JP2006317213A - Distance measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a distance between devices with high resolution, based on a propagation time of an impulse radio wave, without being affected by a noise. <P>SOLUTION: This distance measuring instrument includes a pulse transmitter for transmitting an electromagnetic pulse sequence generated in response to a pseudo-random noise (PN) code, and a receiver, and measures the distance between the transmitter and the receiver, or a relative position thereof, based on a propagation time of an electromagnetic wave. The receiver is provided with a pulse detector 1 for detecting a received pulse, a PN code generation part 2 for outputting the noise (PN) code, a reception time measuring part 3 for measuring a reception time in every of the received pulses, a time selection part 4 for selecting the reception time, and a time average-processing part 5 for averaging the selected reception times. The time selection part 4 selects the reception time of the effective pulse from the reception times measured by the reception time measuring part 3, the time average-processing part 5 averages the selected reception times, and the propagation time of the radio wave is found, based on the averaged reception time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a distance measuring device that measures the distance and relative position between devices from the propagation time of radio waves, and more particularly to a device that measures the distance with high resolution from the propagation time of impulse radio waves.

By measuring the position of movable objects such as people, cars, robots, and mobile devices, it is possible to provide inventory management, enrollment management, flow line management, security management, autopilot, and other services according to position. In order to measure the position of the movable object, it is fundamental to measure the distance between the movable object and the fixed object and measure the position of the movable object by triangulation.
For this purpose, distance measurement is required between the movable object and the fixed object. There are various types of distance measurement, but by measuring the propagation time of the radio wave, it is possible to measure the distance while performing data communication with the radio wave. Measuring distance from the propagation time of radio waves has been done for a long time like GPS, but in particular, by using impulse radio waves having ultra-wideband (UWB) frequencies, high-resolution position measurement Is possible.
However, in the case of a single pulse, if a pulse or other radio wave comes from another device at the same time, it becomes noise, and the pulse detection is erroneous. Therefore, for example, by using a pulse sequence having a small autocorrelation and a small cross-correlation by pseudo-randomizing (PN code) the interval between pulse trains, a time hopping that can detect a pulse train even when uncorrelated noise is superimposed ( (TH) type spread spectrum (SS) type is performed.

When measuring the distance by the SS method, a correlation calculation is performed to obtain a matching timing by shifting the timing of the pulse train of the same pattern (template) as the transmission pulse train, and the time difference between the transmitter and the receiver from the shifted timing amount, that is, Sought propagation time. In this case, in order to obtain the shift timing with high resolution, it is necessary to phase-synchronize the pulse trains on the transmission side and the reception side with high accuracy, and a coherent method in which feedback control is performed so that the phase is the same by a PLL is common. .
However, phase synchronization by PLL requires a complicated circuit or a long synchronization signal (preamble) before the phase is synchronized. The transmitter or receiver is small, lightweight, low price, and low. It is disadvantageous when manufacturing with power consumption.
Therefore, there is a non-coherent method in which the presence or absence of an impulse signal is directly detected by diode detection or envelope detection without phase synchronization of the impulse signal, and the reception sensitivity is worse than that of the coherent method. Only the circuit configuration becomes simple, and the transceiver can be manufactured with small size, light weight, low price and low power consumption. However, in the non-coherent method, it is necessary to directly measure the arrival of an impulse radio wave with a timer. However, since time measurement is performed with one impulse, there is a problem that the time resolution, that is, the distance measurement resolution cannot be increased.

On the other hand, there is a radar technique that measures the distance to a target from the time until the radio wave (light) reflected by the target returns to the device by transmitting radio waves or laser light from the device. Among them, the method described in Patent Document 1 is a method in which a pulse train converted to PN by a laser radar is obtained by rough measurement by a digital timer and precision measurement by a delay circuit, and the precision measurement result is averaged to increase time resolution. It is shown.
FIG. 22 is a diagram illustrating a transmission pulse and a reception pulse when distance measurement is performed from the time until the reflected radio wave returns as described above. In the figure, (a) is a transmission pulse train, (b) is a reception pulse train, (c) is a reception pulse train in a non-coherent receiver (in this example, a case where the clock is shifted) is shown, and a vertical dotted line is The timing of each clock pulse is shown. (A) and (b) show that a pulse train is received after tp1, tp2, ... time has elapsed since the transmission of a pulse train from a transmitter, tpr1, tpr2, ... are reception times by rough measurement, tpf1, tpf2,... indicate reception times by precise measurement.

JP 2002-214369 A

As described above, the spread of the pulse train can be detected even if uncorrelated noise is superimposed by using pseudo-random (PN code) intervals between pulse trains and using pulse trains with small auto-correlation and cross-correlation. (SS) method is performed.
However, when measuring the distance by the SS method, the correlation calculation is performed by shifting the timing of the pulse train of the same pattern (template) as the transmission pulse train, and the time lag between the transmitter and the receiver, that is, the propagation time is calculated from the shifted timing amount. Although there is a certain range of the correlation amount peaking, the time resolution is not so high.

On the other hand, in the method described in Patent Document 1, since the precision measurement results of all received pulses are averaged, an unnecessary pulse value tpfn is also averaged when there is noise in the received signal as shown in FIG. There is a problem that the error becomes large.
Further, by examining the distribution of each of the precise measurement values tpf1, tpf2,..., Tpfm, and excluding the precise measurement values that deviate from others, it is possible to exclude the precise measurement values greatly deviated by the noise pulse, Since noise pulses that are not deviated cannot be excluded, there is a problem that the average value is shifted.

Here, as described in Patent Document 1, in the case of a radar in which a transmitter and a receiver are installed at the same location, the transmission pulse train and the reception pulse train have the same frequency because they receive the pulse train that they output. The timing of the pulse train (pulse train interval) is the same.
For this reason, as shown in FIGS. 22A and 22B, the coarse measurement value of each pulse is always constant, and only the precise measurement value varies. Therefore, it was only necessary to average only the precision measurement values.
However, in the case of non-coherent communication in which the transmitter and the receiver are installed in different locations and the clocks are not synchronized, as shown in FIG. The precision measurement values tf1, tf2,..., Tfm change in accordance with the deviation of.
For this reason, when the received pulse changes beyond the clock, the precision measurement value is greatly different as shown by tf3 in FIG. 22, and the average value cannot be measured correctly by the average of only the precision measurement value. There was a problem that the distance measurement resolution could not be increased.

That is, if the clock period is slightly shifted, the pulse train interval is shifted, so that the coarse measurement value may change without being affected by only the change in the precise measurement value. For example, if the clock is a crystal oscillator and the 20 ppm period is shifted, when the pulse train length is 100 μS, the last pulse is shifted by 2 ns. For this reason, averaging only the precision measurement value causes a large error when the coarse measurement value changes.The present invention was made to solve the above-described problem. It is an object of the present invention to provide a distance measuring device that can measure the distance between devices with high resolution from the propagation time of an impulse radio wave without being affected by noise or the like even if the installation location of the receiver is different.

