JPH05307078A - Measuring device using pseudo-random signal generator - Google Patents

Abstract

PURPOSE:To make measurement of a high resolution, even where the clock frequency of a pseudo-random signal is restricted, by equipping a measuring device concerned with a signal waveform forming means to generate trinary pseudo-random signal which takes a third value between the two values of a binary pseudo-random signal in synchronization therewith. CONSTITUTION:M-series signals are used as pseudo-random signal, and a pseudo- random signal generation part 3 consists of a feedback loop including exclusive logical sum and a shift register by ECL element. This pseudo-random signal generation part 3 generates 3a signal one after another in synchronization with binary pseudo-random symbol signals generated being driven by clock signals fed externally. The generated signal is composed of pulses of +V or -V having a certain width corresponding to each symbol signal and a signal division which takes a third value between + or -V. As a result, a trinary pseudo-random signal 4a is obtained, as the output signal from the generation part 3, which consists of a row of pulses of +V or -V partitioned by the signal division to take the third value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground exploration radar, a level meter in a microwave reactor, etc. that uses a pseudo random signal or a microwave signal modulated by a pseudo random signal, an optical signal, an ultrasonic wave or the like as a transmission signal. The present invention relates to a distance measuring device used, a measuring device such as an optical fiber temperature distribution meter of an optical TDR system, and particularly to a signal waveform of a pseudo random signal thereof.

[0002]

2. Description of the Related Art As a radar-based distance measuring device using a pseudo-random signal, there is, for example, "distance measuring method and device" disclosed in Japanese Patent Laid-Open No. 2-98685. This publication proposes a microwave M-series radar using two M-series signals having the same pattern but slightly different frequencies. In this microwave M-series radar, as shown in FIG.
The M-sequence signal generator shown in FIG. 10 is generated by the M-sequence signal generator configured by the feedback loop including the exclusive OR 101. Then, the microwave signal is phase-modulated by one of the M-sequence signals and is transmitted as a transmission signal from the antenna to the object. When the transmitted signal is radiated to the object and the reflected signal is returned, the reflected signal is multiplied by an M-sequence signal that has the same pattern as the M-sequence signal used for modulation but a slightly different frequency, and the carrier wave The signal is detected with high sensitivity by performing coherent detection, and the distance from the antenna to the object is calculated by measuring the time delay between the transmission and reception of the signal that is required for the signal to propagate from the antenna to the object. , Measuring the position of the object.

Further, as in the above publication, an optical radar type distance measuring apparatus utilizing two M-sequence signals is disclosed in Japanese Patent Laid-Open No. 3-300.
It is proposed in Japanese Patent No. 282289.

[0004]

In a conventional distance measuring device or the like, a pseudo-random signal composed of binary continuous pulse trains corresponding to a pseudo-random code as shown in FIG. In the processing, two pseudo random signals are multiplied and the band is limited by a low-pass filter to obtain a pulsed detection signal and a time reference signal corresponding to the correlation function of the pseudo random signal.

FIG. 11 shows a timing chart at that time. The two pseudo-random signals have the same pattern and two M-sequence signals M with slightly different frequencies.
a and Mb are used, of which the first M-sequence signal Ma is used as the transmission signal, and the reception signal and the second M-sequence signal M are used.
The detection signal pulse is obtained by multiplying with b and band-limiting (integrating) the multiplication result with a low-pass filter. Here, the frequency of the clock signal that drives the M-sequence signal generator is f, and one pulse width τ1 of the M-sequence signal is τ1.
= 1 / f.

