JP2005134215A - System for measuring difference of signal arrival time - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a difference of signal arrival time to be precisely measured, by solving errors caused by such conditions that a time pulse is only generated at a timing synchronizing with a clock inside a receiver, and a measurement clock does not synchronize with the time pulse, and receivers of two stations determine the timing when the time pulse is generated, based on signals from different satellites. <P>SOLUTION: A time pulse signal (1 PPS) approximately synchronizing with a time of a positioning system which is obtained by a positioning operation, is operationally brought to synchronize with the measurement clock (40 MHz) in phase. Additionally, errors ΔTp1, ΔTp2 between a GPS time and 1 PPS are obtained, whereby the difference between count values T<SB>E1</SB>(1), T<SB>E1</SB>(2) of first and second events is compensated. Furthermore, the timing deviation of the time pulse signal is compensated by using a timing determined based on the signal from the identical satellite. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a signal arrival time difference measurement system for observing signals coming from a signal generation source at different locations and measuring the signal arrival time difference.

  For example, when a lightning strike occurs on a power transmission line or a steel tower, a surge occurs from the lightning strike point and propagates through the power transmission line. By observing the arrival time (passing time) of this surge at two locations on the transmission line and obtaining the difference between the arrival times, it is possible to identify at which point between two measurement points a lightning strike has occurred. A system for locating a surge occurrence point by such a method is disclosed in Patent Document 1.

  FIG. 12 shows a configuration example of a conventional surge occurrence point locating system. The steel tower 101 includes a surge detection circuit 12 that detects a surge propagating through the transmission line 100, a clock device 14 that keeps time as accurate as possible, and a counter 16 that measures the surge arrival time.

  FIG. 13 shows the operation of the timepiece device 14 and the counter 16 shown in FIG. 12 as a timing chart. The clock device 14 is provided with a GPS receiver, and for example, a time pulse signal (b) is output every second in synchronization with the internal clock (a) of the GPS receiver. The counter 16 is reset every time the time pulse is given from the timepiece device 14 and counts the measurement clock generated inside the counter 16. The counter 16 latches the count value when the surge detection circuit 12 detects the arrival of a surge.

By performing such processing for each desired steel tower, the time difference measuring device 103 measures the time difference of the timing measured by the timing measuring device 20 provided in different steel towers, so that the transmission line 100 between the two steel towers. Locate the location of the top surge point.
Japanese Patent No. 2599613

  A receiver that can receive radio waves transmitted from positioning satellites and obtain the position of the receiving point and the time of the positioning system, such as a GPS receiver, is more accurate than a general stand-alone watch. Time can be obtained. However, there are the following limitations in order to determine the position of the surge occurrence point with higher accuracy by the above-described surge occurrence point location system.

<< 1st error >>
Since the GPS receiver in the clock device 14 divides the clock in the receiver to generate a time pulse, the time pulse is output only at a timing synchronized with the clock in the GPS receiver. For this reason, as shown in FIG. 13, in practice, a signal from a GPS satellite is received and GPS timing is obtained from the received signal (this operation will be described in detail later. An error ΔTp occurs between the second timing to of the positioning system time (GPS time) obtained by the “calculation”) and the rise of the time pulse.

<< 2nd error >>
The measurement clock generated and counted inside the counter 16 and the time pulse output from the timepiece device 14 are not phase-synchronized. For this reason, as shown in FIG. 13, an error ΔTm occurs between the rising timing of the time pulse and the rising timing of the measurement clock.

<< 3rd error >>
The time timing to of the positioning system shown in FIG. 13 is a timing that is obtained by a timing calculation when a GPS receiver in the timepiece device 14 receives radio waves from one or more GPS satellites. Of course, there is an error. In a surge generation point locating system or the like, the difference in arrival time of surges may be obtained. Therefore, if the same error is included in the timings obtained by the two timing measuring devices, the error is canceled out. However, when the GPS receivers of the respective clock devices use different combinations of satellites for positioning calculation, errors in the positioning system time obtained by the GPS receivers remain.

  For example, as shown in FIG. 14, the timepiece device A can receive only radio waves from GPS satellites A, B, C, and E, and the timepiece device B can receive only radio waves from GPS satellites A, B, D, and F. The GPS receiver of the clock device A obtains the positioning system time timing obtained by the positioning calculation based on the radio waves from the GPS satellites A, B, C, E, and the GPS receiver of the clock device B uses the GPS satellites A, B. , D and F do not exactly match the timing timing to of the positioning system obtained by positioning calculation based on the radio waves from D, F. Therefore, an error corresponding to that occurs.