FIG. 1 shows a schematic configuration of a receiver according to the present invention.
In the present invention, a pulse transmitter that transmits an electromagnetic pulse train generated according to a pseudo random noise (PN) code, a receiver that receives an electromagnetic pulse train, and a transmitter based on the propagation time of electromagnetic waves from pulse transmission to reception In the apparatus for measuring the distance or relative position with respect to the receiver, as shown in FIG. 1, the receiver includes a pulse detector 1 for detecting a received pulse, a synchronization unit 6, and pseudo-random noise. A PN code generation unit 2 that outputs a PN code, a reception time measurement unit 3 that measures a reception time for each received pulse, a time selection unit 4 that selects a valid pulse reception time according to the PN code, and a selection The time average processing unit 5 for averaging the received times is provided, and the propagation time is obtained by the time average of the pulse train averaged by the time average processing unit 5 to improve the resolution.
The time resolution, that is, the distance resolution can be improved by taking the average of the reception times of a plurality of pulses instead of the reception time of one pulse. In addition, since averaging is performed using only valid reception times, it is possible to prevent the average value from being shifted by a pulse due to noise.
Further, in order to perform non-coherent communication in which the clocks of the transmitter and the receiver do not match, the reception time measurement unit 3 includes a coarse measurement unit 3a using a timer that operates in synchronization with the clock of the receiver, and the received pulse. A precision measurement unit 3b that measures the difference between the clock and the clock, and a time calculation unit 3c that calculates the reception time from the rough measurement unit 3a and the precision measurement unit 3b. The time average processing unit 5 uses the calculated reception time. Average.
In non-coherent communication that does not synchronize the clocks of the transmitter and receiver, even if the precision measurement value changes for each pulse, the average value is correctly calculated by using the reception time that combines the coarse measurement value and the precision measurement value. It becomes possible. In addition, because of non-coherent communication, the apparatus can be reduced in size, weight, cost, and power consumption.

Moreover, in this invention, it can also comprise as follows.
(1) In the above, a time scale is obtained from the difference between the transmitter clock and the receiver clock, and the reception time is corrected by the time scale.
By correcting the reception time using the time scale in this way, highly accurate distance measurement can be performed even if there is a clock error.
(2) The precision measuring unit is constituted by a tapped delay circuit.
(3) A table for converting a precise delay amount into a reception time from a delay amount of each tap is provided, and the reception time measuring unit 3 refers to the table and the delay amount of each tap obtained by the delay circuit with taps. Obtain the reception time from
By using a tapped delay circuit as described in (2) above, it is possible to measure the edge position of the input pulse with a finer precision than the clock.
Further, by obtaining the reception time using the table as in (3) above, the reception time can be obtained with a relatively simple circuit.

(4) The reception time measuring unit 3 measures the reception time using the pulse train of the preamble part that is not data-modulated in the transmission pulse train.
(5) The reception time measurement unit 3 measures the reception time using a distance measurement pulse train that is not data-modulated and is sent next to the preamble portion pulse train.
(6) The reception time measuring unit 3 uses the pulse train of the data part subjected to pulse position modulation, corrects the reception time based on the demodulated data, and measures the reception time.
By using preamble pulses that are not data-modulated as in (4) above, there is no need to correct the reception time based on the demodulated data as in the case of measuring time using a data pulse train.
Also, as in (5) above, a transmitter transmits a pulse train for distance measurement that is not data-modulated between the pulse train of the preamble portion and the pulse portion of the data portion, and receives it at the receiver. By measuring the distance using the pulse train, a long shift memory that holds the time is not required, as in the case of measuring the time using the preamble pulse train, and demodulating as in the case of measuring the time using the data pulse train. There is no need to correct the reception time based on the data, and the circuit configuration can be simplified.
Further, as described in (6) above, it is necessary to correct the reception time based on the demodulated data by measuring the reception time using the pulse train of the data part, but using the preamble pulse train as in (5) above. As in the case of measuring time, a long shift memory that holds the time is not required.
(7) A table for storing the time difference between each pulse and a pulse serving as a reference for the PN code is provided, and the reception time measurement unit 3 subtracts the time difference in the table from the reception time of each pulse to receive the reception time of each pulse. Is converted into a reference pulse reception time, and the time average processing unit 5 compares the reference pulse reception time with the converted time, and excludes those having a large difference from the average processing.
(8) A table for storing the pulse interval of the PN code is provided, and the time average processing unit 3 uses the difference between the reception time of each pulse and the previous effective reception time as a result of subtracting the time difference in the table as a reference value. If it is below, the reception time is valid, and if it is equal to or greater than the reference value, the value obtained by adding the time difference in the table to the previous effective reception time is set as the effective reception time, and the average value is obtained from the effective reception time.
By configuring as in the above (7) and (8), even if there is noise or the like, the average value can be obtained correctly, and the accuracy of distance measurement can be improved.

In the present invention, the distance between devices can be measured with high resolution from the propagation time of an impulse radio wave without being affected by noise or the like.
In addition, since the reception times are averaged, the pulse reception time can be obtained with high accuracy, and the distance and position between the devices can be measured with high accuracy.

FIG. 2 is a diagram showing the overall configuration of the distance measuring apparatus according to the embodiment of the present invention.
The distance measuring apparatus according to the present embodiment includes a transmitter / receiver a installed at a first point and a transmitter / receiver b installed at a second point as shown in FIG. The distance between the first point and the second point is obtained from the propagation time of the radio wave between the points.
The transceivers a and b include a spread / data modulation unit 11, a pulse generator 12 that outputs a pulse modulated by the spread data modulation unit 11, a power amplifier PA, and a transmission antenna, and amplifies the modulated pulse. Transmitting means 13 for transmitting and receiving, receiving means 14 having a receiving antenna and a low noise amplifier LNA for receiving and amplifying pulses, a pulse detector 15 for detecting pulses, and despreading for despreading and demodulating the received pulse train / Data demodulator 16, reception time measurement unit 17, and microcomputer 18 that controls the transmission of pulses and the like and measures the distance between the first and second points from the reception time.
In the figure, a pulse radio wave train is transmitted from the transceiver a, the pulse radio wave train is received by the transceiver b, and the reception time of the pulse radio wave is measured. Next, the pulse radio wave train is transmitted from the transceiver b, the pulse radio wave train is received by the transceiver a, and the reception time of the pulse radio wave is measured. At this time, the data of the reception time and the transmission time in the transmitter / receiver b is transmitted on the radio wave and sent back from the transmitter / receiver b to the transmitter / receiver a, whereby the distance between the two transmitters / receivers can be measured by the transmitter / receiver a.