At this time, the M-sequence signals Ma and Mb are as shown in FIG.
As shown in FIG. 1, the pulse train is a continuous pulse train of + and −. M
If the signal patterns of a and Mb are the same,
The multiplication result (Ma × Mb) as shown in (a) of 1
Is a continuous + signal. With the passage of time, the two signal patterns gradually shift from the difference in clock frequency, and the multiplication result (Ma × Mb) becomes a +/− signal sequence,
As shown in FIG. 11B, the deviation between the two patterns is 1
When the number of pulses is less than or equal to the pulse, the multiplication result (Ma × Mb) is 2
The part where the two signals match is +, so there are many + when viewed as a whole. However, when the deviation between the two signal patterns is 1 pulse or more, the multiplication result (Ma × Mb) becomes a completely random +,-signal, as shown in (c) of FIG. 11.

When the above multiplication result (Ma × Mb) is integrated by the low-pass filter, a large + signal is obtained when the two signal patterns match, and when the deviation between the two signal patterns is one pulse or less. Becomes a + signal (because there are many + parts in the entire signal), it becomes a 0 signal when the deviation between the two signal patterns is 1 pulse or more. As a result, a pulsed detection signal is obtained as the output of the low pass filter.

The pulse width of the detection signal is determined by the pulse width of the pulse forming the pseudo-random signal and the frequency difference between the two clock signals. By selecting the clock frequency, a signal pulse of any width can be obtained. However, how much the pulse width of the detection signal corresponds to the distance measurement is determined by the pulse width of the pseudo-random signal, that is, the clock frequency, and the resolution in the distance measurement is determined. Therefore, conventionally, in order to improve the distance resolution, it was necessary to increase the clock frequency of the pseudo random signal generator, but there was a problem that the resolution was limited by the operation limit of the pseudo random signal generator. ..

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a measuring apparatus capable of high-resolution measurement even when the clock frequency of a pseudo-random signal is limited. To aim.

[0010]

A measuring device according to one aspect of the present invention is a measuring device using a pseudo random signal or a signal modulated by a pseudo random signal as a transmission signal, and a binary pseudo random signal. A pseudo random signal generator having a signal waveform forming means for generating a ternary pseudo random signal that takes a third value between the two values in synchronism with the above is used. This pseudo random signal generator synchronizes with a binary pseudo random code signal generated by being driven by a clock signal input from the outside, and generates a + V or -V pulse of a constant width corresponding to each code signal. Third between ± V
And a signal section having the value of As a result, the output signal of the pseudo random signal generator is + V or −V divided by the signal section of the third value.
A three-valued pseudo-random signal composed of the pulse train of is obtained. Here, if the frequency of the clock signal input to the pseudo random signal generator is f, the width of the pulse signal is τ1, and the signal section of the third value is τ0, the relationship of τ1 + τ0 = 1 / f is established.

FIG. 12 is a timing chart showing signal processing by the ternary M-sequence signal when the M-sequence signal is used as the pseudo random signal. Here, the case of distance measurement will be described. The first and second pseudo random signal generators are driven by two clock signals having different frequencies, and the first and second pseudo random signal generators have the same signal pattern but slightly different synchronization.
And second ternary M-sequence signals Ma and Mb.
The first ternary M-sequence signal Ma is used as a transmission signal to be transmitted to the outside, reflected by the object and received by the receiving means, that is, the first ternary M-sequence signal and the second Three
The value is multiplied by the M-sequence signal. This multiplication result changes gradually because the periods of the two signals are different, and when the two signal patterns match, the multiplication result (Ma × Mb) continues + as shown in FIG. The pulse signal train of is obtained. When the shift between the two signal waveform patterns is shifted by one pulse of the pulse forming the ternary M-sequence signal,
As shown in FIG. 12B, the multiplication result (Ma × Mb)
Is a 0 signal. When the two signal waveform patterns are further shifted and shifted by one pulse or more of the pulses forming the ternary M-sequence signal, the multiplication result (Ma × Mb) becomes a +/− random pulse train.

