SU828433A1 - Device for transmitting and receiving digital information - Google Patents

Description

The telephones are combined, and the corresponding output of the first transversal filter is connected to the corresponding input of the third controlled switch.

The drawing shows the electrical structure of the proposed device.

A device for transmitting and receiving digital information contains encoder 1, code converter 2, modulator 3, input filter 4, demodulator 5 with converter, first transversal filter (TF) 6, subtractor 7, resolver 8, second transversal filter (TF) 9 , a decoder 10 with a counter, a memory 11, a delay line 12, five controllable switches 13-17.

The device works as follows. After modulation in modulator 3, the signal enters the continuous channel and then to the filter 4 input of the receiving part limiting the noise band to demodulator 5. Then the sampled and quantized signal from the output of demodulator 5 goes to the circuit consisting of TF 6, a subtractor 7, a resolver 8, a TF 9, a decoder 10, a memory 11, a delay line 12, and switches 13-17, which constitutes a feedback device (SLD).

At the beginning, when the level of errors is small (there are no errors), the SLD is built on the basis of an equalizer with feedback on the solution. To do this, all the switches must be set to position 1. The signal from the output of the demodulator 5 goes to TF 6, then through switch 13 to subtractor 7, then through switch 14 to the resolver 8.

From the output of the resolver 8, the signal simultaneously arrives at the decoder 10 and through the switch 15 to TF 9. From the output of TF 9, the signal arrives at the second input of the subtractor 7 through the switch 16. The delay samples 12 of the demodulator 5 delayed in TF 6 also receive a delay line 12 . The coefficients of TF 6 and TF 9 are chosen so as to minimize the probability of an error during the transmission of a symbol. These coefficients are calculated for the given channel characteristics and are recorded in the storage device AND, from there they enter TF 6 and TF 9.

If an error has occurred, it is detected in the decoder 10, and a control signal is received from the signal output of the decoder 10 to switch all switches to position 2.

In this case, the SOS goes into the linear signal processing mode, and the TF 6 output is connected via switches 13 and 15 to TF 9 input, the output of which is connected via switches 14 and 16 to the input of solver 8. A new set of coefficients is supplied from memory 11 which is selected from the condition of linear processing in the VOS of the output signal of the modulator 3. In addition, from the delay line 12 to the delay elements TF 9, the corresponding set of samples stored there comes from the output of the memory TF 6 to the preceding moments s time.

Thus, from this moment on, TF 6 and TF 9 form a single transversal filter in the straight line of the SLD circuit, which provides linear signal processing. At the same time, estimates of the transmitted signals from the output of the resolver 8 will now be received in the delay line 12.

The linear signal processing mode (all switches in position 2) is stored for n cycles, where n is the number of delay elements in TF 6 and TF 9, after the last block of characters in which an error was detected.

If, after the FBL goes into the linear processing mode from the output of the decoder 10, error detection signals continue to be received, the frequency of which is higher than 1 // g, then this mode is preserved.

If, after the last signal about the detection of an error, n cycles have passed, which is detected in the counter of the decoder 10, then the VOS switches to the nonlinear processing mode in which it was at the initial moment. At the same time, the corresponding coefficients are transferred from the memory device 11 to the TF 9 p TF 6 podgots, and to the delay elements of the TF 9 from the delay line 12 a corresponding set of estimates is received from the resolver 8 during the last n cycles.

Thus, two modes of FBM are used to suppress the error multiplication effect.

Improving data transmission is achieved by automatically suppressing the effect of error multiplication in the preamp part of the proposed device.

Claims (1)

Invention formula A device for transmitting and receiving digital information, comprising on the transmitting side a serially connected code converter, a modulator, on the receiving side serially connected input filter, a demodulator with a converter and a first transversal filter, a subtractor, a second transversal filter and a resolver, characterized in that in order to increase the reliability of the transmission and reception of information, An encoder with a counter, a delay line, a memory device and five controllable switches are entered on the transmitting side of the encoder whose output is connected to the input of the encoder, the first transversal filter, the first control switch, the subtractor, the second control switch, the decider and the decoder with the counter are connected in series with each other; and the first input of the second transversal filter, respectively, the second input of the second transversal filter is connected to one output of the storage device, the other output of which is connected to the corresponding input of the first transversal filter, the output of the delay line is connected to the third input of the second transversal filter, the output of which is through the corresponding input fourth controlled the switch is connected to the corresponding input of the subtractor, the corresponding output of the fourth controlled switch is connected to the corresponding input of the second controlled switch, while the memory input, the output of the decoder with the counter and the corresponding inputs of all five controlled switches are combined, and the corresponding output of the first transversal filter is connected with the corresponding input of the third controlled switch. Sources of information taken into account in the examination 1. Tomlinson M. New Automatic Egualizer Employing Modulo Avithmetic. - “Electronic Letters, v. 7, March 25, 1971, p. 138-139 (prototype).