SU1760632A1 - Impulse-noise compensation method - Google Patents

Abstract

Usage: radio engineering, coherent processing of broadband signals. SUMMARY OF THE INVENTION: when interference is disrupted from the sum of the signal and interference, coherent accumulation of interference sections occurs with its phase and amplitude carrier, which is ensured, in particular, by gating the interval T by discrete duration g, where T and r are the repetition period and the duration of the radio pulse envelope interference, respectively, when this occurs, the compensation of coherent-pulse interference with a comb spectrum. 2 Il.

Description

The invention relates to radio engineering, in particular, to the technique of processing signals, and can be used in pulse-Doppler systems for suppressing radio-frequency interference with a comb spectrum in the form of coherent radio-pulse sequences of several interfering reflections, the level of which substantially exceeds the dynamic range of useful signals.

Compensatory methods for suppressing impulse noise are known, consisting in isolating the voltage of an interference from a voltage containing the sum of the signal and interference, and subtracting interference from the last isolated voltage to interference in the form of a short-term video pulse with a wide smooth spectrum that excites the resonant circuits of the receiving path, While the useful signal has a narrow line spectrum, the interference is produced using band-pass filters that are frustrated over the signal band but have an frequency response that are identical. e with a filter that extracts the useful signal.

However, these methods are unsuitable for isolating and compensating for radio pulse interference with a comb spectrum.

The aim of the invention is to compensate for coherent-pulse noise with a comb spectrum when receiving broadband useful signals with a comb spectrum that does not coincide with the interference spectrum, although the interference pulses may coincide with the signal pulses.

The essence of the invention is that the emission of radio-frequency noise with a comb spectrum is produced by narrow-band filtering at the carrier frequency of the radio-frequency interference after subtracting independently at each interval of the coincidence of the radio-pulse interference envelope with gating pulses in parallel q T / g times by strobes

S

about so

neither the filtered signal by the same gates before and after each 1st filtering (I 1,2, .. q), for which they form q sequences of rectangular strobe pulses with duration g and repetition period T, with strobe pulses i- The second sequence is delayed with respect to the strobe pulses (S) of the sequence for a period of time. After each 1st filtering and gating, before subtraction, interference is amplified, which ensures that the amplitude of the radio pulse is compensated for in each i-th gating interval, and behind the mismatch of carrier signals of the signal pulses and the interference, although they may coincide in time, the signal is not extracted or compensated.

Such a technical solution provides not only the realization of the purpose of the invention, but also automatic compensation of radio pulse interference both when the gain is changed and when the pulse ratio of the radio pulse noise q changes.

FIG. 1 shows a block diagram of a device implementing a method for compensating radio pulse interference; in fig. 2 - time diagrams that show his work.

The device (Fig. 1), which implements the method of compensation of radio pulse interference, consists of a subtractor 1, an interference generator 2, an amplitude detector 3, a comparator 4, a q-channel generator 5 of square pulse sequences, q logic elements And 6, and a driver Interference 2 consists of q parallel channels, each of which contains a chain of series-connected input multiplier (key) 7, narrowband filter 8 and output multiplier (key) 9, and amplifier 10, whose input is connected to the outputs of all q parallel channels, and the output with the second input of the subtractor 1, the output of which is also connected to the inputs of all q parallel channels.

The device (Fig. 1), which implements the method of compensation of radio pulse interference, works as follows.

The input of the device receives the sum of the radio pulses of the signal and interference (Fig. 2, a):

Vbx uce

jWct

+ 2UnreJ (Wnt + CDnr)

g 1

where Uc, Unr are the envelopes of the radio pulses of the signal and the r-th interference respectively. We, Wn are the frequencies of their carriers, Fpg is the carrier phase of the r-th interference, M is the number of radio pulse interference sequences.

