JPH0755939A - High-resolution distance measuring system - Google Patents

Abstract

PURPOSE:To provide a high-resolution distance measuring system which is inexpensive, compact and lightweight, having a high distance resolution. CONSTITUTION:A high-speed clock generating means 13 generates a high-speed clock with a shorter cycle than that of a reference clock, and a delay generating means 14 gives a delay to an artificial random signal using the reference clock. Then, such a modulation wave picks up the correlation between the reception signal and artificial signal that are reflected on an object to be measured, and the distance to the object is calculated by using the delay time as a function, so that the distance resolution equivalent to the cycle of the high-speed clock can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device. More specifically, the present invention relates to a pseudo-random modulation continuous output type laser radar type distance measuring device.

[0002]

2. Description of the Related Art Pseudo-random modulation continuous output type laser radar is a distance measuring device which uses continuous light and has better power supply voltage efficiency and stable operation than the pulsed light system. Conventionally, a pseudo-random modulation continuous output type laser radar type distance measuring apparatus of this type is disclosed in Japanese Patent Publication No. 64-2903. FIG. 10 is a schematic block diagram showing the configuration of the distance measuring device disclosed in Japanese Patent Publication No. 64-2903. In FIG. 10, the transmitting unit 1 includes a laser 2, a modulator 3, a transmitting optical system 4, a pseudo random signal generator 5 and a reference clock generator 6, and a receiving unit 7 includes a receiving optical system 8 and a light receiving detector 9. , Delay correlator 10, high speed storage device 11
And a display recorder 12. Continuous light (also referred to as CW light) emitted from the laser 2 is modulated by a signal generated by the pseudo random signal generator 5 in the modulator 3, for example, a signal such as M series (longest code series) or Barker series. , Is emitted toward the measurement target. The pseudo random signal generator clock is the reference clock generator 6
The output from is used. A part of the light reflected / scattered by the measuring object is received by the receiving optical system 8 and converted into an electric signal by the light receiving detector 9. The received signal is stored in the high-speed storage device 11, the response signal is obtained by correlating with the modulated signal delayed by the delay correlator 10, and the distance to the measurement object is obtained from the response function.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the technique disclosed in No. 903, the distance resolution R to the measurement object is represented by R = t _d C / 2.
(C: speed of light) That is, it is determined by the delay time t _d of the pseudo random signal, and this indicates that the period T _{0 of the} reference clock input to the pseudo random signal generator 5 determines the distance resolution.

By the way, a general-purpose IC or the like (for example, CMOS) is used in order to manufacture the device at low cost, in a small size and in a light weight. In this case, the lower limit of the cycle of the reference clock used in the pseudo random signal generator, or The upper limit of the frequency depends on the response speed of an element such as a CMOS IC used in the circuit, and is limited to a period of about 20 ns or a frequency of about 50 MHz. This corresponds to range resolution, R = 3 m. This type of device is applied to the distance measurement and displacement measurement of reflectors such as bridges, transmission lines and rockets where it is difficult to install optical components with low reflectance and high reflectivity such as corners, cubes and prisms. In that case, there is a problem that the required measurement accuracy cannot be achieved with a measuring device having a distance resolution of 3 m.

In view of the above problems, it is an object of the present invention to provide a high resolution distance measuring device which has a high distance resolution, is inexpensive, and is compact and lightweight.

[0006]

According to a first aspect of the present invention, a light source for emitting continuous light, a reference clock generating means for generating a reference clock, and a pseudo clock using the reference clock are provided. Pseudo-random signal generating means for generating a random signal, modulation means for modulating the continuous light into modulated light with the pseudo-random signal, transmission optical means for transmitting the modulated light to a measurement object, and the measurement object A receiving optical means for receiving the reflected modulated light, a light receiving detecting means for detecting the modulated light received by the receiving optical means and outputting a received signal, and a correlation between the pseudo random signal and the received signal. And a delay correlating means for calculating the distance to the object to be measured as a function of delay time, the distance measuring apparatus having a cycle shorter than that of the reference clock. And the high-speed clock generating means for generating a fast clock, by the high-speed clock is for and a delay amount variable delay generating means for giving a delay to the modulated light to be transmitted to the measurement object.