  The above-mentioned problem is not limited to the surge generation point locating system, but the arrival timing of a signal arriving from any signal generation source is measured at a plurality of measurement points at different positions, and the position of the signal generation source is determined based on the time difference. This is a problem common to such signal arrival time difference measurement systems.

  An object of the present invention is to provide a signal arrival time difference measurement system that solves the above-described problems and measures a signal arrival time difference with high accuracy.

  The present invention provides first and second timing measurement devices provided at at least two measurement points for measuring the arrival timings of signals arriving from a signal generation source, and the signals measured by the two timing measurement devices. In the signal arrival time difference measurement system including a time difference measurement device that measures a time difference of arrival timing, the timing measurement device divides a generated clock signal and transmits radio waves from a plurality of positioning satellites near the measurement point. Time pulse signal generating means for generating a time pulse signal (for example, 1 PPS) that is received at a reception point and is substantially synchronized with the time of a positioning system obtained by calculation based on the received signal, and for measuring the arrival timing of the signal Generates a measurement clock (for example, 40 MHz signal) and uses the timing of the time pulse signal as a reference Counting means for counting the measurement clock and is characterized in that the measuring clock with each and means for phase synchronization with the time pulse signal.

  The present invention also provides first and second timing measurement devices provided at at least two measurement points for measuring the arrival timings of signals arriving from a signal generation source, and the signals measured by the two timing measurement devices. In the signal arrival time difference measurement system comprising a time difference measurement device for measuring the time difference of the arrival timing of the signal, the timing measurement device divides the generated clock signal and transmits radio waves from a plurality of positioning satellites in the vicinity of the measurement point. A time pulse signal generating means for generating a time pulse signal (for example, 1 PPS) that is substantially synchronized with the time of the positioning system obtained by the calculation based on the received signal, and for measuring the arrival timing of the signal The measurement clock (for example, 40 MHz signal) is generated and the timing of the time pulse signal is set. Counting means for counting the measurement clock, and time pulse signal generation timing error detecting means for obtaining an error between the time pulse signal generated by the time pulse signal generating means and the time of the positioning system obtained by the calculation. Each of the time difference measuring devices is detected by the error detected by the time pulse signal generation timing error detecting means of the first timing measuring device and the time pulse signal generation timing error detecting means of the second timing measuring device. There is provided a time pulse signal generation timing error processing means for correcting the count value by the counting means by an amount corresponding to the error.

  The present invention also provides a positioning device that receives radio waves from the positioning satellite in the vicinity of the reception point of the first and second timing measurement devices, and is used by the time pulse signal generation means of the first timing measurement device. Means for obtaining a difference between the time pulse signal generation timing error obtained by a set of satellites and the time pulse signal generation timing error obtained by a set of positioning satellites used by the time pulse signal generation means of the second timing measurement device Is provided, and the time pulse signal generation timing error processing means further corrects the difference.

  Further, the present invention is characterized in that three or more measurement points are provided, and the timing measurement devices at two desired measurement points among the measurement points are the first and second timing measurement devices.

  The calculation based on the received signal (timing calculation) corresponds to a positioning calculation when the position (coordinate on the earth) where the receiver is placed is unknown. That is, the GPS timing is obtained together with the positioning. To obtain the position, it is usually necessary to receive signals from four or more satellites. When the position is known and only the timing is obtained, the timing is calculated by receiving one or more satellites. can do. If the position is already known, it is not always necessary to calculate the position. Even if the number of satellites that can be received is small, the timing is calculated based on the received signal. Just do it.

  According to the present invention, since the measurement clock is phase-synchronized with the time pulse signal substantially synchronized with the time of the positioning system obtained by the timing calculation, the second error ΔTm shown in FIG. 13 does not occur. High accuracy can be achieved.

  According to the invention, the count value of the measurement clock is corrected by the error of the time pulse signal generation timing of the first timing measurement device and the error of the time pulse signal generation timing of the second timing measurement device. The error due to the first error ΔTp shown in FIG. 13 is eliminated, and the signal arrival time difference can be measured with high accuracy.

