SU977956A2 - Device for measuring distances - Google Patents

Description

(54) DEVICE FOR MEASURING DISTANCES

one

The imaging is fire related to geodesic tools for measuring the measurements that are used, for example, in surveying, in surveying and building a large engineering structures.

On the main Aug, sv. N 87O919 is a known distance measuring device comprising a scale frequency generator, an electronic key, an emitter, a measuring channel switch to the reference channel, a photovoltage digital phase meter, in which the counting pulse generator is connected via a pin to a trigger connected to the matching schematics. The coincident inputs are connected to the amplifier-generator and the control generator to the pulse widths, the additional output of which is connected to the control input of the electronic key 1.

This device allows you to measure distance with high accuracy only to a special reflector, for example, in the form of a thrashing prism. To measure the distance to a diffuse surface without a significant decrease in accuracy, a sharp increase in the power of the emitted pulses is required, however, a significant increase in the duration of the pulses of modulated light sent to the distance. However, in the case of short light emulsions, it is impossible to measure the phases in the known device, since in this case only a part of the pfioda etog oscillations will be fed to the output of the single-channel pyphonic phase meter.

15

The purpose of the invention is to provide a measure of the distance to diffuse-protecting surfaces.

The goal is achieved by the fact that between the photodetector and the amplifier 20 by the former of the python phase meter, an annular phase-locked loop with an adjustable oscillator is included, the phase detector of which is. 367 is connected with a receiver unit, and the phase tracking unit at the degenecor output is connected to a generator of control pulses, and the mixer, whose inputs are connected to the local oscillator and tunable generator, and the output to the amplifier driver. This inclusion allows you to receive at the input of the digital phase meter continuous low-frequency bands independently of or the duration of the light pulses. FIG. I shows the block diagram of the proposed device; Fig. 2 shows the egpors of stresses explaining the operation of the circuit. The device contains a generator of I May staff frequencies, an electronic switch 2, from an emitter 3, a reflector 4, a splitter 5, a photoreceiver 6, a switch 7 of the measuring and control channels, a heterodyne 8, a phase memory device 9 containing a phase detector 10, an adjustable oscillator 11 , a follower unit 12, a low-pass filter 13 and a control element 14, a mixer 15, as well as a digital phase meter 16 containing an amplifier driver 17, a matching circuit 18 and 19, a control pulse generator 2O, a trigger 21, a key 22, a generator 23 counting pulses, counter 24 pulses and digital indicator 25. The scale frequency generator, the high-frequency oscillation fj, which is fed to the key switch 2, the electronic key is unlocked to the pulses and, with a repetition frequency, coming from the generator 20, which is located in the phase meter 16, U2 pulses with a filling frequency dd are fed to a 3 kg emitter that modulate its radiation. The duration of the pulses is many times less than the switching period I / Q. The modulated light pulses arrive at the splitter 5 and through it onto the reflecting surface 4, to which it is necessary to measure the distance. The reflected signal is directed to the photodetector 6 through the optical switch 7. A control signal from the splitter 5 is fed to the photodetector via the same switch. Thus, the measuring uj and the control signal (Jn signals) are passed to the photodetector alternately with a low frequency of $ 2/2. for triggering the optical switch, it is carried out from a generator of control pulses 20, C from the local oscillator 8 is fed to the photodetector 6 at a friction 64 of the first heterodyne frequency f. As a result of the conversion at the output of the photothermics pulses U and and with an intermediate filling frequency if |.-f carrying the measuring and monitoring phases of the scale oscillation are made. These radio pulses from the output of the photoreceiver arrive at the input of the device 9 for storing the phase, which instead of short radio pulses are output at the continuous packets The beginning of the second packet is set by the radio pulse UJf, the phase of the intermediate frequency oscillations in the packets remains the same as in the corresponding radio pulses. The phase memory is an annular phase locked loop and operates as follows. Two signals arrive at phase detector H: one continuous from adjustable oscillator II, the other in the form of radio pulses from photodetector 6, IF these two signals are close in frequency, the circuit operates in a beat mode, In this case, beating signals sent to control element 14, oscillates oscillator 11 in frequency. If the oscillator frequency is sufficiently close to the intermediate frequency lf th due to an increase in the amplitude of the beats, it may turn out to be L, At this point, the frequency of the tunable oscillator 11 h This mode goes into synchronization mode. In this mode, an error signal is selected, the amplitude and intensity of which depends on the phase difference of the signals supplied to the phase detector 10, by adjusting the frequency of the adjustable oscillator 11, the moment when the error signal is zero, which corresponds to the initial phase difference of 9 °. The error signal at the output of the detector U will have the form of rectangular impulses, the duration of which is equal to the duration of the radio pulses. In FIG. 2, the pulses (Jc correspond to phase differences, zero to zero, the pulses Uj correspond to phase differences of 18 °). In order to ensure continuous tracking of the phase of the input signal, a tracking block 12 is installed in front of the low-pass filter 13. The output of this block there is already a constant control voltage, the magnitude of which with B1 1 is equal to the amplitude of the pulse ui1byu1. In Fig. 2, the voltage is shown by the dotted line connecting the tops of the pulses U Ur. After filtering the filter 13, the controlled voltage under It is connected to the control element 14, which adjusts the generator II. The ring circuit, in addition to the functions of the phase memory device, plays the role of a selective filter, freeing the input signal from interference.

Voltage packets with a frequency of filling f and phases of the measuring and control signals from the output of a tunable generator, 11 are fed to the input of the mixer 15, to the second input of which the heterodyne frequency f 2 is fed from the output of the local oscillator. A second scaling frequency conversion is necessary to obtain U-packets with a low filling frequency, at which a high-frequency measurement of the phase difference is made with a digital phase meter. In connection with the different optical path lengths of the measuring control signal, the packets U J and U are phase-shifted for the moments of zero crossing of the instantaneous values of the compared oscillations by the value

where UX is the target phase difference, m is an integer number of phase cycles.

Signal packets arrive at the digital phase meter 16, at the input of which there is an amplifier driver 17.

Further measurement of the phase difference and display of measurement results in

discrete digital form occurs in a known manner.

The proposed device makes it possible to measure distances without special reflectors, for example, when shooting rifled and peeling plants with sufficient accuracy. In the case of using reflectors more powerful but short pulses, it becomes possible to significantly expand the range of the device.

Claims (1)

Invention Formula Device for measuring the distance by ed. St. No. 87О919, which is different from the fact that, in order to ensure the measurement of distances to diffusely disturbing surfaces, between the photoreceiver and the amplifier-driver of the digital phase meter, an annular phase-locked loop with a tunable generator is connected, the phase detector of which is connected to the photodetector, and the phase tracking unit at the detector output is connected to the control pulse generator, and the mixer, whose input is connected to the local oscillator and tunable generator, and the output to the amplifier driver. Sources of JI | jurmatia taken into account during aspergosis I, USSR Copyright Certificate No. 87O919, cl. Gi O1 C 3 / O8, t98O. but, P / / ABOUT, P y /