The distance measuring method of the present invention will be described below. First, the case of measuring distance with one pulse, which is a conventional example, will be described with reference to FIG. Note that it is assumed that the times of the transmitter / receiver a and the transmitter / receiver b are shifted because the timers are not synchronized.
Transmitter / receiver a transmits a pulse at time Tat, transmitter / receiver b receives a pulse at time Tbr, then transmitter / receiver b transmits a pulse at time Tbt, and transmitter / receiver a receives a pulse at time Tar Assuming that the propagation time of the radio wave is tp, the time Tbr and the time Tbt are expressed by the following equation (1).
Tbr = Tat + to + tp (1)
Tbt = Tar + to-tp
If these equations are solved for tp and to, the following equation (2) is obtained.
tp = {(Tar-Tat)-(Tbt-Tbr)} / 2 (2)
to = {(Tbr−Tat) + (Tbt−Tar)} / 2 = {(Tbr + Tbt) − (Tat + Tar)} / 2

Accordingly, if the transmitter / receiver b sends the pulse reception time Tbr and the pulse transmission time Tbt to the transmitter / receiver a, the transmitter / receiver a can determine the propagation delay tp and the timer offset to.
If tp is known, if the speed of light is c and the distance between the transceivers ab is Lab, the distance Lab can be obtained by the following equation (3).
Lab = c · tp (3)
The above equation (2) is obtained by subtracting the reflection delay time (Tbt-Tbr) at the transmitter / receiver b from the time (Tar-Tat) from the transmission of the pulse to the return at the transmitter / receiver a. It is a thing. When only tp is obtained, the transmitter / receiver b may send only the reflection delay time (delay time from receiving a pulse to transmitting a pulse) to the transmitter / receiver a.

Next, the case where the distance measurement is performed by using the plural pulses of the present embodiment and performing the averaging process will be described with reference to FIG.
When m pulse trains are transmitted from the transmitter / receiver a to the transmitter / receiver b, the propagation delays tp11, tp12,..., tp1m of each pulse are expressed by the following equation (4).
tp11 = Tbr1-Tat1-to (4)
tp12 = Tbr2-Tat2-to
...
tp1m = Tbrm-Tatm-to
Here, the average value tp1av of the propagation delay time can be expressed by the following equation (5).
tp1av = (tp11 +... + tp1m) / m
= {(Tbr1 +... + Tbrm)-(Tat1 +... + Tatm)} / m-to = Tbrav-Tatav-to (5)
However, Tbrav = (Tbr1 +... + Tbrm) / m, Tatav = (Tat1 +... + Tatm) / m
Similarly, when m pulse trains are returned from the transceiver b to the transceiver a, the propagation delays tp21, tp22,..., Tp2m of each pulse can be expressed by the following equation (6).
tp21 = Tar1-Tbt1 + to (6)
tp22 = Tar2-Tbt2 + to
...
tp2m = Tarm−Tbtm + to

The average value tp2av of the propagation delay time can be expressed by the following equation (7).
tp2av = (tp21 +... + tp2m) / m
= {(Tar1 + ... + Tarm)-(Tbt1 + ... + Tbtm)} / m + to
= Tarav-Tbtav + to (7)
However, Tarav = (Tar1 +... + Tarm) / m, Tbtav = (Tbt1 +... + Tbtm) / m
Therefore, the average tpav of round-trip propagation delay time is expressed by the following equation (8).
tpav = (tp1av + tp2av) / 2 = {(Tarav−Tatav) − (Tbtav−Tbrav)} / 2 (8)
Further, when tp1av = tp2av, to is obtained as in the following equation (9).
to = {(Tbrav−Tatav) + (Tbtav−Tarav)} / 2 = {(Tbrav + Tbtav) − (Tatav + Tarav)} / 2 (9)
In (2), this is equivalent to Tat → Tatav, Tbr → Tbrav, Tbt → Tbtab, Tar → Tarav, and it is only necessary to average the transmission time and the reception time.

Since the pulse train interval at the time of transmission is a PN sequence and is known, the sums Tatst and Tbtst of the time interval between the first pulse and each pulse are known and can be expressed by the following equation (10). Tatst = (Tat2−Tat1) + (Tat3−Tat1) +... + (Tatm−Tat1) = m (Tatav−Tat1) (10)
Tbtst = (Tbt2-Tbt1) + (Tat3-Tbt1) +... + (Tatm-Tbt1) = m (Tbtav-Tbt1)
Substituting this relationship into the equations (8) and (9) to eliminate Tatav and Tbtav, the following equations (11) and (12) are obtained.
tpav = {(Tarav-Tat1-Tatst / m)-(Tbt1 + Tbtst / m-Tbrav)} / 2 (11)
to = {(Tbrav + Tbt1 + Tbtst / m) − (Tat1 + Tattst / m + Tarav)} / 2 (12)
That is, the average value Tbrav of the reception time of the pulse train and the first transmission pulse time Tbt1 may be sent from the transmitter / receiver b to the transmitter / receiver a.

Next, a specific configuration example of the receiving circuit in the distance measuring apparatus according to the present embodiment will be described.
FIG. 5 is a diagram showing the configuration of the receiving circuit according to the first embodiment of the present invention.
In FIG. 5, an impulse radio wave received by the antenna AT is amplified by a low noise amplifier LNA after unnecessary frequency components are removed by a band pass filter F, and the presence or absence of a pulse is detected by a pulse detection circuit 20. The pulse detection circuit 20 can be realized by a known diode detection circuit, envelope circuit + comparator, comparator with hysteresis, and the like.
The detected pulse is sampled at an appropriate sampling, here 10 MHz, and input to the shift register 22 in the correlator (DMF: digital matched filter for synchronization) 21 and detects the rising edge time of the pulse. Therefore, it is input to the reception time measuring unit 23.
The reception time measurement unit 23 includes a coarse measurement unit 23b including a digital timer 231 that operates with a 100 MHz clock, and a fine measurement unit 23a including a tapped delay circuit 232 and a decoder 233.

The configuration of the tapped delay circuit 232 is shown in FIG. 6, and the timing chart of the reception time measuring unit 23 including the tapped delay circuit 232 is shown in FIG. 7.
The tapped delay circuit 232 measures the edge position of the input pulse with a finer precision than the clock. The tapped delay circuit 232 has a structure in which delay elements Dly are connected in series to an input pulse.
Here, since the delay time of the delay element Dly is 1 ns, the delay element Dly includes 10 stages of delay elements in order to cut 10 ns. The input pulse is sampled by the D-flip-flop DFF with a 100 MHz clock and simultaneously input to the delay element Dly.
For this reason, the output of each delay element Dly is shifted by 1 ns, and the delay 0 to delay 4 as the input of the DFF and the delay 0 _ck to delay 4 _{ck as} the output of the DFF are as shown in FIG.
Since the output of each delay element Dly is also sampled by the DFF with a 100 MHz clock, the sampled data is 1 from halfway to 0 depending on the edge position of the input pulse.

