SU1601772A1 - Device for searching for frequency-manipulated signal - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to reduce the search time. A device for searching a frequency-manipulated signal contains threshold blocks 1 and 6, a logic driver 2 control signals, a synthesizer 3 frequencies, a mixer 4, a correlator 5, r-r 7 pseudo-random sequence, a detector 8, a key 9, filters 10 and 13 low-pass, time-scale converter 11, multiplier 12, Fourier processor 14 and delay block 15. The device operates in two stages. At the first stage of the search (search-free detection), a coarse adjustment of the frequency of the synthesizer 3 is performed. In this case, the signal delay is determined with a given accuracy, and the frequency is determined at a specified interval. However, frequency uncertainty remains. 1 hp f-ly, 2 ill.

Description

Fiel

The invention relates to radio engineering can be used in radio receiving devices of the information systems of frequency-manipulated signals with a continuous phase (minimum

 The core of the invention is to reduce

pemeni search.

Fig 1 shows the structural

Electrical circuit of a signal with a frequency shift keying; on bar 2 - a structural electrical circuit of a generator; pseudo-random sequence. A device for searching a signal with frequency shift keying contains the first threshold block 1, a logical Shaper 2 control signals, a 3-frequency synthesizer, a mixer 4, a correlator torus 5, second threshold block 6, pseudo-random sequence generator 7, detector 8. key 9 first low pass filter (low pass filter) - time-scale converter

(IMP) 11, multiplier 12, second low-pass filter Is Fourier processor (PT) And, block 15

 Tenera Ator 7 contains the first key 16, the first switch 17, the counter 18, the shift feedback switchboard 19, the Hnvertor 20, the first trigger 21, the second switch 22, the switch 23, the waiting odnibrator 24 the second trigger 25, the second key 26, the block 27 of the elements And and the decryption device for searching for a signal with frequency manipulation works as follows

 switching on the power sets the initial state: the key V for the KpbiT generator 7 is in the state of the last (L-ro) element of the pseudo-random sequence, the profit center is prepared to record the signal count. Logic shaper 2 gives out on its fourth output at the output of the pool for pidi with frequency and

signal frequency. From the right output, read pulses are received with a frequency, Lf3 (aS + l), where S is the number of elements of the detected signal segment. The input oscillation in mixer 4 is transferred to the range of video frequencies, filtered in the first low-pass filter 10 and fed to the input of the profit center and. In the latter, under the action of recording pulses, the signal is sampled and discrete-analog samples are recorded. At the same time, at each write cycle, there is an acceleration, reading of all the samples recorded in the profit center P. Since the number of read pulses in one write cycle is one more than the number of cells (aS), at each subsequent write cycle, the reading begins with (i + l ) - cells, if the previous one started with (-Y. Along with a cyclically follower. 10 It;

20 ",

- to and

th in e - m This unit's (through ST) update of the contents of each cell of this type of work creates the same effect as “advancing the signal along the delayed line”. filter, and the presence of a correlation response Ja at the time (on the read cycle) when all S elements of the segment are completely written to the profit center 11. Synchronously with reading under the action of the pulses of the first clock output of the logical generator 10, the generator 7 outputs from first to S elements of the demodulating sequence I on the same accelerated time scale. In the multiplier 12, a phase demodulation of the signal and It occurs; Further, after the smoothing second low-pass filter 1.5, the whole sequence of single-frequency coherent pulses arrive at the FP 14, which reproduces the spectrum of the input bursts.

