SU118527A1 - Method for simultaneous transmission of a second telegraph message over existing communication channels of frequency telegraphy - Google Patents

Description

The known systems for carrying out the simultaneous transmission of two messages over a single channel require considerable channel bandwidth expansion.

The disadvantage of this system is that noise immunity, and hence the reliability of communication, is reduced.

The proposed method allows, without expanding the channel bandwidth, to simultaneously transmit two messages on one channel.

For the transmission of the first message, two frequencies are used, the differences of which are chosen to be a multiple of the manipulation frequency, and for the transmission of the second message, the first of these frequencies is manipulated in phase. Upon reception, the second frequency is brought to the first using the manipulation frequency voltage, and the second message is extracted using a delay line and a phase detector.

FIG. 1 shows a block diagram of a transmitter; in fig. 2 is a block diagram of a receiving device.

The first and second manipulation frequencies are chosen such that their difference is a multiple of the manipulation frequency.

In the transmitter (FIG. 1), the frequency of the carrier oscillation i, coming from oscillator i, is manipulated in phase by the manipulator 2 of the phase of the second channel.

If the manipulator 2 receives the telegraph signal of the second channel 3, If a negative current is transmitted through the second channel, the phase of the carrier oscillation i i changes by 180 ° with respect to the phase of the carrier oscillation of the previous premise.

No. 118527-2 -

The output of the manipulator 2 receives signals of the second channel with the first manipulation frequency f.

In order to form the second frequency of the npulation / 2 oscillation, the manipulation frequency FQ is applied to the multiplier 4 frequencies.

After the multiplier, the manipulation frequency FQ multiplied by a constant coefficient K enters the frequency converter 5, allocating a second frequency / 2 equal to the sum of the first frequency / i and the manipulation chart FO multiplied by a constant coefficient k (fz f + / cfo).

The first and second manipulation frequencies enter the manipulator 6, where the frequency manipulation is formed, forming the signals of the first channel. The manipulator 6 also sends a telegraphic signal of the first channel 7. Depending on the polarity of the transmitted current through the first channel, the manipulator 6 passes the output of the current either at the frequency f or at the frequency / 2H at the receiving end (fig-2) of the frequency / j and / 2 arrive at the filters 8. The separated frequencies i and / 2 are fed to the frequency detector 9, at the output of which positive and negative current signals of the first channel 7 are formed.

Simultaneously, the packages containing the frequency / 2 are fed to the frequency converter / O, which converts them into the frequency packages / i.

In cascade 11, the transformed parcels from frequency / 2 to frequency / 1 are added to those packages that are transmitted on the first frequency

As a result of the addition, an oscillation is formed at the output of the cascade 11, whose frequency is equal to the frequency i, it is manipulated in phase in accordance with the signals of the second channel 3.

Signals in the form of negative or positive currents are extracted using a phase detector 12 connected in parallel with delay line 13 (with a delay equal to the duration of one elementary send).

Subject invention

The method of simultaneous transmission of the second telegraph message over the existing communication channels of frequency wiring, characterized in that, in order to reduce the bandwidth and, consequently, increase the noise immunity and reliability of communication, two frequencies are used to transmit the first message, the difference of which is a multiple of manipulation, and for transmitting the second message 0 | 0, the first of these frequencies is manipulated in phase, and at reception the second frequency is reduced to the first by voltage pilots at monipul tion and selection of the second message signal t is produced by the delay line and the phase detector.