SU815964A1 - Facsimile signal simulator - Google Patents

Description

(54) SIMULATOR OF FAX SIGNALS

The invention relates to radio engineering and can be used to control and adjust receiving phototelegraph equipment.

A facsimile signal simulator is known, comprising a reference frequency generator, a modulator, a first frequency divider, the output of which is connected to the input of the second frequency divider and the first input of the phase pulse former, and an attenuator 1.

However, the known simulator has low accuracy and a variety of signals.

The purpose of the invention is to increase the variety of simulated signals and their accuracy.

The goal is achieved by introducing the third and fourth frequency dividers into the facsimile signal simulator, a digital-to-analog converter (DAC), two control units, a switch and a trigger, while the output of the reference frequency generator is connected to the input of the third frequency splitter, the output of which is connected to the first input of the module the torus and the input of the first frequency divider, and to the first input of the fourth divider

frequency, the reference frequency generator input is connected to the output of the first control unit, the input of which is connected to the output of the DAC, and the input of the DAC is connected to the first input of the second control unit, to

the second input of which is connected to the output of the first frequency divider, and to the output of the phase pulse former, to the second input of which is connected the output of the second frequency divider and the second input of the fourth

frequency divider, to the third input of which a trigger of the phase pulse generator is connected via a trigger, and the output of the fourth frequency divider is connected to the first input of the switch, the second input of which is connected to the input of the DAC, the third input is the second input of the second control unit, the fourth input of the switch is connected via an attenuator to the output the second control unit; the switch output is connected to the second input of the modulator.

The drawing shows a structural electrical circuit of the proposed simulator.

The facsimile signal simulator contains a reference frequency generator 1, a modulator 2, a first 3, a second 4, a third 5 and a fourth 6 frequency dividers, a phase pulse former 7, an attenuator 8, a digital-to-analog converter (DAC) 9, a GO and 11 control blocks, a switch 12 trigger 13.

The simulator works as follows.

The reference signal from the output of the generator 1 is fed to the input of the third divider 5, from the output of which the carrier signal goes to the modulator 2 and the first divider 3, then the signal goes to the second divider 4 and shaper 7.

The signals from the output of the second divider 4 are used to control the operation of the fourth divider 6 and to separate the phase pulse in the driver 7.

These signals are rectangular pulses, the duration of which is equal to the period of the clock frequency, and the period of the unwinding, and the pulses are shifted relative to each other by the period of the clock frequency. The signal of the reference frequency from generator 1 is fed to the input of the fourth divider 6. Thus, during one sweep period, the frequency of the signal at the output of the fourth divider 6 changes stepwise as many times as the clock frequency is higher than the frequency of the sweep, i.e. the number of signal groups for The resolution checks are determined by the division ratio of the second divider 4, and one of the pulses from its output is taken as zero and serves to receive the phase signal in the shaper 7, one of the inputs of which is supplied with a clock frequency, and on the other, a zero pulse from the output of the second divider 4. At a time corresponding to the passage of the phase pulse, the division factor of the fourth divider b is set so that the signal frequency at its output becomes equal to one of the phase pulse modulation frequencies.

A trigger 13 is applied for time division transmission. A phase signal from the driver output 7 is applied to the input of the trigger 13 operating in the frequency division mode.

A controlled attenuator 8 with a block 11 is designed to form a halftone wedge signal. The generated halftone wedge signal varies according to a logarithmic law and consists of 16 stages with intervals of 2 dB between them.

The signal of the resolution of the output of the fourth divider 6, the signal of the phase from the output of the driver 7 and the signal of the halftone wedge from the output of the attenuator 8 arrive at the switch 12, the signal from the output of which goes to the modulator 2.

In addition, to separate the groups of pulses simulating the signals for checking the resolution, the clock pulses in the form of square positive pulses with a duty cycle of two are supplied to the input of the switch 12 from the output of the first divider 3.

When reproducing the staggered -Field signal, a clock signal is applied to the input of the modulator 2, the phase of which changes to the opposite one over a time interval during which n sweep periods occur. The simulator output signal continuously contains a phase pulse, which corresponds to the real signal of an artificial satellite of the Earth, in which the phase pulse is not excluded.

From the output of the imaging unit 7, a phase pulse is applied to the DAC 9, the linearly increasing step voltage from the output of which is applied to the unit, 10, due to personnel), the frequency of the Heater 1 is tuned and distortions of the output of the simulator appear, similar to the distortions arising from the effect Doppler. The number of bits of the D / A converter 9 is chosen so that the complete cycle of changing the frequency of the oscillator 1 occurs in the time corresponding to the transfer of one blank.

The proposed simulator makes it possible to simulate signals from a satellite and thereby check the corresponding reception equipment.

Claims (1)

Invention Formula A facsimile signal simulator containing a reference frequency generator, a modulator, a first frequency divider, the output of which is connected to the input of the second frequency divider and the first input of the phase pulse former, an attenuator, characterized in that, in order to increase the variety of simulated signals and their accuracy, a third and the fourth frequency dividers, a digital-to-analog converter, two control units, a switch and a trigger, while the output of the reference frequency generator is connected to the input of the third frequency splitter, the output of which It is connected to the first input of the modulator and the input of the first frequency divider, and to the first input of the fourth frequency divider, the input of the reference frequency generator is connected to the output of the first control unit, the input of which is connected to the output of the digital-to-analog converter, and the input of the digital-analog converter is connected to the first input of the second block control, to the second input of which the output of the first frequency divider is connected, and to the output of the phase pulse former, to the second input of which the output of the second divider is connected and the second input of the fourth frequency splitter, to the third input of which, via a trigger, the output of the phase pulse former is connected, and the output of the fourth frequency splitter is connected to the first input of the switch, the second input of which is connected to the input of the digital to analogue converter, the third input to the second input of the second control unit The fourth input of the switch is connected via an attenuator to the output of the second control unit, the output of the switch is connected to the second input of the modulator. Sources of information taken into account in the examination 1. US Patent No. 3489849, cl. H 04 N 1/00, H 04 N 7/00, 1976 (prototype).