Further, according to the third and fourth aspects, a light source for emitting continuous light, a reference clock generating means for generating a reference clock, and a pseudo random signal for generating a pseudo random signal using the reference clock. Generating means, modulating means for modulating the continuous light into modulated light by the pseudo random signal, transmission optical means for transmitting the modulated light to a measurement object, and receiving the modulated light reflected by the measurement object In a distance measuring device comprising a receiving optical unit for detecting the modulated light received by the receiving optical unit and outputting a received signal, the distance measuring device has a cycle slightly different from the cycle of the reference clock. Second clock generation means for generating a second clock; phase synchronization control means for controlling phase synchronization between the reference clock and the second clock; and the second clock. Taking a second pseudo random signal generating means for generating a second pseudo random signal, the correlation between the second pseudo random signal and the reception signal using,
And a delay correlation means for calculating the distance to the measurement object as a function of the delay time.

The high-speed storage means is added to the apparatus described in claims 2 and 4.

[0009]

The modulated light modulated by the pseudo random signal using the reference clock is transmitted to the object to be measured after being delayed by the high speed clock generated by the high speed clock generating means. A reception signal of the modulated light reflected by the measurement object and received is obtained. By correlating this received signal with a pseudo-random signal generated using a reference clock, the distance to the measurement object is calculated as a function of the delay time, and the distance resolution corresponding to the cycle of the high speed clock is obtained.

Alternatively, the modulated light modulated by the pseudo random signal using the reference clock is transmitted to the object to be measured, and the received signal of the reflected modulated light is obtained. Correlating the received signal with the pseudo-random signal using the second clock having a period slightly different from that of the reference clock,
The distance to the measurement object is calculated as a function of the delay time to obtain the distance resolution corresponding to the difference between the cycle of the reference clock and the cycle of the second clock.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. The transmitter 1 includes a laser 2, a modulator 3, a transmission optical system 4,
It comprises a pseudo random signal generator 5, a reference clock generator 6, a high speed clock generator 13 and a delay generator 14. The laser 2 is a light source that emits continuous light. The reference clock generator 6 outputs the basic clock to the pseudo random signal generator 5, and the high speed clock generator 13 outputs the high speed clock to the delay generator 14. The delay generator 14 is a circuit which receives a pseudo random signal from the pseudo random signal generator 5 and gives a variable delay thereto by a high speed clock from the high speed clock generator 13. The modulator 3 modulates continuous light with a signal generated by the pseudo random signal generator 5 and provided with a variable delay by a high-speed clock, for example, an M-sequence (longest code sequence) signal. The transmission optical system 4 is an objective lens that emits the modulated light toward the measurement target.

The receiving section 7 comprises a receiving optical system 8, a light receiving detector 9, a delay correlator 10, a high speed storage device 11 and a display recorder 12. The receiving optical system 8 is an objective lens that receives a part of the light reflected and scattered by the measurement object.
The light receiving detector 9 is a photoelectric element that converts received light into an electric signal and outputs a received signal. The high-speed storage device 11 stores this received signal in a shift register having the number of elements of the pseudo-random signal by, for example, repeating 4095 cycles cyclically and continuously for each cycle of the pseudo-random signal, and stores the integrated received signal obtained every fixed number of additions. To a delay correlator 10. The delay correlator 10 obtains a response function by correlating the correlation between the pseudo random signal and the integrated reception signal while changing the delay time, and thereby obtains the distance to the measurement object. The display recorder 12 is a recorder for displaying and recording the obtained distance.

Here, the basic operation of the pseudo random modulation continuous output type distance finder will be described. The pseudo random signal generated by the pseudo random signal generator 5 using the reference clock is M (t) (cycle T). Continuous light is modulated with a pseudo-random signal and transmitted to the measurement object at a cycle T.
In addition, the output signal P ₀ of the transmission signal to the measurement object is changed to P ₀ M
Represented as (t). The light reflected and scattered by the measurement target and received is converted into an electric signal. The received signal P (t) is stored in the high speed storage device 11, and the delayed correlator 10 correlates with the delayed modulated signal M (t + t _d ) to obtain the response function S (t _d ). The response function S (t _d ) is an echo signal.

The response function S (t _d ) is expressed by the equation (1) using the property of M (t) for the pseudo random signal.

