Laser ranging system

Abstract

The application relates to a laser ranging system. The system comprises a processing unit, a modulation signal generating unit, a laser driving unit, a laser light source, a laser receiving end, a first receiving unit, a second receiving unit, a first reference receiving unit and a second reference receiving unit. The processing unit can obtain a fine measurement distance value of a target to be measured after processing a first digital signal and a first reference digital signal; i is 1, 2,..., N, and a fine measurement distance value of the target to be measured is calculated by using square wave signals V m1 (t) and square wave signals V m2 (t). A final processing unit calculates a distance value of the target to be measured, wherein INT is an integral function. Thus, the problems of slow ranging speed of a phase type ranging system and low ranging precision of a pulse type ranging system are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser ranging, in particular to a laser ranging system. BACKGROUND

[0002] Because of the phase ambiguity problem of single frequency phase ranging, the general phase ranging uses multiple different frequency measuring rulers to solve this problem. However, this method needs a long time for the multiple measuring rulers to emit alternately, thereby reducing the measurement frequency. The measurement frequency is very low, generally below 10 Hz under the premise of ensuring measurement accuracy, and the system has weak anti-interference ability.

[0003] In many practical applications, a ranging device with high ranging accuracy and high measurement speed is needed, such as precise positioning and speed measurement in warehouse and conveying systems. In view of the contradiction between the ranging accuracy and the measurement range of the phase method laser ranging system, the ranging accuracy and the measurement speed, the ranging accuracy of the pulse ranging system, and the low signal-to-noise ratio of the laser ranging system, there are many patents and research methods at home and abroad.

[0004] Chinese patent CN111158007A discloses a method for realizing mixing and pulse phase measurement based on FPGA digital circuit, which extracts the phase difference of the pulse signal. This method has high requirements for the laser pulse receiving circuit and complex digital signal processing. SUMMARY

[0005] Therefore, it is necessary to provide a laser ranging system with high speed and high accuracy in view of the above technical problems.

[0006] In a first aspect, the present application provides a laser ranging system. The system comprises:

[0007] a processing unit;

[0008] a modulation signal generation unit for generating a transmission modulation signal Am1 wherein V (t) is filled with an integer number of periods A1cos(2πf1t+θ1) during the high level time;

[0009] a laser driving unit for receiving the transmission modulation signal V Am1 (t) and outputting a driving signal to a laser light source;

[0010] the laser light source for receiving the driving signal of the laser driving unit and emitting a modulated transmission light;

[0011] a laser receiving end for receiving a received light reflected by a to-be-measured target and converting the received light into a received signal through photoelectric conversion;

[0012] a filter circuit for filtering noise of the received signal and obtaining a signal the signal V Am2 (t) is a modulated signal with time-of-flight difference and with phase information θ2 corresponding to the transmitted modulated signal V Am1 (t) and has a time-of-flight difference with the transmitted modulated signal V Am1 (t) and has a time-of-flight difference with the transmitted modulated signal V

[0013] a first receiving unit for conditioning and amplifying the signal V Am2 (t) into a signal S m (t) and converting it into a first digital signal for transmission to the processing unit, the signal S m (t) containing phase information θ2;

[0014] a second receiving unit for demodulating and edge shaping the signal V Am2 (t) to form a square wave signal V m2 (t) for transmission to the processing unit; the rising edge of the pulse of the square wave signal V m2 (t) triggers a timer in the processing unit to stop timing as the time end point t m2 (t) of the square wave signal V 2i ;

[0015] a first reference receiving unit for conditioning and amplifying the transmitted modulated signal V Am1 (t) into a first reference signal S r (t) and converting it into a first reference digital signal for transmission to the processing unit;

[0016] a second reference receiving unit for demodulating and edge shaping the transmitted modulated signal V Am1 (t) to form a square wave signal V m1 (t) for transmission to the processing unit; the rising edge of the pulse of the square wave signal V m1 (t) triggers a timer in the processing unit to start timing as the time start point t m1 (t) of the square wave signal V 1i ;

