RU1840981C - Pulse range meter - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: device comprises series-connected count pulse generator (1), time selector (2) and counter (3). The device also includes a write flip-flop (11), a register (4) and series-connected additional counter (6), decoder (7) and inhibit flip-flop (8). One of the inputs of the inhibit flip-flop (8) is connected to one of the inputs of a receive flip-flop (5). The other input, as well as the output of the receive flip-flop (5) are respectively connected to inputs of a NOR element (10), the time selector (2) and the counter (3). The output of the counter (3) is connected to one of the inputs of the register (4), the other input of which is connected to the output of the write flip-flop (11). The inputs of the write flip-flop (11) are respectively connected to the outputs of AND and NOR elements (9, 10). The inputs of the AND element (9) are connected to the outputs of the count pulse generator (1) and the inhibit flip-flop (8). The inputs of the additional counter (6) are respectively connected to the outputs of the count pulse generator (1) and the write flip-flop (11).

EFFECT: high measurement accuracy.

1 dwg

Description

The invention relates to the field of radio engineering and measuring equipment and can be used in systems of radio reconnaissance (RTR) and passive target designation (PTC) using the long-range tropospheric propagation of ultrashort radio waves (DTR VHF) to measure the duration of signals received by radar stations. Known devices for measuring the duration of pulse signals (USSR AS No. 424088, MKI G01r 29/02, publ. 1972; USSR AS No. 318013, MKI G01r 29/02, publ. 1974), which can be used in RTR and PTsU systems in the conditions of reception of signals in direct visibility (within the radio horizon).

According to the principle of operation, these meters can be conditionally divided into two types. The first type includes devices containing a counting pulse generator, a time selector, a pulse counter, an indicating device (AS USSR No. 424088, MKI G01r 29/02, published in 1972) and working on the principle of counting the number of pulses of a counting pulse generator during the duration of the measured pulse.

The second type includes devices containing a delay line with taps, comparators and an indicator (AS USSR No. 318013, MKI G01r 29/02, published in 1974). In such devices, the pulse duration is determined by the triggered comparators, which are uniquely associated with the numbers of the taps of the delay line.

The measurement accuracy of such devices is determined mainly either by the frequency of the counting pulses, or by the intervals of the measuring delay line.

Such devices measure the duration of single radar pulses whose shape is close to rectangular and not distorted (there are no dips at the top of the pulse).

However, these devices will give significant measurement errors in RTR systems using the VHF DTR phenomenon, because under these conditions, due to the multipath propagation, the radar signals at the input of the receiver of the RTR system and the PCC are distorted. These distortions are expressed in dips in the envelope of the video signal, which leads to a fragmentation of the received pulse into several separate pulses, the duration of which is much less than the signal duration of the reconnaissance radar.

Therefore, the errors in measuring the pulse duration by such devices are significant and can be up to 50% of the measured value.

The closest technical solution to the proposed device is a time interval meter using the discrete counting method used in the measurement mode of the rectangular pulse duration (G.Ya. Mirsky. Radio-electronic measurements. M., "Energy", 1975, pp. 176-177) comprising a counting pulse generator, a time selector, a counter. The output of the counter pulse generator is connected to the first input of the temporary selector, the output of which is connected to the counter input of the counter; the measured pulse is fed to the second input of the temporary selector.

The disadvantage of this device is the inability to measure the true duration of the radar pulse in the presence of dips in it, because the counter will consistently record the duration codes of individual pulses, separated by the time intervals of the dips in the envelope of the received signal. Therefore, when measuring the pulse duration of a reconnaissance radar by the indicated devices, an error will inevitably occur due to the presence of dips in the envelope of the signal that has passed the VHF DTR channel, leading to an unacceptable decrease in the measurement accuracy for solving the following tasks: separation of signals and recognition of the radar type.

The aim of the present invention is to improve the accuracy of measuring the duration of radar signals in RTR systems and PCUs operating in DTR VHF conditions. This goal is achieved by the fact that in the well-known meter containing a counting pulse generator, a time selector and a pulse counter (first counter), a reception trigger, a second counter, a decoder, a prohibition trigger, an AND circuit, an OR-NOT circuit, a trigger are introduced records and register, and the first input of the receive trigger is connected to the second input of the inhibit trigger, the first input of which is connected to the output of the decoder, and the output is connected to the second input of the "And" circuit, the first inputs of the "And" circuit and the temporary selector are connected to the counting input of the second counter Ika, the output of which is connected to the decoder; the second inputs of the OR-NOT circuit and the receive trigger are interconnected; the second input of the temporary selector, the first input of the "OR-NOT" circuit, the input of setting the first counter to "0" is connected to the output of the receive trigger, the output of the first counter is connected to the register, and the outputs of the "AND" and "OR-NOT" circuit are connected respectively to the first and second inputs of the recording trigger, the output of which is connected to the installation input at “0” of the second counter and the register write input.

The introduction of these elements allows you to analyze the duration of the failure and if its duration exceeds a predetermined value; the duration of the measured pulse is counted from the leading edge to the beginning of the dip; otherwise, if the duration of the dip is less than the specified value, the duration of the measured pulse is counted from the leading edge to the end of the pulse, including the duration of the dip.

The drawing shows a functional diagram of the described device, where 1 is a counting pulse generator, 2 is a time selector, 3 is a first counter, 4 is a register, 5 is a receive trigger, 6 is a second counter, 7 is a decoder, 8 is a ban trigger, 9 is "I" circuit, 10 - "OR NOT" circuit, 11 - recording trigger.

