SU845139A1 - Meter of measuring time intervals at radiolocation of objects - Google Patents

Description

(54) METHOD OF MEASURING INTERVALS OF TIME DURING RADARING OF OBJECTS

I

The invention relates to radio measurements and can be used in radar to study moving objects, such as meteors, which are irradiated by radar pulses.

An oscillographic method for measuring time intervals is known, in which the measured interval is limited by the start and end pulses 1.

However, recording the measurement results on the oscilloscope screen does not allow automating the process of determining the duration of time intervals.

Closest to the proposed electron-counting method, based on the sequential counting of clock pulses from a reference oscillator in an interval bounded by pulses at the beginning and end of the count, formed at certain signal levels 2.

The disadvantage of this method is that the measurement of the time interval to the pulse of the end of the count, formed when the signal drops to a certain level, can lead to errors in determining the duration of the reflected signal. This is explained by the fact that the signal declines to the level

The formation of a stop pulse can be caused not only by the end of the signal, but also by interference or interference phenomena observed when the signals are reflected, after which the signal level will increase. In these cases, the registration stops until the end of the reflected signal, and the measured duration of the time interval will not correspond to the true time of the existence of the reflected signal.

The aim of the invention is to increase

10 accuracy and noise immunity measurements.

The goal is achieved by measuring time intervals in a manner based on a sequential counting of clock pulses in an interval limited to 15 pulses of the beginning and end of measurements, the pulse of the start of measurements is formed upon receipt of two initial neighboring reflected pulses, at each drop in the measured signal to a predetermined level „N generate a delay signal during which time interval measurement is continued; the pulse of the end of measurements is formed at the end of the delay signal, provided that during this time

impulses are reflected from the object. The true value of the measured interval is defined as the difference between the interval bounded by the start and end pulses of the measurements and the duration of the delay signal.

FIG. 1 shows a device that implements this method; in fig. 2 - time diagrams that show his work.

The device consists of a counter 1 and a reversible counter 2, the inputs of which are combined and connected to the clock pulse generator 3. The inputs “Start of the counter 1

and "Restoring the reversible counter 2 is connected to one output of the forming unit 4.

FIG. 2 marked:

2a - time-varying reflected signal ;;

26 is a diagram explaining the generation of a delay signal after each fall of the reflected signal;

2 in -, a diagram explaining the formation of the measurement of the 1 interval.

The method is based on the fact that the measurement of the time interval is also carried out after the signal reaches a predetermined level, i.e. after the arrival of the reflected pulses for a predetermined delay time. Thus, if the signal decay was caused, for example, by interference, then the counting during the operation of the interference (for the delay time) does not stop. Therefore, the interference does not affect the measurement accuracy.

If, however, no reflected pulses are received during the delay time, the counting pulse is generated, and the time interval measurement is stopped. This condition is necessary to ensure termination of the counting of the lisch after the end of the existence of the reflected signal.

Formation of the pulse of the start of counting from two initially arriving neighboring pulses also increases the noise immunity of the measurements.

The magnitude of the delay is determined by the technical data of the radars and the physical characteristics of the object. For example, for a meteoric, medium-power radar, the delay time is 0.75-1.25 s.

The device works as follows.

Reflected radio pulses arrive at the input of the formation unit in which a counting pulse is formed along the two adjacent initially received pulses, which starts counter 1 and returns reversing counter 2 to its initial state. Counter 1 starts counting the clock pulses from generator 3.

As soon as the reflected pulses cease to enter the input of the forming unit 4, a pulse is formed in it. This pulse is applied to the "Start Counter 2,

and he starts counting clock pulses. Upon reaching the delay time, which corresponds to a certain number of clock pulses that are installed on the counter 2 in advance, an end of count pulse is generated, which is fed to the input "Stop5 of the counter 1.

In the case of the arrival of reflected pulses before the end of the delay time in block 4, a pulse is formed, which restores the initial state of counter 2. At

About this counter 1 continues to count clock pulses.

Since the counter 1 counts the clock pulses and during the delay time, a relative number of pulses corresponding to the delay time is preset on it. Consequently, the counter shows the true value of the time interval during which the reflected signal exists.

The introduction of a reversible counter with presetting ensures that the counting continues for a delay time and the counting stops only after the arrival of reflected signals.

The initial state of counter 1 is restored at the end of the registration of the measured time interval, and counter 2 at the end of the delay time, and the device is ready for further measurements.

0 The application of this method improves the accuracy and noise immunity of measurements of time intervals, as it eliminates the influence of interference, provides reliable recording of results in the presence of interference phenomena observed in the reflection of radio signals.

The method and device for its realization can be used to measure the duration of any other ELES whose amplitude is subject to fluctuations, for example in seismology, to record the duration and intensity of seismic waves.

Claims (2)

1. Avttsrskoe certificate of the USSR No. 524162, cl. G 04 F 10/04, 1972. 2.Valitov R.A., Sretensky V.I. Radio Measurement Measurements, “Owls. radio, M., 1970, p. 586-588 (prototype). Star / 77 / Table 8o {: emffffff e // y Cf ffjff / 77o F1 / year / F1 / 3.