SU1425446A1 - Light range finder - Google Patents

Abstract

The invention relates to the field of geodetic instrumentation and allows extending the distance measurement range towards small distances by light-rangefinders with frequency-tunable modulation oscillators by artificially increasing the constant device by introducing a time delay in the form of a connected signal the first mixer 21, the tunable filter 23 of the first intermediate frequency, the second mixer 24 and the tunable filter 25 of the second prom the daily frequency, as well as the auxiliary generator 22, the direct and inverse outputs of which are respectively connected to the second inputs of the first and second mixers 21 and 24, the frequency of the second filter 25 being set equal to the frequency of the input signal applied to the input of the time delay circuit 11. The delay time of the signal is determined by the time interval of the half-period of the frequency of the auxiliary generator 22. In addition, a saw-generator (a shaped voltage, a trigger and two elements I.) is added to the light-distance meter circuit. 1 Cp f-crystals, 2 ill. &Amp;&; (L

Description

IND

ate

four

about:

FIG. 2

114

The invention relates to the field of geodetic instrumentation, in particular, to light-range-distance meters with planned frequency-tunable modulation towers.

The purpose of the invention is to expand the range of measurements.

FIG. 1 is a block diagram of a distance meter; in fig. 2 - the same, time delay circuits,

The range finder contains a button 1 Reference, control circuit 2, sawtooth generator 3, variable frequency generator 4, modulator 5, radiator 6, lens of a transmitting optical system, objective 8 of a receiving optical system,; photodetector 9, amplifier 10, time delay circuit 11, phase detectors; torus 12, scheme 13 null-organ, trig: ger 14, element I 15, arithmetic; device 16, element 17, generator-18 clock pulses, digital display 19, power supply unit 20. Besides that; Go, time delay circuit 11: keeps first frequency mixer 21,: auxiliary generator 22, first tunable; first pp filter 23; intermediate frequency, the second mixer; 24 frequencies, the second tunable; The filter 25 is the second intermediate frequency, I t, tunable to the frequency of the input signal.

I One of the contacts of the button 1 is connected to the case of the device, the other is fed I to the control input of the control-2 circuit; laziness, the output of which is fed to the permitting inputs of the generator 3 sawtooth image

voltage and generator 4 trans

frequency tuning. The output of the sawtooth voltage generator 3 is applied to the controlled inputs of the tunable frequency generator 4 and the time delay circuit 11. generator 4 through modulator 5 is fed to radiator 6. The light beam generated by radiator 6 is collimated by lens 7 and directed to the measured distance. The reflected (measuring) light signal is focused by the object 8 of the receiving optical system on the photodetector 9, which through amplifier 10 is fed to the information input of the time delay circuit 11.

the output of which is fed to the first input of the phase detector 12, the second input of which is connected to the code of the tunable frequency generator 4, and the output

Q

5 0 5 About

five

0

five

0

five

through the circuit 13 the zero-organ is connected to the counting input of the trigger 14, the forward output of the trigger 14 is connected to the first input of the element 15, and the inverse to the first input of the element 17, and the second inputs of the specified elements 15 and 17 are combined and connected to the output generator 4 tunable frequency. The output of the element And 15 is connected with the summation of the 1 input of the arithmetic unit 16, and the output of the element And 17 with the output of its input. The third input of the arithmetic unit 16 is connected to the generator output 18 clock pulses, and the output of the arithmetic unit 16 is fed to a digital display 19. The elements of the light-measuring circuit are fed from the power supply unit 20 (the output outputs of the power supply unit 20 are not shown in the circuit elements).

The input signal (from the output of the photodetector 9, fed through the amplifier 10) is fed to the first input of the frequency mixer 21, the second input of which is connected to the direct output of the auxiliary generator 22, and the output through the first intermediate frequency filter 23 that connects to the first input of the second mixer 24 frequencies. The second input of the second mixer 24 frequency is connected to the inverse {LM output of the generator 22, and the output through the second tunable filter 25, tuned to the frequency of the input signal, is fed to the output of the time delay circuit 11.

The arithmetic unit 16 is generally a frequency meter with a memory, a subtractor, and a conventional circuit for converting the difference values into a code of the indicators of the digital display. The arithmetic unit 16 also subtracts from the obtained frequency difference the digital value of the time delay value of the circuit 11 inserted in the device memory.

The range finder works as follows.

When button 1 is pressed, the output to the output of the control circuit 2 to the generator 3 input of the sawtooth voltage and to the corresponding generator 4 input of the tunable frequency receives an enable signal from which the generator 3 output to the controlled generator 4 input (for example,

3

cap connected: oscillator circuit 4) receives sawtooth voltage signals, as a result generator 4 begins to generate signals varying in frequency; From generator 4 output signals through modulator 5 are sent to radiator 6, which generates a light beam modulated by amplitude indicated by the frequency of the generator 4. The light beam from the radiator 6 is collimated by the lens 7 and directed to the measured distance. The reflected signal (measuring) is collected by the lens 8 and focused on the photosensitive area of the photodetector 9. Transformed into electrical, these signals are transmitted through the amplifier 10 to the input of the time delay circuit 11, in which the phases of the measuring (coming from the distance) signals are delayed by a predetermined time interval imitating the time of passage of a certain distance by a light beam. This is done in order to reduce the value of if the required frequency tuning of oscillator 4, which is especially important when the distances are small.

To measure a distance of 5m, it is necessary to have an LU equal to C

.

14

where C is the speed of light, m / s;

L is the measured distance, m. In the distance meter, the introduction of a time delay into the channel of the measuring signal of the circuit 11 is equivalent to the introduction of a constant Lp in the light distance meter. In this case, bf of the measured distance, for example, equal to 5 m, is determined by the formula

2 (Lo + L) Pick-up values of L, and consequently, if, it is possible to have discreteness values about and others, for example, 1 Hz / cm, 2 Hz / cm, etc.

