CN107678010A - The multistage high pass of pulse lidar holds resistance moment discrimination circuit - Google Patents

Abstract

The invention discloses a multi-order high-pass capacitive-resistance moment discrimination circuit of a pulse laser radar. Including high-pass filter circuit, high-speed sampling circuit, high-speed comparison circuit, gate circuit and controller, in the high-pass filter circuit, the input pulse signal is converted into a bipolar signal and output; the high-speed sampling circuit samples and filters the output signal and transmits it to the controller; the gate Circuit 1 is connected in reverse parallel with the high-pass filter circuit, and gate circuit 2 is connected in series with the output terminal of the high-pass filter circuit and the non-inverting input terminal of the high-speed comparator; the controller analyzes the filtered output data and controls the strobe status of gate circuit 1 and gate circuit 2; The reverse input terminal of the comparator is connected to zero level, the transition of the high-speed comparator occurs when the two input signals are equal, and the output signal of the high-speed comparator is the identified laser echo time. The invention can effectively compress the timing drift error caused by the rising edge of the echo signal and noise interference, and improve the precision of time identification.

Description

Multi-order high-pass capacitance-resistance moment discrimination circuit for pulsed lidar

technical field

The invention relates to the field of laser radar, in particular to a high-precision time discrimination circuit, which is applied to the field of laser measurement.

technical background

With the development of laser radar technology, the accuracy of laser measurement is getting higher and higher, among which pulse laser ranging develops rapidly and has a wide range of applications. Pulsed laser measurement uses a laser to emit laser light, which is reflected by the target object and received by the receiving end. The receiving system measures the round-trip time of the laser light and calculates the distance between the laser radar and the target. As an active detection sensor, lidar has the advantages of simple structure, high precision, and strong anti-interference performance. It has been widely used in military, industrial manufacturing, and social life.

The moment discrimination circuit is to determine the moment when the echo signal arrives at the lidar receiver. The traditional time identification methods include leading edge time identification, constant ratio timing identification, and high-pass capacitive resistance time identification; the accuracy of frontier time identification is affected by the threshold, and a high or low threshold will cause missed detection and false alarms; constant ratio timing identification requires Wide echo signal, when the pulse width of the echo signal is very small, the performance requirements of the measurement electronic device are high; the high-pass capacitive resistance moment identification converts the unipolar signal into a bipolar signal, and the timing point is determined by comparing the zero point. The peak point of the signal, but the time drift is large. In order to simultaneously solve the timing drift error caused by the time variation of the rising edge of the echo signal and the amplitude, it is necessary to improve the above-mentioned time discrimination circuit.

Contents of the invention

The purpose of the present invention is to provide a multi-order high-pass capacitance-resistance time discrimination circuit for pulse laser radar, which can effectively avoid timing drift errors caused by the time variation and amplitude of the rising edge of the echo signal, compress timing errors, and reduce missed detection and false alarms. The alarm probability is improved, and the accuracy of time identification is improved, so as to further effectively improve the accuracy of pulsed laser measurement.

For realizing the purpose of the present invention, adopt following technical scheme to realize: a kind of multi-order high-pass capacitive-resistance moment discrimination circuit of pulse laser radar, comprise high-pass filtering circuit, high-speed sampling circuit, high-speed comparing circuit, gate circuit and controller; In the circuit, the input pulse signal is converted into a bipolar signal and output; the high-speed sampling circuit samples the filtered output signal; the gate circuit one is connected in reverse parallel with the high-pass filter circuit, and the gate circuit two is connected in series at the output end of the high-pass filter circuit and the high-speed comparator Non-inverting input terminal; the controller analyzes the filtered output data and controls the strobe status of gate circuit one and gate circuit two; the reverse input terminal of the high-speed comparator is connected to zero level, and the transition of the high-speed comparator occurs when the two input signals are equal time, the output signal of the high-speed comparator is the identified laser echo time.