[0017] the processing unit can obtain θ 2i -θ 1i after processing the first digital signal and the first reference digital signal, wherein θ 2i -θ 1i represents the phase angle difference of the received signal relative to the transmitted modulated signal V Am1 (t);

[0018] the processing unit calculates the precise distance value of the target to be measured: i i is 1, 2, …, N;

[0019] The processing unit calculates the initial distance value of the target to be measured: i is 1, 2, …, N;

[0020] The processing unit calculates the distance value L of the target to be measured:

[0021] Wherein, INT is an integer function.

[0022] In a second aspect, the application further provides a laser ranging system. The system comprises:

[0023] A processing unit;

[0024] A modulation signal generating unit for generating a transmitting modulation signal V Am1 (t) and a receiving mixed signal V h (t), wherein V h (t) = A2cos(2πf2t+θ1), V Am1 (t) is filled with an integer number of periods A1cos(2πf1t+θ1) in the high level time of V h (t), and the receiving mixed signal V Am1 (t) has the same initial phase as the transmitting modulation signal V Am1 (t);

[0025] A laser driving unit for receiving the transmitting modulation signal V Am1 (t) and outputting a driving signal to a laser light source;

[0026] The laser light source for receiving the driving signal of the laser driving unit and emitting a modulated transmitting light, the transmitting light being transmitted to the outside for detecting a target to be measured, and the transmitting light forming a receiving light after being reflected by the target to be measured;

[0027] A laser receiving end for receiving the receiving light reflected by the target to be measured and converting the receiving light into a receiving signal through photoelectric conversion;

[0028] A filter circuit for filtering out the noise of the receiving signal and obtaining a signal V Am2 (t), the signal V Am2 (t) being a modulation signal corresponding to the transmitting modulation signal V Am1 (t) and having a time-of-flight difference with the transmitting modulation signal V Am1 (t) and carrying phase information θ2;

[0029] A first receiving unit for receiving the signal V Am2 (t) and the mixed signal V h(t) and the signal S m (t) is transmitted to the processing unit, and the signal S m (t) is conditioned, amplified and converted into a first digital signal and transmitted to the processing unit, and the signal S where Δf = f2-f1, the signal S

[0030] A second receiving unit is configured to demodulate and edge-shape the signal V Am2 (t) to form a square wave signal V m1 (t) and transmit it to the processing unit; the square wave signal V m1 (t) triggers a timer in the processing unit to stop timing as a time end point t m1 (t) of the square wave signal V 2i ;

[0031] A first reference receiving unit is configured to mix the transmitted modulated signal V Am1 (t) and the received mixed signal V h (t) to obtain a signal S r (t), and transmit the signal S where Δf = f2-f1, the signal S r (t) is conditioned, amplified and converted into a first reference digital signal and transmitted to the processing unit;

[0032] A second reference receiving unit is configured to demodulate and edge-shape the signal V Am2 (t) to form a square wave signal V m2 (t) and transmit it to the processing unit; the square wave signal V m2 (t) triggers a timer in the processing unit to start timing as a time start point t m2 (t) of the square wave signal V 1i ;

[0033] The processing unit can obtain θ 2i -θ 1i after processing the first digital signal and the first reference digital signal, where θ 2i -θ 1i represents a phase shift angle difference of the received signal relative to the transmitted modulated signal V Am1 (t).

[0034] The processing unit calculates a fine measurement distance value of the target to be measured: i is 1, 2,..., N;

[0035] The processing unit calculates a preliminary measurement distance value of the target to be measured: i is 1, 2,..., N;

[0036] The processing unit calculates the target distance value as follows: (Preliminary distance value + Precise distance value)

[0037] Here, INT is the floor function.

