SU1160591A1 - Device for reception of frequency-shift keyed signals - Google Patents

Abstract

A DEVICE FOR RECEPTION OF SIGNALS OF FREQUENCY TELEGRAPHY, containing a series-connected amplifier-limiter, frequency discriminator, amplitude discriminator and electronic relay, characterized in that, in order to improve the noise immunity, the frequency discriminator consists of a differential amplifier, two integrators, a layer-dependent element, and a layer of a dependent element. which through a frequency-dependent element is connected to the inputs of the first and second integrators, the outputs of which are connected to the unit and nvertiruyuschemu inputs of a differential amplifier whose output is the output of the frequency discriminator, the input of which is the detector input.

Description

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The invention relates to telegraph communication and can be used to receive frequency telegraphy signals.

A device for receiving frequency telegraphy signals is known, comprising a reception filter connected in series, an amplifier, an amplitude limiter, a frequency discriminator, the output of which is connected through amplitude detectors to the corresponding inputs of a comparator unit 1.

The disadvantage of this device is low reliability of reception.

The closest technical solution to the invention is a device for receiving frequency telegraphy signals comprising a series-connected amplifier-organizer, a frequency discriminator, an amplitude discriminator and an electronic relay 2.

However, the known device has low noise immunity.

The purpose of the invention is to improve noise immunity.

The goal is achieved by the fact that in a device for receiving frequency telegraphy signals containing a series-connected limiting amplifier, a frequency discriminator, an amplitude discriminator and an electronic relay, the frequency discriminator consists of a differential jc and j matrix, two integrators, a frequency-dependent element and a detector, the output of which is dependent on the element is connected to the inputs of the first and second integrators, the outputs of which are connected, respectively, to a differential unit and an inverting unit; of the amplifier, whose output is the output of the frequency discriminator, the input of which is the detector input.

FIG. 1 shows a structural electrical circuit of the proposed device; in fig. 2 - time diagrams.

The proposed device for receiving frequency telegraphy signals comprises an amplifier-organizer 1, a detector 2, a frequency-dependent element 3, the first and second integrators 4 and 5, a differential amplifier 6, an amplitude discriminator 7, an electronic relay 8, a frequency discriminator 9.

The device works as follows

A frequency-controlled sine wave signal is applied to the input of the device.

(Fig. 2a), which is converted by Limiting Amplifier 1 into a signal that is close in shape to rectangular. After detection by detector 2, the signal (FIG. 2 b) arrives at the frequency-dependent element 3, which converts the frequency-manipulated signal (FIG. 2 b) into an amplitude-modulated (FIG. 2 c). The constant time ti of integrator 4 is chosen from the condition

-§- 0.3,

where tji is the pulse duration of the information signal.

At the same time, by the end of the information pulse, at the output of the integrator 4, the maximum voltage value is set (Fig. 2 g), equal to the amplitude of the information signal (Fig. 2 a). The integrator 5 generates a voltage level (FIG. 2 d) corresponding to the carrier frequency of the received signal. The constant of the time integrator 5 fTj is chosen as 10 Si in order, on the one hand, to prevent a significant decrease in the amplitude of the information signal at the output of the differential amplifier 6 and on the other, to ensure a relatively fast response of the device to changes in the carrier frequency of the received signal. The output of the differential amplifier 6 receives a signal

(Fig. 2e), proportional to the difference of the voltage of the signals (Fig. 2d id). The amplitude discriminator 7 operates at a zero value of the output voltage of the differential amplifier 6 and, thus, generates a control signal by the telegraph apparatus (Fig. 2 g). The trigger level of the amplitude discriminator 7 is chosen to be zero in order for its output signal to strictly comply with the law of manipulation of the received signal.

The output signal (Fig. 2 g) of the amplitude discriminator 7 through the electronic relay 8 is fed to the winding of the telegraph control electromagnet (not shown).

The amplitude discriminator 7 triggers when there is 4 pulse at the input of the integrator, the duration of which is more than a certain value, which ensures noise immunity, since the device does not respond to short pulses.

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Claims (1)

DEVICE FOR RECEIVING FREQUENCY TELEGRAPHY SIGNALS, comprising serially connected amplifier-limiter, frequency discriminator, amplitude discriminator and electronic relay, characterized in that, in order to increase noise immunity, the frequency discriminator consists of a differential amplifier, two integrators, a frequency-dependent element and a detector, the output of which through a frequency-dependent element is connected to the inputs of the first and second integrators, the outputs of which are connected respectively to unit and invert the input of the differential amplifier, the output of which is the output of the frequency discriminator, the input of which is the input of the detector. figure 1