SU907816A1 - Device for searching noise-like signals - Google Patents

Description

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The invention relates to communication technology and can be used in radio systems.

A device for searching noise-like signals is known. It contains two keys combined on an input, three circuits, each of which consists of a consistently connected matched filter, a detector and a threshold block, as well as serially connected logic block, a signal copy generator, a correlator and a threshold block, the output of which connected to the first input of the logic unit, the second and third outputs of which are connected to the control inputs of the first and second keys, while the output of the first key is connected to the inputs matched filter, and the second switch output is connected to the second input of the correlator 1.

However, the known device has a large search time when the power level of the interference at the input of the receiving device changes.

 The purpose of the invention is to reduce the average search time for a noise-like signal with variations in the power level of the interference.

The goal is achieved by the fact that a device for searching for noise-like signals containing two keys combined at the input, three circuits, each of which consists of a consistently connected matched filter, a detector and a threshold unit, as well as serially connected logic block, a copy generator

15 signal, correlator and threshold unit, the output of which is connected to the first input of the logic unit, the second and third outputs of which are connected to the control inputs of the first and second keys, while the output of the first key is connected to the inputs of matched filters, and the output of the second club is connected to the second input of the correlator, a master element, two delay blocks, a coincidence block, and a series-connected account are introduced. the number, voltage, voltage converter, comparison unit and threshold voltage generator, the output of which is connected to the control inputs of the threshold blocks of each circuit, the output of the threshold block of the first circuit connected to the counter input and the first input of the coincidence block, to the second and the third inputs of which through the delay blocks are connected to the outputs of the threshold blocks of the second and third circuits, and the output of the matching block is connected to the second input of the logic block, while the output of the master element is connected to the second input of the comparison block. The drawing shows a structural electrical circuit of the device. The device contains the first key 1, the second key 2, matched filters 3-5 detectors 6-8, threshold blocks 9-11, blocks 12 and 13 delays, block 14 matches, logic block 15, correlator 16, generator 17 copies of the signal, threshold block 18, counter 19, register 20, transducer 21 number — voltage, comparison block 22, driver 23 voltage threshold generator 2. The device works as follows. At the beginning of the search, the first key 1 is open, and the second key 2 is closed. The input signal, mixed with interference, arrives at matched filters 3-5, the voltages from which after detection are received, at threshold blocks 9-11, where at intervals of time equal to the duration of the signal element T5 are compared with the threshold voltage. The search for a signal in the first stage is considered complete if the threshold at the output of all three filters is exceeded at the moment they are filled with the corresponding segments of the signal. In delay block 12, the signal for exceeding the threshold is delayed by a time equal to the interval between the first and third segments, and in block 13 the delay is delayed by a time equal to the interval between the second and third segments of the input signal. As a result, the threshold exceeding signals to the block of coincidence arrive simultaneously. The logic unit 15 closes the first key 1 according to the signal of the coincidence unit 14, opens the second key 2 and turns on the generator 17 of the signal copies. The signal and interference through the second key 2 are fed to the correlator) 16, which also receives copies of the signal from the generator 17 copies of the signal. After accumulating the signal for a time equal to the duration of the signal Tg, the output voltage of the correlator 1b is compared in threshold block 18 with the threshold voltage Uj. the result of the comparison in the logic device makes a decision either to resume the search mode (if the threshold is not exceeded), for which the keys 1 and 2 and the generator 17 of the signal copies from the signals from the logic unit 15 are returned to the initial state, or the end of the search. The minimum average search time in a wide range of interference power variation is provided by stabilizing the relative threshold where D (v) is the interference dispersion at the output of the matched filter. For this, the number of false thresholds exceeded for time T is counted by counter 19, rewritten into register 20, the number is converted and the voltage is converted by voltage and converter 21 and compared in block 22 comparison with voltage UQ of master element 23. Voltage of master element 23 UQ proportional to the optimal number of thresholds exceeding, which is a constant value for a given circuit. The result of comparing the di and - Uj-j voltages in the comparison block 22 affects the voltage generator 2k, a threshold voltage that changes the voltage of the threshold Uy, so that with a positive di voltage, Uj increases and decreases with a negative uU. The number of thresholds exceeding P tends to the optimum value of uU tends to zero, the value of the relative threshold P tends to the optimal value of DQ T Thus, the proposed device allows reducing the average search time of the PSS by 2-2.5 times while changing the interference power at the device input twice.

Claims (1)

1. Noise-like signals to the information transmission system. Ed. V.B. Pestre koaa. M., Soviet Radio, 1973, p. 170-172, fig. 5.5.1 (prototype)