This change in the multiplication result occurs periodically, and when the multiplication result is band-limited (integrated) by a low-pass filter, a periodic pulse signal is obtained as a detection signal. On the other hand, by directly multiplying the first and second M sequences and band-limiting the multiplication result, a similar pulse signal is obtained as a time reference signal, and the time difference between the detection signal pulse and the time reference signal pulse is obtained. The distance is calculated by obtaining the signal delay due to the signal propagation between transmission and reception.

At this time, the pulse period T and the pulse width t0 of the detection signal and the time reference signal are the code period tc of the M series signal (pseudo random signal) and the M series signal (pseudo random signal).
Determined by the clock frequency f for driving the generator, the frequency difference Δf between the two clock signals, and the pulse width τ1 of the pulses that make up the M-sequence signal (pseudo-random signal),
T = tc × (τ1 + τ0) × f / Δf = 1 / Δ
f, t0 = 2 × τ1 × f / Δf. Further, there is a relationship of τ = τ ′ × Δf / f between the signal delay τ due to signal propagation between transmission and reception and the time difference τ ′ between the time reference signal and the detection signal. Here, the signal propagation distance L where the signal propagation velocity is v is represented by L = τ × v = τ ′ × Δf / f × v.

The above-described processing of the three-valued pseudo-random signal is similarly applied to other distance measuring devices and temperature distribution measuring devices.

[0015]

1 is a block diagram showing the configuration of a ternary pseudo-random signal generator according to an embodiment of the present invention. The ternary pseudo random signal generator 1 includes a pseudo random signal generator 3 and a signal waveform generator 4. In this embodiment, an M-sequence signal is used as a pseudo-random signal, and the pseudo-random signal generator 3 is composed of a shift register including an ECL element and a feedback loop including an exclusive OR, and is driven by a clock signal input from the outside. To be done.

FIG. 2 is a timing chart showing waveform diagrams of the binary M-sequence signal 3a output from the pseudo-random signal generator 3 and the ternary M-sequence signal 4a output from the signal waveform formation unit 4, respectively. is there. Pseudo-random signal generator 3
Generates a binary M-sequence signal 3a as shown, which is input to the signal waveform forming section 4. The signal waveform forming section 4 is also composed of an ECL element, and generates a ternary M-sequence signal 4a as shown by a logical operation of the inputted binary M-sequence signal 3a and a clock signal from the outside.

FIG. 3 is a block diagram showing a concrete example of the structure of a ternary pseudo random signal generator. In this embodiment, an M-sequence signal generator is used as the pseudo-random signal generator 3, and the M-sequence signal generator 3 uses the shift register 103.
, 103n. The signal waveform forming unit 4 is
AND circuits 105a and 105b and pulse transformer Tr
And a pulse signal of ± V having a width of ½ of the cycle of the clock signal and a 0 signal section having a width of ½.
Value of the M-sequence signal is generated.

FIG. 4 is a block diagram showing another concrete example of the structure of the ternary pseudo random signal generator. In the signal waveform forming unit 4 of the present embodiment, shaping circuits 106a to 106d and a delay line 107 are provided in addition to the above configuration. In the embodiment of FIG. 3, the pulse width of the ternary M-sequence signal is set to ½ of the drive clock signal period, but in the present embodiment, a narrower pulse is generated by the signal waveform forming unit 4 having the above configuration. Formed to obtain higher resolution.

In each of the above-described embodiments, an example of the M-sequence signal generator is described. However, if another pseudo-random signal generator such as Barker code or Gold code is used as the pseudo-random signal generator, M-sequence signal generator is used. It is also possible to generate a ternary pseudo-random signal corresponding to a binary pseudo-random signal other than the series signal.