The interference voltage is released in the driver 2 from the output voltage of the subtractor 1, while at any gating interval of the 1st channel of the driver 2, when the keys 7 and 9 are open, the negative feedback loop is closed, and the output voltage in the steady state is determined is expressed

VBb.x VBX / {1 + NFOOLML / f) K / qi. where K is the gain in each channel of the driver 2, together with the amplifier 10, q is the gating duty cycle,

H (() is the normalized frequency response of the narrow-band filter 8, UUf is its resonant frequency (at W L / f Nf (0) 1. Therefore, if the sum of the signal and interference at the device output is received at the device input, we get

VBblx UcejWct / {1 +) K / d} +

+ 2Lfnrej (Wnt + CDnr / {1 +) K / h}.

r 1

All filters 8 are narrowband and tuned to the L / f frequency of the Wn interference, therefore H0D (Wn-Wn) - NF (0) 1, (Wc-Wn) “1 and

Wow UcejWct + 2 Unrej (Wnt + CDnr / {1 + K / a}).

g 1

Thus, the signal at the output of the device passes almost unchanged, and the interference in the gating interval with zero detuning is maximally compensated and suppressed 1 + K / q times (Fig. 2, s). The compensation error is

b 1 / (1 + k / q),. and the required gain factor

K-q (1-d),

which is mainly implemented in amplifier 10. Thus, with b 0.01 and q 10 K 990, that, when amplifying multipliers (keys) 7 and 9, equal to 3 in each, requires amplification in

amplifier 10 equals 110, which is quite realizable.

Strobe pulses (Fig. 2, k, l, m, n, n) are formed at the coincidence intervals of the radio pulse envelope received at the output of the amplitude detector 3 (Fig. 2.6) and normalized in amplitude at the comparator 4 (Fig. 2, c) with sequences of video pulses of the corresponding channels of the generator 5 (FIG.

2, g, d, e, g, and), spaced over the pulse duration g, with the help of the corresponding logic elements I 6, producing strobe pulses at their outputs only with the simultaneous presence at their inputs of the pulses from the output of the comparator 4 and from the corresponding output generator 5, which, when gating the filter channels of the driver 2, allows the output of amplifier 10 to compensate radio pulses at the frequency of interference, which coincide with the corresponding radio pulses of interference to the first input of the subtractor 2 (Fig.

2, P).

The reference voltage U0, applied to comparator 4, determines the level of its response from the envelope of the radio impulses. This level can be permanently set so that the normalized interference video pulses are generated only when the radio interference envelope level exceeds the maximum output radio signal impulse level (Do UCM), which is allowed at the output of the device of FIG. 1. In this case, at lower levels of interference, the compensation is turned off, since gating pulses are not generated. At the Uo UCM exhibition, gating pulses will also be generated at intervals of action of pulses of useful signals exceeding Uo, but compensating radio pulses will not occur at the output of shaper 2, since radio pulses of useful signals do not coincide in frequency with the setting of narrow-band filters 8.

Claims (1)

The use of the invention will significantly increase the noise immunity of the receiving paths of the pulse-Doppler systems from radio pulse interference (interfering reflections) at a high (intermediate) frequency, while ensuring synchronism of the compensator with a pulse repetition rate due to the fact that the formation of probe and gating pulses and the reception of signals mc in these systems in one place. A method for compensating radio pulse interference, based on subtracting radio pulse noise, obtained by filtering an additive mixture of a signal and radio pulse interference, characterized in that, in order to compensate for coherent pulse noise with a comb spectrum, filtering is performed after subtracting in parallel q T t times, where T and t are the repetition period and the duration of the radio pulse interference envelope, respectively, form q sequences rectangular pulses of duration G and repetition period T, rectangular pulses of the i-th (i 1,2, ... q) sequence of rectangular pulses delay relative to rectangular pulses (i-1) and the sequence of rectangular pulses by time t, Before each 1st filtering, the filtered signal is strobed for the time of coincidence of the envelope of the radio pulse interference with the rectangular pulses of the 1st sequence of rectangular pulses, and before subtraction, the signal selected at each i-th filtering is gated with the same signals as before the 1st filtering by rectangular pulses and amplify K q (1 - e) times, where g is the nominal error of compensation. Evil g-sh Fig. 1 -out . I. I I and frwft LflL -UiiL. -i, t-pYJTp ILfl I Uli