[0015]

[Equation 1]

The received signal P (t) has a response function S
It is expressed as in Expression (2) using (t _d ).

[0017]

[Equation 2]

When equation (2) is substituted into equation (1) and expanded, the term containing b ₀ (t) is eliminated due to the nature of the M series. Therefore, the response function S (t _d ) is expressed by the equation (3).

[0019]

[Equation 3]

[0020] _{However, R = t d C / 2} η: Efficiency A _r of the light-receiving optical system: the area of the light receiving telescope beta _r (R): The distance backscatter coefficient at R T (R): transmittance Y (R): Field of view overlap function (ratio in which transmitted light is included in the field of view of the receiving telescope) C: Light velocity.

Next, the operation of this embodiment will be described. A continuous wave of the output signal P ₀ is emitted from the laser 2. On the other hand, the pseudo random signal M (t) generated by the pseudo random signal generator 5 using the basic clock from the reference clock generator 6 is an M sequence (longest code sequence) signal,
In the delay generator 14, a variable delay is given by the high speed clock from the high speed clock generator 13. The variable delay amount given is δT × N (N = 0, 1, 2, ...
・) Here, δT is the period of the high-speed clock generated by the high-speed clock generator 13, N is an integer of 0 or more, and δT × N <T ₀ . The continuous light of the output signal P ₀ becomes modulated light that is modulated into a periodic pseudo random code by the modulator 3 by the delayed pseudo random signal M (t). This transmitted signal is represented by P ₀ M (t).
Modulated light is emitted from the transmission optical system 4 toward the measurement target.

A part of the light reflected and scattered by the object to be measured is received by the receiving optical system 8. The received light is photoelectrically converted and the received signal P (t) is output. The received signal P (t) is repeatedly and periodically added to the shift register having the number of elements of the pseudo random signal in the high speed storage device 11 and stored for each cycle of the pseudo random signal. Then, the obtained integrated reception signal is transferred to the delay correlator 10 every fixed number of additions. A response function is obtained by correlating the pseudo random signal, the integrated reception signal, and the delay time while changing the delay time, and the distance to the measurement object is obtained from the response function. The obtained distance is displayed and recorded by the display recorder 1.
2 is displayed and recorded.

The amount of delay provided by the delay generator 14 is variable, and the distance is measured by sequentially changing it to an integral multiple (including 0) of the period δT of the high speed clock. First, when the delay amount of 0 (N = 0) is selected in the delay generation circuit 14, the modulated light modulated by the pseudo random signal M (t) is transmitted signal P.
It is radiated to the measuring object at ₀ M (t). Received signal P of the light reflected / scattered by the measuring object and incident on the receiving optical system 8
(T) is a pseudo random signal M as an integrated reception signal
Correlation is performed while changing the delay time Td of (t). As a result, it is possible to obtain the response function S (Td), that is, the profile of the measurement object multiplied by the distance function T ² (R) / R ² and calculate the distance from this to the measurement object. can do.

Next, in the delay generation circuit 14, the delay amount δ
When T (N = 1) is selected, the pseudo random signal M (t) input to the modulator 3 is delayed by the delay amount δT. The same process as above is performed by the pseudo random signal M (t) delayed by the delay amount δT. Further, the delay amount is set to 2δT, ..., N
The same processing as above is performed as δT, and a value is obtained for each delay amount. Then, the highest value of the correlation level is obtained as the distance measurement value. By this processing, the distance resolution is increased to a size corresponding to δT.

The phase relationship and distance resolution of each signal will be described with reference to FIG. In FIG. 2, (1) is a reference clock signal, (2) is a pseudo-random signal, (3) is a delayed signal of an amount corresponding to N periods of the high-speed clock, (4) is a transmission signal, (5) is a reception signal, (6) shows the result of delayed correlation. It should be noted that (7) and (8) are for explaining the delay due to the sawtooth wave signal in the second embodiment described later. The reference clock has a period T ₀ , and a pseudo-random signal using this and a high-speed clock for N periods (N × δT)
The delay signals of are synchronized. The transmission signal is delayed from the pseudo random signal by the delay signal of (3). The light takes about K × T ₀ to reciprocate to the object to be measured, the received signal is output with a delay of about K times the period T ₀ of the reference clock signal, and the result of the delay correlation is Td≈K × T _0. Obtained and the distance to the measurement object is measured.