[0038] This invention calculates the precise distance value of the target under test using a first digital signal and a first reference digital signal, and transmits the result via a square wave signal V. m1 (t) and square wave signal V m2 (t) calculates the initial distance value of the target to be measured, and thus finally obtains the distance value of the target to be measured, which solves the problems of slow ranging speed of phase ranging system and low ranging accuracy of pulse ranging system. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a laser ranging system in one embodiment;

[0040] Figure 2 for Figure 1 The diagram shows the relevant signals of the laser ranging system.

[0041] Figure 3 This is a schematic diagram of a laser ranging system in another embodiment.

[0042] Figure 4 Figure 3 The diagram shows the relevant signals of the laser ranging system.

[0043] Figure 5 Transmit modulated signal V Am1 (t) Schematic diagram of modulated pseudo-random code signal. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0045] In one embodiment, such as Figure 1 As shown, a laser ranging system is provided, comprising:

[0046] The processing unit 110 can be an FPGA (Field Programmable Gate Array) or an MCU (Microcontroller Unit).

[0047] Modulation signal generation unit 111 is used to generate a transmitted modulation signal. Square wave Vm1 The duty cycle and period of (t) can be adjusted, and in order to reduce the spectral leakage and phase distortion of the echo, the transmitting modulated signal V Am1 (t) is filled with an integer number of periods A1cos(2πf1t+θ1) during the high level time of (t);

[0048] In this embodiment, the modulated signal generating unit 111 is preferably a digital frequency synthesizer (DDS), which is used to receive the digital signal sent by the receiving processing unit 110 and generate the signal V Am1 (t);

[0049] The laser driving unit 112 is used to receive the signal V Am1 (t) and output a driving signal to the laser light source 113;

[0050] The laser light source 113 is used to receive the driving signal from the laser driving unit 112 and emit a modulated transmitting light, which is emitted to the outside for detecting the target to be detected, and forms a receiving light after being reflected by the target to be detected;

[0051] The laser receiving end 114 is used to receive the receiving light reflected by the target to be detected and convert the receiving light into a receiving signal through photoelectric conversion;

[0052] The filter circuit 116 is used to filter out the noise of the receiving signal and obtain the signal V Am2 (t), and the signal V Am2 (t) is a modulated signal corresponding to the transmitting modulated signal V Am1 (t) and having a time-of-flight difference with the transmitting modulated signal V Am1 (t) and carrying phase information θ2;

[0053] The first receiving unit is used to condition and amplify the signal V Am2 (t) into a signal S m (t) and convert it into a first digital signal for transmission to the processing unit 110; the signal S m (t) contains phase information θ2;

[0054] In this embodiment, the first receiving unit includes a first signal conditioning circuit 117 and a first analog-to-digital converter 118, and the signal V Am2 (t) is input to the processing unit 110 after passing through the first signal conditioning circuit 117 and the first analog-to-digital converter 118;

[0055] The second receiving unit is used to demodulate and edge shape the signal V Am2 (t) to form a square wave signal V m2 (t) for transmission to the processing unit 110; the square wave signal V m2The pulse rising edge of (t) triggers a timer in the processing unit 110 to stop timing as the square wave signal V m2 (t) The time end t of the timing 2i ;

[0056] In this embodiment, the second receiving unit includes a first RF detector 119 and a first edge shaping circuit 120, and the signal V Am2 (t) is input to the processing unit 110 after passing through the first RF detector 119 and the first edge shaping circuit 120.

[0057] The first reference receiving unit is used to demodulate the transmitted modulated signal V Am1 (t) into a first reference signal S r (t) and convert it into a first reference digital signal transmitted to the processing unit 110.

[0058] In this embodiment, the first reference receiving unit includes a second signal conditioning circuit 121 and a second analog-to-digital converter 122, and the signal V Am1 (t) is input to the processing unit 110 after passing through the second signal conditioning circuit 121 and the second analog-to-digital converter 122.