Therefore, when the number of 1 is counted (encoded), the edge position within 10 ns is known. Here, since there are five 1s, it can be seen that there is an edge at the 5 ns position. By latching the encoded value and the value of the digital timer 231 of the coarse measuring unit 23b at this time, the rising edge position of the pulse, that is, the pulse reception time can be measured.
As for the coarse measurement value and the fine measurement value, the reception time can be calculated by coarse measurement value × constant 1 + precision measurement value × constant 2. Here, since the coarse measurement value is 10 ns and the fine measurement value is 1 ns, the constant 1 may be set to 10 and the constant 2 may be set to 1.
However, since the scale of the multiplication circuit is large, a table as shown in FIG. 8 is prepared when encoding the precise measurement value, and the table is tabulated as constant 1 = 256 and constant 2 = 25.6. If encoding is performed in this way, it is only necessary to combine the fine measurement value as the lower 8 digits (8 bits) and the coarse measurement value as the upper digits, and the circuit becomes simple.
Furthermore, when the delay amount of the delay element is not constant and varies, there is a method in which the variation is measured in advance and a table as shown in FIG. 9 is created.
If the i-th delay amount is Di and the sum of delay amounts up to the i-th is Si, the i-th table may store S _i-1 × constant 1 / rough measurement value unit. For example, if constant 1 = 256, coarse measurement value unit = 10 ns, and delay amounts are alternately 0.8 ns and 1.0 ns, 12 delay elements are required, and the table is as shown in FIG.

Returning to FIG. 5, the pulse reception time measured by the reception time measurement unit 23 is latched by the latch 24 and stored in the reception time shift memory 25 operating at 10 MHz, similarly to the shift register 22. That is, when 1 is set in the shift register 22, the edge time is in the shift memory 25.
Since the shift register 22 and the shift memory 25 operate at 10 MHz, data is sequentially input in units of 100 ns.
In the correlator (DMF) 21, the known PN sequence bit string 21a held in advance and the data in the shift register 22 are compared by the exclusive OR circuit, and the comparison result is added by the adder 21b. If the output of the adder 21b is greater than a preset threshold, the threshold determination circuit 21c determines that a PN sequence pulse train has been received and captures synchronization.
When the synchronization is captured, the contents of the shift memory 25 are fixed, the time is extracted as will be described later, and the averaging process is performed by the averaging processor 28.

The transmission / reception data format is shown in FIG.
The transmission data is time-hopped with an 8-value Reed-Solomon RS sequence, which is a kind of PN sequence, and further data-modulated with pulse position modulation (PPM).
When 576421 is used as the RS sequence for one chip of 100 ns, the first pulse is time-hopped (TH) in the position of 500 ns and the next pulse is in the position of 700 ns in the pulse section of 1 μs (FIG. 10). (See TH data).
As shown in the figure, the communication data is composed of a data non-modulated preamble portion and a data portion, and the synchronization data non-modulated preamble portion is 7 pulses 7 μs, followed by the data portion. The data part is also time-hopped by the same RS sequence, but when the data is 1, pulse position modulation PPM is performed in which the position of one chip pulse is shifted.
For example, in the case of 0110 data, the 5762... RS sequence is modulated as 5873..., And pulses are hopped at 500 ns, 800 ns, 700 ns, and 300 ns positions. Since the preamble part is not modulated, it remains 5663.

  The receiving side samples the received pulse at 100 ns, but when it is stored in the shift register 22 in order and the preamble part is stored, it corresponds to the PN sequence bit string stored in advance, that is, 5863. 00000100 0000000100 0000001000 000000000000... Are compared. That is, as described above, the degree of coincidence of each bit between the shift register 22 and the PN series bit string 21a is detected by the exclusive OR circuit, and the detection result is added by the adder 21b and compared with the threshold value by the threshold value determination circuit 21c. If the degree of coincidence is equal to or greater than the threshold value, it is determined that they coincide and a synchronization acquisition signal is output.

In this embodiment, the reception times of 7 pulses in the preamble part that is not data-modulated are averaged.
As shown in FIG. 5, the time selection unit 26 includes PN sequence TH data 26a (data in which pulse positions are recorded as shown in FIG. 10) and a selector 26b. The selector 26b selectively extracts the time data held in the shift memory 25 by the PH series TH data 26a.
Since the pulse arrival time is stored at the corresponding position of the shift memory 25 at the time when the synchronization acquisition signal is output, the time data corresponding to the pulse position is extracted by the selector 26b.
For example, as shown in FIG. 10, since the RS sequence is 5763..., For the first ten from the right of the shift memory 25, the sixth from the right is extracted. Similarly, the next 10 are the eighth, the next 10 are the seventh, and the next 10 are the fourth. For example, as shown by the received pulse in FIG. 10, even if an erroneous pulse due to noise enters between the first pulse and the second pulse, this memory is not selected, so the average value will not be erroneous.
The reception time selected by the time selection unit 26 is sent to the average processing unit 28. The average processing unit 28 calculates the average value of the seven pulse reception times. Thereby, Tbrav shown in the equation (11) is obtained.

On the other hand, as shown in FIG. 5, the TH / PPM decoding unit 27 includes a selector 27a for selectively extracting data held in the shift register 22 by the PN sequence TH data 26a, and a data register 27b for storing the extracted data. .
Since the shift register 22 is updated every 70 samples (7 μs) after the acquisition of synchronization, the corresponding bits are extracted from the shift register in units of 10 bits in the same manner as the data is extracted from the shift memory 25. Store in the data register 27b. Here, as described above, since the data portion is subjected to pulse position modulation (PPM), 2 bits are extracted at the time of extraction, and it is determined whether the data is 0 or 1 depending on whether it is 10 or 01.
For example, since the RS sequence is 5763..., As shown in the data portion of the received pulse in FIG. 10, for the 10 bits from the right of the shift register, the sixth and seventh 10s from the right are extracted. Since this is 10, it is determined that the data is 0 because the position is not modulated. Similarly, for the next 10 bits, the eighth and ninth bits are extracted and are 01, so that it is determined as data 1. The extracted data is stored in the data register 27b.
In the above, the pulse transmission of the transmitter a and the pulse reception of the receiver b have been described, but the same applies to the case where the pulse is sent back from the transmitter b to the transmitter a.