When the transmitted signal is in phase with the pseudo-random signal, the range resolution depends on T ₀ . However, when the transmission signal is delayed by an amount corresponding to N cycles of the high-speed clock in the pseudo random signal, the relationship between the delay amount and the correlation level is shown in FIGS. Four
As is clear from the above, the distance resolution depends on the period δT of the high-speed clock and is δT × C / 2. The distance D is D = (K × T ₀ + N × δT) × C / 2 (C: speed of light). In this way, by adding the high-speed clock generator and the delay generation circuit, the distance resolution is reduced from the conventional T ₀ to δT, and the distance resolution is improved.

In this way, when the received signals are periodically continuously added by the high speed storage device to obtain the integrated received signal and the correlation is obtained,
It can be used with sufficient distance accuracy to measure the distance to a measurement object that has low reflectance and is difficult to install a retro reflector, and also can measure the spatial profile of the measurement object such as a scattering object in the medium. It is possible.

Since the high-speed storage device 11 is for improving the S / N ratio with respect to a weak received signal from the measuring object having a low reflectance, the measuring object is a corner cube prism. The high-speed storage device 11 can be omitted when a strong reception signal is obtained while being limited to one point, as described above.

Next, a second embodiment will be described with reference to FIG. The description of the same or similar points as the first is omitted. In this embodiment, the method of generating the high speed clock is different from that of the first embodiment, and the sawtooth wave is generated using the reference clock generated by the reference clock generator 6 in the sawtooth wave generation circuit 15. As shown in (7) and (8) of FIG.
The delay amount is determined by comparing the output of the sawtooth wave with the DC signal. By varying the level of the DC signal, the delay amount is changed to be longer or shorter. The pseudo random signal is delay-modulated by a predetermined delay amount.

Next, a third embodiment will be described with reference to FIG. The description of the same or similar points as the first is omitted. In the present embodiment, the reference clock generator 6 has a reference clock (cycle T ₀ ) and the second clock generator 16 has a second clock having a cycle slightly different from the cycle T _{0 of the} basic clock.
Generate a clock (cycle T ₂ ) and generate a reference clock and a second
Both clocks are input to the phase synchronization control circuit 17.

The phase synchronization control circuit 17 synchronizes the rising edge or falling edge of the basic clock and the second clock, synchronizes the basic clock with the second clock, and then starts output. The reference clock output in phase synchronization from the phase synchronization control circuit 17 is input to the pseudo random signal generator 5. Then, using this reference clock, the pseudo random signal generator 5 outputs the pseudo random signal M
(T) occurs. This pseudo-random signal M (t) is output to the modulator 3, and the modulator 3 modulates the continuous light from the laser 2 with the pseudo-random signal M (t), and the modulated light passes through the transmission optical system 4 and is measured. It is radiated to objects. The emitted light is
The light is reflected / scattered by the object to be measured, part of the light is received by the receiving optical system 8 and photoelectrically converted by the light receiving detector 9, and the output signal is stored in the high speed storage device 11 as a pseudo random signal M (t).
Are repeatedly added to the shift register having the number of elements at a cycle T (T = To × the number of elements), and are transferred to the delay correlator 10 as an integrated reception signal at every constant number of additions.

On the other hand, the second clock output in phase synchronization from the phase synchronization control circuit 17 is output to the pseudo random signal generator 18. The pseudo random signal generator 18 has almost the same configuration as the pseudo random signal generator 5, and the pseudo random signal generator 18 generates a pseudo random signal M ′ (t) using the second clock and delay correlation. Output to the container 10.

In the delay correlator 10, the integrated reception signal from the high speed storage device 11 and the pseudo random signal M '(t) generated by the pseudo random signal generator 18 are correlated. This makes it possible to obtain the response function S (Td), that is, the product of the profile of the measuring object multiplied by the function of distance T ² (R) / R ² , and calculate the distance from this to the measuring object. can do.

