CN211698204U - Pulse width detection circuit and laser radar ranging circuit - Google Patents
Pulse width detection circuit and laser radar ranging circuit Download PDFInfo
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- CN211698204U CN211698204U CN201921331177.4U CN201921331177U CN211698204U CN 211698204 U CN211698204 U CN 211698204U CN 201921331177 U CN201921331177 U CN 201921331177U CN 211698204 U CN211698204 U CN 211698204U
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Abstract
The application relates to the field of laser radar circuits, in particular to a pulse width detection circuit and a laser radar ranging circuit. The application provides a pulse width detection circuit, which comprises an in-phase comparator, an inverse phase comparator and a TDC timer, wherein the in-phase comparator and the inverse phase comparator are connected with the TDC timer, and are used for receiving a pulse signal and a threshold value, comparing the pulse signal and the threshold value and outputting a signal according to a comparison result; the TDC timer is used for recording the time of the output signal. A lidar ranging circuit including a pulse width detection circuit is also provided. The pulse signal and the threshold value are received by the in-phase comparator and the anti-phase comparator and are compared, the TDC timer records the time of outputting the signal, the pulse width is calculated according to the two times, the echo pulse peak value is detected through the pulse width, the measurement of the pulse width is not limited by signal saturation, and the problem that the echo pulse peak value cannot be accurately measured in a signal saturation state is solved.
Description
Technical Field
The utility model discloses the application relates to laser radar technical field especially relates to a peak detection circuit.
Background
In the laser radar, the peak detection of the echo signal is of great significance, the peak value can be used for testing the reflectivity of an object, and the measurement distance can be corrected, so that the measurement precision is improved.
The current peak value detection circuit generally adopts a peak value holding circuit to detect the peak value of the pulse, and the current general peak value holding circuits mainly have two types: voltage type and transconductance type, the voltage type circuit is simple, but the response speed is slow, does not have the characteristic of fast response, and is difficult to process high-speed pulse signals. The transconductance type peak holding circuit has the advantages of high response speed, large dynamic range and small error, but the circuit structure is relatively complex.
However, the existing peak value detection circuits cannot solve the problem that the pulse peak value cannot be accurately detected when the echo signal of the laser radar is saturated.
SUMMERY OF THE UTILITY MODEL
The embodiment of the application provides a pulse width detection circuit, which solves the problem that a pulse peak value cannot be accurately detected under a signal saturation condition in the prior art.
To achieve the purpose, the application embodiment of the present invention adopts the following technical solutions:
on one hand, the pulse width detection circuit comprises an in-phase comparator, an inverse phase comparator and a TDC timer, wherein the in-phase comparator and the inverse phase comparator are connected with the TDC timer,
the in-phase comparator and the reverse-phase comparator compare the pulse signal with the threshold value and output a signal according to a comparison result;
the TDC timer is used for recording the time when the in-phase comparator and the reverse-phase comparator output signals, and obtaining the time interval between the two signals, namely the pulse width.
In a possible implementation manner, the in-phase comparator and the reverse-phase comparator are used for comparing the pulse signal with a threshold, and according to the comparison result, the in-phase comparator outputs a signal at the rising edge of the pulse signal, and the reverse-phase comparator outputs a signal at the falling edge of the pulse signal.
On the other hand, the laser radar ranging circuit comprises a pulse width detection circuit, wherein the pulse width detection circuit comprises an in-phase comparator, an inverse phase comparator and a TDC timer, the in-phase comparator and the inverse phase comparator are connected with the TDC timer, and the in-phase comparator and the inverse phase comparator compare a pulse signal with a threshold value and output a signal according to a comparison result; the TDC timer is used for recording the time when the in-phase comparator and the reverse-phase comparator output signals to obtain the time interval between the two signals, namely the pulse width;
still include the control unit, the emission unit, the receiving element, the control unit is connected with emission unit, pulse width detection circuitry respectively, and the receiving element is connected with pulse width detection circuitry, wherein:
the transmitting unit is used for transmitting laser pulses;
the receiving unit is used for receiving the reflected laser pulse, converting the reflected laser pulse into a pulse signal and sending the pulse signal to the pulse width detection circuit and the control unit;
the peak value detection circuit is used for obtaining the pulse width according to the pulse signal and the threshold value;
the control unit is used for controlling the transmitting unit and the peak value detection circuit, calculating the distance according to the pulse signal transmitted by the receiving unit and correcting the distance by combining the pulse width.
In a possible implementation manner, the receiving unit includes an avalanche diode for receiving the laser pulse and converting it into a current signal, and a transimpedance amplifier for amplifying and converting the current signal into a pulse signal.