[0059] The second reference receiving unit is used to demodulate the transmitted modulated signal V Am1 (t) into a square wave signal V m1 (t) transmitted to the processing unit 110; the pulse rising edge of the square wave signal V m1 (t) triggers a timer in the processing unit 110 to start timing as the square wave signal V m1 (t) The time start t of the timing 1i ;

[0060] In this embodiment, the second reference receiving unit includes a second RF detector 123 and a second edge shaping circuit 124, and the signal V Am2 (t) is input to the processing unit 110 after passing through the second RF detector 123 and the second edge shaping circuit 124.

[0061] In this embodiment, the processing unit 110 can obtain the phase difference θ 2i -θ 1i of the distance information after processing the first digital signal and the first reference digital signal, that is, the phase shift angle difference of the received signal relative to the transmitted modulated signal V Am1 (t); The method for obtaining the phase shift angle difference of the two signals is a prior art, for example, the paper "High-speed phase laser ranging technology based on vector inner product method" published in Infrared and Laser Engineering, Vol. 51, No. 4, April 2022, introduces how to extract the phase difference in the phase laser ranging system.

[0062] Processing unit 110 via θ 2i -θ 1i Calculate the precise distance value of the target to be measured:

[0063]

[0064] Processing unit 110 passes through (t) 2i -t 1i The initial distance to the target can be calculated: i is 1, 2, ..., N.

[0065] Therefore, the processing unit 110 calculates the distance value of the target to be measured:

[0066] Here, INT is the floor function.

[0067] This invention calculates the precise distance value of the target under test using a first digital signal and a first reference digital signal, and transmits the result via a square wave signal V. m1 (t) and square wave signal V m2 (t) Calculates the initial distance value of the target to be measured, thereby finally obtaining the distance value of the target to be measured, solving the problems of slow ranging speed of phase ranging system and low ranging accuracy of pulse ranging system. Furthermore, the emitted light of this invention is a sinusoidal signal A1cos(2πf1t+θ1) and a square wave signal V. m1 (t) Modulated OOK keying signal V Am1 (t), such as Figure 5 As shown, it can be adjusted by adjusting the square wave V m1 (t) duty cycle or using square wave V m1 (t) forms a pseudo-random code to improve the anti-interference capability of the receiving system.

[0068] In another embodiment, such as Figure 3 As shown, the laser ranging system includes:

[0069] The processing unit 110 can be an FPGA (Field Programmable Gate Array) or an MCU (Microcontroller Unit).

[0070] Modulation signal generation unit 111 is used to generate a transmitted modulation signal. and receive the mixing signal V h (t)=A2cos(2πf2t+θ1), in order to reduce the spectral leakage and phase distortion of the echo, V is required to Am1(t) The high-level time is filled with an integer number of cycles of sine wave A1cos(2πf1t+θ1);

[0071] Receive mixing signal V h (t) is a sinusoidal signal, and is modulated by the transmitted signal V. Am1 (t) have the same initial phase and receive the mixing signal V. h (t) is simultaneously the input signal of the second mixer 130 of the first reference receiving unit and the input signal of the first mixer 129 of the first receiving unit.

[0072] In this embodiment, the modulation signal generating unit 111 is preferably a Direct Digital Synthesizer (DDS). The DDS is used to receive the digital signal emitted by the processing unit 110 and generate the transmit modulation signal V. Am1 (t) and the received mixing signal V h (t);

[0073] Laser driving unit 112 is used to receive the transmitted modulation signal V Am1 (t) and outputs a drive signal to the laser source 113;

[0074] The laser source 113 is used to receive the driving signal of the laser driving unit 112 and emit modulated emission light. The emission light is emitted to the outside world to detect the target under test. The emission light is reflected by the target under test to form the receiving light.

