SU1133671A1 - Device for protecting againts pulse noise - Google Patents

Abstract

yCTPCtfiCTBO PUSH PROTECTION, containing in series a first delay element, the input of which is the device input, and a key, the code of which is the device output, the amplitude detector, the input of which is connected to the device input. and a second delay element, characterized in that, in order to increase the interference with extended pulse interference, an attenuator is introduced into it, the input of which is connected to the output of the second delay element made N-tapped, the OR element whose output is connected to the controller Jup their key input, N subtractors, the first input of each of which is connected to the corresponding tap of the second delay element, N comparators, the input of each of which is connected to the output of the corresponding subtractor, and the output is connected to the corresponding vuyuschim input element (A OR, second inputs of subtractors soes: dineny yield attenuator and the second delay element input coupled to the output 00 of the amplitude detector 00 1.

Description

"1 The invention relates to radio engineering and can be used in the processing of complex signals in the presence of impulse noise of a small duty cycle. A device for protection against impulse noise, containing a series-connected delay element and a key, is known. Between the input of the delay element and the control input of the switch, an amplifier with an AGC, an amplitude detector and a blocking pulse shaper L are connected in series. However, this device is not efficient enough because it cannot provide detection of impulse noise with a low duty cycle with sufficiently high reliability. The closest in technical essence to the invention is an impulse noise protection device comprising a serially connected first delay element whose input is the device input and a key whose output is the device output, the amplitude detector, the input connected to the device input, and the second delay element, adder, filter, time unit, and sampler 2J. However, the use of the proposed device under conditions of pulsed noise with a low duty cycle, leads to a high probability of a pulse signal being transmitted, and, consequently, to a deterioration of the noise immunity. The purpose of the invention is to improve noise immunity in relation to extended pulse interference. The goal is achieved by the fact that a protection device against impulse circuits containing a first delayed element connected in series, whose input is the input of the device and a key whose output is the output of the device, a fflly detector, the input of which is connected to the input of the device, and the second delay element, an ator is entered, the input of which is connected to the output of the second delay element made by the N-tap; the lH element whose output is connected to the control input of the key, N subtractors, the first input of each of They are connected to the corresponding output of the second delay element, N comparators, each input is connected to the output of the corresponding subtractor, and the output is connected to the corresponding input of the OR element, the second inputs of the subtractor are connected to the output of the attenuator, and the input of the second delay element is connected to the output of the amplitude the detector. The drawing shows a structural electrical circuit of the proposed device. The device for protection against impulse noise contains the first delay element 1, key 2, element W 3, amplitude detector 4, second delay element 5, attenuator 6, attenuator 7, comparators 8. The impulse noise protection device operates as follows. . The radio frequency input process, which is an additive mixture of a complex useful signal, noise and impulse noise, is simultaneously fed to the inputs of the first element 1 and the amplitude detector 4. From the output of the amplitude detector 4, the instantaneous envelope is fed to the second delay element 5, from each equal distance which is then fed to the inputs of the subtractors 6, and from the output of the second delay element 5 after attenuation, the attenuator 7 is applied C times to the second inputs of the subtractors 6. With the help of the comparators 8, it is checked The sign of the differential output signal 6. vychitatoley. . - If at least one of the difference signals is positive, then it arrives at the corresponding input of the SHSh 3 element, and the key 2 is locked, i.e. At this point, a decision is made on the presence of a pulse interference. Considering that the total delay time of the second delay element 5 and the first delay element 1 is the same, key 2 produces the blanking of the impulse noise contained in the input process at the required time. For normal operation of the device, it is necessary that the number of positions of a complex signal ttrevtalo number of taps of the second delay element 5. The operation of an impulse noise detector included in the device containing the second element 5 is delayed 31

ki, subtractor 6, attenuator 7, comparators 8 and the element OR 3, can be described by the following explanations: a decision is made about the presence of impulse noise in the K-th element if at least one of the following inequalities is fulfilled:

С .0 С Ujj-U.jyO

Soo,

where C is the attenuator transfer ratio 7, which determines the likelihood of a false detection of F pulse interference;

Uj voltages at the Kth tap of the second delay element 5.

The value C for normal interference is determined by the expression C F / N (1-F), for example, for F 10 and N 5 C 2.22 OR. In this case, the probability of correct detection of impulse noise is equal to

D "C (Mjf + L) / H-C (Mjf ++ L),

1336714

where L is the number of resolution elements affected by impulse noise; M N-L;

jf is the power ratio of the mixture j. impulse noise and noise to power pumas.

Calculations showed that with L / N 0.5 and U 10 dB,, 5.

An analysis of the results also suggests that the proposed device provides effective detection and suppression of extended impulse noise, the duration of which, expressed in resolution elements, does not exceed the value of L 4 N-1, while the known device effectively works only in the case of the duration of the interference equal to one element of the range resolution (L 1).

Thus, the proposed device provides for the effective suppression of the pulse-like interferences with a time-to-time ratio that have a low duty cycle.

Claims (1)

PULSE INTERFERENCE DEVICE, comprising a first delay element connected in series, the input of which is the input of the device, and a key whose output is the output of the device, an amplitude detector, the input of which is connected to the input of the device, and a second delay element, characterized in that, for the purpose of to increase the noise immunity with respect to extended pulse interference, an attenuator is introduced into it, the input of which is connected to the output of the second delay element made by the N-tap, OR element, the output of which is inen with a key control input, N subtractors, the first input of each of which is connected to the corresponding tap of the second delay element, N comparators, the input of each of which is connected to the output of the corresponding subtractor, and the output is connected to the corresponding input of the OR element, the second inputs of the subtractors are connected to the output of the attenuator, and the input of the second delay element is connected to the output of the amplitude detector. >