift ends, and the process returns to the process shown in the flowchart of FIG. Also, in the determination process of S312, when it is determined that the above-described difference exceeds the third threshold (in the case of NO), the process of calculating the average value of the clock drift is completed, and the process shown in the flowchart of FIG. Return to.

  As described above, when the difference value is determined to be equal to or smaller than the threshold value in the determination process in S302, the clock drift average value update count (cumulative value) is calculated based on the determination process result in S303, S307, or S312. The adoption ratio of the latest clock drift (in other words, the latest clock drift calculation value) can be increased by calculating the clock drift average value by adopting the corresponding clock drift average value updating method. In other words, when the clock drift average value update count is small, it is estimated that the reliability of the clock drift average value until the previous positioning is low, so by increasing the adoption ratio of the most recent clock drift, Reliability can be increased.

  Further, when it is determined that the clock drift average value update count is large (S303: NO, S307: NO), the difference between the latest clock drift calculated value and the previous clock drift average value is the third threshold value (for example, 1.0 [Hz]) or less (S312: YES), the calculation unit 106 calculates the clock drift average value (S313, S314), while being influenced by the multipath wave. When the clock drift calculation value is gradually shifted, it is possible to prevent an erroneous clock drift value from being used for calculating the clock drift average value.

  When the process of calculating the average value of the clock drift is completed, the process returns to the flowchart of FIG. 2, and the calculation unit 106 calculates and updates the clock drift non-update time (S205). The calculation unit 106 determines whether or not the calculated clock drift non-update time has a length equal to or shorter than a threshold (for example, 10 s) (S206). If it is determined that the length of the clock drift non-update time is equal to or less than the threshold value (in the case of YES), the clock drift value obtained by the most recent computation is abnormal or obtained by computation. Processing for determining whether the obtained speed is abnormal is performed by the arithmetic unit 106 (S207).

  Specifically, the difference between the latest clock drift value and the previous clock drift average value exceeds the clock drift threshold (predetermined threshold), or the difference between the latest speed value and the previous speed. Is determined whether the speed exceeds the speed threshold. Here, the latest speed value is the speed value obtained by the latest calculation, and the previous speed is the speed value obtained by the previous calculation.

  Note that the above-described clock drift threshold and speed threshold are values that are appropriately determined according to the application in which the GPS receiver 100 is used. For example, when usage modes with large speed fluctuations are assumed (specifically, when used in racing vehicles, private cars, etc.), these threshold values are set large, and usage modes with low speed fluctuations are assumed. (Specifically, when used for agricultural vehicles, pedestrians, etc.), these threshold values can be set small.

When it is determined that the clock drift or the speed is abnormal in the determination process of S207 (in the case of YES), the calculation unit 106 determines the four unknowns (X, Y, Z direction speed components obtained by the speed calculation and the clock) A process of performing a speed calculation by substituting the clock drift average value for the clock drift value of the drift value) is executed (S208).
Here, a general observed Doppler frequency is expressed by the following equation (5).

In the speed calculation process of S208, the above-described equation (5) is used. Specifically, the speed calculation processing is performed in a state where the clock drift average value is substituted into the clock drift term (fourth term on the left side) of Equation (5) and the unknown at the time of speed calculation is reduced by one.
For example, when the number of positioning satellites is 5, what is defined as follows is defined as equation (6).

  When the clock drift average value is substituted into the clock drift term of Expression (6), Expression (6) is expressed by Expression (7) below. In equation (7), there are three unknowns related to speed.

Here, d ′ _j is obtained by subtracting the clock drift average value from d as shown in Expression (8).
When Expression (5) is expressed using Expression (7) described above, Expression (9) shown below is obtained.

Therefore, the speed can be calculated by using the following formula (10).

  In the determination process of S207, an example of determining based on the presence or absence of a sudden speed change exceeding a threshold can be given as a condition for determining whether or not there is a speed abnormality. At this time, since the speed error increases according to the speed of the vehicle speed, the above threshold value may be changed so as to increase according to the vehicle speed.

