SU81243A1 - The method of transmitting synchronizing oscillations to the system of the tunnel telegraph with phase modulation - Google Patents

Description

The object of the present invention is a method of transmitting synchronization oscillations in a phase modulated tone telegraph system using a standard channel for transmitting two frequencies whose beat frequency is at the receiver; (o: communication after multiplication is used for synchronization).

In the known systems of chi} anis; an; ioi: a, bnoro re.ierpa with two frequencies, the beat frequency of which, after multiplying, is used for synchronization, are used frequencies that are outside | 01-g, of the spector, near the cutoff frequency of the phase cut; 1B) s, which affects the quality of the transmission of synchronization frequencies.

In the proposed method, this disadvantage may be suzapep. For this, one of the sand frequencies of the standard channel of the voice telegraph, formed from the odd harmonic of the fundamental frequency of 60 Hz or being in an odd-multiple relation to the fundamental frequency (/ o 60-rt Hz, where n 7, 9, II), is modulated by sinusoidal oscillation frequency 30 Hz, representing a harmonic of the same fundamental frequency.

The resulting double-sided madule frequencies with an interval of 60 Hz are sent to the line. At the receiving station, the frequency of the Frcii beats of these two side frequencies is extracted and used as a synchronizing frequency by a conventional method, i.e. multiplied by the channel numbers corresponding to the channel number and sent to the phase detectors in the form of synchronous oscillations after preliminary phasing with carrier frequencies.

Since at the transmitting station the modulating frequency of the synchronization channel and the carrier frequencies of all I-; U: ;;.: OB, in the synchronization channel, are derived from the same frequency of 60 Hz

J 81243-2 -

and between them a strictly defined ratio of the phases is constantly maintained, and at the moment the frequency division does not affect the proposed method, the proposed sync sync pattern does not cause sound of the 10th phase.

ia drawing prestplv «1a ekhemp channel snfroschishchinov with kolnya, evyu modulator, i -, oTopoii 1-de.titel axis on frequency GO g / {, 2-ring modulator, / J-output filter channel synchronous. 4-transmission lines, 5-input receive channel filter, 6-amplitude detector, 7-narrowband filter to select beat frequencies, 8-amplitude; limiter and 5-band filter channel sync.

From the analysis of the current equation on the filter output 3, it follows that the synchronization channel will transmit oscillations of two frequencies, more distant from each other.

 / P - / (7N

 / R -. : -g: rl

, (, 0g - y - v / - ge.oh ,,,

and identical to two Pspr1) in the transmitted transmittance, 1m bank, where / o is the frequency, is a multiple of the fundamental, a / g,.;, is the axial frequency (frequency pn), equal to 60 Hz. Therefore, if the transmission of two control oscillations is carried out by the scheme shown in the drawing, then such a non-liaison will not require a wider spectrum: the frequency sniffer occupied by the working channel and it is possible for any of the 18 channels of the voice-frequency telegraph to be recorded for synchronization purposes. . The latter is extremely convenient, since the best channel can be selected for transmitting K oscillations.

The modulating frequency of 30 Hz can be obtained either by dividing the frequency of 60 Hz into two (just such a case is shown in the diagram of the drawing), or by chasing the source of the source setting its frequency directly at 30 Hz. Then the harmonics forming the carrier waves must have a doubled number.

The receiving part of the circuit consists of the receiving filter 5; amklntudnogo detector about; narrow band filter 7, non-random 1; filtering the beat frequency Fr-ai 60 Hz due to the effects of line noise and high-frequency hosts and amplitude limiter 8 with narrow-band filter 9 to eliminate the effect of changes in the input level on the amplitude of the sno-timing filter.

After (due to the modulus null asymmetry, the residuals of the non suppressive frequency can pass into the line. Filter 7 protects the synchronized 1 frequency from the disturbing rest of the mismatch of the circuit.

Subject invention

The method of transmitting their synchronized oscillations in the tone telegraph system with phase modulation by transmitting two frequencies, which beat the beat after multiplying, is used for synchronization, so that, in order to use the standard channel for synchronization tonal telegraph, at a non-terminating end, the signal allocates a second subharmonic of the fundamental frequency, which modulates the carrier frequency of one of the telegraph channels, and the resulting two side signals are transmitted over this channel.