  Further, according to the present invention, the third timing measuring device is similar to the time pulse signal generation timing error obtained by the set of positioning satellites used by the time pulse signal generating means of the first and second timing measuring devices. By calculating the difference from the time pulse signal generation timing error in the timing measurement device of No. 2 and further correcting this difference, the error correction due to the difference in the combination of positioning satellites in the first and second timing measurement devices Is done. Therefore, the signal arrival time difference measurement with higher accuracy can be performed.

  In addition, according to the present invention, among the three or more measurement points, the first and second timing measurement devices are arranged for each adjacent measurement point, thereby being divided into three or more measurement points. The location of the signal source can be determined within a wide range.

First, the configuration of the surge generation point locating system according to the first embodiment corresponding to claims 1 and 2 will be described with reference to FIGS.
FIG. 1 is a block diagram showing the overall configuration of the surge occurrence point locating system. The measuring station 110 is provided in a predetermined steel tower 101. The management station 120 collects data from the plurality of measurement stations 110 and determines the surge occurrence point. Each measurement station 110 includes a surge detection circuit 12 that detects the arrival of a surge that propagates through the transmission line 100, a timing measurement device 20 that measures the detection timing, and a control device 111 that performs data transmission control with the management station 120. I have.

  The management station 120 is a communication control device 121 that performs data communication with each measurement station 110, an arithmetic control device 122 that determines a surge occurrence point based on data collected via the communication control device 121, and an output that outputs the determination result. A device 123 and a GPS receiver 124 for correcting an error due to a difference in the combination of GPS satellites used by the timing measurement device 20 of each measurement station as described later are provided.

  FIG. 2 is a block diagram showing a configuration of the timing measurement device 20 shown in FIG. The timing measurement device 20 includes a GPS receiver 22 and a count control circuit 23. The GPS receiver 22 receives a radio wave from one or more GPS satellites by the GPS antenna 21 and performs timing calculation, and a time pulse signal (hereinafter referred to as “1PPS”) having a period of 1 second substantially synchronized with the GPS time which is the time of the positioning system. To the count control circuit 23. A clock signal generated inside the GPS receiver 22 is given to the count control circuit 23. Further, various data described later are output.

  The count control circuit 23 receives a surge detection signal from the surge detection circuit 12, obtains a count value indicating the timing, and outputs it to the control device 111.

3A is a block diagram illustrating the configuration of the GPS receiver 22, and FIG. 3B is a block diagram illustrating the configuration of the count control circuit 23.
In (A), the receiving circuit 221 of the GPS receiver 22 includes a down converter that converts the frequency of the signal from the GPS antenna 21 and an AD converter that converts the signal into digital data. The processor 222 removes the carrier component from the receiving circuit 221 and performs control for capturing and tracking the C / A code to obtain the C / A code phase. The oscillator 224 is an oscillator that generates a clock signal, and the processor 222 controls the time pulse generation circuit 225 so that the time pulse is closest to the second timing of the GPS time. The GPS time is obtained by the processor 222 performing a process for obtaining the timing. Since 1PPS is a signal obtained by dividing the clock signal output from the oscillator 224, it does not coincide with the accurate second timing of the GPS time obtained by the timing calculation. However, since the error is known from the processing result, the error is corrected as described later.

  3B, in the count control circuit 23, the frequency divider 231 divides the clock signal (in this example, a 11.605 MHz signal) output from the GPS receiver 22. The oscillator 233 generates a measurement clock signal (40 MHz signal in this example) to be supplied to the counter 235, and the frequency divider 234 divides the frequency to make it the same frequency as the signal output from the frequency divider 231. The phase comparator 232 obtains the phase difference between the output signals of the frequency dividers 231 and 234 and controls the oscillation frequency of the oscillator 233 accordingly. This constitutes a PLL circuit.