  Further, in the present embodiment, the operation in the GPS receiver 100 based on the formulas and threshold values shown in the above formulas (1) to (10) has been described, but depending on the purpose of the use and characteristics of the GPS receiver 100, The formula or threshold value used may be changed and is not particularly limited.

  Next, the operation result in the GPS receiver 100 of this embodiment is demonstrated. FIG. 4 is a graph showing a temporal change in speed obtained by the GPS receiver 100 of the present embodiment and a conventional GPS receiver, and is obtained when a vehicle equipped with the GPS receiver is run in an urban area. It represents the time change of the measured speed.

  As shown in FIG. 4, it can be seen that the speed obtained by the conventional GPS receiver changes rapidly at the points A, B, and C surrounded by circles. At other points in time, the speed obtained by the GPS receiver 100 of the present embodiment and the speed obtained by the conventional GPS receiver are substantially the same.

  According to the GPS receiver 100 having the above configuration, when the clock drift value calculated in S202 changes suddenly, it is determined that the GPS receiver 100 has received a multipath wave, and the X-direction velocity component, Y Since the calculation method for obtaining the direction velocity component, the Z direction velocity component, and the clock drift is changed to a calculation method with less influence of the multipath wave, even if the GPS receiver 100 receives only the multipath wave, the movement speed Can be suppressed.

  That is, if the difference between the latest clock drift value and the clock drift average value exceeds a predetermined threshold, it is determined that the GPS receiver 100 has received a multipath wave, and the clock drift average value is X-direction velocity component, Y-direction velocity component obtained by the velocity calculation processing for obtaining the X-direction velocity component, Y-direction velocity component, and Z-direction velocity component excluding the clock drift, The Z direction speed component is adopted as the X direction speed component, the Y direction speed component, and the Z direction speed component obtained by the latest speed calculation process. As a result, it is possible to suppress erroneous calculation of the moving speed due to reception of only multipath waves.

  In addition, by using the GPS receiver 100 of the present embodiment in a car navigation system that uses hybrid navigation, a better vehicle trajectory can be obtained compared to the case of using a conventional GPS receiver.

  In the hybrid navigation, the vehicle trajectory is calculated by combining the positioning result by the GPS receiver 100 and the estimated position based on the output of the in-vehicle sensor, and the output correction of the in-vehicle sensor is performed using the positioning result by the GPS receiver 100. Has been done. In other words, by suppressing the occurrence of an abnormality in the positioning result by the GPS receiver 100, for example, an abnormality in the obtained speed, the correction accuracy of the sensor corrected using the positioning result, such as a vehicle speed sensor or a gyro sensor, is improved. Deterioration can be suppressed. As a result, it is possible to suppress the deterioration of the accuracy of the positioning result by the GPS receiver 100 and the accuracy of the estimated position based on the output of the in-vehicle sensor and obtain a good vehicle trajectory.

  Conversely, when a conventional GPS receiver is used, if an abnormality occurs in the positioning result, the sensor correction accuracy corrected using the positioning result deteriorates. In particular, if the vehicle trajectory is calculated only by the output of the sensor when the GPS satellite positioning signal is not received, the accuracy of the vehicle trajectory tends to be lowered.

  A weight for the clock drift average value (past average value) calculated from a plurality of clock drifts obtained in a state where radio waves transmitted from GPS satellites are directly received is obtained in a state where only multipath waves are received. By making it heavier than the weighting for the latest clock drift, it is possible to suppress errors in the values of the X-direction velocity component, the Y-direction velocity component, the Z-direction velocity component, and the clock drift due to the multipath wave.

  In addition, according to the number of updates of the clock drift average value (past average value), the weight for the clock drift average value (past average value) is changed to be heavier than the weight for the latest clock drift. It is possible to suppress errors in the values of the X-direction velocity component, the Y-direction velocity component, the Z-direction velocity component, and the clock drift due to.

  In this embodiment, the accuracy of the calculated speed is suppressed by using the clock drift. However, the accuracy of the calculated positioning position is also suppressed by using the clock bias in the same manner. There is no particular limitation.