FIG. 11 shows a processing flow of distance measurement in the transceivers a and b.
The transmitter / receiver a transmits the preamble data and simultaneously stores the leading pulse transmission time Tat1. The transmitter / receiver b calculates the average reception time Tbrav of the pulse train at the same time as acquiring synchronization with the preamble.
In the transceiver a, following the preamble, a data measurement command (ranging command) is sent as data in the data section. The transmitter / receiver b receives the command data after capturing the synchronization, and if it is determined to be a distance measurement command, it returns the pulse train and simultaneously stores the transmission time Tbt1 of the leading pulse at that time.
The receiver a calculates the average reception time Tarav of the pulse train at the same time as acquiring synchronization with the preamble. In the transmitter / receiver b, the time data Tbrav and Tbt1 stored in the data portion are transmitted as data following the preamble. The transmitter / receiver a receives time data after acquisition of synchronization, calculates the average propagation time Tpav according to the equation (11), and determines the inter-device distance in (3).

Next, a receiving circuit according to a second embodiment of the present invention is shown in FIG. In the present embodiment, an unmodulated distance measuring preamble portion is inserted between the preamble portion and the data portion, and the distance measurement is performed as described above by this distance measuring preamble portion.
The overall configuration of the transceiver and the delay circuit with a tap are the same as in the first embodiment, but the difference from the first embodiment is that the distance measurement is performed after acquiring the synchronization without measuring the pulse reception time in the preamble section. This is to measure the pulse reception time of the preamble section for measuring distance. FIG. 13 shows a processing flow of distance measurement.
When the transmitter / receiver a transmits the preamble data, the transmitter / receiver b acquires the synchronization by the preamble. The transmitter / receiver a transmits the data of the distance measurement preamble portion following the preamble, and at the same time stores the leading pulse transmission time Tat1.
The transceiver b receives the data of the distance measurement preamble portion following the preamble and calculates the average reception time Tbrav of the pulse train at the same time.
Next, the transmitter / receiver a sends a command for distance measurement in the data section as data. If the transmitter / receiver b determines that the command is a distance measurement command, it sends back a pulse train.
The transmitter / receiver a acquires synchronization by using a preamble. The transmitter / receiver b transmits the distance measurement preamble portion following the preamble portion, and at the same time stores the leading pulse transmission time Tbt1.
When the transmitter / receiver a receives m pulses of the distance measurement preamble portion following the preamble, the average reception time Tarav of the pulse train is calculated.
In the transmitter / receiver b, the data section sends the saved time data Tbrav and Tbt1. In the transmitter / receiver a, when the reception of this time data is completed, the average propagation time Tpav is obtained according to (11) as in the first embodiment, and the inter-device distance is obtained in (3).

The synchronization acquisition, reception time measurement, and data decoding of this embodiment will be described with reference to FIG.
As in the first embodiment, the input signal is sampled at 10 MHz and stored in the shift register 22. When synchronization is acquired by the correlator (DMF) 21 in the same manner as in the first embodiment, the reception time of the next pulse of the distance measurement preamble section is measured and averaged.
When the synchronization is captured, the PN sequence bit string stored in the PN sequence rotation register 21d is shifted in rotation as soon as data is input to the shift register 22 and shifted.
For example, if the PN sequence is 5763..., The PN sequence bit string is 00000100,000,000,100,000,000,000,000,000,000 as viewed from the right. Further, when 1-bit shift rotation is performed, 1 appears second from the left end.
At this timing, the reception time data measured by the time measuring unit 23 and latched in the latch 24 is latched by the latch 26c of the time selecting unit 26.
The latched data is integrated by the average processing unit 28. If m pieces are integrated, 1 / m is obtained as average value data.

The data part is then received. The PN sequence bit string stored in the PN sequence rotation register 21d is shifted and rotated simultaneously with the shift register 22. As described above, when the 6-bit shift rotation is performed, 1 appears from the right end to the left end, and when the 1-bit shift rotation is performed, the left end 1 appears second from.
Therefore, whether or not there is 1 at the left end and the second end from the left end of the shift register is checked by the AND gates 27c and 27d of the TH / PPM decoding unit 27. If it is the second from the left end, it is determined that the data is not modulated because it is data 0, and if it is located at the left end, it is determined that the data is modulated because it is data modulated. This 0/1 data is stored in the data register 27b.
In this embodiment, since a long shift memory as in the first embodiment is unnecessary, the circuit is simplified. Also, when the distance measurement preamble part is transmitted next to the preamble part, the synchronization is acquired by the first preamble part, and the time is measured by the next distance measurement preamble part. Thus, time correction by data modulation becomes unnecessary.

Next, the receiving circuit of the third embodiment is shown in FIG.
The overall structure of the transceiver, the tapped delay circuit, and the transmission / reception data format are the same as in the first embodiment. The difference from the first embodiment is that the pulse reception time is measured in the data portion after acquisition of synchronization without measuring the pulse reception time in the preamble portion. FIG. 15 shows a processing flow of distance measurement.
When the transmitter / receiver a transmits the preamble data, the transmitter / receiver b acquires the synchronization by the preamble. In the transmitter / receiver a, a command for distance measurement is sent as data in the data section following the preamble, and at the same time the leading pulse transmission time Tat1 is stored. The transceiver b receives the command data following the preamble and calculates the average reception time Tbrav of the pulse train at the same time. At this time, if m pulses are received in advance, an average value is obtained. If the transmitter / receiver b determines that the command is a distance measurement command, it sends back a pulse train. The transmitter / receiver a acquires synchronization by using a preamble. The transceiver b saves the head pulse transmission time Tbt1 of the data portion following the preamble, and simultaneously sends the saved time data Tbrav and Tbt1 in the data portion. The transceiver a receives time data following the preamble, and at the same time, receives m pulses and calculates an average reception time Tarav of the pulse train. When the received data is completed, as in the first embodiment, the average propagation time Tpav is obtained according to the equation (11), and the inter-device distance is obtained by the equation (3).

In FIG. 14, synchronization acquisition, reception time measurement, and data decoding will be described.
As in the first embodiment, the input signal is sampled at 10 MHz and stored in the shift register 22. At this time, the reception time is not held before acquisition of synchronization. If synchronization is acquired by the correlator (DMF) 21 as in the first embodiment, as described in the second embodiment, the PN sequence bit string contained in the PN sequence rotation register 21d is the shift register 22 and At the same time, the rotation is shifted.
For example, if the PN sequence is 5763..., The PN sequence bit string is 00000100,000,000,100,000,000,000,000,000,000 as viewed from the right. Further, when 1-bit shift rotation is performed, 1 appears second from the left end.
Therefore, whether or not there is 1 at the left end and the second end from the left end of the shift register 22 is viewed from the AND gates 27c and 27d of the TH / PPM decoding unit 27, and if it is the second from the left end, data modulation is not performed. If data 0 is at the left end, it can be determined as data 1 since data modulation is performed.