[0075] The first laser receiver 114 is used to receive the light reflected by the target and convert it into a receiving signal through photoelectric conversion;

[0076] Filter circuit 116 is used to filter out noise from the received signal and obtain signal V. Am2 (t), signal V Am2 (t) is related to the transmitted modulation signal V Am1 (t) corresponds to and is related to the transmitted modulation signal V Am1 (t) A modulated signal with a time-of-flight difference and phase information θ2;

[0077] The first receiving unit is used to receive signal V Am2 (t) and the received mixing signal V h (t) The signal S is obtained after mixing. m (t), and the signal S m (t) The signal is conditioned, amplified, and converted into a first digital signal, which is then transmitted to the processing unit 110. Where Δf = f2 - f1;

[0078] In the embodiment, the first receiving unit comprises a first mixer 129, a first signal conditioning circuit 117 and a first analog-to-digital converter 118, the first mixer 129 is used to mix the signal V Am2 (t) with the received mixed signal V h (t) to obtain S m (t) after filtering high frequency components; S m (t) is input to the processing unit 110 after signal conditioning amplification by the first signal conditioning circuit 117 and sampling by the first analog-to-digital converter 118;

[0079] The second receiving unit is used to demodulate and edge-shape the signal V Am2 (t) to form a square wave signal V m2 (t) transmitted to the processing unit 110; the pulse rising edge of the square wave signal V m2 (t) triggers a timer in the processing unit 110 to stop timing, as the time end point t m2 (t) of the square wave signal V 2i ;

[0080] In the embodiment, the second receiving unit comprises a first RF detector 119 and a first edge-shaping circuit 120, the signal V Am2 (t) is input to the processing unit 110 after passing through the first RF detector 119 and the first edge-shaping circuit 120;

[0081] The first reference receiving unit is used to mix the transmitted modulated signal V Am1 (t) with the received mixed signal V h (t) to obtain a signal S r (t); the signal S where Δf = f2-f1, the signal S r (t) is amplified and converted into a first reference digital signal transmitted to the processing unit 110;

[0082] In the embodiment, the first reference receiving unit comprises a second mixer 130, a second signal conditioning circuit 121 and a second analog-to-digital converter 122, the second mixer 130 is used to mix the transmitted modulated signal V Am1 (t) with the received mixed signal V h (t) to obtain a signal S r (t), the signal S r (t) is input to the processing unit 110 after amplification by the second signal conditioning circuit 121 and sampling by the second analog-to-digital converter 122;

[0083] The second reference receiving unit is used to demodulate and edge-shape the signal V Am2 (t) to form a square wave signal Vm2 (t) to the processing unit 110; the square wave signal V m2 (t) triggers a timer within the processing unit 110 to start timing at the rising edge of the pulse of the square wave signal V m2 (t) as the time origin t 1i ;

[0084] In this embodiment, the second receiving unit includes a second RF detector 123 and a second edge shaping circuit 124, and the signal V Am2 (t) is input to the processing unit 110 after passing through the second RF detector 123 and the second edge shaping circuit 124;

[0085] In this embodiment, the processing unit 110 can obtain the phase difference θ 2i -θ 1i after processing the first digital signal and the first reference digital signal, which is the fine measurement distance value of the target to be measured: m (t) relative to the signal S r (t), which is the fine measurement distance value of the target to be measured:

[0086] The processing unit 110 can calculate the preliminary measurement distance value of the target to be measured by (t 2i -t 1i ): i is 1, 2,..., N.

[0087] Therefore, the processing unit 110 calculates the distance value of the target to be measured as:

[0088] Where, INT is the integer function.

[0089] It should be understood that although each step in the flowchart involved in each of the above embodiments is displayed in sequence according to the arrow, these steps are not necessarily executed in sequence according to the arrow. Unless otherwise stated herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other orders. Moreover, as described above, at least part of the steps in the flowchart involved in each of the above embodiments can include multiple steps or stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least part of other steps or steps or stages in other steps.

