SU1406814A1 - Device for receiving frequency-manipulated signals - Google Patents

Abstract

The invention relates to the field of telecommunications. The purpose of the invention is to increase the noise immunity to impulse noise. The device contains an input matching unit 1, a threshold unit 2, a software detector 3 signals and a digital filter 4. A shaper 5, an interference suppression unit 6 and a clock generator 7 are entered into the device. The device suppresses both impulse noise acting in the absence of a frequency signal and impulse noise received together with the frequency signal and applied to it, and the detection time is set taking into account the intensity of the impulse noise, i.e. the decision is made on the basis of the set number of analysis samples. 1 hp f-ly 2 ill. s (c

Description

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The invention relates to telecommunications and can be used in receiving devices of systems using frequency shift keying.

The purpose of the invention is to increase noise immunity to impulse noise.

Fig. 1 shows a structural electrical circuit of a device for receiving frequency-manipulated signals; Fig. 2 is a structural electrical circuit of a software signal detector.

The device for receiving frequency-modulated signals contains an input matching unit 1, a threshold unit 2, a software detector 3 signals and a digital filter 4j, as well as a code generator 5, an interference suppression unit 6, and a clock generator 7.

The software detector of the 3 signals is made in the form of n detection channels 8-i, each of which is inclusive. reads shaper 9 pulses, delay element 10, element NOT 11, ele, ment OR 12, counter 13, or block 14, first 15 and second 16 trigger, and element 17.

The device receiving the frequency-manipula of the signaling works as follows.

Before starting work (after turning on the power supply), the device input is given a start-up impulse, the duration of which exceeds the transient time in the device blocks. In this case, the circuit is brought to its initial state, in which a low potential is constantly present at the output of the threshold unit 2. The output of the interference suppression unit 6 and the outputs of the digital filter 4 in the initial state also have a low potential. The generator 7 clock pulses generates a sequence of clock pulses. The binary number K, the Impulse acting at the device installation input; is set to the zero initial state of the first 15 and second 16 triggers and the counter 13 in each of the 8-i detection channels on the start. At the end of the installation pulse, a high potential is present at the outputs of the driver of the nine pulses.

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the outputs of the delay element 10, the element 17, the element OR 12 and the comparison unit 14 are low potential.

If there are only impulse noises at the information inputs of the device, they through the input matching unit 1 arrive at the threshold b: lok 2. Under the influence of impulse noise of sufficient amplitude, the threshold unit 2 is generated. The interference sequence formed by the threshold unit 2 enters the block 6, where the pulse duration is selected. At the output of the interference suppression unit 6, a low potential is constantly present at this time, and the device retains its original state.

When an additive mixture of a signal with a detection frequency and impulse noise arrives, threshold block 2 is triggered when the frequency threshold is exceeded or by an interference pulse imposed on the frequency signal, and when the frequency threshold is exceeded, the pulse generated at the output of threshold 2 corresponds approximately to the half-period of the signal frequency, and when the triggering threshold is exceeded by a pulse interfering on the frequency signal, the pulse duration at the output of the threshold block ka 2 corresponds to the duration of the psmehi. Thus, a sequence of short pulses arrives at the input of the interference suppression unit 6; Due to noise and wide pulses from the frequency signal, in block 6 pulses are selected for the duration at which short pulses of interference are suppressed, j and wide pulses from the frequency signal are gated approximately in the middle of the clock pulses of the generator 7 clock pulses 5 so that the output An interference suppression unit 6 generates a received signal sequence that is free from impulse noise 5, and the duration of the clock pulses is much less than the period T of the received frequency signal la: t.J-y "T.

In digital filter 4, the duration of the interval T between the incoming pulses is monitored, and in fact the period Tj since T T ttu T, Since the period T is equal to

the detection period T, or the detection period T for which digital filter 4 is set, then digital filter 4 transmits pulses from the detection periods to the corresponding outputs and then to the input of the software detector 3 signals.

Software detector 3 signals works as follows.

When the first pulse arrives at the input of the program detector of 3 signals, it passes to the information input of the corresponding channel

detection, e.g. channel 8-1. With 15 pry trigger 16, the output of which

This switches the first trigger 15 to a single state, at which a high potential is established at its output, allowing the counter 13 and the second trigger 16 to operate. A high potential from the trigger output 15 goes through the OR element 12 channel 8-2 to the trigger input 15 and prohibits switching it

the front of the detection pulse is formed, arriving at the corresponding

device output. The detection pulse acts for the time of the received signal with the detection frequency.

When pulses (from the output of digital filter 4) arrive at the information input of another detection channel with frequency F, to which our trigger, and consequently, operation of 25 triples, for example, channel 8-2 of the detected counter 13 and trigger 16 of this channel No, the output of the detection signal on the la. Thus, after arrival, the output is made similarly, the first impulse to the input of one of the proposed device characterization of the detection channels is further detected by the increased compared to the signal produced only by this channel, the operation of other bone detection channels is interfered with by the known device. The proposed device is prohibited. At the same time, when the first pulse arrives, the pulse shaper 9 is started, which at the first output generates a pulse that appears along the front of the input pulse and is equal to 35

both pulsed psmera operating in the absence of a frequency signal and pulsed interference received and superimposed on the frequency signal are suppressed, and the detection time is set taking into account the intensity of the impulsive noise, i.e. the decision is made on the basis of the set number of analysis samples.

approximately T, and the pulse at the second output of the imaging unit 9 is formed with a delay of about 3/4 T relative to the front of the input pulse and does not exceed T in duration (g, where T is the period of frequency F, the detection to which channel 8 is tuned 1. Detection. A pulse from the second output of the pulse former 9 passes through delay element 10 with a delay time approximately equal to T, ji, and the delayed pulse duration does not exceed T,. The pulses from the first output of the pulse former 9 pulse prevent the arrival of corresponding pulseslementa 10 delays the output of the AND 17 and switching to the original state through an OR gate 12, flip-flop 15, the detection channel 8-1. The pulses arriving at the data input of the detection channel counter podschitgaayuts

13. If the pulse sequence is interrupted before the counter 13 counts the number K, then the signal from the output of the delay element 10 through the OR element 12 resets the first trigger 15, after which the counter 13 is reset to its initial state, as a result the software detector 3 signals appears in its original state. When recording into the counter of the 13 K-th pulse, the comparison unit 14 starts up and the pulse of the detection pulse arriving at the corresponding

When pulses (from the output of digital filter 4) are received at the information input of another detection channel with frequency F, which is set to 25 times, for example, detection channel 8-2, the output detection signal is produced similarly. Provides increased noise immunity compared with the known device. In the proposed device

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both pulsed psmeh operating in the absence of a frequency signal and pulsed interference received and superimposed on the frequency signal are suppressed, and the detection time is set taking into account the intensity of impulse noise, i.e. the decision is made on the basis of the set number of analysis samples.

Claims (1)

1. A device for receiving frequency-controlled signals, containing a series-connected input matching unit and a threshold unit, software signal detector and i -. a digital filter whose outputs are connected to the information inputs of a software signal detector, whose outputs are device outputs, informational and installation. the inputs of which are respectively the inputs of the input matching unit and the installation of the installation of a software signal detector, characterized in that five Editor A. Ogar Order 3210/56 Fin g Compiled by V. Zenkin Tehred A. Kravchuk Proofreader M. Maksimishinets Circulation 660 Subscription VNIIPI USSR State Committee for inventions and discoveries P3035, Moscow, Zh-35 ,, Raushsk nab. , d, 4/5