This 0/1 data is stored in the data register 27b. Further, the reception time data measured by the time measurement unit 23 at this timing and latched in the latch 24 is selected.
However, in the case of data 1, since the data is modulated and the pulse position is shifted by 100 ns, data obtained by subtracting 100 ns from the latched data is selected. That is, the time selector 26 is provided with a subtractor 26e, which subtracts 100 ns from the time latched by the subtractor 26e, and latched by the selector 26d or subtracted according to the outputs of the AND gates 27c and 27d. The time output by the device 26e is selected.
The selected data is integrated by the average processing unit 28, and if m pieces are integrated, 1 / m is obtained as average value data.
In the third embodiment, since a long shift memory as in the first embodiment is unnecessary, the circuit is simplified. Note that the first embodiment and the third embodiment may be merged, and averaging processing may be performed using both the preamble portion and the data portion pulses.

Next, a fourth embodiment will be described. The configuration of the transceiver is the same as that of the above embodiment, but the average processing part is changed.
When a pulse train is received, not all pulses can be correctly input. In this embodiment, only pulses that have been correctly input are averaged.
Here, the time interval T1i between the first pulse (reference pulse) and the i-th pulse at the time of transmission is known, and the reference pulse time difference of time hopping data is as shown in FIG. 16, for example. Accordingly, by referring to the table shown in FIG. 16, the time interval T1i between the first pulse and the i-th pulse at the time of transmission can be obtained.
In the present embodiment, only the pulses that have been correctly input are extracted and averaged using the known time interval T1i between the first pulse and the i-th pulse at the time of transmission.

In the present embodiment, the averaging process is performed as follows using the known data.
Times Tbr12,..., Tbr1m obtained by converting each received pulse to the head pulse position are defined as the following expression (13) using the reference pulse time differences T12,.
Tbr12 = Tbr2-T12 (13)
...
Tbr1m = Tbrm−T1m
If defined as above, T1i = Tati−Tat1, and therefore, the following equation (14) is obtained.
Tbr1 = tp11 + to + Tat1 (14)
Tbr12 = Tbr2- (Tat2-Tat1) = tp12 + to + Tat1
...
Tbr1m = Tbrm− (Tatm−Tat1) = tp1m + to + Tat1

Tbr12,..., Tbr1m should be almost the same value as Tbr1. Therefore, if these values do not deviate greatly, it can be determined that a pulse is correctly input. Therefore, if br (<= m) of Tbr1x which is greatly deviated is used and averaged by using mb (<= m), the following equation (15) is obtained.
Tbr1av = (Tbr1 + Tbr12 +... + Tbr1m) / mb (15)
Similarly, the following equation (16) is obtained.
Tar1 = tp21−to + Tat1 (16)
Tar12 = Tar2- (Tbt2-Tbt1) = tp22-to + Tbt1
...
Tar1m = Tarm− (Tbtm−Tbt1) = tp2m−to + Tbt1
Tar1av = (Tar1 + Tar12 +... + Tar1m) / ma

Using the partial average values Tbr1av and Tar1av described above, the following equation (17) is obtained when Tat → Tat1, Tbr → Tbr1av, Tbt → Tbt1, and Tar → Tar1av in the above equation (2).
tp = {(Tar1av−Tat1) − (Tbt1−Tbr1av)} / 2 (17)
to = {(Tbr1av + Tbt1)-(Tat1 + Tar1av)} / 2
That is, Tbr1av and Tbt1 may be sent from the transceiver b to the transceiver a.

FIG. 17 shows a processing flow for obtaining the above average value.
In FIG. 17, first, Tbr1 is put into Sum, i is set to 2, and n is set to 1 (step S1). Next, the reference pulse time difference T1i is obtained with reference to the table of FIG. 16, Tbr-T1i is set to Tbr1i, and whether or not | Tbri-Tbr1 | <ε is checked (steps S2 and S3).
If | Tbri−Tbr1 | <ε, go to Step S5. If | Tbri−Tbr1 | <ε, Sum + Tbr1i is set to Sum, n + 1 is set to n, and the process goes to Step S5. In step S5, i + 1 is set to i, and it is checked whether i> m is satisfied (step S6). If i> m, the process returns to step S2, and the above process is repeated. If i> m, Sum / n is set to Tbr1av (step S7).

Next, a fifth embodiment will be described.
When a general crystal clock is used as a timer used in a transceiver, there is an error of several tens of ppm.
In the present invention, since clock synchronization is not performed between the transceivers, a clock error may be a problem. For example, if it takes 200 μs after transmitting a pulse from the transceiver a until the transceiver b returns the pulse, an error of 4 ns (= 1.2 m) occurs when there is a 20 ppm timer error.
That is, in order to measure the distance with high accuracy, it is necessary to correct the scale error due to the clock deviation. In this embodiment, the scale error is corrected as follows.
If the transmitter / receiver a transmits a pulse train at the time interval Taw in advance and the transmitter / receiver b can receive at the time interval Tbw, the timer of the transmitter / receiver b has a scale error of sc = Tbw / Taw compared to the transmitter / receiver a. I understand.

Assuming that the time of the transmitter / receiver a is used as a reference and the timer offset to and the propagation delay tp are expressed by the timer a, the equation (1) can be expressed as the following equation (18).
Tbr = sc {Tat + to + tp} (18)
Tbt = sc {Tar + to-tp}
If this is solved for tp and to, the following equation (19) is obtained.
tp = {(Tar−Tat) − (Tbt−Tbr) / sc} / 2 (19)
to = {(Tbr / sc-Tat) + (Tbt / sc-Tar)} / 2 = {(Tbr + Tbt) / sc- (Tat + Tar)} / 2
Comparing the equation (19) with the equation (2), it can be seen that the time Tbx in the transceiver b of the equation (1) should be multiplied by 1 / sc.
When averaging with a plurality of pulses, if Tbxx → Tbxx / sc in the above equations (8) and (11), the following equation (20) is obtained.
tpav = {(Tarav−Tatav) − (Tbtav−Tbrav) / sc} / 2 = {(Tarav−Tat1−Tattst / m) − (Tbt1 + Tbtst / m−Tbrav) / sc} / 2 (20)
to = {(Tbrav + Tbtav) / sc- (Tatav + Tarav)} / 2
= {(Tbrav + Tbt1 + Tbtst / m) / sc- (Tat1 + Tattst / m + Tarav)} / 2

That is, the average value Tbrav of the reception time of the pulse train and the first transmission pulse time Tbt1 are sent from the transmitter / receiver b to the transmitter / receiver a in the same manner as when no clock error is considered, and the value received by the transmitter / receiver a is 1 / sc Just do it.
However, if all the pulses cannot be correctly input as in the fourth embodiment and the scale error cannot be ignored, the scale error is included in Tbr1i in the flow of FIG. 17, so that even if Tbr1i is averaged, Tbr1 It is not the average of
This is because in the calculation of Tbr1i = Tbti−T1i, the difference between T1i and T1i / sc cannot be ignored as i increases and the time interval from the first pulse increases.
Although it is possible to calculate correctly by calculating as Tbr1i = Tbri−T1i / sc, it is necessary to calculate sc by the transmitter / receiver b every time. However, since sc is close to 1, a fixed point with a long bit length so as not to drop digits. Arithmetic and floating point operations are required, which increases the circuit scale.

