SU1388926A1 - Information receiver - Google Patents

Abstract

The invention relates to remote control and can be used in remote alarm systems. The purpose of the invention is to improve the noise immunity of the device. The device contains filters 1, 3, 6, 10, amplifier 2, rectifiers 4, 11, adder 5, threshold elements 7, 8, 14, generator 9, delay element 15, element OR - NOT 16. A positive effect is achieved by introducing notch filters 12 and 13, which eliminate the signal distorted by impulse noise by applying voltage to the keys 17 and 18. I Il.

Description

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The invention relates to telemechanics and can be used to receive frequency-manipulated signals from a tele-alarm system.

The purpose of the invention is to improve noise immunity.

The drawing schematically shows the proposed device.

The device contains the first filter 1, the amplifier 2, the second filter 3, the first rectifier 4, the adder 5, the fourth filter 6, the first threshold element 7, the second threshold element 8, the generator 9, the third filter 10, the second rectifier 11, the fifth filter 12, fest filter 13, the third threshold element 14, the delay element 15, the element OR NOT 16, the first 17 and the second 18 keys.

The device works as follows.

Heperator 9 generates signals at its outputs in the form of rectangular pulses with frequencies, respectively, N (fi) ± Af) 1 De N - the number of channels of N-channel filters; f is the average frequency of the received signal; L1 - frequency deviation. The input signal is extracted by filter 1, for example, bandpass, limited by amplifier-limiter 2 to eliminate the influence of multiplicative interference, and is fed to the inputs of filters 3 and 10, the other inputs of which receive pulses from the reference oscillator 9. If the input signal is frequency, it is allocated filter 3 and through the rectifier 4 is fed to the input of the adder 5, on the other input of which there is a residual rectified voltage of another polarity from the filter 10. The output voltage of the adder 5 is smoothed by the low-pass filter 6 arrives at the threshold elements 7 and 8 which are activated respectively by positive and negative polarities.

However, when impulse noise appears in the input signal, the response of the bandpass filter 1 is superimposed on the useful signal, the signals on the B1e1 filter inputs 3 and 10 but the level approaches each other, the number of omvi6o4Hbix solutions at the output of the threshold elements 7 and 8 increases.

To eliminate this drawback, the signal from the output of the bandpass filter 1 passes through pos. 5 notch filters 12 and 13, the zeros of the transfer characteristic of which are respectively equal to the frequencies fo ± Ai. Since the useful signal at both frequencies is suppressed by the reject filters 12 and 13, in the absence of impulse noise the signal at the input of the third threshold element 14 is zero, through the OR-NOT 16 scheme the level of the logical unit is fed to the control inputs of the keys 17 and 18 the signals from the outputs of the threshold elements 7 and 8 through the keys 17 and 18 are output.

Filters 12 and 13, such as notch filters, pass through the input pulses due to their broadband, almost without attenuation, and are fixed by the threshold element 14. The level of the logical unit from the output of element 14 / is inverted by the OR-NOT circuit and closes the keys 17 and 18 on impulse interference time. Since the signal at the input of element 14 is oscillatory in nature, to eliminate the activation of keys 17 and 18 at the moments of signal transition

zero element introduced delay G5. Due to it, at the moment the input signal of the threshold element 14 passes through zero at another input of the OR circuit — the level of the logical unit from the output of the delay element 15 is NOT maintained.

0 The proposed implementation of the device for receiving information allows to exclude signal portions affected by impulse noise (the detection amplitude is specified by the threshold of element 14), which significantly increases the noise immunity of the reception.

Claims (1)

Invention Formula A device for receiving information comprising a first filter, the input of which is the device input, the output of the first 0 filter through an amplifier connected to the first inputs of the second and third filters, the outputs of the first and second rectifiers are connected respectively to the first and second inputs of the adder, the output of which through the fourth filter is connected to the inputs 5 first and second threshold elements, fifth and sixth filters, a generator, the first and second outputs of which are connected to the second inputs of the second and third filters, respectively, characterized in that, in order to improve noise immunity, a third threshold element is introduced into the device, the element OR NOT and keys, the output of the first filter through the fifth and sixth filters connected in series and the third threshold element 5 is connected to the first input of the element OR — NOT and the input of the delay element whose output is connected to the second input of the element OR NOT; the output of the element OR is NOT connected to the first inputs of the first and second keys, the second inputs of which are connected to the outputs of the first and the second threshold elements, the outputs of the second and third filters are connected to the inputs of the first and second rectifiers, respectively, the outputs of the first and second switches are the first and second outputs of the device, respectively. 0