  The counter 235 is reset every time it receives 1 PPS, and counts the clock signal output from the oscillator 233. The buffer 236 latches the value of the counter 235 when a surge detection signal is input from the surge detection circuit. As described later, by synchronizing the measurement clock with the time pulse signal by the PLL circuit, the rising timing of the signal output from the frequency divider 231 (or 234) is set to the time of the positioning system and the time pulse signal. It is used as a reference timing for correcting the deviation from

3-2 is a block diagram illustrating another configuration example of the GPS receiver 22 illustrated in FIG.
3-2, the receiving circuit 221 of the GPS receiver 22 includes a down converter that converts the frequency of the signal from the GPS antenna 21 and an AD converter that converts the signal into digital data. The processor 222 removes the carrier component from the receiving circuit 221 and performs control for capturing and tracking the C / A code to obtain the C / A code phase. The VC-OCXO 224 is an oscillator that generates a clock signal, and the processor 222 gives control data to the DA converter 223 to control its oscillation frequency. This clock signal is supplied to the processor 222 and the receiving circuit 221. The frequency divider 225 divides the clock signal output from the oscillator 224 by a predetermined frequency dividing ratio and outputs 1 PPS. The processor 222 controls data supplied to the DA converter 223 so that the 1PPS follows the second timing of the GPS time. The GPS time is obtained by the processor 222 performing timing calculation.

  According to this configuration, since 1 PPS is a signal obtained by dividing the clock signal output from the oscillator 224, 1 PPS substantially coincides with the second timing of the accurate GPS time obtained by the timing calculation. Therefore, the first error ΔTp shown in FIG.

Next, processing contents of the GPS receiver 22 in the timing measurement device 20 of each measurement station 110 will be described with reference to FIGS.
FIG. 4A is a processing procedure for obtaining an error ΔTp between the GPS time that is the time of the positioning system and 1 PPS in the GPS receiver shown in FIG. 3A. First, the GPS time is obtained by timing calculation (S1). Then, parameters to be given to the time pulse generation circuit 225 shown in FIG. 3A according to the obtained GPS time are obtained, and the data is given to the time pulse generation circuit 225 (S2). By repeating this process every second, an error ΔTp between the actually output 1PPS and the accurate GPS time is obtained.

  FIG. 4B is a processing procedure for causing 1 PPS to follow the GPS time in the GPS receiver shown in FIG. 3B. First, the GPS time is obtained by positioning calculation (S1). Then, the deviation of the timing of the actually output 1PPS with respect to the obtained GPS time is obtained, the output value to be given to the DA converter 223 shown in FIG. 3-2 is obtained accordingly, and the data is given to the DA converter 223 (S2 → S3). By repeating this process at regular intervals, 1 PPS is synchronized with GPS time as much as possible.

FIG. 5 shows the relationship between the 11.605 MHz clock signal from the GPS receiver, the signal output from the frequency divider 231 (or 234), the 40 MHz clock signal for the counter 235, and the change in the counter count value. Yes. Here, ta is the timing at which the phase (rise timing) of the 11.605 MHz clock signal and the 40 MHz clock signal coincide. Further, to is the second timing of the GPS time, t ₁₁ is the timing of 1 PPS actually generated by dividing the clock signal of 11.605 MHz, and t ₄₀ is the rising timing of 40 MHz, which is the timing closest to to.

  As described above, 1PPS is generated by dividing the clock signal of 11.605 MHz. However, since the counter counts the clock signal of 40 MHz, a deviation of ΔTpm occurs between the rising timings of both. That is, this error ΔTpm is included in the count value.

FIG. 6 is a flowchart showing the procedure of the timing measurement apparatus for correcting the error ΔTpm shown in FIG.
First, the GPS time is obtained by timing calculation (S11). Then, a time x from the phase matching timing ta of the 11.605 MHz signal and the 40 MHz signal to the second timing to of the GPS time is obtained (S12). Similarly, a time y from the phase matching timing ta to the second timing of 40 MHz is obtained (S13). Further, a time z from the phase matching timing ta to 1 PPS is obtained (S14). Then, the difference between the time y and the time z is obtained as the above ΔTpm. Here, if the wave number of 11.605 MHz is m, the period is Tm, the wave number of 40 MHz is n, and the period is Tn, ΔTpm = m × Tm−n × Tn is obtained. Therefore, if the value counted by the counter 235 shown in FIG. 3-1 (B) is corrected by ΔTpm, an error (ΔTp shown in FIG. 13) due to the deviation of the 1PPS from the second timing of the GPS time is obtained. The error (ΔTm shown in FIG. 13) due to the difference in frequency between the reference clock signal for generating 1PPS and the clock signal counted by the counter can be corrected simultaneously.

  In this way, the measurement clock is phase-synchronized with the time pulse signal, and the deviation between the actual generation timing of the time pulse (1PPS) and the time of the positioning system obtained by calculation (second timing of GPS time) is calculated. Thus, the deviation can be corrected for the count value.