Therefore, it is determined whether Tbri is correct based on the difference from the immediately preceding pulse where the error can be ignored, not the difference from the leading reference pulse.
Since the interval between the reception pulses at the known station b is almost equal to the transmission pulse interval at the known station a and sc is nearly 1, the following equation (21) holds.
Tbri−Tbri ₋₁ ≈sc (Tati−Tati ₋₁ ) ≈Tati−Tati ₋₁
... (21)
Therefore, if defined as Tdi = Tati−Tati− ₁ , it can be determined whether or not the i-th pulse is a correct pulse by the following equation (22).
Tbrdlti = | (Tbri−Tbrpi ₋₁ ) −Tdi | <ε (22)
The Tdi may be calculated in advance and entered in a table, and each pulse interval of the time hopping data is as shown in FIG. Therefore, it can be obtained by referring to the table shown in FIG.
Furthermore, if the received pulse is not correct, Tbrpi = Tbr _-1 + Tdi is used as the provisional pulse arrival time for use in the averaging process, and the pseudo average value of the pulse arrival time is expressed by the following equation (23).
Tbrpav = (Tbr1 + Tbrp2 +... + Tbrpm) / m (23)
Similarly, the transmitter / receiver a is expressed by the following equation (24).
Tardlti = | (Tari−Tapi ₋₁ ) −Tdi | (24)
Tarpi = Tari-1 + Tdi if (Tbrdlti> = ε)
Tarpi = Tari if (Tbrdlti <ε)
Tarpav = (Tar1 + Tarp2 + ... + Tarpm) / m

When the equation (20) is modified using these pseudo average values, the following equation (25) is obtained.
tpav = {(Tarpav−Tat1−Tatst / m) − (Tbt1 + Tbtst / m−Tbrpav) / sc} / 2 (25)
to = {(Tbrpav + Tbt1 + Tbtst / m) / sc- (Tat1 + Tastst / m + Tarpav)} / 2
The pseudo average values Tbrpav and Tbt1 may be sent from the transceiver b to the transceiver a.
The feature of this calculation method is that if the average value is obtained without using the pulse when the pulse is not correct, tp1av cannot be obtained correctly with the equation (8), so that it is a pseudo value from the previous received pulse. To generate a pulse that seems to be correct.
At this time, since the pulse is generated from the previous pulse, the error can be ignored because the pulse interval is short without performing sc calculation that is likely to cause a digit loss. That is, it is not necessary to calculate sc, which is likely to cause a digit loss, in the transceiver b including whether the pulse is correct.
If the transceiver a is a device with abundant computing resources such as a PC (personal computer), and the transceiver b is a device with few computing resources such as peripheral devices and tags, the transceiver b does not perform multiplication or division of decimal points. Therefore, the circuit of the transceiver b can be simplified.

This is shown in a flowchart in FIG.
Tbr1 is put into Sum, Tbrp1 is set to Tbr1, and i is set to 2 (step S1). Next, Tdi is obtained with reference to the table shown in FIG. 18, and | (Tbri-Tbrpi _-1 ) -Tdi | is set to Tbrdlti (step S2).
Next, it is checked whether Tbrdlti <ε (step S3). If Tbrdlti <ε, Tbrpi is set to Tbri (step S4), and the process goes to step S5. If Tbrdlti <ε, Tbrpi ₋₁ + Tdi is set as Tbrpi (step S8), and the process goes to step S5.
In step S5, Sum + Tbrpi is set to Sum, and i + 1 is set to i. If i> m, the process returns to step S2, otherwise Sum / m is set to Tbrpav (steps S6 and S7).

The above has been described as a method for increasing the resolution of the distance measurement between two devices. As shown in FIG. 20, for a transmitter / receiver A1, A2, A3 whose positions are known, In the transmitter / receiver M whose position is unknown, if the M-A1 distance L1, the M-A2 distance L2, and the M-A3 distance L3 are measured with high resolution, the position of the transmitter / receiver M is solved by solving the following simultaneous equations: Can be measured with high resolution.
(X−xi) ² + (y−yi) ² + (z−zi) ² = Li ²
Furthermore, the present invention can be applied not only to transmission / reception of bidirectional radio waves, but also to position measurement using unidirectional radio waves such as the GPS type and the reverse GPS type as shown in FIGS. .
For example, in the reverse GPS type shown in FIG. 21A, in the transmitter M whose position for transmitting the impulse radio wave is unknown and in the receivers A1, A2, A3, and A4 where the position for receiving the impulse radio wave is known, The position of the transmitter M can be obtained by solving the following simultaneous equations based on the arrival time difference TDOA (Time Difference of Arrival).
√ {(x−xi) ² + (y−yi) ² + (z−zi) ² } −√ {(x−xj) ² + (y−yj) ² + (z−zj) ² } = c ( ti-tj)
Here, ti and tj are pulse arrival times, and ti = t1 to t4 and tj = t1 to tj (i ≠ j) in FIG.

At that time, in the receivers A1 to A4, the time difference is obtained with high resolution by averaging the reception time of each pulse train according to the present invention, and thereby the position is obtained with high resolution. Similarly, for the GPS type, the receiver M averages the reception time of each pulse train, so that the time difference is obtained with high resolution. Therefore, the position is obtained with high resolution.
In the above description, the data modulation has been described by the pulse position modulation PPM. However, the pulse presence / absence modulation OOK (On-Off-Keying) functions similarly.
Furthermore, in the above description, it is described that radio waves are used. However, the present invention can be similarly applied to the case where distance measurement is performed using visible light or other light.