In a possible implementation manner, the receiving unit further includes a secondary amplifier, and the secondary amplifier is respectively connected to the transimpedance amplifier and the pulse width detection circuit, and is configured to further amplify the pulse signal.
In a possible implementation manner, the control unit is a microprocessor or a single chip microcomputer, and the emission unit is a semiconductor laser or a solid laser.
According to the embodiment of the application, the pulse signal and the threshold value are received by the in-phase comparator and the reverse-phase comparator and compared, the signal is output, the TDC timer calculates the pulse width according to the signal, the signal strength and the reflectivity can be calculated through the pulse width, the measured distance can be corrected, the measurement of the pulse width is not limited by signal saturation, and the problem that the echo pulse peak value cannot be accurately measured in a signal saturation state is solved.
Drawings
Fig. 1 is a schematic diagram of a pulse width detection circuit according to an embodiment of the present application.
Fig. 2 is a waveform diagram of an embodiment of the present application.
Fig. 3 is a schematic diagram of a laser ranging circuit according to an embodiment of the present application.
Fig. 4 is a schematic diagram of a receiving unit according to an embodiment of the present application.
In the figure: 1. an in-phase comparator; 2. an inverting comparator; 3. a TDC timer; 4. a control unit; 5. a transmitting unit; 6. a receiving unit; 7. an avalanche diode; 8. a transimpedance amplifier; 9. a two-stage amplifier.
Detailed Description
The technical scheme of the application is further explained by the specific implementation mode in combination with the attached drawings.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The embodiments of the present application
Referring to fig. 1, a pulse width detection circuit includes an in-phase comparator 1, an inverted-phase comparator 2, and a TDC timer 3, wherein the in-phase comparator 1 and the inverted-phase comparator 2 are connected to the TDC timer 3,
the in-phase comparator 1 and the reverse-phase comparator 2 compare the pulse signal with a threshold value and output a signal according to a comparison result;
the TDC timer 3 is used for recording the time when the in-phase comparator 1 and the reverse-phase comparator 2 output signals, and obtaining the time interval between the two signals, namely the pulse width. The calculation of the time interval may also be performed by an external processor.
In this embodiment, the pulse width is defined as the time during which the echo signal intensity is maintained above the threshold.
As shown in fig. 2, the laser radar pulse signal waveform is generally a triangular wave or a similar triangular wave when the signal is not saturated, and the pulse signal waveform may also be a rectangular wave, a sawtooth wave, or a spike wave, which has a spike. When the waveform has a peak, the peak value can be measured by adopting a peak value holding method, and parameters such as pulse signal intensity and the like are further calculated. However, when the pulse signal is saturated, the waveform of the pulse signal is a trapezoidal wave, the signal in a certain time interval is a fixed value, and the peak value cannot be directly measured by the peak value holding method.
The in-phase comparator 1 and the reverse-phase comparator 2 are used for comparing the pulse signal with a threshold, according to the comparison result, the in-phase comparator 1 outputs the signal when the rising edge of the pulse signal reaches the trigger threshold, the reverse-phase comparator outputs the signal when the falling edge of the pulse signal reaches the trigger threshold, the rising edge of the pulse signal refers to the edge of the pulse signal rising from the lowest amplitude to the highest amplitude, and the falling edge of the pulse signal refers to the edge of the pulse signal falling from the highest amplitude to the lowest amplitude.
The method for detecting the pulse width by adopting the pulse width detection circuit comprises the following steps:
a. the in-phase comparator 1 compares the pulse signal with a threshold value, and outputs a signal at a rising edge of the pulse signal when the pulse signal rises from less than the threshold value to more than the threshold value;
b. the inverse comparator 2 compares the pulse signal with a threshold value, and outputs a signal at the falling edge of the pulse signal when the pulse signal falls from being larger than the threshold value to being smaller than the threshold value;
c. after receiving the signals output in steps a and b, the TDC timer 3 records the time when the signals are received, and obtains the time interval between the two signals, i.e. the pulse width.
The signals output by the homodromous comparator 1 and the inverting comparator 2 are preferably positive step signals.
The threshold is a predetermined value and is input to the in-phase comparator 1 and the reverse-phase comparator 2 before pulse width detection.