  The above correction may be performed in each measurement station, and the corrected data may be transmitted to the management station. The management station collects data before correction from each measurement station and performs the correction. You may go by side.

Next, the configuration of the surge generation point locating system according to the second embodiment corresponding to claim 3 will be described with reference to FIGS.
FIG. 7 shows an example of a timing chart in the timing measurement device 20 of the two measurement stations 110 provided at the first and second measurement points. 7 is a timing chart at the first measurement point, and the lower half is a timing chart at the second measurement point.

  In FIG. 7, 1PPS (1) is a time pulse signal obtained by the GPS receiver 22 at the first measurement point based on radio waves from a plurality of GPS satellites. The 40 MHz clock is a measurement clock signal supplied to the counter 235 by the oscillator 233 shown in FIG. However, in the example of FIG. 7, the rise timing of the 40 MHz signal and the rise timing of 1 PPS are shown to be coincident. As described above, since 1 PPS is generated by dividing the clock (11.605 MHz) signal in the GPS receiver, the rise of the 40 MHz signal does not always coincide with the rise of 1 PPS. The deviation can be corrected by the method shown in the first embodiment.

In FIG. 7, the first surge detection signal is generated when the surge intensity reaches the first threshold, and the second surge detection signal is generated when the surge intensity exceeds a second threshold higher than the first threshold. Generated. The first event occurrence detection timing is the rise timing of the measurement clock signal immediately after the rise of the first surge detection signal, and the first event count value T _E1 (1) is the count value when the first event occurs. Similarly, the second event occurrence detection timing is the rise timing of the measurement clock signal immediately after the second surge detection signal rises, and the second event count value T _E2 (1) is the count value when the second event occurs. .

The same applies to the second measurement point. 1PPS (2) is a time pulse signal obtained by the GPS receiver 22 at the second measurement point based on radio waves from one or more GPS satellites, and a first event count value T. _E1 (2) is the count value when the first event occurs, and the second event count value T _E2 (2) is the count value when the second event occurs.

The 1PPS (1) includes an error indicated by ΔTp1 with respect to the true GPS time. Similarly, 1PPS (2) includes an error represented by ΔTp2 with respect to the true GPS time. Therefore, the true time difference when the first event occurs is given by

True time difference = (1PPS (1) + T _E1 (1))-(1PPS (2) + T _E1 (2))
= (T _E1 (1) −T _E1 (2)) + (ΔTp1−ΔTp2) (1)
Since the time difference that can be observed here is the first term on the right side of the equation (1), the following equation is obtained.

Required time difference = (T _E1 (1)-T _E1 (2))
= True time difference- (ΔTp1-ΔTp2) (2)
Here, the second term on the right side of equation (2), (ΔTp1−ΔTp2) is defined as “error a”.

However, what is more problematic here is the above-mentioned “third error”. Each GPS receiver calculates GPS time at the first and second measurement points. However, if the combination of the satellites used for the processing for obtaining the timing by both GPS receivers is different, the GPS time calculated by both GPS receivers is used. Will contain different errors. If both GPS receivers perform processing to obtain timing with the same combination of GPS satellites, the calculated GPS time will contain the same error, so when calculating the difference in signal arrival time, By taking the error, the error included in the GPS time is canceled.

Therefore, using the timing obtained from one of the satellites received in common at the first and second measurement points or a combination thereof, the arrival time difference of the signals is obtained as follows. (Here, the calculation method is shown by taking as an example the timing obtained using the satellite A that is commonly received at the first and second measurement points.)
Time difference to be obtained = (T _E1 (1) + ΔTa (1))-(T _E1 (2) + ΔTa (2))
= (T _E1 (1)-T _E1 (2)) + (ΔTa (1)-ΔTa (2))
= True time difference-(ΔTp1-ΔTp2) + (ΔTa (1)-ΔTa (2))
= True time difference-((ΔTp1-ΔTa (1))-(ΔTp2-ΔTa (2)))
= True time difference-(Δta (1)-Δta (2)) (3)
Δta (1) = ΔTp1−ΔTa (1))
Δta (2) = ΔTp2−ΔTa (2))
It is.

Here, the second term (Δta (1) −Δta (2)) on the right side of equation (3) is defined as “error b”.