Here, the frequency of the basic clock used for the pseudo random signal M (t) for the transmission signal, that is, the reception signal, and the second clock used for the pseudo random signal M '(t) for the delay correlation. The frequencies are slightly different,
The relative phase of the integrated reception signal and the pseudo random signal M ′ (t) using the second clock continuously and gradually changes. That is, the delay time T _d required to obtain the delayed correlation function gradually changes. The basic clock cycle T _O and the difference between the period T ₂ of the second clock δT = | T ₀ -T ₂ | distance resolution &Dgr; R = .DELTA.Tc / 2 corresponding to obtain.
That is, since the difference between T ₀ and T ₂ is extremely small, and δT is much smaller than T _0, it is possible to realize high resolution of the pseudo random modulation continuous output distance measuring device.

Next, a fourth embodiment will be described with reference to FIGS. 7 and 8. In FIG. 7, the entire apparatus includes a transmitter 21 and a receiver 22 and is accompanied by a controller (not shown). The transmitter 21 includes a clock generator 23, a subcarrier generator 24, a pseudo random signal generator 25, and a P
It comprises an SK (Phase Shift Keying) modulator 26, a light emitter 27 and a transmission optical system 28, and the receiver 22 includes a reception optical system 29, a light reception detector 30, an A / D converter 31, a high-speed integration memory 32, D / A converter 33, integrator 34, bandpass filter 35, phase measuring device 36,
The PSK demodulator 37, the correlator 38, the calculator 39, the display recorder 40, and the delay device 41 are included.

Next, the operation of each section will be described. In FIG. 8, (a), (b), (c), (d), (e),
(F), (g), (h) and (i) show the waveforms of the respective signals. That is, (a) is the clock S1, (b)
Is a transmission subcarrier S2, (c) is a transmission pseudo random signal S3, (d) is a transmission PSK modulated wave S4, (e) is a transmission light S6, (f) is a reception light S7, and (g) is a reception PSK modulation wave. S8 and integrated PSK modulated wave S9, (h) shows the received subcarrier S12, and (i) shows the received pseudorandom S10 waveform.

In the transmission section 21, the subcarrier generator 24 uses the clock S1 (a) generated from the clock generator 23 to generate the transmission subcarrier S2 (b) which is a sine wave, and also generates the pseudo random signal. The device 25 generates a transmission pseudo random signal S3 (c). (A), (b),
As shown in (c), the transmission subcarrier S2 is synchronized with the transmission pseudo random signal S3 by the clock S1.

The transmission subcarrier S2 is a PSK modulator 2
In 6 the transmission P is modulated by the transmission pseudo random signal S3
The SK modulated wave S4 (d) is generated, and the transmitted PSK modulated wave S4 amplitude-modulates the light source of the light emitter 27 to generate the modulated light S5. The modulated light S5 is transmitted from the transmission optical system 28 to the transmission light S6 (e).
Is emitted to the measurement object as

In the receiver 22, the received light S7 (f) reflected and returned from the object to be measured is received by the receiving optical system 29.
Incident on. In FIGS. 15E and 15F, the transmission light S6 and the reception light S7 are written side by side, but in reality they are delayed by the time required for the light to reciprocate to the measurement object.
The received light S7 is photoelectrically converted and amplified by the light reception detector 30 to become a received PSK modulated wave S8 (g). The received PSK modulated wave S8 is digitally converted by the A / D converter 31 and repeatedly added by the high-speed integration storage unit 32 at a cycle of the number of elements of the pseudo-random signal, and the D / A converter 3 is added every fixed number of additions.
In 3 the analog signal is returned to the integrated PSK modulated wave S9
It is transferred to the PSK demodulator 37 as (g). The received pseudo random S10 (i) demodulated by the PSK demodulator 37 is correlated with the delayed pseudo random signal S11 by the correlator 38. The delayed pseudo-random signal S11 is generated by delaying the transmission pseudo-random signal S3 by the delay device 41 every one clock of the clock S1.

On the other hand, the integrated PSK modulated wave S9 is transferred to the integrator 34.
Is also output to, is integrated with the delayed pseudo random signal S11, and is passed through the band pass filter 35. Since the bandpass filter 35 removes the signal component that is not synchronized with the delayed pseudo random signal S11 of the integrated PSK modulated wave S9 and passes only the component that is synchronized and becomes a continuous sine wave, the reception subcarrier S12 (h) is demodulated. It

Further, the phase of the reception subcarrier S12 is measured by the phase measuring device 36 with reference to the transmission subcarrier S2.
The calculator 39 calculates the distance to the object to be measured by the correlation value S13 from the correlator 38, the phase measurement value S14 from the phase measuring device 36, and the delay amount S15 from the delay device 41, and the display recorder 40 Display and record by. The CPU (not shown) controls the operation of the series of transmitter 21 and receiver 22.
Done by.