On the other hand, a laser radar ranging circuit, include pulse width detection circuit, still include control unit 4, transmitting element 5, receiving element 6, control unit 4 is connected with transmitting element 5, pulse width detection circuit respectively, and receiving element 6 is connected with pulse width detection circuit, wherein:
the transmitting unit 5 is used for transmitting laser pulses;
the receiving unit 6 is used for receiving the reflected laser pulse, converting the reflected laser pulse into a pulse signal and sending the pulse signal to the pulse width detection circuit and the control unit 4;
the peak value detection circuit is used for obtaining the pulse width according to the pulse signal and the threshold value;
the control unit 4 is used for controlling the transmitting unit 5 and the peak detection circuit, calculating the distance according to the pulse signal transmitted by the receiving unit 6, and correcting the distance by combining the pulse width.
The control unit 4 is a microprocessor or a single chip microcomputer and also has the function of storing a threshold value. The emitting unit 5 is a semiconductor laser or a solid laser.
The receiving unit 6 comprises an avalanche diode 7 and a transimpedance amplifier 8, wherein the avalanche diode 7 is used for receiving the laser pulse and converting the laser pulse into a current signal, and the transimpedance amplifier 8 is used for amplifying the current signal and converting the current signal into a pulse signal. The pulse signal converted by the transimpedance amplifier 8 is generally a voltage pulse signal.
Because the rise time of a pulse signal of the laser radar is very short, the response requirement on a pulse width detection circuit is also very high, and the traditional voltage type detection circuit has low response speed and does not have the characteristic of fast response and can not meet the response requirement. The transconductance type holding circuit has the advantages of high response speed, large dynamic range and small error, and adopts a transconductance amplifier to convert a laser pulse signal into current without overshoot and feedback. However, the transconductance amplifier needs dual power supplies to work and is expensive, and the laser radar circuit has complex design and high manufacturing cost. The laser pulse signal is converted into the pulse signal by the trans-impedance amplifier 8, the circuit design is simple, and the response requirement can be met.
The receiving unit 6 further comprises a secondary amplifier 9, and the secondary amplifier 9 is respectively connected with the transimpedance amplifier and the pulse width detection circuit and is used for further amplifying the pulse signal.
When pulse signals are amplified through the trans-impedance amplifier 8, the gain of first-stage amplification signals is not large, otherwise, the signals are unstable, secondary amplification is needed to be carried out in order to meet measurement requirements, and the secondary amplifier 9 is adopted for secondary amplification in the embodiment of the application.
The laser radar ranging method adopting the laser radar ranging circuit comprises the steps that the transmitting unit 5 continuously transmits light pulses to a target, then the receiving unit 6 receives light returned from an object, the control unit 4 calculates the flight time of the light pulses to obtain the distance of the target object, the pulse width detection step and the distance measurement correction step are included, the pulse width detection step is to adopt the pulse width detection circuit to measure the pulse width of the laser pulses, and the distance measurement correction step is to correct the measured distance according to the pulse width.
The laser radar ranging method specifically comprises the following steps:
101. the control unit 4 sends an instruction to the emission unit 5, the emission unit 5 receives the instruction and sends out laser pulse, and the control unit 4 records the emission time of the laser pulse;
102. the laser pulse enters the receiving unit 6 after being reflected by the measured object, the receiving unit 6 receives the laser pulse, amplifies the laser pulse, converts the laser pulse into a pulse signal and transmits the pulse signal to the peak value detection circuit and the control unit 4;
103. the control unit 4 inputs a threshold value to the peak value detection circuit, and the peak value detection circuit receives the pulse signal obtained in the step 102 and compares the pulse signal with the threshold value to calculate the pulse width;
104. the control unit 4 receives the pulse signal sent by the receiving unit 6, records the laser pulse return time, and calculates the distance between the radar and the measured object according to the laser pulse transmitting time and the laser pulse return time;
105. the control unit 4 receives the pulse width sent by the peak detection circuit and further corrects the distance between the radar and the object to be measured.
The control unit 4 comprises a laser ranging circuit, when the laser ranging circuit measures, the laser pulse emission time is subtracted from the laser pulse return time, and then the emission delay of laser, namely the delay from the laser pulse emission to the laser pulse emission, is subtracted to obtain the round-trip time T of the laser pulse between the laser radar and the measured object, wherein the laser emission delay is a fixed value and can be compensated through fixed distance calibration. The round-trip time T of the laser pulse between the laser radar and the measured object is divided by 2 and multiplied by the speed of light c, and then the distance between the radar and the measured object can be obtained.
The step of correcting the measured distance comprises: and calculating to obtain the intensity of the echo signal, inputting the intensity of the echo signal into a relation formula between the signal intensity and the distance prestored in the control unit, calculating to obtain the corrected distance, and correcting all measurement results.
The relationship between the signal intensity and the distance is obtained by the following method: a group of measured distances and echo intensity data under each distance can be obtained by measuring at a specific distance, curve fitting is carried out on the data through mathematical analysis software, a relation curve between the measured distances and the echo intensity is obtained, and a formula for correcting the distances can be obtained according to the curve.
