SU455477A1 - Analog-to-digital converter - Google Patents

Description

one

The invention of OTIIOCHTCH is to telecommunications and is intended for use as part of a modulating device that converts an analog (pure voice signal) into digital form from transmission over a discrete communication line.

A device is known that contains an electronic attenuator connected through an amplifier to the input of a subtractive circuit of the actual aialo-digital converter and the input of a low-frequency detector that controls the electronic attenuator.

However, due to the discrete number, the number of transmitted on the channel is level in systems of this type and there is no sphenifical interference, “Quantization information, the KOTOpoii value (when working with a strong signal) does not determine the signal-to-noise ratio in the channel, but depends only on the number of quantized levels and the relationship between the amplitude of the quantization levels and the magnitude of the non-reducible signal.

Therefore, in discrete analog signal transmission systems, maintaining the nominal signal level at the modulator input plays a significant role.

The purpose of the invention is to improve the quality of the transmitted signal.

This goal is achieved by introducing an additional subtractive circuit into the converter.

and an additional detector, the input of which is connected to the output of the approximating voltage forcing unit of the actual analog-digital converter, the output is connected to an additional subtractive circuit, also connected to the output of the main detector, the output of the additional subtracting circuit is connected to the low-pass filter.

The drawing shows a block diagram of the device.

The device contains a syllable compressor 1, an input 2 of a syllable compressor, an electronic attenuator 3, an amplifier 4, a detector 5, an additional subtractive circuit 6, up to an additional approximate detector 7, a low-pass filter 8, a subtracting circuit 9, an amplifying voltage generating unit 10 controlled key circuit II with separate outputs, clock generator 12, integrator 13, output 14 of the approximate voltage shaping unit.

A slope compressor 1, input 2 of which is an input intended for supplying a low-frequency signal, contains an electronic attenuator 3. in series with which amplifier 4 is connected. The output of amplifier 4 through detector 5 is connected to one of the additional subtraction circuit 6 inputs to Wto. - 3

The input of which is connected to DONOLITNESL), 1st detector of approximating signal 7. The output of additional voltage 6 is connected through the low-pass filter 8 to the control input of the electronic attenuator 3. The output of the amplifier 4 is connected to one of the inputs of the subtractive circuit 9, which is the input of the approximating voltage shaping unit 10. The output of the subtractive circuit 9 is connected to the key circuit 1 i with separate outputs, to the control iixo; iv of which the clock generator 12 is connected, Both outputs of the key circuit 11 podklk) are connected to the integrator 13, the output of which, in turn, is connected to the second input of the subtractor circuit 9 and the input of the additional detector 7 approximating signal. One of the outputs of the key circuit 11 is the output 14 of an approximating voltage forming unit.

The analog signal to be transmitted is fed to syllabic compressor 1 through input 2. At the same time, it is weakened by electronic attenuator 3, then amplified by amplifier 4. Total electric gain of first attenuator 3 and amplifier 4 should provide the nominal value of the signal level for all oscillations input level and sensitivity of the demodulator. The output voltage of amplifier 4 falls simultaneously on detector 5 and on the subtractive circuit 9 of block 10. Subtractive circuit 9 calculates the difference between the approximating signal received by integrator 13 from pulse M from key circuit 11.

The key circuit 11 is driven by a clock generator 12, and one of its output is the output of block 10. AiproximpuPy Sigal is also supplied to an additional polishing detector 7 of the approximating signal, the output of which is fed to the additional subtractive circuit 6. An additional subtracting circuit 6 performs the calculation the difference between the level of the analog signal to be transmitted and the level of the auxiliary signal. Employment proportional to the difference, and liquefying through the filter 8 lower) 1 each, controls the operation of the electronic attenuator 3. In the case when the voltage of the iroximating signal is greater than the voltage of the analog signal, this is minimal at the attenuation of iopa attenuator 2

0 and the Ioko signal at the output of the nirreipaTOpa 13. At this voltage from the additional detector 7, the voltage from the detector 5 appears. When s1-1 appears, the integrator 13 quickly goes into saturation, which npis1SOLES to know the sign of the difference the voltages of the detectors 5 and 7. The evaporation, proportional to this difference, controls the operation of the attenuator 3, reducing the signal level,

0 arriving at block 10, Thus, automatic tracking of the optimal level of the speech signal is made regardless of its level at the input and the sensitivity of the block 10.

Subject and d on and e and

An analog-to-digital converter containing an electrical attenuator, connected via an amplifier to the input of the subtractive circuit of an analog-to-digital converter and detector input, filter n1; their frequencies controlling electronic attatonoToj) OM, tl and h Sch n and so that, with a view

5 improve the quality of the non-reversible signal, an additional subtractive circuit and an additional circuit are introduced into it, the input of which is connected by the output of the unit for forming an anero-vibrating signal, for example,

analog-to-digital converter, the output is connected to an additional subtractive exciter, also connected to the output of the main detector, the output of the additional subtractive circuit is connected to a 1F1 filter.