Since the distance between the first measurement point and the second measurement point is very close compared to the distance between the GPS satellite and the reception point, the radio wave propagation path from the same GPS satellite to the GPS receivers of the first and second measurement points is It is almost the same, and it can be considered that ionospheric delays and atmospheric delays work in the same way. Therefore, for example, the second timings ta (1) and ta (2) of the GPS time obtained by the satellite A coincide with high accuracy in calculation. Similarly, the second timings tb (1) and tb (2) of the GPS time obtained by the satellite B coincide with each other with high accuracy in calculation.

Therefore, when the combination of the satellites from which 1PPS (1) and 1PPS (2) are obtained is different, the above error A and error B have the relationship of “absolute value of error A> absolute value of error B”. Therefore, instead of (T _E1 (1) -T _E1 (2)), the time difference to be calculated is (T _E1 (1) + ta (1))-(T _E1 (2) + ta (2)) Furthermore, the arrival time difference of signals can be obtained with high accuracy.

Therefore, the time differences ΔTa (1), ΔTb (1), ΔTc (1), ΔTa (2), ΔTb (2), ΔTd (2), etc. from the rise timing of 1PPS output from each GPS receiver are calculated. To obtain and output.

  FIG. 8 shows the processing contents of the GPS receiver 22 in the timing measuring device 20 for that purpose. The GPS receiver receives radio waves from a plurality of GPS satellites necessary for positioning calculation, and performs timing calculation (S11 → S12). Once the position of the reception point and the GPS time are obtained by performing the positioning calculation, the second timing of the GPS time for each satellite is obtained from the reception point position, the satellite, and the C / A code phase of the signal from the satellite. Then, differences ΔTa, ΔTb, ΔTc,... Between this timing and the actually generated 1 PPS are calculated (S13 → S14).

  FIG. 9 is a flowchart showing the processing contents of the control device 111. First, the presence or absence of a surge detection signal from the surge detection circuit 12 is determined, and if a surge is detected, the data measured by the timing measurement device 20 is read (S21 → S22) and transmitted to the management station 120 (S23). The data at this time includes the GPS time obtained by the GPS receiver, the GPS time for each satellite, the deviations ΔTa, ΔTb, ΔTc... From the PPS, and the count value obtained by the timing measuring device 20.

  FIG. 10 is a flowchart showing a processing procedure of the arithmetic and control unit of the management station. If a new surge is detected from the data collected from each measurement station 110, the occurrence timing of the same event is extracted (S31 → S32). Then, the surge arrival time difference is calculated (S33). When the surge arrival time difference is calculated, the correction calculation for the above (ΔTa (1) −ΔTa (2)) is performed. Subsequently, the position of the surge source between the two measurement stations is obtained from the difference in arrival time of the surge and the distance between the two measurement stations (S34). Then, information on the surge occurrence point is output (S35).

FIG. 11 is a flowchart showing the processing contents of the GPS receiver 124 of the management station in the surge occurrence point locating system according to the third embodiment.
In this embodiment, based on the information from the GPS receiver 124 provided in the management station 120, the GPS receiver at the first and second measurement points performs a positioning calculation with a combination of different satellites, and the amount of deviation of 1 PPS is generated. Make corrections. First, the radio wave from each GPS satellite is received, and the GPS receiver of the first timing measurement device (the timing measurement device 20 of the first measurement station) uses the same combination as the satellite set used to obtain 1PPS (1). Timing A is obtained (S51 → S52). The combination of the satellites when the GPS receiver of the first timing measurement device performs the positioning calculation is included in the information obtained from the GPS receiver, and can be known based on the information.

  Similarly, the timing B is obtained in the same combination as the satellite set used by the GPS receiver of the second timing measurement device (timing measurement device 20 of the second measurement station) to obtain 1PPS (2) (S53).

  Subsequently, by obtaining timing A−timing B, (ΔTp1−ΔTp2), that is, “error a” in the management station can be known.

Then, (T _E1 (1) −T _E1 (2)) + A−B is set as a time difference to be obtained.

  In this manner, the 1PPS deviation generated as a result of the positioning calculation by the combination of different satellites by the GPS receivers at the first and second measurement points is corrected.

  In each of the embodiments described above, the time until the surge detection signal is input is counted by the counter, but conversely, the count is started from the point when the surge detection signal is input (the counter is reset). However, the contents of the counter may be latched in the buffer at the rise of 1 PPS.

