SU815970A1 - Pulse signal discriminating device - Google Patents

Description

(54) DEVICE FOR ISOLATING PULSE

SIGNALS

I

The invention relates to radio engineering and can be used in transmission and processing systems of signals for the separation of information pulses from noise and impulse noise.

A device for isolating pulsed signals is known, comprising an amplifier, a serially connected first adder, an amplitude discriminator, a second adder, a differentiating circuit, a threshold element and a standard duration pulse shaper, the first input of the first adder through the serially connected first delay line and an inverter connected to the second input of the first adder , each of the second amplitude discriminator through the second delay line is connected to another input of the adder 1.

However, such a device has a low noise immunity when exposed to multiplicative interference.

The purpose of the invention is to improve noise immunity.

The goal is achieved by the fact that in a device for extracting pulse signals, containing an amplifier, a series-connected first adder, an amplitude

a discriminator, a second adder, a differentiating circuit, a threshold element and a pulse shaper of standard duration, the first input of the first adder through a serially connected first delay line and the inverter is connected to the second input of the first adder, another output of the amplitude discriminator through the second delay line is connected to another input of the second adder, Inserted series allocation unit.

0 envelope and headband unit, as well as a third delay line and an isolator connected in series, the input of the third delay line and the input of the envelope selection unit are combined and connected to the amplifier output, the output of the limiter is connected to the first input of the first adder, the outputs of the scale unit are connected to others inputs respectively cutter and threshold element.

The drawing shows the electrical circuit diagram of a device for extracting pulse signals.

The device contains an amplifier 1, the first adder 2, the amplitude discriminator 3, the second adder 4, differentiating

circuit 5, threshold element b, shaper 7 pulses of standard duration, first delay line 8, inverter 9, second delay line 10, envelope selection block 11, scale unit 12, third delay line 13, limiter 14.

The device works as follows.

A pulse signal, struck by modulating, pulsed and noise interference, is fed to amplifier 1 and from its output to the inputs of the third delay line 13 and the envelope allocation unit 11. The envelope extraction unit 1 selects the signal envelope, for example, by peak detection. The constant time of the envelope selection block 11 is chosen such that during the envelope selection process it does not respond to interference pulses with durations shorter than the duration of information pulses. The selected envelope voltage is filtered in the scale unit 12 and fed to the control input of the limiter 14. At the same time, the envelope voltage on a scale of one to one repeats the change in amplitude of the input signal. The third delay line 13 delays the input signal by the time required to receive and form the envelope voltage in blocks 11 and 12. Restrictor 14 restricts the inlet mixture from above according to the law of variation of the control voltage of the envelope. This operation allows you to avoid short impulse signals with amplitudes exceeding the amplitude of useful pulses entering the path of further signal processing.

From the output of limiter 14, the signal is applied to the inputs of the first adder 2 and the first delay line 8. The signal delayed by half by the duration of the information signal by the delay line 8 and the inverted 9 signal with noises and impulse noise enters the second input of the first adder 2. As a result of the first summing operation, the overlapping parts of the information signal and the part of the noise whose correlation time of the spectral components is longer half the duration of the information pulse. The impulse noise is not destroyed by the first summation. For further processing, a signal with partially suppressed noise is fed to an amplitude discriminator 3, which separates it into positive and negative pulses at a zero level. The positive polarity signal passes the second delay line 10, which, like the first one, delays the input signal by half the information pulse duration and goes to one of the inputs of the second adder 4.

The negative polarity signal from the output of the amplitude discriminator 3 is supplied

directly to the other input of the second sumgmator 4. As a result of the second summation, there is a complete suppression of the noise components, as well as impulse noise, since the correlation coefficient

The summed signals are equal to minus one, i.e., impulse noise and sound noise coincide completely in the temporal position and are opposite in sign. The output of the second adder 4 does not suppress the pulse interference, which is separated from the information pulse by a time equal to half the useful pulse duration from both the leading and trailing edges of the pulse. Final pulse rejection

It is carried out by differentiation of the signal by differentiating circuit 5, followed by limiting the signal to the level in threshold element 6.

The limit threshold varies in accordance with the change in the envelope of the input signal and exceeds the instantaneous amplitude of the signal by 1.5-1.8 times. The formation of this voltage produces a scale unit 12. Changing the limiting threshold according to the law of variation of the envelope of the input signal makes it possible to avoid on one side the passage of interference pulses to the driver 7 pulses of standard duration. On the other hand, cases of non-separation of useful differentiated signal pulses due to exceeding the threshold of their amplitude are excluded. Since, when differentiating a signal, the derivative of the difference between the positive and negative parts of the information pulse has one sign, they 5 pulses of the result of differentiation exceed the amplitude of the pulses of the original signal in the ideal case twice. Real differentiation taking into account fluctuations of pulse fronts under the influence of

 noise gives a slightly smaller value of the pulse amplitude. As a result, the most appropriate limitation threshold is maintained at 1.5-1.8 times the instantaneous amplitude at the input of the differentiating circuit 5.

With such an extraction of the useful signal, a selection is made, of pulses in duration, for pulses with a duration longer than the duration of information pulses during differentiation are not

0 give double amplitude and do not exceed the limit threshold. The shaper 7 pulses of standard duration of the pulses that have passed the threshold element 6, generates pulses of the desired duration.

 The proposed device for extracting pulsed signals has an increased noise immunity to the effects of noise and impulse noise and makes it possible to eliminate

Claims (1)

Claim Device for allocation of pulse signals, the amplifier comprising serially connected first adder am- plitudny discriminator _10, a second adder, a differentiating circuit, the threshold element and the generator of standard duration pulses, the first input of the first adder via a serially coupled first delay line and an inverter ¹⁵ is connected to a second the input of the first adder, another output of the amplitude discriminator through the second delay line is connected to another input of the second adder, characterized in that, for the purpose of To improve noise immunity, a series-connected envelope separation unit and a scale block are introduced, as well as a third delay line and a limiter connected in series, while the input of the third delay line and the input of the envelope separation unit are combined and connected to the amplifier output, the limiter output is connected to the first input of the first adder, the outputs of the scale block are connected to other inputs of the limiter and threshold element, respectively.