RU2304286C2 - Adaptive digital recirculating device - Google Patents

Abstract

FIELD: radio engineering, possible use for accumulating signals in concealed radiolocation complexes with impulse-Doppler radiolocation stations used as supporting stations, under conditions of unknown or changing repeat period of probing signals.

SUBSTANCE: known recirculating device contains serially connected adder, device for forming check connection signals, random-access memory. In accordance to invention, following devices are introduced: repeat period meter, decoder, a set of keys, number of which depends on changing range of repeat period and number of shift registers of random-access memory. The output of the repeat period meter is connected to decoder, from where information is sent to controlling inputs of keys, at information inputs of which signals from shift registers of random-access memory are received. Outputs of keys, depending on signal from decoder, are connected to second input of arithmetic device adder.

EFFECT: introduction of new elements and connections into suggested device allows expanded functional capabilities of digital recirculating device, providing for its adaptation to change of repeat period of probing signals of opponent's radiolocation stations.

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Description

This invention relates to the field of radio engineering and is intended for the accumulation of signals in covert radar complexes with pulse-Doppler radars as reference, in the conditions of an unknown or changing repetition period of probing signals.

From [2], p. 451, a recirculator is known for accumulating radar signals. It contains an adder, a delay line for the repetition period, a feedback line with an adjustable gain. The accumulation of pulses in the recirculator is ensured by summing the incoming next pulse of the packet with the sum of the pulses received at the previous stages of the device and returned to the input via the feedback circuit. To prevent self-excitation, the feedback coefficient β is chosen less than unity.

The disadvantage of this device is the inability to accumulate signals with an unknown repetition period.

Of the known recirculators, the digital recirculator described in [1], p.336 is the closest to the claimed one in terms of technical nature. It consists of an adder, a feedback signal conditioning device and RAM, which is a digital memory described in [1], p. 333, Fig. 5.44.

In this recirculator, the input signal comes from the device combining the quadrature system of the SDC to the adder of the arithmetic device of the recirculator. From here, through the feedback signal conditioning device, it is fed to RAM and to the output of the recirculator. After the repetition period of the radar, information from the RAM output goes to the second input of the adder.

The recirculator operates as follows. The drive does not have such high requirements for bit capacity as in the SDS system. Therefore, to reduce the amount of memory before entering the recirculator by combining the lower digits, rounding, for example, of a 7-bit binary word to 5-bit occurs [1], p. 337, Fig. 5.49.

This word is fed to the first input of the adder of the arithmetic device of the recirculator, and then to the feedback signal generating device, which is an 8-bit parallel type adder with serial transfer of one. The input 5-bit information is supplied in direct code to the inputs of the 4th, 5th, 6th, 7th, 8th digits, and in the inverse code to the inputs of the 1st to 5th digits. 0 is supplied to the free inputs of the 1st-3rd digits, and 1 is fed to the free inputs of the 6th-8th digits. As a result, the feedback coefficient β changes from 0.875 (for maximum) to 1 (for minimum signals). After rounding to 5 digits, the word is written into RAM and simultaneously goes to the output of the device. After a period of repeating radar information from the output of RAM is fed to the second input of the adder arithmetic device. The performance of the recirculator elements (totalizer and RAM) is provided by clock pulses.

When changing the repetition period, it is necessary to change the number of RAM registers that perform the function of a delay line. In secretive radar complexes, the signals of enemy radar transmitters are used as probing. Since in this case the repetition period and the law of its change are unknown, the recirculator is inoperative.

Thus, the disadvantage of this recirculator is that it is not able to ensure the accumulation of signals with an unknown or changing repetition period.

Useful signals arriving at the inputs of the receivers of the covert radar system are signals reflected from air targets illuminated by the reference radars of the airborne early warning systems and direct signals from the reference radar. The main DRLO aviation complex is the pulse-Doppler mode of operation, in which the repetition frequency is tuned from pack to pack and the repetition period remains constant within the pack of pulses.

The aim of the invention is the adaptation of the digital recirculator to change the repetition period of the probing signals by measuring it.

This goal is achieved by the fact that in the known device containing the adder of an arithmetic device, a device for generating a feedback signal, RAM, are introduced: a meter of the repetition period, a decoder and a set of keys. The number of elements in the key set depends on the sampling interval and the range of variation of the repetition period of the probing signals.