FIG. 5 is a block diagram showing the configuration of a distance measuring device according to an embodiment of the present invention. 1, 2
Is a ternary M-sequence signal generator, 5 and 6 are clock signal generators, 7 and 8 are multipliers using a double balanced mixer, and 9 and 10 are low-pass filters. 11 is a transmission antenna for transmitting a transmission signal, 12 is a reception antenna for detecting a reception signal, and 13 is a measurement object,
Reference numeral 31 is a signal processing device. In the present embodiment, the shift registers of the M-sequence signal generators of the M-sequence signal generators 1 and 2 have seven stages and generate M-sequence signals corresponding to the M-sequence code having the code period 127. The clock frequencies of the clock signal generators 5 and 6 are 220.000 MHz and 22 respectively.
3 with a pulse width of about 2.3 nsec at 0.005 MHz
Generate an M-sequence signal of values.

The output signal of the M-sequence signal generator 1 is transmitted as a transmission signal from the transmission antenna 11, and the measurement object 13
The reflected signal from is detected by the receiving antenna 12, the obtained received signal and the output signal of the M-sequence signal generator 2 are multiplied by the multiplier 8, and the low pass filter 10 band-limits to obtain a detection signal. Similarly, the time reference signal is obtained by the multiplier 7 and the low pass filter 9.
The time reference signal and the detection signal are input to the signal processing device 31 configured by a computer or the like, the time interval between each signal pulse is measured, and the distance to the measurement target 13 is calculated.

In the present embodiment, the pulse width of the detection signal pulse and the time reference signal pulse is about 0.2 msec, which is 0.68 m when converted into distance. In actual distance measurement, even if there are multiple measurement objects, if the pulses corresponding to the reflected signals from each object are separated by more than the half width of the signal pulse, they will not be affected by other pulse signals. The distance can be calculated, and the distance measuring device according to the present embodiment can measure the distance to a plurality of measurement objects separated by 0.34 m or more.

Further, in this embodiment, an M having a frequency of several hundred MHz is used.
The serial signal is directly used as a transmission signal, and can be used for an underground exploration radar used for underground exploration where electromagnetic waves are severely attenuated. Furthermore, in the present embodiment, the radar of the method of transmitting the transmission signal to the target object and detecting the reflected signal is described, but the transmitting and receiving antennas are installed in separate boreholes, and the signals are propagated between the boreholes to detect signals. It can also be used as a borehole radar for observing the stratum condition between boreholes from waveforms.

FIG. 6 is a block diagram showing the structure of a distance measuring device according to another embodiment of the present invention. In the figure, 1
4, 15, 16 are multipliers, 17 is a low-pass filter, 1
8 and 19 are distributors, 20 is a hybrid coupler, 21 and
22 is a squarer, 23 is an adder, 24 is a microwave signal oscillator, and 25 is an amplifier. The M-sequence signal generators 1 and 2, the clock signal generators 5 and 6, the multiplier 7 and the low-pass filter 9 perform the same operation as in the embodiment of FIG. 5, and the time reference signal is obtained as the output of the low-pass filter 9.

The output of the microwave signal oscillator 24 is input to the distributor 18, and the distributed signals are input to the multiplier 8 and the hybrid coupler 20, respectively. The hybrid coupler 20 outputs a signal R having an in-phase component and a signal I having a quadrature component of the input microwave signal, and the multipliers 15 and 16
To each. To the multiplier 8, the M-sequence signal generator I
Is also input, and the microwave signal modulated by the M-sequence signal is output. The modulated microwave signal is transmitted from the transmission antenna 11 as a transmission signal. The signal reflected from the measuring object 13 is received by the receiving antenna 12, the received signal is amplified by the amplifier 25, then input to the multiplier 14, and is multiplied by the output signal of the M-sequence signal generator 2. The output of the multiplier 14 is distributed by the distributor 19, is input to the multipliers 15 and 16, respectively, and is multiplied by the R signal and the I signal which are the outputs of the hybrid combiner 20, respectively. The output signals of the multipliers 15 and 16 are band-limited by the low pass filters 10 and 17. The outputs of the low-pass filters 10 and 17 are squared by the squarers 21 and 22 and then added by the adder 23, and a detection signal is obtained as the output of the adder 23. The time reference signal and the detection signal are input to the signal processing device 31 configured by a computer or the like, the time interval between each signal pulse is measured, and the distance between the objects is calculated.