(Supplementary note 1) A pulse transmitter that transmits an electromagnetic pulse train generated according to a pseudo-random noise code, a receiver that receives an electromagnetic pulse train, and a transmitter and a receiver based on the propagation time of electromagnetic waves from pulse transmission to reception A device for measuring the distance or relative position of
A reception time measurement unit that measures the reception time for each received pulse, a time selection unit that selects a valid pulse reception time according to the PN code, and a time average processing unit that averages the selected reception times. And calculating the distance based on the averaged reception time.
(Supplementary Note 2) The reception time measurement unit includes a coarse measurement unit using a timer that operates in synchronization with the clock of the receiver, a precision measurement unit that measures a difference between the received pulse and the clock, a coarse measurement unit, and a precision measurement unit. A time calculation unit for calculating the reception time from the value measured by
The distance measuring apparatus according to appendix 1, wherein the averaging processing unit performs averaging using the calculated reception time.
(Supplementary note 3) The distance measuring device according to supplementary note 1 or supplementary note 2, wherein a time scale is obtained from a difference between a transmitter clock and a receiver clock, and the reception time is corrected by the time scale.
(Supplementary note 4) The distance measuring device according to supplementary note 2 or supplementary note 3, wherein the precision measuring unit is configured by a tapped delay circuit.
(Additional remark 5) It has the table | surface which converts the precise delay amount into the reception time from the delay amount of each tap, The said reception time measurement part refers to the said table, The delay of each tap calculated | required by the said delay circuit with a tap The distance measuring device according to appendix 4, wherein the reception time is obtained from the quantity.
(Additional remark 6) The said reception time measurement part measures reception time using the pulse sequence of the preamble part which is not data-modulated in a transmission pulse train, Additional remark 1, 2, 3, 4 or Additional remark 5 Distance measuring device.
(Additional remark 7) The said reception time measurement part measures reception time using the pulse train for distance measurement which is sent after the pulse train of a preamble part and is not data-modulated, The additional notes 1, 2, The distance measuring device according to 3, 4 or appendix 5.
(Additional remark 8) The said reception time measurement part correct | amends reception time based on demodulation data using the pulse train of the data part which carried out the pulse position modulation, and measures reception time, It is characterized by the above-mentioned. , 4 or appendix 5 distance measuring device.
(Additional remark 9) It has the table | surface which stores the time difference of each pulse and the pulse used as the reference | standard of PN code | symbol, The said reception time measurement part receives each pulse by subtracting the time difference in a table | surface from the reception time of each pulse. Convert the time to the reference pulse reception time,
The time average processing unit compares the reference pulse reception time with the converted time, and those having a large difference are excluded from the average processing. 1, 2, 3, 4, 5, 6, 7 The distance measuring device according to appendix 8.
(Supplementary note 10) It has a table for storing the pulse interval of the PN code,
If the absolute value of the difference between the reception time of each pulse and the previous effective reception time minus the time difference in the table is equal to or less than the reference value, the time averaging processing unit validates the reception time and must be greater than or equal to the reference value. For example, the value obtained by adding the time difference in the table to the previous effective reception time is set as the effective reception time, and the average value is obtained from the effective reception time. 8. Distance measuring device.

It is a figure which shows schematic structure of the receiver of this invention. It is a figure which shows the whole structure of the distance measuring apparatus of the Example of this invention. It is a figure explaining the case where distance measurement is carried out using one pulse. It is a figure explaining the case where a distance measurement is performed by using a plurality of pulses and performing an averaging process. It is a figure which shows the structure of the receiving circuit of 1st Example of this invention. It is a figure which shows the structure of the delay circuit with a tap. It is a timing chart which shows operation | movement of a reception time measurement part. It is a figure which shows a precise measurement value concord table (1). It is a figure which shows a precision measured value concord table | surface (2). It is a figure which shows a transmission data format. It is a figure which shows the processing flow of the distance measurement by the receiving circuit of a 1st Example. It is a figure which shows the structure of the receiving circuit of the 2nd Example of this invention. It is a figure which shows the processing flow of the distance measurement by the receiving circuit of a 2nd Example. It is a figure which shows the structure of the receiving circuit of the 3rd Example of this invention. It is a figure which shows the processing flow of the distance measurement by the receiver circuit of a 3rd Example. It is a figure which shows an example of the reference pulse time difference of time hopping data. It is a figure which shows the processing flow which calculates | requires the average value of a 4th Example. It is a figure which shows an example of the pulse interval of time hopping data. It is a figure which shows the processing flow which calculates | requires the average value of a 5th Example. It is a figure which shows the position measurement example (1) using distance measurement. It is a figure which shows the position measurement example (2) using distance measurement. It is a figure explaining the case where distance measurement is carried out from pulse arrival time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pulse detector 2 PN code generation part 3 Reception time measurement part 4 Time selection part 5 Time average process part 6 Synchronization part 11 Spread data modulation part 12, 15 Pulse generator 13 Transmission means 14 Reception means 16 Despreading / data demodulation part 17 Reception Time Measurement Unit 18 Microcomputer 20 Pulse Detector 21 Correlator (DMF)
22 Shift register 23 Reception time measurement unit 24 Latch 25 Shift memory 26 Time selection unit 27 TH / PPM decoding unit 28 Average processing unit

Claims (5)

A pulse transmitter that transmits an electromagnetic pulse train generated according to a pseudo-random noise code, a receiver that receives the electromagnetic pulse train, and the distance between the transmitter and the receiver from the propagation time of the electromagnetic waves from pulse transmission to reception, or A device for measuring the relative position,
A reception time measurement unit that measures the reception time for each received pulse, a time selection unit that selects a valid pulse reception time according to the PN code, and a time average processing unit that averages the selected reception times. And calculating the distance based on the averaged reception time. The reception time measurement unit was measured by a coarse measurement unit using a timer that operates in synchronization with the clock of the receiver, a precision measurement unit that measures the difference between the received pulse and the clock, and a coarse measurement unit and a precision measurement unit. It has a time calculation unit that calculates the reception time from the value,
The distance measuring apparatus according to claim 1, wherein the averaging processing unit performs averaging using the calculated reception time. 3. The distance measuring apparatus according to claim 1, wherein a time scale is obtained from a difference between a transmitter clock and a receiver clock, and the reception time is corrected by the time scale. It has a table that stores the time difference between each pulse and the pulse that becomes the reference of the PN code, and the reception time measurement unit subtracts the time difference in the table from the reception time of each pulse to determine the reception time of each pulse as a reference pulse. Converted to
4. The distance measuring apparatus according to claim 1, wherein the time average processing unit compares the reference pulse reception time with the converted time, and excludes those having a large difference from the average processing. A table storing pulse intervals of PN codes;
If the absolute value of the difference between the reception time of each pulse and the previous effective reception time minus the time difference in the table is equal to or less than the reference value, the time averaging processing unit validates the reception time and must be greater than or equal to the reference value. 5. The distance measuring device according to claim 1, wherein a value obtained by adding a time difference in the table to a previous effective reception time is used as an effective reception time, and an average value is obtained from the effective reception time.

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