The beneficial effects of the present invention are: a multi-order high-pass capacitive-resistance time discrimination circuit of a pulse laser radar is adopted, including a high-pass filter circuit, a high-speed sampling circuit, a high-speed comparison circuit, a combination of a gate circuit and a controller, and the high-pass filter circuit is aimed at echo The differential operation of the signal slope characteristics reduces the probability of missed detection and false alarm; the controller analyzes the filtered output data, controls the order of the filtering operation, and improves the timing accuracy; on the one hand, the high-pass filter circuit avoids the laser echo pulse amplitude change caused Missed detection and false alarm, so that the time identification operation is not affected by the change of the echo amplitude; on the other hand, the controller is combined with the high-speed sampling circuit, which can effectively obtain the pulse width, rising edge time and other data of the high-pass filter output signal, Controlling the number of filters by setting parameters can avoid time identification errors caused by too many high-pass filter operations; the invention is suitable for detection of high-energy narrow pulses and large distance ranges, and can overcome timing errors caused by waveform changes and noise interference .

Description of drawings

Fig. 1 is a schematic diagram of the present invention.

FIG. 2 is a diagram of the relationship between the input and output signals identified by the multi-order high-pass capacitive resistance of the present invention at any time.

detailed description

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

Example:

Combined with Figure 1, a multi-order high-pass capacitive-resistance time discrimination circuit for pulse laser radar includes a high-pass filter circuit, a high-speed sampling circuit, a high-speed comparison circuit, a gate circuit and a controller. In the high-pass filter circuit, the input pulse signal is converted into a bipolar and output the signal; the high-speed sampling circuit samples and filters the output signal and transmits it to the controller through the bus; the gate circuit one is connected in reverse parallel with the high-pass filter circuit, and the gate circuit two is connected in series at the output terminal of the high-pass filter circuit and the non-inverting input terminal of the high-speed comparator; control The filter analyzes the output data of the filter and controls the gating status of the gate circuit 1 and the gate circuit 2; the reverse input terminal of the high-speed comparator is connected to zero level, and the transition of the high-speed comparator occurs when the two input signals are equal, and the high-speed comparator The output signal of is the identified laser echo time.

Combined with Figure 1, the high-pass filter circuit includes a capacitor C1 and a resistor R1, the first end of the capacitor C1 is used as a signal input, the second end of the capacitor C1 is connected to the first end of the resistor R1; the input end of the gate circuit 1 is connected to the resistor R1 The second terminal is connected, the output terminal of the gate circuit 1 is connected with the first terminal of the capacitor C1, the control terminal of the gate circuit 1 is connected with the controller, the input terminal of the gate circuit 2 is connected with the second terminal of the resistor R1, and the gate circuit 2 The output terminal is connected to the same direction input terminal of the high-speed comparator, the control terminal of gate circuit 2 is connected to the controller; the reverse input terminal of the high-speed comparator is connected to zero level; the same direction bias of the high-speed sampling circuit is connected to 10V DC power supply , the reverse bias voltage is connected to zero level, the clock source is connected to +5V/100Hz~2GHz clock signal, the signal sampling input terminal is connected to the second terminal of resistor R1, the sampling output terminal is connected to the data receiving terminal of the controller, and the high-speed sampling circuit is enabled terminal is connected to the first terminal of resistor R2; the power supply terminal of the controller is connected to +5V TTL level, the ground terminal is grounded, and the control output terminal is respectively connected to the second terminal of resistor R2, the control terminal of gate circuit one and the control terminal of gate circuit two connected.

Combined with Figure 1, the initial state of gate circuit 1 and gate circuit 2 is cut-off, the high-pass filter circuit performs high-pass filtering on the input signal, the output signal is sampled by a high-speed sampler, and the controller converts the pulse width and amplitude of the filtered output signal contained in the sampled data Value, rising edge time and other characteristic data are compared with the preset threshold value. When the threshold value is met, the controller controls the gate circuit one to be turned on and the gate circuit two to be cut off. When the threshold is not met, the controller controls gate one to be cut off, gate two to be turned on, and the filtered output signal enters the high-speed comparator for comparison with zero level, and outputs a timing point signal.