Figure 1 shows a diagram of an adaptive digital recirculator; figure 2 is a variant of the meter of the repetition period.

The adaptive digital recirculator contains an adder 1 of an arithmetic device, a feedback signal generating device 2, a repetition period meter 3, a decoder 4, a set of keys 5, RAM 6.

The repetition period meter 3 contains: a clock pulse generator 7, an amplitude detector 8, a threshold device 9, differentiating circuits 10 and 15, a T-trigger 11, a key 12, a pulse counter 13, a register 14, diodes 16 and 17.

The adaptive digital recirculator elements are connected as follows: the output of the adder 1 of the arithmetic device is connected to the input of the feedback signal generating device 2. The output of the feedback signal generating device 2 is connected to the RAM input 6 and at the same time is the output of the device. The output of RAM 6 is connected to the information inputs of the key set 5. The output of the meter of the repetition period 3 is connected to the input of the decoder 4, the output of which is connected to the control inputs of the key set 5. The outputs of the key set 5 are connected to the second input of the adder 1 of the arithmetic device. The first input of the adder 1 is the input of the recirculator.

The elements of the meter of the repetition period 3 are connected as follows: the input of the device is the input of the amplitude detector 8, the output of which is connected to the input of the threshold device 9, the output of which is connected to the input of the differentiating circuit 10. The output of the differentiating circuit 10 is connected to the input of the T-trigger 11, the direct output of which connected to the input of the differentiating circuit 15 and the control input of the key 12. The output of the key 12 is connected to the input of the pulse counter 13, the output of which is connected to the input of the register 14. The output of the differentiating circuit 15 is connected to diode strokes. The output of the diode 16 is connected to the zeroing input of the pulse counter, and the output of the diode 17 is connected to the control input of the register. The output of the clock generator 7 is connected to the input of the key 12.

Adaptive digital recirculator operates as follows. From the output of the device combining the quadrature channels, after rounding the lower digits, the 5-bit word is fed to the first input of the adder 1 of the arithmetic device of the recirculator. From here, through the feedback signal generating device 2, the description and operation principle of which is given in [1], p. 337, information is fed to the output of the device and to the shift registers of RAM 6. The direct signal of the reference radar goes to the meter of the repetition period 3. Measured code the repetition period is maintained at the output of the meter of the repetition period 3 and at the input of the decoder 4 during the repetition period. The decoder 4 controls the set of keys 5 in such a way as to connect to the second input of the adder 1 of the arithmetic device that shift register of RAM 6, which corresponds to the measured repetition period.

The meter repetition period 3 works as follows. A direct signal of the reference radar is fed to the amplitude detector 8 and then to the threshold device 9, which limits the noise in the channel. The differentiating circuit 10 selects the leading edge of the output pulses of the threshold device 9 and provides switching of the T-trigger 11. The signal from the direct output of the T-trigger 11 is fed to the control input of the key 12 and allows the passage of pulses from the clock generator 7 to the pulse counter 13, while T- trigger 11 is in a single state, i.e. during the repetition period. In addition, from the direct output of the T-flip-flop 11, the signal is fed to the input of the differentiating circuit 15, from the output of which the signal of positive polarity through the diode 16 is fed to the zeroing input of the pulse counter 13, and the signal of negative polarity through the diode 17 at the end of the repetition period is fed to the register 14 and serves to record the readings of the pulse counter 13, i.e. code of the measured repetition period. The output of register 14 is the output of the repetition period meter 3.

Thus, the introduction of new elements and new connections in the proposed device allows you to expand the functionality of a digital recirculator, providing its adaptation to changing the repetition period of the probe signals of the enemy radar.

INFORMATION SOURCES

1. M.I. Finkelstein. Basics of radar. - Radio and communications, 1983.

2. Theoretical foundations of radar. Edited by Y.D.Shirman. - M .: Soviet Radio, 1970.

Claims (1)

A digital recirculator containing a series-connected adder, the first input of which is a recirculator input, a feedback signal generating device, RAM, characterized in that a repetition period meter is inserted into it, the input of which receives a direct signal of the reference radar, a decoder and a set of keys, and the output the repetition period meter is connected to the input of the decoder, the output of which is connected to the control inputs of the keys, to the information inputs of which the outputs of the corresponding shift registers are connected RAM, and the key outputs are connected to the second input of the adder.

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