In this embodiment, the M-sequence signal generator 1,
The second shift register has 10 stages and generates an M-sequence signal corresponding to an M-sequence code having a code period 1023. The clock frequencies of the clock signal generators 5 and 6 are 22 respectively.
A ternary M-sequence signal with a pulse width of about 2.3 nsec is generated at 0.000 MHz and 220.010 MHz. Further, the pulse width of the detection signal pulse and the time reference signal pulse is about 0.1 msec, which is 0.68 m when converted to the distance. In the present embodiment, a microwave signal having a frequency of 10 GHz is used as the carrier signal to enhance the directivity of the transmission signal and measure the distance even when there is an unnecessary reflection object other than the target object such as in-reactor level measurement. It can be carried out. Further, although the case where the microwave signal is used as the carrier wave has been described in the present embodiment, an electromagnetic wave signal in another frequency band such as a millimeter wave band can also be used as the carrier wave.

FIG. 7 is a block diagram showing the configuration of a distance measuring apparatus according to another embodiment of the present invention, in which an optical signal is used. In the figure, 27 is a semiconductor laser, 28 is a transmitting optical system, 29 is a receiving optical system, and 30
Is a photodiode. M-sequence signal generators 1, 2,
The clock signal generators 5, 6, the multiplier 7, and the low-pass filter 9 perform the same operation as that of the embodiment of FIG. 5, and the time reference signal is obtained as the output of the low-pass filter 9.

In this embodiment, when the output signal of the M-sequence signal generator is input to the semiconductor laser 27, laser light intensity-modulated by the M-sequence signal is generated. The laser light is measured by the transmission optical system 28 composed of a lens or the like.
Projected on. The laser light reflected from the object 13 is input to the photodiode 30 via the lens, the filter, etc. of the receiving optical system 29, the intensity of the reflected light is converted into an electric signal, and the electric signal is output. The received signal is multiplied by the output signal of the M-sequence signal generator 2 by the multiplier 8 and band-limited by the output low-pass filter 10 of the multiplier,
A pulsed detection signal is obtained. A signal processing device 31 configured by a computer or the like for the time reference signal and the detection signal
, The time interval between each signal pulse is measured, and the distance to the object is calculated. In this embodiment, it is possible to perform the high-resolution distance measurement by narrowing the signal pulse and using the laser light.

FIG. 8 shows an optical TDR according to another embodiment of the present invention.
It is a block diagram which shows the structure of the optical fiber temperature distribution measuring apparatus using the. In the figure, 32 is an optical directional coupler,
33 is an optical fiber, 34 and 35 are optical filters, 36 is a photodiode, and 37 is an optical branch path. The M-sequence signal generators 1 and 2, the clock signal generators 5 and 6, the multiplier 7, and the low-pass filter 9 perform the same operations as in the embodiment shown in FIG. 5, and the time reference signal is obtained as the output of the low-pass filter 9. ..

In this embodiment, by inputting the output signal of the M-sequence signal generator to the semiconductor laser 27, intensity-modulated laser light is generated. The intensity-modulated laser light is input to the optical fiber 33 via the optical directional coupler 32. The optical signal input to the optical fiber is reflected and scattered at each point in the optical fiber. In the optical directional coupler 32, the optical signal reflected and scattered in the optical fiber and returned to the input end is taken out and distributed by the optical branch path 37 to the optical filters 34,
35, respectively. The outputs of the optical filters 34 and 35 are converted into electric signals according to the strength of the optical signal by the photodiodes 30 and 36, respectively. The output signals of the photodiodes 30 and 36 are input to the multipliers 8 and 14, and M
A detection signal is obtained by multiplying the output signal of the sequence signal generator 2 and band-limiting with the low-pass filters 10 and 17.