After detection, these responses are received in block 15, at the output of which a cumulative response and two single signals occur. In accordance with the frequency of the signal uncertainty frequency, logic driver 2 from its control output, and generates a strobe pulse that opens the time of its operation is 9, as a result of which the first threshold unit 1 is connected to the output of unit 15. In the case of the triggering of threshold unit 1, the pulse from its output goes to the logic driver 2 and generator 7

In the logic driver 2, the time interval between the e fronts of the strobe pulse and the output pulse of the threshold block 1 is measured. In accordance with this, or is formed; the control voltage, which, when applied to the input of the synthesizer 3, makes a rough (with an accuracy of 1 / 5G) adjustment of its frequency. After that, the first stage of the search (searchless detection) is considered complete. In this case, the signal delay of 40 oplelen with an accuracy of ± Г / 2, and the frequency in the Interval is 1/57, i.e., t remains, point frequency uncertainty, rd

 t / nGop the throne is eliminated at the 45th stage.

According to the output impulse of the threshold block 1, the generator 7 continues to generate the sequence I with the unit element, but already in real time.

without time (under the action of the recording pulse). The signal after the mixer 4 is fed to the input of the correlator 5, where its phase demodulation and accumulation occur over the duration LT. Countdown Determined by the impulse from the controller

the output of generator 7 to the Control input of the logic driver 2. According to the J0 pulse, the logic driver 2 changes the control voltage at its output so that the frequency of the synthesizer 3 is changed to 1 / L7.

If the frequency of the synthesizer 3 matches the frequency of the signal, the response at the output of the correlator 5 exceeds the threshold of the block b, and the signal from its output acting on the logic driver 2 changes the frequency of the synthesizer 3 to stop. The search is considered complete. In the event of an unsatisfactory outcome (failure to exceed the threshold in block b after all the t / cells have been checked), the descriptor in the logic driver 2 is triggered, the device returns to the first stage.

Claims (2)

Invention Formula . A device for searching a frequency-manipulated signal, comprising a serially connected first threshold unit, a logic driver of control signals, a frequency synthesizer and a mixer, a serially connected correlator and a second threshold unit, a key, a detector and a pseudo-random sequence generator (GPS), the output of the second threshold the block is connected to the signal input of the logic driver of the control signals, the control output of which is connected to the key input of the same name, the output of the first threshold the unit is connected to the control input of the CAP, the first and second clock inputs of which are connected respectively to the first and second clock outputs of the logic driver of control signals, the signal output of the CAP is connected to the reference input of the correlator, and the input of the mixer is the input of the device to search for a signal with frequency manipulation, characterized in that, in order to reduce the search time, a delay block and series-connected are introduced into it — the first low-pass filter (LPF), the scale-time transform l, a multiplier, a second low-pass filter and a Fourier processor, whose output is connected through the detector to the input of delay unit, whose output is connected to the signal hodu key, whose output is the key to input the first threshold unit, a control input of a logic control signal shaper is connected to the iClCl output of the same name, the signal input of which is connected to the second one: the multiplier input, the first and the second sockets of the time-scale. SU body are connected respectively to the first clock inputs of the GPS and Fourier processor and the output of the logic driver of the control signals, and to the second clock input of the CAP and the output of the logic driver of the control signals, the signal input of the correlator is connected to the input of the first LPF and the output of the mixer. 2. A device according to claim 1, characterized in that the GPRS comprises a first key connected in series, a first switch, a counter, a feedback shift register, an inverter, a first Tpiirrep and a second switch, a series connected decryptor, a switch waiting for one the new vibrator, the second key and the second trigger, as well as the block of elements AND whose output is connected to the control inputs of the switch and the first switch, the first and second inputs of the block of elements AND are connected respectively to the first control input of the second key, which is axes control input CST, n to the first and second control inputs of the first -; 0, the second key, the output of the second key is connected to the setup inputs of the feedback shift register, the first trigger and the second switch, are signal; | the input of which is connected to the signal output of the shift register with feedback and 5 through a second trigger with a control input, the output of the second switch is the identical output of the CST, n inputs of the decoder are connected to the corresponding n outputs of the shift register with feedback; -. when etsm clock The inputs of the first switch and the first key are, respectively, the first and second clock inputs of the CAP, whose control output is the output of a standby one-shot clock. five Fie.2