The description of the operation of the circuit 11 temporary delay below.

The signals from the output of the time delay circuit 11 are fed to the first input of the phase detector 12, the second input of which is fed to the signals from the output of oscillator 4. At the time when the phases of the signals from oscillator 4 (reference signal) g and from the time delay circuit 11 are shifted

15

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a phase of 90 °, a zero potential appears at the output of phase detector 12. At the same time, at the output of the circuit 13 of the zero-organ connected to the output of the phase detector 12, a pulse appears, which arrives at the counting input of the trigger 14 and overturns it.

Up to this point, signals from the output of the generator 4 through the first input of the element 15 (opened at the second input by the resolving potential from the direct output of the trigger 14 set to the initial state) are fed to the sum input of the arithmetic unit 16, and the measured frequency of the generator 4 in the moment of arrival of the pulse from the circuit 13 is memorized in it. In the initial state of the circuit, the element And 17 is closed at the second input by the inhibitory potential from the inverse output of the trigger 14.

When the flip-flop 14 is tilted, the element 15 is closed at the second input, and the element 17 opens and the signals from the generator 4 begin to flow to the subtractive input of the arithmetic device 16. The frequency of the generator 4 continues to change in the same direction. At the moment of time when the phases of the signals from generator 4 (reference) and measured from circuit 11

20

25

thirty

th

35

40

45

the time delays again have a phase shift of 90, and a zero potential is again set at the output of the phase detector 12. At the same time, at the output of the circuit 13, the zero-body receives a second impulse, which, arriving at the counting input of the trigger 14, returns it to the initial state. This signal from the output of the 13-organ circuit 13, applied to the second input of the control circuit 2, removes the permit signal from the output of the latter, fed to the corresponding inputs of the sawtooth generator 3 and the tunable clock generator TOTl.

The frequency difference, measured in the arithmetic unit 16 by means of clock pulses from the generator 18, is converted into indications of the measured distance, for which the frequency of the clock pulses of the generator 1855 is set to a multiple of the speed of light. In addition, in the arithmetic unit 16, a subtraction is made from the value L,

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The differential frequency of the reference and measurable signals, the constant LO device, preset in the memory of the arithmetic device 16, The final result of the calculations in the arithmetic device 16 is converted into a digital display indicator code; 19 connected to the output of the specified I I arithmetic device T6

The power of the range finder circuit is supplied from power supply unit 20 (power supply circuits are not shown).

Scheme 11 time delay (Fig. 2) works as follows.

To the input of the circuit 11, which is the first input of the first mixer 21,; nocTyna; jT measuring signals from the photodetector 9 through the amplifier 10; (Fig. 1). Signals from the direct I output of the auxiliary generator-22 I are fed to the second input of the mixer 21 (Fig. 2). The signal arriving at the first input of the first mixer 21

and, V, is sin (u, t + q),),

where cp is the phase shift of the signal, containing (its information about the time; which is spent by the light beam on the passage of the measured distance back and forth. The signal arriving at the second input

the first mixer 21 with a direct generator 22

Ua v sino, j, c.

 At the output of the filter 23 of the first intermediate frequency included at the output of the first mixer 21 and tuned by HorOj, for example, a signal is output to the difference frequency

o, oi, v, v, cos (u, -co,) t4- (,.

This signal is fed to the first input of the second mixer 24, to the second input of which a signal is fed from the inverted output of the generator 22

. sin (oD, t + q ,, g),

where cf o is the phase shift of the voltage of the generator 22, which forms a time delay in the output signal of the mixer 24.

The output of the filter 25 of the second intermediate frequency included at the output of the second mixer 25 and tuned in this case to the total

the frequency, and in fact, the frequency of the input signal of the circuit 1 1 is temporary; delay, the signal is released

2g

, v a, Vf Vj sin | (Cx), - Qj + 02) +

) ajV, (co, t + q, + Cf ,,

bblXj

(tf, + Cf2

(80

Those. the voltages at the output of the time delay circuit 11 (output of the filter 25) and at the input of the time delay circuit 11 are equal in frequency and differ in

8o

those..

the phase shift by the value of (j the output signal over time has a delay determined by the frequency of the auxiliary generator 22, i.e.

t -1- 2.f,

where f is the frequency of the auxiliary generator 22.

Claims (2)

1. A light range finder that contains a tunable oscillator, a modulator, an emitter, an output optical unit, an optical input unit, a photoreceiver, an amplifier, a phase detector and a zero organ, a control unit and a calculator unit connected to the output of the clock generator and with an input of a display unit of information, characterized in that, in order to expand the range, it is provided with a sawtooth generator, a time delay unit and a trigger connected to the outputs respectively with the first inputs ction of the first and second AND gates, whose second inputs coupled to the output of the tunable oscillator, and outputs - respectively with the summing and subtracting inputs of the calculating unit, the output of the control unit is connected to the corresponding inputs give the tunable generator directly and through the sawtooth generator, the output of which is connected to the corresponding input of the time delay unit, through which the amplifier is connected to the phase detector, the corresponding input of which is connected to the output of the adjustable oscillator, and the zero-output output is connected to the inputs trigger and control unit. 2. A light range finder according to claim 1, characterized in that the block 7l423 +46 the time delay is made in the form of a filter and an additional generator, serially connected first mixer and tunable filter, second mixer and tunable the direct and inverse outputs of which are connected to the corresponding inputs of the first and second mixers, nineteen filter and additional generator the direct and inverse outputs of which are connected to the corresponding inputs of the first and second mixers, R J figure 1