In this embodiment, the optical filter 34,
As the reference numeral 35, one having the optical characteristic of transmitting only Stokes light and anti-Stokes light due to Raman scattering among the reflected and scattered light in the optical fiber is used, and the Raman scattering among the reflected and scattered light from each point of the optical fiber is used as a detection signal. Stokes light intensity and anti-Stokes light intensity are obtained. This Raman scattering has a high dependency on the temperature of the optical fiber, and the temperature of the location where Raman scattered light is generated in the optical fiber can be calculated from the intensity of Stokes light and anti-Stokes light.

In this embodiment, the propagation delay of the optical signal is calculated from the time difference between the detection signal and the time reference signal, the Raman scattered light intensity at a specific position of the optical fiber is obtained, and the temperature of the optical fiber is calculated from this Raman scattered light intensity. Is measured to measure the temperature distribution along the optical fiber.

Further, in this embodiment, the M-sequence signal generator of the M-sequence signal generator is composed of a SAW device, and the signal waveform forming portion is composed of a gallium arsenide logic element. The frequency of the clock signal is 500MHz,
A ternary M-sequence signal with a pulse width of 1 nsec is generated. Also, the difference between the two clock frequencies is 5 KHz,
The pulse width of the time reference signal and the detection signal is 0.2 msec. At this time, the signal propagation speed in the optical fiber is 2 ×
Assuming 10 ⁸ m / sec, the half value of the pulse signal is 100 m
Corresponding to m, the temperature distribution can be measured with extremely high resolution.

[0034]

As described above, according to the present invention, by using a pseudo random signal generator for generating a three-valued pseudo random signal, it is possible to increase the operating clock frequency of the pseudo random signal generator without increasing the operating clock frequency. The pulse width of the detection signal pulse can be narrowed, so that the distance or temperature distribution can be measured with high accuracy. Further, even when there are a plurality of objects, reflected signals, etc., interference of each signal can be reduced and high-resolution measurement can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a pseudo random signal generator according to an embodiment of the present invention.

FIG. 2 is a timing chart showing operation waveforms of the pseudo random signal generator of FIG.

FIG. 3 is a block diagram showing a specific configuration example of the pseudo random signal generator of FIG.

FIG. 4 is a block diagram showing another specific configuration example of the pseudo random signal generator of FIG.

FIG. 5 is a block diagram showing a configuration of a distance measuring device according to another embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a distance measuring device according to another embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a distance measuring device according to another embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of an optical fiber temperature distribution measuring device of an optical TDR system according to another embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a conventional M-sequence signal generator.

FIG. 10 is a timing chart showing a binary M-sequence signal waveform.

FIG. 11 is an explanatory diagram of processing of a binary M-sequence signal.

FIG. 12 is an explanatory diagram of processing of a ternary M-sequence signal according to the present invention.

[Explanation of symbols]

 1, 2- and 3-valued M-sequence signal generator 3 Pseudo-random signal generator 4 Signal waveform generator 5 and 6 Clock signal generator 7 and 8 Double balanced mixer multiplier 9 and 10 Low-pass filter 11 Transmit transmission signal For transmitting 12 reception antenna for detecting received signal 13 measurement object 14, 15, 16 multiplier 17 low-pass filter 18, 19 distributor 20 hybrid coupler 21, 22 squarer 23 adder 24 microwave signal Oscillator 25 Amplifier 27 Semiconductor laser 28 Transmitting optical system 29 Receiving optical system 30 Photodiode 31 Signal processing device 32 Optical directional coupler 33 Optical fiber 34, 35 Optical filter 36 Photodiode 37 Optical branch path

Claims (5)