[0090] Any technical features in the above embodiments can be combined, and for the sake of brevity, not all possible combinations are described above, however, as long as the combinations of technical features do not have contradictions, they shall be considered within the scope of the present disclosure.

[0091] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these shall be within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A laser ranging system, characterized in that, The system includes: Processing unit; Modulation signal generation unit, used to generate transmitted modulation signal Where V Am1 (t) The high-level time is filled by an integer number of cycles A1cos(2πf1t+θ1); The laser driving unit is used to receive the transmitted modulation signal V. Am1 (t) and outputs a drive signal to the laser source; The laser source is used to receive the drive signal from the laser driving unit and emit modulated emitted light; The laser receiver is used to receive the light reflected by the target and convert the light into a signal through photoelectric conversion. A filtering circuit is used to filter out noise from the received signal and obtain the signal. The signal V Am2 (t) is related to the transmitted modulation signal V Am1 (t) corresponds to and is related to the transmitted modulation signal V Am1 (t) A modulated signal with a time-of-flight difference and phase information θ2; The first receiving unit is used to receive the signal V Am2 (t) Conditioning and amplification into signal S m (t) and convert it into a first digital signal and transmit it to the processing unit, the signal S m (t) contains phase information θ2; The second receiving unit is used to receive the signal V Am2 (t) Demodulation and edge trimming to form a square wave signal V m2 (t) is transmitted to the processing unit; the square wave signal V m2 The rising edge of the pulse (t) triggers the timer in the processing unit to stop counting, which is the square wave signal V. m2 (t) The end of the timing t 2i ; The first reference receiving unit is used to transmit the modulated signal V Am1 (t) Conditioned and amplified into the first reference signal S r (t) and convert it into a first reference digital signal and transmit it to the processing unit; The second reference receiving unit is used to transmit the modulated signal V. Am1 (t) Demodulation and edge shaping to form a square wave signal V m1 (t) is transmitted to the processing unit; the square wave signal V m1 The rising edge of the pulse (t) triggers the timer in the processing unit to start counting, which is a square wave signal V. m1 (t) The starting point of the timing t 1i ; The processing unit can obtain θ after processing the first digital signal and the first reference digital signal. 2i -θ 1i , the θ 2i -θ 1i Represents the received signal relative to the transmitted modulated signal V Am1 The phase shift angle difference of (t); The processing unit calculates the precise distance value of the target to be measured: ii represents 1, 2, ..., N; The processing unit calculates the initial distance value of the target to be measured: i is 1, 2, ..., N; The processing unit calculates the distance value L of the target to be measured: Here, INT is the floor function.

2. The system according to claim 1, characterized in that, The first receiving unit includes a first signal conditioning circuit and a first analog-to-digital converter, wherein the signal V Am2 (t) is input to the processing unit after passing through the first signal conditioning circuit and the first analog-to-digital converter.

3. The system according to claim 1, characterized in that, The second receiving unit includes a first RF detector and a first edge shaping circuit, wherein the signal V Am2 (t) is input to the processing unit after passing through the first RF detector and the first edge shaping circuit.

4. The system according to claim 1, characterized in that, The first reference receiving unit includes a second signal conditioning circuit and a second analog-to-digital converter, wherein the signal V Am1 (t) After passing through the second signal conditioning circuit and the second analog-to-digital converter, it is input to the processing unit.

5. The system according to claim 1, characterized in that, The second reference receiving unit includes a second RF detector and a second edge shaping circuit, wherein the signal V Am2 (t) After passing through the second RF detector and the second edge shaping circuit, it is input to the corresponding processing unit.

