SU822063A1 - Digital delay meter - Google Patents

Description

(54) DIGITAL DELAY METER

1- The invention relates to radio measurements, in particular to devices for measuring the time delay between two narrowband signals, and can be used in radar and sonar, as well as in tractor measurement techniques. A device for measuring the delay time between two signals is known, comprising a multi-tap delay element, M multipliers connected by the first inputs to the M branches of the delay element, the second outputs of all M multipliers are combined, M integrators whose inputs are connected to the outputs of the multipliers, as well as a detection unit The inputs of which are connected to the corresponding outputs of the integrators, the signals under study are fed to the input of the multi-tap element of the delay and to the combined M inputs of the multipliers. In each of its channels, the specified device forms discrete correlation integral samples calculated for a set of fixed delay values (discrete step, determined by the time interval between adjacent latency delays). The detection unit, by comparing the samples of the correlation integral, finds the largest of them and thus forms at its output a rough estimate of the delay. The advantage of this device is the possibility of parallel viewing of the entire a priori range of possible delay values, which provides for obtaining real-time estimates of l. .. Disadvantages delay meter -. large instrumental volume; the accuracy of the measurements is low, since the delay is estimated up to discrete (the time distance between the taps of the delay line). The closest technical solution to the invention is a digital delay meter containing a series-connected trigger, a first key, a counter, an indicating device, and a synchronizer, the first synchronizer output connected to the second control input of the first key, the second synchronizer output connected to the control the input of the display device, which are set, the trigger inputs are connected to the outputs of the drivers, the inputs of which are the signal inputs of the delay measurement device. Merits

The devices are a small hardware volume; high speed and high residual with significant signal over interference, measurement accuracy 2.

The disadvantage of this meter is a drastic deterioration in measurement accuracy and the delay estimation at low signal-to-noise ratios, when there are naturally abnormal errors in recording zero (intersections) of the transition times of the voltage fronts of limited signals through a zero voltage level.

The purpose of the invention is to improve the noise immunity of the digital delay meter.

The goal is achieved by the fact that the device containing the sequentially connected trigger, the first key and the counter, as well as the synchronizer and the indicating device and the OR element, the first input of the synchronizer is connected to the control input of the first key, the setup inputs of the trigger are connected to the outputs of the drivers which are connected to the signal buses, introduced two identical chains of serially connected first permanent storage devices (ROM), accumulating adders and second keys, and also tr key, divider and second ROM, with the inputs of both chains combined and connected to the information output of the counter via a third key, the outputs of the chains connected via a serially connected divider and the second ROM are connected to the display device, and the outputs of the third key are connected to the counter input The second output of the synchronizer is connected to the combined control inputs. the second keys, the control input of the third key is connected to the inverse output of the trigger, and the setup inputs of the accumulating adders are connected to the third output of the synchronizer.

The drawing shows a block diagram of a digital delay meter.

Digital delay meter contains shaper 1, trigger 2, first key 3, counter 4, synchronizer 5,. First ROM b, accumulating adders 7, second keys 8, third key 9, divider 10, second ROM 11, display 12, element OR 13, while the setup inputs of the trigger 2 are connected to the outputs of the drivers, inputs 14 and 15 are the signal inputs of the digital delay meter, the first output of the synchronizer 5 is connected to the control input of the first α-key 3, the outputs of the first ROM B through accumulating adders 7 and the second keys 8 connections with the divider Yu, the output of which through the second ROM 11 is connected to the display device 12, the outputs, the third key 9 through the element OR il3 is connected to the installation input of the counter 4, the second input of the synchronizer 5 is connected to the combined control inputs of the second keys 8, the control input the third key 9 is connected to the inverted output of the trigger 2, and the installation input of accumulating adders 7 is connected to the third output of the synchronizer 5.

The device works as follows.

The signals, the mutual delay between which must be measured, are given at input 14 and 15 of the formers 1. Rectangular fronts (:: formed from input signals, flip over trigger 2. At the forward output of trigger 2, pulses of positive polarity are formed, the duration of which is the time distance between-adjacent (subsequent) zero-intersections of two narrow-band signal seals. These pulses, arriving at the input of the first key 3, allow the passage of high-frequency filling pulses generated by synchronization Oromo 5 in the counter 4. Thus the measurement is the duration of a positive pulse at the output of the forward latch 2.

At the moment of flip-flop of trigger 2, the third key 9 is opened with a control signal from the inverse output of flip-flop 2, and the number recorded in counter 4 is fed to the combined address buses of the first ROM b. At the same time, it is set to the zero state of the counter 4 under the influence of a positive pulse from the output of the element OR 13, whose inputs are combined with the inputs of the first ROM 6. The numbers read from the outputs of the first ROM 6 enter the accumulating adders 7, where they are added with the contents of the adders. During . the observation interval in adders 7 accumulates statistics sufficient to unambiguously measure the delay time between narrow-band signals.

After the observation interval ends, the control inputs of the second keys 8 are given a signal from the synchronizer 5, as a result of which the numbers accumulated in the adders 7 are fed to the inputs of the divider 10. The result of the division, affecting the address buses of the second ROM 11, causes a sample of the number from its corresponding lines. This number, which is the result of the measurement, is fed to the display device 12.

The measurement of the delay between the nearest null intersections is organized with the help of the formers 1 and the sequentially connected trigger 2,

the first key 3 and Counter 4, while the control input of counter 4 is fed with high-frequency pulses from synchronizer 5. In order to improve speed, the proposed device implements a tabular method for calculating trigonometric functions: the corresponding line of one of the first ROMs is selected from the measured delay value in which the values of trigonometric functions calculated for a set of specific delay values on one frequency period are pre-recorded. Statistics are accumulated using accumulative adders 7, Statistics are divided using second keys, 8 and divider 10. The result of dividing a multi-digit binary number is fed to the address buses of the second ROM 11, in which the measurement results corresponding to a set of specific values of re. the result of the division.

The proposed digital delay meter can be used to measure the mutual delays between high-frequency narrow-band random processes, whose carrier frequency is about an order of magnitude lower than the clock frequency of the digital element base used.

Claims (2)

1. Sirobub I I. et al. Fundamentals of the theory of radio engineering measurements of motion parameters Publishing house MO USSR 5 1971, .С.198. . . 2.Smirnov P. T., Digital phase meters, L., Energie, 1974, p.33.