  Furthermore, the invention of the present application may be applied to GPS as in the present embodiment, and may be applied to GNSS systems such as GLONASS, Galileo, etc. without being limited to GPS. Further, the average value of a plurality of clock drifts up to the previous time and the latest clock drift may be used as the latest average value, and the latest average value may be used as the latest clock drift.

  DESCRIPTION OF SYMBOLS 100 ... GPS receiver (positioning satellite signal receiver), 106 ... Calculation part (calculation means, computer)

Claims (5)

A positioning satellite signal receiver comprising at least a calculation unit that repeatedly performs a speed calculation process for obtaining a plurality of directional speed components and clock drifts that are unknown based on the positioning satellite signal of the received positioning satellite,
The calculation unit has a predetermined difference between a most recent clock drift obtained by the most recent speed calculation process and a past average value of a plurality of clock drifts obtained by the speed calculation process performed so far. Perform a process to determine whether the threshold is exceeded,
If it is determined that the difference exceeds the predetermined threshold,
The past average value of the plurality of clock drifts obtained by the speed calculation processing performed so far is adopted as the most recent clock drift,
In order to reduce the unknown at the time of speed calculation by one, using the past average value of the plurality of clock drifts as a known value at the time of speed calculation, a plurality of speed calculation processes determined by the speed calculation processing for determining the plurality of directional speed components A positioning satellite signal receiver that employs direction velocity components as a plurality of direction velocity components obtained by the latest velocity calculation processing. When the arithmetic unit determines that the difference is equal to or less than the predetermined threshold,
Storing the latest average value, which is an average of the past clock drift values of the plurality of clock drifts and the latest clock drift, as the past average value used when obtaining the difference,
The positioning satellite signal receiver according to claim 1, wherein the latest average value is obtained by a weighted average calculation process in which the past average value is heavily weighted with respect to the latest clock drift.   The weighting coefficient used in the processing of the weighted average calculation is such that the weight of the past average value with respect to the latest clock drift becomes heavier as the number of updates of the plurality of clock drifts used in the calculation of the past average value increases. The positioning satellite signal receiver according to claim 2, wherein the positioning satellite signal receiver is changed to be Based on a received positioning satellite signal of a positioning satellite, a processing method of a positioning satellite signal receiver that repeatedly performs a speed calculation process for obtaining a plurality of directional speed components and clock drifts that are unknown,
Whether the difference between the most recent clock drift obtained by the latest speed calculation process and the past average value of the plurality of clock drifts obtained by the speed calculation process performed so far exceeds a predetermined threshold value To determine whether
If it is determined that the difference exceeds the predetermined threshold,
The past average value of the plurality of clock drifts obtained by the speed calculation processing performed so far is adopted as the most recent clock drift,
In order to reduce the unknown at the time of speed calculation by one, using the past average value of the plurality of clock drifts as a known value at the time of speed calculation, a plurality of speed calculation processes determined by the speed calculation processing for determining the plurality of directional speed components A processing method for a positioning satellite signal receiver, wherein directional velocity components are adopted as a plurality of directional velocity components obtained by the latest velocity calculation processing. A program for functioning as a positioning satellite signal receiver for obtaining a plurality of directional velocity components and clock drift based on a positioning satellite signal of a received positioning satellite,
On the computer,
Based on the positioning satellite signal, a plurality of directional speed components that are unknown and a speed calculation process for obtaining clock drift are repeatedly performed,
Whether the difference between the most recent clock drift obtained by the latest speed calculation process and the past average value of the plurality of clock drifts obtained by the speed calculation process performed so far exceeds a predetermined threshold value To determine whether
If it is determined that the difference exceeds the predetermined threshold,
The past average value of the plurality of clock drifts obtained by the speed calculation processing performed so far is adopted as the most recent clock drift,
In order to reduce the unknown at the time of speed calculation by one, using the past average value of the plurality of clock drifts as a known value at the time of speed calculation, a plurality of speed calculation processes determined by the speed calculation processing for determining the plurality of directional speed components A program that causes a direction velocity component to function as a calculation unit that employs a plurality of direction velocity components obtained by the latest velocity calculation process.