SU497707A2 - Simulator of errors in the binary communication channel with fading - Google Patents

Description

one

The invention relates to radio engineering and can be used in simulating real fading channels.

According to the main author. St. No. 363174 is known to simulate errors in a binary communication channel with fading.

The purpose of the invention is to provide imitation of errors in the channel with Rays fading.

To do this, a serially connected sinusoidal oscillator, an attenuator and an adder connected between the output of the noise generator and the input of the narrowband filter are introduced into the simulator.

The drawing shows a block diagram of the simulator.

It consists of an input device 1, an adder 2 modulo two, an output device 3, a noise generator 4, a limiter 5 with a controlled threshold, a narrowband filter 6, an amplitude detector 7, an amplifier 8, a coincidence circuit 9, a synchronizer 10, an error generator 11 , the switch 12, the metering device 13, connected in series to a sinusoidal oscillator 14, an attenuator 15 and an adder 16, / connected between the output of the noise generator 4 and the input of the narrowband filter 6.

Simulator. Works as follows.

The source of binary information through the input device 1 is fed to one input of the modulo two adder, which, depending on the presence or absence of error pulses at the second input, transmits a pulse of information through the output device 3 to the input of the binary information, respectively, in the transformed (erroneous) form or without distortions.

The input device 1 coordinates the simulator with various sources of binary information, and the output device 3 coordinates the output of the simulator with the inputs of various information receivers.

Noise generator 4 generates broadband noise oscillations, which are fed to limiter 5 with a controlled threshold, generating a sequence of random pulses corresponding to the moments of emission of noise oscillations beyond the limitation threshold. The average frequency of occurrence of these pulses depends on the threshold set, so that when it changes, the individual pulses in the sequence follow, grouped together in bundles, thus achieving an imitation of errors in non-stationary communication channels. A random sequence of pulses from the output of limiter 5 is fed to one input of the coincidence circuit 9, to the other input of which clock pulses are supplied from the synchronizer 10, which generates them under the influence of information pulses received at the input of the synchronizer 10 from the input device 1. The coincidence circuit 9 at the moments of pulse coincidence at its inputs, it produces short pulses that are fed further to the error pulse shaper AND, which produces error pulses corresponding to the transit time through the adder a modulo two pulses distort information. Pulses of errors from the imager come to the second input of the modulo two adder, which transforms the passing pulses of binary information to opposite ones, thus introducing errors into the binary information passed through the simulator. The error pulses from the driver and the clock pulses from the synchronizer 10 are also supplied to the calculating indicator device 13, which serves to monitor the passing information and the errors introduced into it.

The oscillations of the noise generator 4 are also transmitted to one input of the adder 16, to the other input of which sinusoidal oscillations are received from the generator of sinusoidal oscillations 14 through an adjustable attenuator 15. From the output of the adder 16 a mixture of noise and sinusoidal oscillations passes through the narrow-band filter 6 to the amplitude detector 7, which allocates a voltage proportional to the envelope of the narrow-band random process at the output of the narrow-band filter 6. Through the amplifier 8 and the switch 12, which is in position a, this voltage is It is applied to the control input of the limiter 5, which determines its threshold for restriction and thereby simulates fading in the communication channel. A sinusoidal oscillation generator 14 generates sinusoidal oscillations at a frequency that falls within the passband of the narrowband filter 6. These oscillations pass through the narrowband filter 6 along with the noise fluctuations in the corresponding frequency band. Since the envelope

the sums of harmonic oscillations and normal noise, obtained at the output of the narrow-band filter, are distributed according to the generalized Relay law, in this case they are imitated

Rissian fading.

The fading rate of the signals and their average intensity are selected by adjusting the bandwidth of the narrowband filter 6 and the gain of the amplifier 8. The parameter of the district fading characterizing the relative regular component of the signal in the communication channel is adjusted by adjusting the level of sinusoidal oscillations by means of an adjustable attenuator 15. The attenuator is in the initial position 15 has a transmission coefficient equal to zero, i.e., does not allow sinusoidal oscillations of the generator of sinusoidal oscillations 14 per sou mmator 16. Since only noise oscillations, whose envelope is distributed according to the Relay law, pass to the output of a narrow-band filter 6, Rayleigh fading is imitated in this case. In position b of switch 12, the supply is possible

to the control input of the constant voltage limiter 5, which imitates the operation of communication channels without fading, or from alternating voltages from external sources to simulate communication channels in other conditions,

for example, under the conditions of prolonged impulse noise, interference from broadcasting stations, under intermittent communication conditions.

Subject invention

Error simulator in a binary channel with fading on auth. St. No. 363174, distinguished by the fact that, in order to ensure errors in the channel with regional fading, serially connected sinusoidal oscillator, attenuator and adder connected between the output of the noise generator and the input of the narrow-band filter are introduced.