SU1290528A1 - Delta modulator - Google Patents

Abstract

The invention relates to automation, can be used in telemetry, television and phototelegraphic systems. The aim of the invention is to improve the accuracy of the delta modulator for. input waveform count. The delta-modulator contains a clock pulse generator 1, a transmitter 2, a two-level quantizer 3, an approximator 4, a selector 5 packs of symbols, and a block 6 of comparison. By introducing a comparison unit 6, the overload distortion is reduced (deny some signal distortion in magnitude), which makes it possible to more accurately transmit jumps in the signal. 2 Il.

Description

The invention relates to automation and can be used in telemetry, phototelegraph and television transmission systems.

The purpose of the invention is to improve the accuracy of the delta modulator by ensuring the transmission of the output waveform.

1 shows a block diagram of a delta modulator; Fig. 2 shows timing diagrams explaining its principle of operation.

The delta modulator contains a clock pulse generator 1, a subtractor 2, a two-level quantizer 3, an approximator 4, a selector 5 packs of symbols, and a block 6 of comparison.

Subtractor 2 can be performed on an operational amplifier. The two-level quantizer 3 is a clocked trigger with an input comparator. The approximator 4 includes an integrator, a stable current generator, and a controllable switch and provides an approximation signal. The selector 5 packs of characters can be performed on a shear resistor and an equivalence element. The size of the shift register is determined by the number of identical symbols j beginning with which the overload distortion is considered unacceptable. Comparison unit 6 in the simplest case is a key.

The delta modulator operates as follows.

The analog input signal U (t) in the subtractor 2 is compared with the approximate voltage U (t).

The residual signal U (t) -U (t) noAa per quantizer 3, controlled by a sequence of clock pulses from generator 1.

At the output of the quantizer 3, an information sequence of pulses is formed.

  The information sequence of pulses from the output of the quantized L 3 arrives, firstly, to the input of the approximator 4 and, secondly, to the input of the selector 5 packs of symbols.

The approximator 4 can be either with a secondment or without it. In FIG. 2, as an example, timing diagrams are given for the case where the secondment is not used in the approximator.

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In the delta modulator scheme, it is provided that, for example, the characters 1 (the presence of

5 pulses) in the information sequence at the output of the delta modulator ri, an increase in the approximating voltage at the output of the approximator 4, and a negative polarity - sym 0 waves O and a decrease in the approximating voltage. At the same time, each symbol 1 increases, and each symbol O, on the contrary, decreases the approximating voltage,

 - If the number of elements (O or 1) in packs of characters of the output information sequence (Fig.26)

- exceeds the specified value (for example, 4, as shown in Fig. 26),

2- at the output of the selector 5 of packs, symbols, a control signal is generated, which is fed to the control input of the level binding unit 6, the information signal of which receives the input signal U (t).

The signal from the output of the selector 5 packs of symbols causes the level of the approximating voltage U, (t) to be tied to the level of the input signal U (t) (times t, and tj, Fig. 2), and the selector 5 packs of symbols are simultaneously reset in the initial state.

Two more signals are shown in Fig. 2a: U (t) is the signal reconstructed at the receiving side without using the level matching circuit. (without overload correction), 11 (t) is the signal recovered at the receiving side using the level matching circuit (with overload correction).

As can be seen from Fig. 2a, the approximating signal and (t) on the transmitting side, respectively, the reconstructed signal Uj (t) on the receiving side more accurately convey the character of the change in the shape of the input signal IS (t). Than the approximating signal U (t) „

Thus, despite some distortion in magnitude, it is provided - transfer of the shape (especially of the jumps) of the input signal.

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Claims (1)

Invention Formula A delta modulator containing a subtractor whose first input is the input of a delta modulator, the output is connected to the information input of a quantizer whose output is the output of the delta modulator and is connected to the information input of the symbol pack selector and to the first input of the approximator, the output of which is connected to the second input of the subtractor, a clock pulse generator, the output of which is connected to the clock input of the quantizer, which distinguishes In order to increase the accuracy of the delta modulator by transmitting the input waveform, a comparison block is inserted into it, the output of which is connected to the second input of the approximator, the output of the symbol pack selector is connected to the reset input of the symbol pack selector and the control the input of the comparison unit, the information input of which is connected to the input of the delta modulator. ti L. Pcholinska FIA.2 Compiled by O. Revinsky Tehred I.Popovich Cor 7916/57 Circulation 922 Subscription VNSHSHI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 Proofreader E. Sirohman