SU1283975A2 - Communication device with delta modulation - Google Patents

Abstract

The invention relates to computing and is an improvement of the device according to the author's certificate No. 1095395. The use of the invention in information transmission devices improves the accuracy of the transmission. The device contains encoding and decoding nodes. The coding node includes a subtractor, a binary modulator, an integrator, a synchronizer, three keys, and a meander decoder consisting of a shift register, n modulators two, the And element, and a driver. The decoding node includes a synchronizer, an integrator, a low-pass filter, a key, and a meander decoder, similar to the meander dejfrator of the encoding node. An introduction to the coding and decoding nodes of an additional key, a block of the falling edge and a source of constant voltage reduces the time required for the integrators to set up during the transition from pause to an array of information. 2 Il. F (L

Description

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 The invention relates to computing, can be used in data transmission systems and is an improvement of the device according to the author. No. 1095395.

The purpose of the invention is to improve the accuracy of transmission.

Figure 1 shows the functional diagram of the coding node of the device; figure 2 - functional diagram of the decoding device node.

The communication device with the delta modulation contains the coding node 1, which includes the subtraction unit 2, the binary modulator 3, the integrator 4, the synchronizer 3, the keys 6-8, the decoder 9 square wave, the shift register 10, adders 11 modulo two, element 12, shaper 13, constant voltage source 14, block of the falling edge 15 and additional key 16, and decoding node 17, including synchronizer 18, integrator 19, low-pass filter 20, key 21, decoder 22 meander, shift register 23, adders 24 modulo two, element I 25, driver 26, a constant voltage source 27, a trailing edge selection unit 28 and an additional key 29.

Binary modulator 3 may be a trigger. As the synchronizer 5, a pulse generator with the required repetition rate is used. The synchronizer 18 can be made in the form of a pulse generator with external synchronization. ... Shapters 13 and 26 are made on the element I, one input of which is combined with the input of the element NO, the output of which is connected to another input of the element I. through the delay element. The delay time of the delay element determines the pulse duration of the driver.

Blocks 15 and 28 of the falling edge can be made on the element AND, the inputs of which are connected to the outputs of the element NOT and the element of delay, whose inputs are combined and are the input of the block. The delay time of the delay element determines the pulse duration from the output of the block.

Constant voltage sources 14 and 27 serve to set the level equal to the expectation

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transmitted between, two signal pauses.

The delta modulation communication device operates as follows.

At coding node 1, the input signal through a closed key 7 is fed to subtraction unit 2, where it is compared with the approximate voltage coming from integrator 4. A differential signal is fed to binary modulator 3, in which a sequence of rectangular pulses is formed according to the sign of this signal , where the pulses correspond to the time intervals during which the input signal exceeds the approximating signal, and the pauses - the time intervals during which the input signal is less than the approximating signal. The sequence of rectangular pulses, which are the output signal of the coding node 1, also goes to the integrator 4, where the approximating voltage is formed, and to the decoder 9 of the square wave. When a null pause between arrays of information is transmitted, the output of binary modulator 3 will be a sequence of rectangular

pulses, representing a meander. If the meander length equals or exceeds n clock ticks, where n is the number of adders 11 modulo two in the decoder of 9 meanders, then at the output of the trimmer 13 of the decoder 9 a short pulse appears, which goes to the control inputs of keys 6-8. this key 7 is disconnected, remove the input signal from the input of block 2

subtract, -key 8 short-circuits this input. At the same time, the key 6 ensures that the approximation voltage at the output of the integrator 4 is equal to zero, the latter shorting,

At the end of the pulse produced by the shaper 13 of the decoder 9, the input signal is fed to the input of the subtraction unit 2 via the key 7, the keys 6 and 8 break the corresponding circuits

short circuit and at the output of the binary modulator 3 in accordance with the mechanism of delta modulation, a delta-modulated signal is generated. As soon as after the transmission of the zero pause, an array of information begins to be transmitted, at the output of the binary modulator 3 a sequence different from the meander is formed, and at the input of the block 15 in the back side of the rear edge

This difference appears as a unit — zero. From this differential, unit 15 forms a short pulse that opens key 16, and constant voltage source 14 is connected to the third input of the integrator .4. Integrator 4 is charged to the expectation level of the transmitted signal.

After the end of the pulse generated by the unit 15, the key 16 is closed and at the output of the binary modulator 3 a delta-modulated signal is formed in accordance with the delta modulation mechanism.

The operation of the coding node is synchronized by synchronizer pulses 5

In the decoding node 17, the input signal is fed to the decoder 22 of the meander, the synchronizer 18 and the integrator 19. In the integrator 19, the received pulse sequence is integrated. The output voltage of the integrator 19 is fed to a low-pass filter 20, the output of which removes the reconstructed signal, which is close in shape to the original signal at the input of the coding node 1. The synchronous operation mode of the transmitting and receiving sides is provided by the synchronizer 18.

If the input signal is a square wave with a duration of n or more cycles, then a first control pulse appears at the first output of the decoder 22 of the meander, which is applied to the control input of the switch 21, which terminates the output of the integrator 19. Thus, the output of the decoding Node 17 provides a zero signal.

As soon as after receiving the meander, a sequence other than the meander begins to arrive at the input of the decoding node 17, the second output

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decoder 22 meander on the Wits differential unit - zero. From this differential, the falling edge separation unit 28 forms a short pulse that opens key 29, and d:;;:; sd of the constant voltage source 27 is connected to the third input of the integrator 19. The integrator 19 is charged to the expected value of the transmitted signal

After the end of the pulse from the output of the trailing edge selection unit 28, the key 29 is closed and the decoding node 17 will operate in accordance with the delta modulation mechanism.

Thus, during the transition from transmission to information arrays, the signal establishment time at the outputs of the integrators 4 and 19 in the coding and decoding nodes 1 and 17 will be significantly less than in the known device, since the signals will be transmitted to the devices more accurately.

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Claims (1)

Invention Formula Device for communication with delta modulation according to auth.St. No. 1095395, characterized in that, in order to increase the transmission accuracy-., The coding and decoding nodes are inserted into a block of the falling edge, a constant voltage source and an additional key, the information input of which is connected to the output voltage of the constant voltage source, output connected to the third input of the integrator; the control input of the additional key is connected to the output of the block of the falling edge, the input of which is connected to the output of the ANDR decoder element of the meander. srig.1