In this way, the reception subcarrier S12
Of the received pseudo-random signal S10
It is possible to obtain a resolution equal to or higher than the period of the clock.

Further, if the cycle of the transmission subcarrier S2 and the reception subcarrier S12 is much shorter than the cycle of the clock of the reception pseudo random S10, the resolution can be further improved. Integrator 34, bandpass filter 35, PS
The K demodulator 37, the correlator 38, and the delay device 41 can be replaced with a code synchronization circuit (delay lock loop) (not shown), a matched filter (not shown), or a convolver (not shown). In this case, the integrated PSK modulated wave S9 is input to the code synchronization circuit, and the output reception subcarrier is input to the phase measuring device 36, whereby the calculator 39 calculates the phase measurement value S14 and the delay amount from the code synchronizing circuit. Calculate the distance to the object to be measured with the display recorder 35
Can be displayed and recorded. In this case, A /
D converter 31, high-speed integration memory 32, D / A converter 33
It is possible to simplify the circuit by removing the above and including an integration storage unit in the integration unit 39. When the measurement object is limited to one point and the received light S7 is strong, the A / D converter 31, the high speed integration memory 32 and the D / A converter 33 can be omitted. In addition, a part of the function performed by the reception unit 22 is executed by software processing, and the D / A converter 33, the delay device 41, the integrator 34, the band pass filter 35, the phase measuring device 36, the PSK demodulator 37, Correlator 38, calculator 39
It is also possible to replace etc. with a computer. At this time, the transmission subcarrier S2 is A / D converted and input to the computer.

Next, a fifth embodiment will be described. In the fifth embodiment, the PSK modulator 26 and the PSK demodulator 37 in the fourth embodiment are replaced with ASK (Amplitude).
Since an eShift Keying modulator and an ASK demodulator are provided and there is no other change, detailed description thereof will be omitted. In the transmitting section, the subcarriers are ASK-modulated with the pseudo-random signal, and in the receiving section, the subcarriers are reproduced by the bandpass filter using the PLL, and the phase can be measured in the same manner as in the fourth embodiment.

The operation of the fifth embodiment will be described with reference to FIG. In FIG. 9, (a) shows the clock S1,
(B) is transmission subcarrier S2, (c) is transmission pseudo random signal S3, (d) is transmission ASK modulated wave S4, (e)
Is transmitted light S6, (f) is received light S7, (g) is received AS
The K modulation wave S8 and the integrated ASK modulation wave S9, (h) is the reception subcarrier S12, and (i) is the reception pseudo random S10.
Shows the waveform of. The waveforms of the transmission light S6 shown in (e) and the reception light S7 shown in (f) are shown in FIG. 8 of the fourth embodiment.
(E) of the transmitted light S6 and (f) of the received light S7
The waveform is different. This is because the ASK modulation superimposes a constant amplitude modulation on a predetermined amplitude of light.

[0046]

According to the present invention, it is possible to provide an inexpensive, small-sized and high-resolution high-resolution distance measuring device which has improved distance resolution and can be used for a measuring object having a low reflectance.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a diagram showing a time chart example and a correlation level example of each signal according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a delay amount of a reception signal and a correlation level with respect to a transmission signal according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a delay amount of a reception signal and a correlation level with respect to a transmission signal according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a second embodiment of the present invention.

FIG. 6 is a block diagram of a third embodiment of the present invention.

FIG. 7 is a block diagram of a fourth embodiment of the present invention.

FIG. 8 is a diagram showing an example of a time chart of each signal according to the fourth embodiment of the present invention.

FIG. 9 is a diagram showing an example of a time chart of each signal according to the fifth embodiment of the present invention.

FIG. 10 is a block diagram of a conventional example.

