SU773942A1 - Discrete information transmitting method - Google Patents

Description

one

The invention relates to a technique for transmitting data over communication channels and can be used in discrete information transmission systems.

A known method of transmitting discrete information with relative phase modulation of carrier frequencies is based on splitting n (where n 1 is an integer) of carrier frequencies into m JQ (where H1 1 is an integer) of groups with simultaneous manipulation of one carrier of each group by frequency and

M phase

However, the disadvantage of this method is the reduction in noise immunity with increasing number of frequencies due to a decrease in the level of the signal transmitted over each frequency in channels with a limited total power.

The purpose of the invention is to increase the noise immunity of the transmitted information.

In order to achieve the goal of 25, when transmitting discrete information with relative phase modulation of carrier frequencies, it is based on a partition of n (where n 1 is an integer) (carrier frequencies per m (where is tse-j zo

A number of groups with simultaneous manipulation of one carrier of each group in frequency and phase, cyclically manipulate the other carrier frequency in phase in each of the m groups.

For example, 8 frequencies are used to transmit binary information: f,

With this, fft

f2.

B

H

  , 4 (С

develop 4 groups of frequencies: 1 group f, fj, group 2 - f3. Group 4 - fj, group - 7%

One information transfer cycle, for example, consists of the following combinations of frequencies: when transmitting the first single element, frequencies f, f, f,, fy are transmitted simultaneously, i.e. simultaneously transmit two frequencies from the first group, modulated in phase, and in one frequency from the other groups, modulated in frequency and phase. When transmitting the second unit element, the frequencies f, f, fj, f, fa, i.e. at the same time, two frequencies from the second group are transmitted, phase-controlled, and one frequency from the other groups, modulated by frequency

And phase and t, .d. When transmitting the fourth unit element, two are simultaneously present in the communication channel, frequencies from the fourth group and one frequency from the other groups. Then the cycle is repeated.

This method enhances the pomekostoykosti transmitted information by reducing the number of frequencies transmitted simultaneously over the communication channel and the corresponding increase in the signal level of each of the alternated frequencies at the same total power in the communication channel.

Thus, when transferring binary information using the proposed method using single relative phase modulation and frequency modulation, four groups of frequencies, two frequencies each, with the total transmission rate equivalent to the known method, the signal level is increased by one CC of each group, in tGraz, leaving without changing the level of the signals of the frequencies of the group f from which the shells are transmitted simultaneously. At the same time, on the receiving side, it is determined by the presence of two frequencies of the corresponding group which part of the multi-bit code combination is transmitted, or, on the contrary, it is judged that the code combination is correctly received. There is no need for additional synchronization,

With two-fold relative, phase modulation and frequency modulation of the transmitted frequencies, this method produces an increase in the signal-to-noise ratio by 3 dB compared to lime — rspn reduction in the total rate is less than 25%, while for other transmission methods an equivalent change in speed occurs and signal stability with respect to the signal-to-gomech ratio: increasing the transmission rate of information by a factor of two causes a change in the signal-to-noise ratio by at least 3 dB.

When transmitting information on the proposed method using single relative phase modulation and double frequency modulation, the average speed is obtained when transferring one single element fog 4 s | + 3 7.5 bits, i.e. Almost the same data transfer rate as in a known way, but on the communication channel there are only 3 frequencies instead of 8.

When switching to two-fold relative phase modulation and two-fold frequency modulation, the signal-to-noise ratio of the proposed method does not decrease, while

as the 3 known method is reduced by 3 dB.

Thus, this method of transmitting discrete information makes it possible to increase the immunity of the transmitted information by decreasing. the number of frequencies transmitted simultaneously in the communication channel.

Claims (1)

1. Hearth A.M. et al. Phase Difference Modulation. M ,, Holy Hour, 1967, p. 63.