The laser radar ranging method further comprises the step of detecting the reflectivity, wherein the step of detecting the reflectivity comprises the step of calculating the intensity of an echo signal; and inputting the intensity of the echo signal into a relational formula of the signal intensity, the measuring distance and the reflectivity prestored in the control unit to obtain the reflectivity.
The relation formula of the signal intensity, the measuring distance and the reflectivity is obtained by the following method: firstly, measuring by using a reflector with specific reflectivity at different distances to obtain data of echo intensities and distances at different distances, then carrying out curve fitting by using mathematical software to obtain a calculation formula of the echo intensities at different reflectivities, then carrying out verification by using the reflector with the target reflectivity, revising and the like to finally obtain an accurate reflectivity calculation formula.
The technical principles of the present application have been described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the present application and is not to be construed in any way as limiting the scope of the application. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present application without inventive effort, which shall fall within the scope of the present application.
Claims (6)
1. A pulse width detection circuit is characterized by comprising an in-phase comparator, an inverse phase comparator and a TDC timer, wherein the in-phase comparator and the inverse phase comparator are connected with the TDC timer,
the in-phase comparator and the reverse-phase comparator compare the pulse signal with the threshold value and output a signal according to a comparison result;
the TDC timer is used for recording the time when the in-phase comparator and the reverse-phase comparator output signals, and obtaining the time interval between the two signals, namely the pulse width.
2. The circuit of claim 1, wherein the in-phase comparator and the inverse comparator are configured to compare the pulse signal with a threshold, and based on the comparison result, the in-phase comparator outputs a signal at a rising edge of the pulse signal and the inverse comparator outputs a signal at a falling edge of the pulse signal.
3. A lidar ranging circuit comprising the pulse width detection circuit of claim 1 or 2, further comprising a control unit, a transmitting unit, and a receiving unit, wherein the control unit is connected to the transmitting unit and the pulse width detection circuit, respectively, and the receiving unit is connected to the pulse width detection circuit, wherein:
the transmitting unit is used for transmitting laser pulses;
the receiving unit is used for receiving the reflected laser pulse, converting the reflected laser pulse into a pulse signal and sending the pulse signal to the pulse width detection circuit and the control unit;
the peak value detection circuit is used for obtaining the pulse width according to the pulse signal and the threshold value;
the control unit is used for controlling the transmitting unit and the peak value detection circuit, calculating the distance according to the pulse signal transmitted by the receiving unit and correcting the distance by combining the pulse width.
4. The lidar ranging circuit of claim 3, wherein the receiving unit comprises an avalanche diode and a transimpedance amplifier, the avalanche diode being configured to receive the laser pulse and convert it into a current signal, the transimpedance amplifier being configured to amplify the current signal and convert it into a pulse signal.
5. The lidar ranging circuit of claim 4, wherein the receiving unit further comprises a secondary amplifier, and the secondary amplifier is respectively connected to the transimpedance amplifier and the pulse width detection circuit, and is configured to further amplify the pulse signal.
6. The lidar ranging circuit according to claim 5, wherein the control unit is a microprocessor or a single chip microcomputer, and the transmitting unit is a semiconductor laser or a solid laser.
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| CN201921331177.4U CN211698204U (en) | 2019-08-16 | 2019-08-16 | Pulse width detection circuit and laser radar ranging circuit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112444819A (en) * | 2019-08-16 | 2021-03-05 | 北醒（北京）光子科技有限公司 | Pulse width detection circuit, distance measurement circuit, detection method and distance measurement method |
| CN114740274A (en) * | 2022-04-02 | 2022-07-12 | 南通探维光电科技有限公司 | Pulse width measuring method, device and system for laser ranging signal |
| CN115184907A (en) * | 2022-09-08 | 2022-10-14 | 北醒（北京）光子科技有限公司 | Balance detection circuit and laser ranging system |
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2019
- 2019-08-16 CN CN201921331177.4U patent/CN211698204U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112444819A (en) * | 2019-08-16 | 2021-03-05 | 北醒（北京）光子科技有限公司 | Pulse width detection circuit, distance measurement circuit, detection method and distance measurement method |
| CN114740274A (en) * | 2022-04-02 | 2022-07-12 | 南通探维光电科技有限公司 | Pulse width measuring method, device and system for laser ranging signal |
| CN115184907A (en) * | 2022-09-08 | 2022-10-14 | 北醒（北京）光子科技有限公司 | Balance detection circuit and laser ranging system |
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