The device operates as follows: the initial setup pulse is supplied to the first input of the receive trigger 5 and the second input of the inhibit trigger 8, setting them in such a way that the potential at the output of the receive trigger 5 closes the time selector 2, resets the first counter 3 and through the OR-NOT circuit "10 sets the recording trigger 11 to its initial state, and the potential at the output of the inhibit trigger 8 opens the" And "9 circuit through which the counting pulses from the counting pulse generator 1 arrive at the counting (first) input of the recording trigger 11.

The potential at the output of the recording trigger 11, held at the installation input 2 by the potential from the output of the receiving trigger 5, resets the second counter 6.

After the initial setup pulse ends, with a delay, a measured pulse arrives at the second (counting) input of receive trigger 5, which transfers the receive trigger 5 with its leading edge. The polarity of the signal at the output of receive trigger 5 changes to the opposite, so the time selector opens and the first counter starts counting incoming counting pulses.

The measured pulse has the same polarity as the potential at the output of the receive trigger 5 after the initial installation, and since these signals are combined in the OR-NOT circuit 10, the state of the recording trigger 11 until the end of the measured pulse or the appearance of a dip in it does not change .

As trigger of reception 5, trigger of record 11, trigger of prohibition 8, “D” trigger (series 133) is applied, at the information inputs of which constant potentials are set. The initial setting pulse to the ban trigger 8 and the receive trigger 5 is supplied through the installation inputs, and the output of the circuit "OR NOT 10" is also connected to the installation input of the recording trigger 11.

After the trailing edge appears in the measured pulse, the potential at the output of the OR-NOT circuit 10 changes its polarity and does not hold the recording trigger 11 in the previous state, therefore, when the counting pulse arrives through the AND circuit 9, along its leading edge, the recording trigger 11 will change its state, and the front that arose at the output of the recording trigger 11 enters the counting inputs of the triggers forming register 4, and the code of the number located at that moment in the first counter 3 is recorded in the last one.

This code corresponds to the duration of the measured pulse (with an accuracy of one discrete) from its leading edge to the incoming trailing edge.

The potential of the changed polarity at the output of the recording trigger 11 does not reset the second counter 6. The second counter 6 starts counting the pulses and the code combinations taken from its outputs go to the input of the decoder 7. In the event that the incoming trailing edge of the measured pulse was a result of a failure in it and the duration of this dip is less than the maximum permissible value, that is, the number calculated in the second counter 6 does not reach the value of the corresponding maximum set duration of the dip and the code at the output of the second counter 6 will not be equal to the code on which the decoder 7 is configured, the potential at the decoder output will not change, the ban trigger 8 will also retain its previous state.

After the failure at the output of the OR-NOT circuit 10, a potential is established that returns the recording trigger 11 to its initial state corresponding to the state to which it is set by the initial setting pulse, as a result of which the second counter 6 is reset and stops counting.

During the failure, the receive trigger 5 does not change its state, that is, the time selector 2 is open and the first counter 3 continues to count.

At the end of the measured pulse in the above sequence, the recording trigger 11 is triggered and a new number corresponding to the pulse duration is written to the register 4 from the first counter 3, the second counter 6 starts to count simultaneously. When the code at the output of the second counter 6 becomes equal to the code to which the decoder is configured 7, an impulse appears at the output of the decoder 7, along the leading edge of which the inhibit trigger 8 changes its state and the inhibitory potential arrives at the "And" 9 circuit, as a result of which the counting pulses cease to blunt to the count (first) input of flip-flop 11 and re-record entry in the measurement cycle would be impossible.

To ensure the correct recording of the number from the first counter 3 in the register 4, the states of the first counter 3 change on the trailing edge of the counting pulses, and the number is written in the register 4 on the leading edge of the counting pulses.

To ensure the correct operation of the meter, it is necessary that the capacity of the first counter 3 provides a record of a number known to be larger than the number corresponding to the maximum duration of the measured pulse taking into account the dips, and the excess of the capacity of the counter over the maximum duration of the measured pulse should be greater than the number corresponding to the maximum duration of the failure.

The proposed device for measuring the pulse duration in RTR and PCC systems using the reception of radar signals that have passed the DTR VHF channel allows, by eliminating dips in the envelope of the radar signal, to improve the accuracy of measuring the pulse duration. Improving the accuracy of measuring the pulse duration makes it possible to reduce the likelihood of separation errors of the radar signals and to exclude fragmentation of the target according to the specified parameter, when the carrier frequency of the reconnaissance radar is changed.

Claims (1)

The pulse duration meter containing a series-connected counting pulse generator, a time selector and a counter, characterized in that, in order to increase the measurement accuracy, it is equipped with a recording trigger, a register and series-connected additional counter, decoder and trigger, prohibition, the other input of which is connected to one of the inputs of the reception trigger, the other input of which, as well as its output, are connected to the inputs of the element "OR-NOT", a temporary selector and counter, the output of which is connected with one of the inputs of the register, the other input of which is connected to the output of the recording trigger, the inputs of which are connected to the outputs of the elements "AND" and "OR NOT", respectively, while the inputs of the element "And" are connected to the outputs of the counting pulse generator and the inhibit trigger, and the inputs of the additional counter are connected to the outputs of the counter pulse generator and recording trigger, respectively.