  Although FIG. 1 shows a set of two measurement stations 110 among a plurality of measurement stations, three or more measurement stations are arranged in order to determine the surge occurrence point over a wide range, and a desired one of them is arranged. The two measurement stations are selected as a set, and the surge occurrence point between them is determined.

A block diagram showing the overall configuration of a surge occurrence point locating system commonly used in each embodiment Block diagram showing the configuration of the timing measurement device Block diagram showing configurations of GPS receiver and count control circuit Block diagram showing the configuration of another GPS receiver Flowchart showing the processing contents of the GPS receiver in FIG. The flowchart which shows the processing contents of the GPS receiver in Figure 3-2 The figure which shows the relationship between the time pulse signal and the clock signal for measurement etc. in the surge occurrence point locating system The flowchart which shows the processing contents of the timing measurement device in the surge occurrence point location system The figure which shows the timing relationship of each part in the surge occurrence point location system which concerns on 2nd Embodiment. The flowchart which shows the processing content of the GPS receiver in the surge occurrence point location system The flowchart which shows the processing contents of the control device in the surge occurrence point location system The flowchart which shows the processing content of the arithmetic and control unit of the management station in the surge occurrence point locating system The flowchart which shows the processing content of the GPS receiver by the side of a management station in the surge occurrence point location system which concerns on 3rd Embodiment. Block diagram showing the configuration of a conventional surge location system The figure which shows the 1st, 2nd error which arises in the conventional signal arrival time difference measurement system The figure which shows the factor which the 3rd error produces in the conventional signal arrival time difference measurement system

Explanation of symbols

20-Timing measuring device 100-Transmission line 101-Steel tower 103-Time difference measuring device

Claims (4)

First and second timing measurement devices provided at at least two measurement points for measuring the arrival timings of signals arriving from a signal generation source, and the time difference between the arrival timings of the signals measured by the two timing measurement devices In a signal arrival time difference measurement system comprising a time difference measurement device for measuring
The timing measurement device divides the generated clock signal and receives radio waves from a plurality of positioning satellites at reception points near the measurement point, and is approximately at the time of the positioning system obtained by calculation based on the received signal. Time pulse signal generating means for generating a synchronized time pulse signal;
Generating a measurement clock for measuring the arrival timing of the signal, and counting means for counting the measurement clock with reference to the timing of the time pulse signal;
A signal arrival time difference measuring system comprising: means for synchronizing the measurement clock with the time pulse signal, respectively. First and second timing measurement devices provided at at least two measurement points for measuring the arrival timings of signals arriving from a signal generation source, and the time difference between the arrival timings of the signals measured by the two timing measurement devices In a signal arrival time difference measurement system comprising a time difference measurement device for measuring
The timing measurement device divides the generated clock signal and receives radio waves from a plurality of positioning satellites at reception points near the measurement point, and is approximately at the time of the positioning system obtained by calculation based on the received signal. Time pulse signal generating means for generating a synchronized time pulse signal;
Generating a measurement clock for measuring the arrival timing of the signal, and counting means for counting the measurement clock with reference to the timing of the time pulse signal;
A time pulse signal generation timing error detecting means for obtaining an error between the time pulse signal generated by the time pulse signal generating means and the time of the positioning system obtained by the calculation;
The time difference measuring device includes an error detected by the time pulse signal generation timing error detecting means of the first timing measuring device and an error detected by the time pulse signal generating timing error detecting means of the second timing measuring device. A signal arrival time difference measurement system comprising a time pulse signal generation timing error processing means for correcting the count value by the counting means by an amount of minutes. A radio wave from the positioning satellite is received in the vicinity of the reception point of the first and second timing measurement devices, and is obtained from a set of positioning satellites used by the time pulse signal generating means of the first timing measurement device. A third means for obtaining a difference between the time pulse signal generation timing error and the time pulse signal generation timing error determined by a set of positioning satellites used by the time pulse signal generation means of the second timing measurement device; The timing measurement device of
The signal arrival time difference measurement system according to claim 2, wherein the time pulse signal generation timing error processing means further corrects the difference.   A signal having three or more measurement points and the timing measurement devices at two desired measurement points among the measurement points as the first and second timing measurement devices according to any one of claims 1 to 3. Arrival time difference measurement system.

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