SU1059658A1 - Demodulator of pulse-amplitude modulated signals - Google Patents

Abstract

DEMODULATOR SIGNALS WITH AMPLITUDE-PULSE MODULATION, which contains sequentially connected signal filters, whose input is the input of a demodulator of amplitude-pulse-modulated signals, and an amplifier with an automatic gain control circuit, an amplitude detector, a low-pass filter, a symmetrical shaping unit, and a modulator, and an amplitude detector, a low-pass filter, and a symmetrical shaping circuit and a modulator, and an amplitude detector the output of which is the output of the demodulator of signals with amplitude-pulse modulation, as well as the protection unit in the pause, connected between the output of the signal conditioner and the control the input of the balancing unit, in order to reduce signal distortions in the presence of fast fading in the communication channel, between the amplifier output with the automatic gain control circuit and the amplitude detector input, a controlled limiting amplifier is inserted, and between the signal filter input and the control (The interfering filter and the noise voltage detector are introduced by the control input of the controllable limiting amplifier.

Description

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This invention relates to radio shading and may be used in receiving devices.

A signal demodulator with amplitude-pulse modulation is known, comprising a filter, an amplitude detector and an allocation unit Sch.

However, in a demodulator with a presence in the communication channel of fast fading, a splitting of the signal appears.

The closest in technical essence to the present invention is a signal demodulator with amplitude-pulse modulation containing a signal filter connected in series, the input of which is an input of a signal demodulator with aiMp-pulse 1 output, and an amplifier with an automatic gain control circuit, an amplitude detector, a low-pass filter, a balancing unit and signal shaping, the output of which is an output of a demodulator of signals with amplitude-pulse modulation, as well as a protection unit in pause, on chenny between the output of the signals and a control input unit 2. The balance.

However, in a known demodulator of signals with amplitude-modulated modulation, signal distortions are observed in the presence of a fast fading saturation channel, which manifests itself in the form of signal splitting.

The purpose of the invention is to reduce signal distortion in the presence of fast fading in the communication channel.

To achieve a goal in a demodulator of signals with amplitude-impulse modulation, containing successively connected filter signals, whose input is an input of a demodulator of signals with amplitude-pulse modulation, and an amplifier with an automatic gain control circuit, amplitude detector, low-pass filter , a balancing unit and forming a signal, whose output is an output of a demodulator of signals with amplitude-pulse modulation, as well as a block of protection in the parallel, connected between the output of a signal generator A controlled amplifier-limiter is inserted between the output of the amplifier with an automatic gain control circuit and the input of the amplitude detector, and the series-connected noise filter between the input of the signal filter and the control input of the controlled amplifier-limiter and interference voltage detector.

Figure 1 shows a structural electrical circuit of a demodulator.

signals with pulse amplitude modulation; and FIG. 2 shows stress plots explaining its operation.

The demodulator of signals with amplitude-pulse modulation contains a signal filter 1, an amplifier 2 with an automatic control circuit, an amplification (AGC) 3, a controlled amplifier-limiter 4, a noise voltage detector 5, a noise filter 6. noise detector 7, filter 8 low frequencies, block 9 balancing, driver 10 signals, block 11 protection in the pause.

A demodulator of signals with pulse-amplitude modulation operates as follows.

The radio signals are sent to the signal filter, then after filtering the signal from the noise to amplifier 2. The amplifier gain control is controlled automatically by the control voltage supplied through the AGC circuit 3. Since the time constant of the AGC circuit 3 is performed to distort radio signal by distortion and protection from signal pause interferences should be longer than the repetition period of the radio signal pulses, then the AGC circuit 3 does not have time to emit fast fading of the radio signal plates and they appear at the output de amplifier 2 in the form of dips in the radio signal (figure 2; a, dashed line). If these dips are not eliminated, they will appear at the output of the signal demodulator with amplitude-pulse modulation in the form of pulse crushing (Fig. 25, dashed line). Therefore, for the purpose of eliminating crushing, a controlled amplifier-limiter 4 is introduced. Due to a deep limitation, the dips in the radio signal are eliminated (Fig. 2a, splitting line). So, a deep radio signal limitation in the controlled amplifier-limiter 4 adversely affects the noise immunity of the radio signal reception at large levels of interference, and automatic gain control (and hence the depth of the noise level restriction) is introduced into it. Interference filter 6 extracts the interfering component of the spectrum in: one p audio signal. After detecting interference in the voltage detector 5, the control voltage control (DC) is used to adjust the gain of the controllable limiting amplifier 4. At the HIGH noise level, the controllable limit amplifier 4 operates in a linear mode, without compromising noise immunity receive radio signals. Thanks to automatic adjustment

the gain in noise level of the controlled amplifier limiting forkshravatel 10 triggers in the event that the output signal level exceeds the level of interference, i.e. The next threshold for triggering FSHIM 10 is affected by the level of interference. . The radio signal from the output of the controllable limiting amplifier 4 is fed to an amplitude detector 7, which conducts the radio bend, and then to a low-pass filter 8 which suppresses high-frequency noise. From the output of the filter 8, the lower signal is fed to the balancing unit 9, which provides a symmetrical arrangement of the signal relative to

Shaper 10 Trigger Shaper 10 provides, at the output of a demodulator of signals with amplitude-pulse modulation, a pulse signal with a large slope.

S fronts. The pause protection unit 11 protects a demodulator of signals with amplitude-pulse modulation against interference in the case of a long pause.

10 As a result of tracking the fast fading in the proposed signal demodulator with amplitude-pulse modulation, a sufficiently high interference tolerance is achieved, which leads to a significant technical and economic effect.

Claims (1)

SIGNAL DEMODULATOR WITH AMPLITUDE-PULSE MODULATION, containing a signal filter connected in series, the input of which is an input of a signal demodulator with pulse-amplitude modulation, and a amplifier with an automatic gain control circuit, an amplitude detector, a low-pass filter / signal balancer and signal former, output which is the output of a signal demodulator with pulse-amplitude modulation, as well as a pause protection unit connected between the output of the signal generator and the control input m of a balancing unit, characterized in that, in order to reduce signal distortion in the presence of fast fading in the communication channel, a controlled amplifier-limiter is introduced between the output of the amplifier with an automatic gain control circuit and the input of the amplitude detector, and between the signal filter input and the control input of the controlled an amplifier-limiter, a series-connected interference filter and an interference voltage detector are introduced. next to cx> next