[Claims] 1. A measuring device using a pseudo-random signal or a signal modulated by a pseudo-random signal as a transmission signal, wherein a third device between the two values is synchronized with the binary pseudo-random signal.
A measuring device using a pseudo-random signal generator having a signal waveform forming means for generating a ternary pseudo-random signal taking the value of. 2. A first clock signal generator, a second clock signal generator for generating a clock signal whose frequency is slightly different from the output signal of the first clock signal generator, and the first and second clock signal generators. First and second pseudo-random signal generators that respectively input two clock signals and output two pseudo-random signals having the same pattern and slightly different frequencies; the first pseudo-random signal and the second pseudo-random signal generator; A first multiplier that multiplies the pseudo random signal of 1. with a transmitting unit that transmits the first pseudo random signal as a transmission signal; a receiving unit that receives a propagation signal to obtain a reception signal; A second multiplier that multiplies with a second pseudo-random signal; first and second low-pass filters that input the outputs of the first and second multipliers and limit the band; Means for calculating a signal propagation distance from a time interval between the time when the maximum value of the output signal of the high-pass filter occurs and the time when the output signal of the second low-pass filter has the maximum value, and the first and second A distance measuring device using the pseudo random signal generator according to claim 1 as the pseudo random signal generator. 3. A first clock signal generator, a second clock signal generator for generating a clock signal whose frequency is slightly different from the output signal of the first clock signal generator, and the first and second clock signal generators. First and second pseudo-random signal generators that respectively input two clock signals and output two pseudo-random signals having the same pattern and slightly different frequencies; the first pseudo-random signal and the second pseudo-random signal generator; And a means for generating a carrier signal, the output signal of the carrier signal generating means is modulated by the first pseudo-random signal, and is transmitted as a transmission signal to the object. Means for transmitting, receiving means for receiving a reflected signal from the object to obtain a received signal, means for detecting a carrier component of an output signal of the receiving means, and output of the detecting means A multiplier that multiplies a signal by the second pseudo random signal; first and second low-pass filters that limit the band by inputting the output signals of the first and second multipliers; The distance calculation means for calculating the distance from the time interval of the time when the output signal of the second low-pass filter has the maximum value to the object, and the first and second pseudo random signal generators. A distance measuring device using the described pseudo-random signal generator. 4. A first clock signal generator, a second clock signal generator for generating a clock signal whose frequency is slightly different from the output signal of the first clock signal generator, and the first and second clock signal generators. First and second pseudo-random signal generators that respectively input two clock signals and output two pseudo-random signals having the same pattern but slightly different frequencies; the first pseudo-random signal and the second pseudo-random signal generator; A first multiplier that multiplies a pseudo random signal, a unit that generates an optical signal modulated by the first pseudo random signal, and an optical signal output of the optical signal generation unit that projects the optical signal output to an object. Means, means for detecting an optical signal reflected by an object, a second multiplier for multiplying the output signal of the detection means by the second pseudo random signal, the first and second powers A first and a second low-pass filter for inputting the output signal of the device to limit the band, and a distance from the time interval at which the output signal of each of the first and the second low-pass filters has a maximum value to the object. A distance measuring device using a pseudo-random signal generator according to claim 1 as the first and second pseudo-random signal generators. 5. A first clock signal generator, a second clock signal generator for generating a clock signal whose frequency is slightly different from the output signal of the first clock signal generator, and the first and second clock signal generators. First and second pseudo-random signal generators that respectively input two clock signals and output two pseudo-random signals having the same pattern and slightly different frequencies; the first pseudo-random signal and the second pseudo-random signal generator; A first multiplier for multiplying the pseudo-random signal by the first pseudo-random signal, means for generating an optical signal modulated by the first pseudo-random signal, and an output signal of the optical signal generating means to an optical waveguide unit. Means for detecting a reflected signal from the inside of the optical waveguide section, a multiplier for multiplying the output signal of the detecting means by the second pseudo-random signal, and an output of the first and second multipliers. And first and second low-pass filter for inputting a signal band-limited, claim 1 as said first and second pseudo random signal generator
An optical TDR type optical fiber temperature distribution measuring device using the described pseudo-random signal generator.