Combined with Figure 2, determine the limit threshold of the high-pass filter order, set the first peak point of the echo as the timing point, the minimum rising edge time is T _min , the minimum signal amplitude is V _min , and the final high-pass filter times satisfy And T _n <T _min , where k is the number of filters, λ is the attenuation coefficient of the high-pass filter circuit, V is the amplitude of the echo signal, and T _n is the rising edge time of the last filtered output signal. Assuming that the amplitude of the echo signal is 5V, the minimum signal amplitude is 500μV, and the attenuation coefficient of the high-pass filter circuit is 0.97, then the maximum number of filtering times is 3. The circuit parameters determined at this time are: the resistance R1 is 1 ohm, the resistance R2 is 2 ohms, and the capacitor C1 is 1 picofarad.

Combined with Figure 2, according to theoretical analysis and experimental verification, the input and output waveforms of the multi-order high-pass capacitance-resistance moment discrimination circuit are shown in Figure 2, in which V _i (t) is the input signal waveform, and V ₁ (t) is the first-order High-pass filter output signal, V ₂ (t) is the second-order high-pass filter output signal, V ₃ (t) is the final high-pass filter output signal, V ₃ (t) is output by a high-speed comparator to identify the trigger pulse signal V _o (t) .

Claims (3)

1. a kind of multistage high pass of pulse lidar holds resistance moment discrimination circuit, including high-pass filtering circuit, high-speed sampling electricity Road, high speed comparison circuit, gate circuit and controller, it is characterised in that in the high-pass filtering circuit, the conversion of input pulse signal Into bipolar signal and export；High speed sampling circuit samples to filtered output signals；Gate circuit one and high-pass filtering circuit are reverse Parallel connection, gate circuit two are connected on the in-phase input end of high-pass filtering circuit output end and high-speed comparator；Controller analysis filtering Output data and the strobe state for controlling gate circuit one and gate circuit two；The reverse input end connecting to neutral level of high-speed comparator is high The transition of fast comparator betide two input signals it is equal at the time of, the output signal of high-speed comparator is the laser that is identified The echo moment.

2. the multistage high pass of pulse lidar according to claim 1 holds resistance moment discrimination circuit, it is characterised in that institute Stating high-pass filtering circuit includes electric capacity C1 and resistance R1, the input of electric capacity C1 first end as signal, electric capacity C1 the second end It is connected with resistance R1 first end；The input of gate circuit one is connected with resistance R1 the second end, the output end of gate circuit one with Electric capacity C1 first end is connected, and the control terminal of gate circuit one is connected with controller, and the of the input of gate circuit two and resistance R1 Two ends are connected, and the output end of gate circuit two is connected with the input in the same direction of high-speed comparator, the control terminal of gate circuit two and control Device is connected；The reverse input end of high-speed comparator is connected with zero level；The bias in the same direction of high speed sampling circuit connects 10V direct currents Source, reverse biased connecting to neutral level, clock source connect+5V/100Hz ~ 2GHz clock signals, signal sampling input connection resistance R1's Second end, sampled output are connected with controller data receiving terminal, and the data bit width of high speed sampling circuit is 8 ~ 64, is adopted at a high speed Sample circuit Enable Pin is connected with resistance R2 first end；Controller power source termination+5V Transistor-Transistor Logic levels, earth terminal ground connection, control are defeated Go out to hold the control terminal at the second end with resistance R2, the control terminal of gate circuit one and gate circuit two to be respectively connected.

3. the multistage high pass of pulse lidar according to claim 2 holds resistance moment discrimination circuit, it is characterised in that institute Gate circuit one and the initial state of gate circuit two is stated to be sampled by high-speed sampler for cut-off, high-pass filtering output signal, and by total Line is transmitted to controller, and controller obtains filtered output signals correlated characteristic data, and the threshold with pre-setting according to sampled data Value is made comparisons, and the strobe state of gate circuit one and gate circuit two is controlled with this.