6. A laser ranging system, characterized in that, The system includes: Processing unit; Modulation signal generation unit, used to generate transmitted modulation signal V Am1 (t) and the received mixing signal V h (t), where V h (t)=A2cos(2πf2t+θ1), V Am1 The high-level time of (t) is filled with an integer number of periods A1cos(2πf1t+θ1), and the received mixing signal V h (t) and the transmitted modulation signal V Am1 (t) have the same initial phase; The laser driving unit is used to receive the transmitted modulation signal V. Am1 (t) and outputs a drive signal to the laser source; The laser source is used to receive the driving signal from the laser driving unit and emit modulated light. The emitted light is emitted to the outside world to detect the target under test. The emitted light is reflected by the target under test to form the receiving light. The laser receiver is used to receive the light reflected by the target and convert it into a received signal through photoelectric conversion; The filtering circuit is used to filter out noise from the received signal and obtain signal V. Am2 (t), the signal V Am2 (t) is related to the transmitted modulation signal V Am1 (t) corresponds to and is related to the transmitted modulation signal V Am1 (t) A modulated signal with a time-of-flight difference and phase information θ2; The first receiving unit is used to receive the signal V Am2 (t) and the mixing signal V h (t) The signal S is obtained after mixing. m (t), and the signal S m (t) The signal is conditioned, amplified, and converted into a first digital signal, which is then transmitted to the processing unit. Where Δf = f2 - f1; The second receiving unit is used to receive the signal V Am2 (t) Demodulation and edge shaping to form a square wave signal V m1 (t) is transmitted to the processing unit; the square wave signal V m1 The rising edge of the pulse (t) triggers the timer in the processing unit to stop counting, which is the square wave signal V. m1 (t) The end of the timing t 2i ; The first reference receiving unit is used to transmit the modulated signal V Am1 (t) and the received mixing signal V h (t) The signal S is obtained after mixing. r (t), the signal Where Δf = f2 - f1, the signal S r (t) Conditioning, amplifying, and converting the signal into a first reference digital signal, which is then transmitted to the processing unit; The second reference receiving unit is used to receive the signal V Am2 (t) Demodulation and edge shaping to form a square wave signal V m2 (t) is transmitted to the processing unit; the square wave signal V m2 The rising edge of the pulse (t) triggers the timer in the processing unit to start counting, which serves as the square wave signal V. m2 (t) The starting point of the timing t 1i ; The processing unit can obtain θ after processing the first digital signal and the first reference digital signal. 2i -θ 1i , the θ 2i -θ 1i Represents the received signal relative to the transmitted modulated signal V Am1 The phase shift angle difference of (t); The processing unit calculates the precise distance value of the target to be measured: i is 1, 2, ..., N; The processing unit calculates the initial distance value of the target to be measured: i is 1, 2, ..., N; The processing unit calculates the target distance value as follows: (Preliminary distance value + Precise distance value) Here, INT is the floor function.

7. The system according to claim 6, characterized in that, The first receiving unit includes a first mixer, a first signal conditioning circuit, and a first analog-to-digital converter. The first mixer is used to convert the signal V... Am2 (t) is mixed with the aforementioned mixing signal, and after filtering out the high-frequency components, the S is obtained. m (t); the S m (t) The signal is amplified by the first signal conditioning circuit and sampled by the first analog-to-digital converter before being input to the processing unit.

8. The system according to claim 6, characterized in that, The second receiving unit includes a first RF detector and a first edge shaping circuit, wherein the signal V Am2 (t) is input to the processing unit after passing through the first RF detector and the first edge shaping circuit.

9. The system according to claim 6, characterized in that, The first reference receiving unit includes a second mixer, a second signal conditioning circuit, and a second analog-to-digital converter. The second mixer is used to convert the transmitted modulated signal V... Am1 (t) and the received mixing signal V h (t) After mixing and filtering out high-frequency components, the signal S is obtained. r (t), the signal S r (t) After being conditioned and amplified by the second signal conditioning circuit and sampled by the second analog-to-digital converter, it is input to the processing unit.

10. The system according to claim 6, characterized in that, The second reference receiving unit includes a second RF detector and a second edge shaping circuit, wherein the signal V Am2 (t) is input to the processing unit after passing through the second RF detector and the second edge shaping circuit.

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