[Explanation of symbols]

 1-Transmitting unit 2--Laser 3--Modulator 4--Transmitting optical system 5--Pseudo random signal generator 6-Reference Clock generator 7-Reception unit 8-Reception optical system 9-Reception detector 10-Delay correlator 11-High-speed storage device 12 ...・ ・ ・ Display recorder 13 ・ ・ ・ High-speed clock generator 14 ・ ・ ・ Delay generator 15 ・ ・ ・ Sawtooth wave generation circuit 16 ・ ・ ・ ・ ・ Second clock generator 17 ・ ・ ・... Phase synchronization control circuit 18 ... Pseudo random signal generator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Ueno 1-33 Yayoicho, Inage-ku, Chiba-shi, Chiba University Chiba University (72) Inobu Takeuchi 1-33 Yayoi-cho, Inage-ku, Chiba Prefecture Chiba University

Claims (4)

[Claims] 1. A light source for emitting continuous light, a reference clock generating means for generating a reference clock, a pseudo random signal generating means for generating a pseudo random signal using the reference clock, and the continuous light for the pseudo random signal. A modulating means for modulating the modulated light with a signal, a transmitting optical means for transmitting the modulated light to an object to be measured, a receiving optical means for receiving the modulated light reflected by the object to be measured, and the receiving optical means. A light receiving detection unit that detects the received modulated light and outputs a received signal, and a delay that calculates the distance to the measurement object as a function of delay time by correlating the pseudo random signal and the received signal. A distance measuring device comprising a correlating means, a high-speed clock generating means for generating a high-speed clock having a cycle shorter than that of the reference clock, and the high-speed clock. Click, the high resolution distance measurement apparatus characterized by comprising a delay amount variable delay generating means for giving a delay to the modulated light to be transmitted to the measurement object. 2. A light source for emitting continuous light, a reference clock generating means for generating a reference clock, a pseudo random signal generating means for generating a pseudo random signal using the reference clock, and the continuous light for the pseudo random signal. A modulating means for modulating the modulated light with a signal, a transmitting optical means for transmitting the modulated light to an object to be measured, a receiving optical means for receiving the modulated light reflected by the object to be measured, and the receiving optical means. Light receiving detection means for detecting the received modulated light and outputting a received signal, high-speed storage means for outputting the integrated received signal by periodically and continuously adding the received signals, the pseudo-random signal and the integrated received signal In the distance measuring device, the distance measuring device is provided with a delay correlating means for calculating a distance to the object to be measured as a function of delay time. A high-speed clock generating means for generating a high-speed clock having a constant period; and a delay-variable delay generating means for delaying the modulated light transmitted to the measurement object by the high-speed clock. High resolution distance measuring device. 3. A light source for emitting continuous light, a reference clock generating means for generating a reference clock, a pseudo random signal generating means for generating a pseudo random signal using the reference clock, and the continuous light for the pseudo random signal. A modulating means for modulating the modulated light with a signal, a transmitting optical means for transmitting the modulated light to an object to be measured, a receiving optical means for receiving the modulated light reflected by the object to be measured, and the receiving optical means. In a distance measuring device comprising a received light detecting means for detecting the received modulated light and outputting a received signal, a second clock generating means for generating a second clock having a cycle slightly different from the cycle of the reference clock. And phase synchronization control means for controlling the phase synchronization between the reference clock and the second clock, and a second pseudo-random signal generated using the second clock. And a delay correlating means for calculating the distance to the object to be measured as a function of delay time by correlating the second pseudo random signal with the received signal. A high resolution distance measuring device characterized in that 4. A light source for emitting continuous light, a reference clock generating means for generating a reference clock, a pseudo random signal generating means for generating a pseudo random signal using the reference clock, and the continuous light for the pseudo random signal. A modulating means for modulating the modulated light with a signal, a transmitting optical means for transmitting the modulated light to an object to be measured, a receiving optical means for receiving the modulated light reflected by the object to be measured, and the receiving optical means. In the distance measuring device, the received light detecting unit for detecting the received modulated light and outputting the received signal, and the high-speed storage unit for periodically and continuously adding the received signals and outputting an integrated received signal are provided. Phase synchronization between the second clock generating means for generating a second clock having a cycle slightly different from that of the clock and the reference clock and the second clock is controlled. Phase correlation control means, second pseudo random signal generation means for generating a second pseudo random signal using the second clock, and correlation between the second pseudo random signal and the integrated received signal, A high-resolution distance measuring device, comprising: delay correlating means for calculating a distance to the measurement object as a function of delay time.