SU786039A1 - Discrete information transmitting method - Google Patents

Description

one

The invention relates to radio engineering and can be used for transmitting data from information sources to (ECL), as well as for transmitting information at lower levels of automated control systems.

A known method of transmitting discrete information by signals consisting of several carriers, in which the transmitter side modulates the frequency and phase of each carrier in accordance with the transmitted sequence of information symbols, and on the receiver side compares the form received signal with a set of reference signals and according to the coincidence of the forms received and reference signals on the interval of a single element of the signal decide to receive the corresponding information symbol Q

However, when implementing a known method, there is a wide frequency spectrum of transmitted signals, and the transmission rate is low.

The purpose of the invention is to reduce the frequency spectrum of the transmitted signals and increase the transmission rate.

To do this, in the method of transmitting discrete information by signals consisting of several carriers, in which the transmitting side modulates the frequency and phase of each carrier in accordance with the transmitting chain of information symbols, and at the receiving side compares the form of the received signal with a set of reference signals and by matching the forms of the accepted and reference

10 signals on the interval of a single element of a signal make a decision on the reception of the corresponding information symbol, on the transmitting side, before modulation, they sum up 5 carriers, the sum of the phases of which is equal to zero at the beginning and at the end of the interval of a single signal element.

FIG. 1 shows a signal shaping circuit according to the proposed

20 with frequency ratios and double phase manipulation; in fig. 2 - structurally electrical. ka diagram of the device for implementing the proposed method, in FIG.

3 (j, six phase shifters 3, source 4

messages, manipulator 5, switch b and adder 7.

The proposed method is carried out as follows.

The case is chosen as an example. when they are produced by summing up two harmonic carriers with frequencies I, € o and the phases and n moreover. K 2.

Let it be required to transmit four symbols L, L, C, T) (see graph, c, fig. 1). For this, four signals are required, for the information parameter of which the form of oscillations is chosen in the interval of a single element. To separate the waveforms, the carriers are summed with the phase difference.

e, j,:

(one)

for example, for the symbol A equal to O, for the symbol b L equal to –180, for the symbol C equal to 9 (I, for the symbol t) f equal to –90 °.

The duration of the single elements of the signal is chosen equal to T 1D, and they are formed at the moments when the phase of the reference oscillation is equal to zero (graph, b, Fig. 1). At the beginning of a single element of the signal, the phases of the oscillation components must be mutually compensated, therefore, the equality

, (2)

The joint solution of the equality {) and (2) determines in which phases fi the components must be located at the beginning of the unit signal elements. For this example, the results are tabulated.

When transmitting the symbol AO O), the normal phases are components with frequencies and {t. choose equal, (see Fig. 1,. | u). For the symbol b, the initial phase of the first component is chosen to be - (graph), and the second (graph g). Accordingly, the table chooses the initial phases for the transfer of the remaining symbols of the character.

The form of the total vibrations (graph.Ch) corresponding to the transmitted symbols is taken as a reference, i.e. For each symbol, one specific form of oscillations is fixed for subsequent recognition on the receiving side. Recognition is carried out with the help of a reference, or, knowing the corresponding ratios of A, b, C, T) frequency and phase difference ratios, continuous oscillations of the same forms on the receiving side are reproduced.

If, for example, the reception is a comparison of the received signals with a set of standards, then an oscillation is reproduced on the screen of the oscilloscope, for example, corresponding to the symbol A. At first, a positive half-wave T / 3 appears. Patterns A, C, T correspond to this moment. Next, negative and positive half-waves of T / 6 are reproduced on the screen, and then negative, T / 3. So the sequence for patterns C and 15 is not typical, therefore, they decide to receive the character f, A similar comparison is made for the oscillations of other forms;

The reference signal with frequency f from generator 1 of sinusoidal oscillations is fed to frequency multiplier 2. Phase shifters 3 shift the initial phases to the required angle Ф. Information from the source 4 messages is sent to the manipulator 5, which synchronizes with the reference signal and switches the manipulator 5. In accordance with the information symbols transmitted, the dual switch of switch 6 at the beginning of the unit signal moments is fed to the inputs of the adder 7 oscillations with the corresponding initial phases. The sum signal from the output of the adder 7 is transmitted over the communication line.

For simplicity, the receiving side is shown in FIG. 3 as an oscilloscope at the input. X of which is signal from the link. The beam produces, on the screen, the form of received vibrations. According to the results of comparison with standards, the transmitted information is judged.

Claims (1)

The use of the proposed method for transmitting discrete information essentially preserves the main advantage of the prototype — the use of codes with a high base, since the phase difference in the example given can take eight values; 0 °, 900, 180 ° / 270 °, 360, - .90 °, - 180 ° and - 270 ° (four of them have been chosen for the illustration), and the total fluctuations corresponding to these differences have a different shape. The performed studies prove the narrowing of the frequency spectrum of a signal compared to a signal with ordinary relative phase shift keying (OFM). Compared with the transmission of information by OFM signals, this method allows to increase the transmission rate up to 15% (depending on the length of the data block and the level of interference in the communication line) due to the absence of the need for a starting message. In addition, the proposed method does not require application at the receiving side of the delay line. A narrowing of the frequency spectrum of the signal and an increase in the speed of data transmission make it possible to increase the efficiency of using communication lines and information transmission systems in general. The Invention Method for transmitting discrete information by signals consisting of several carriers, in which on the transmitting side the frequency and phase of each carrier are modulated in accordance with the transmitted sequence of information symbols, and on the receiving side, the CC1T form of the received signal is compared with a set of reference signals and by coincidence the forms of the received and reference signals in the interval of a single element of the signal make a decision on the reception of the corresponding information symbol, characterized in that that, in order to reduce the frequency spectrum of the transmitted signals and increase the transmission speed, carriers are summed before modulation on the transmitting side, the sum of the phases of which is zero at the beginning and at the end of the interval of a single signal element. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 377972, cl. H 04 L5 / 12, 1971 (prototype). / . 7 BUT WITH / BUT at at vyi V7 7 : L BUT V