RU2208294C2 - Noise killing device - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: noise killing device that may be used in duplex control channels and burst on-line command radio-communication links has broadband intermediate-frequency amplifier, narrow-band noise suppressor incorporating n parallel channels, counter, adder, matching filter, two parallel-to- serial code converters, clock generator, decoder, two frequency-spectrum compression units each incorporating flip-flops, coincidence units, counters, heterodynes, and mixers. EFFECT: enhanced noise immunity in reception. 1 cl, 3 dwg

Description

 The invention relates to the field of radio engineering and can be used mainly in duplex radio control channels and packet radio networks of command-and-control communications and position areas under the influence of narrow-band interference.

 A device for suppressing narrow-band interference (for example, AS USSR 754681, N 04 V 1/10), containing n connected in series self-tuning notch filters. However, this device, along with interference, suppresses part of the spectrum of the useful signal.

 A device is also known in which a comb of switched filters is used to suppress narrowband interference (A.S. USSR 720730, Н 04 В 1/10).

 The disadvantage of such a device is its complexity due to the presence of a comb of narrow-band switched filters, and additional electrical losses caused by the non-identity and time instability of the amplitude and phase-frequency characteristics of individual filters.

 Closest to the technical nature of the claimed object is a device for suppressing narrow-band interference, given in the book: Interference immunity of radio networks with complex signals / Ed. G.I. Tuzova. - M .: RIS, 1986, p. 211, Fig. 7.3a, taken as a prototype.

In FIG. 1 shows a structural diagram of a prototype device, where the following notation is introduced:
1 - broadband amplifier of intermediate frequency (UPCH);
2 - narrowband jammer (protection unit);
3 - adder
4 - matched filter;
5 ₁ -5 _n - narrow-band amplifiers of intermediate frequency;
6 ₁ -6 _n - elements for suppressing narrowband interference;
7 - multiplier;
8 - integrator;
9 - reference signal generator.

The prototype device has the following functional relationships: broadband UPCH1, the input of which is the input of the device, the output is connected to the input of the suppressor of narrowband interference 2, consisting of n parallel channels, each of which contains serially connected narrowband UPCH5 ₁ and the suppression element of narrowband interference 6 ₁ , with this inputs narrow-band UPCH5 ₁ -5 _n are interconnected; The n outputs of the narrow-band jammer 2 are connected respectively to the n inputs of the adder 3, the output of which is connected to the input of the matched filter 4, consisting of a series multiplier 7 and an integrator 8, the output of which is the output of the device, and a reference signal generator 9, the output of which is connected to the second multiplier input 7.

 The device prototype works as follows.

 The adopted SHPS after frequency conversion is fed to broadband UPCH1, where it is amplified to the required value.

The signal amplified in UPCH1 is fed to a narrow-band jammer 2 (narrow-band jammer protection block), consisting of n narrow-band amplifiers 5 ₁ -5 _n and n narrow-band jammers 6 ₁ -6 _n .

где Δf - ширина полосы одного парциального канала;
ΔF - ширина полосы принятого ШПС;
n - число парциальных каналов.With the help of filters included in narrow-band UCHF5, the entire NWB band is divided into n partial channels:

where Δf is the bandwidth of one partial channel;
ΔF is the bandwidth of the received ShPS;
n is the number of partial channels.

 The bandwidth of all n partial channels should be the same and, in addition, the frequency bands of the partial channels should not overlap, therefore, the amplitude-frequency and phase-frequency characteristics of the frequency response and phase response of the noise suppressor is represented as the sum of the frequency response and phase response of individual channels.

The selection of the bandwidth of each partial channel is made in such a way that no more than one narrow-band interference gets into each partial channel. If there is narrowband interference in any of the partial channels, it is suppressed in the suppression elements 6 ₁ -6 _n , which are nonlinear elements operating either in the input mixture restriction mode or in the key mode (the channel is open at low noise levels and closed at high levels of interference).

From n outputs of narrowband interference suppression elements 6 ₁ -6 _{n, the} signal is supplied to the corresponding n inputs of adder 3, where it is summed over the frequency band ΔF = n • Δf. From the output of the adder 3, the broadband signal is supplied to the matched filter 4.

 In the prototype device, both a passive matched filter based on a multi-tap delay line and an active matched filter correlator can be used as a matched filter.

 Using the matched filter 4, the broadband modulation is removed, i.e. folding.

 But this prototype device has the following disadvantages: as a result of the rejection of individual sections of the frequency components, the signal response at the output of the matched filter has a central - main - outlier and numerous side outliers that are comparable in amplitude to the main outlier. When the interference environment changes, the lateral signal emissions at the output of the matched filter 4 change in amplitude and move in time, while some of them disappear, and new ones appear. Under these conditions, the signal is often detected by side outliers, and the mutual synchronization system is subject to constant exits from the tracking mode when the interference environment changes. At the same time, ensuring a given noise immunity of the communication system is very problematic, since the amplitude of the side emissions is less than the amplitude of the main emission, that is, the noise immunity of the reception is reduced.

 To increase the noise immunity of receiving into a noise suppression device containing a broadband intermediate-frequency amplifier, the input of which is the input of the device, and the output of the intermediate-frequency amplifier is connected to the input of the narrow-band jammer containing n partial channels, each channel consists of a narrow-band amplifier connected in series intermediate frequency and narrowband interference suppression element, and all inputs of narrowband intermediate frequency amplifiers are connected between among themselves and with the output of broadband amplifier of intermediate frequency; as well as a series-connected adder and a matched filter, consisting of a series-connected multiplier, the first input of which is connected to the input of the matched filter, and an integrator, the output of which is the output of the device, and a reference signal generator, the output of which is connected to the second input of the multiplier, the first and second parallel-to-serial converters, sequentially connected in series with a clock generator, connected by a second output to the input of the first counter, K outputs otorrhea connected to the K inputs of the decoder, and first and second compression blocks of the frequency spectrum; moreover, the outputs of the first group of narrow-band amplifiers of intermediate frequency from the first to n / 2 are connected respectively to the second, signal inputs of the mixers of the first compression unit of the frequency spectrum, and the n outputs of the second group of narrow-band amplifiers of intermediate frequency from n (2 + 1) to n are connected respectively to the second , the signal inputs of the mixers of the second compression unit of the frequency spectrum.

 The outputs of the narrowband interference suppression elements of the first group from the first to n / 2 are connected to the n inputs of the first parallel-to-serial code converter, the output of which is connected to the second inputs of the matching blocks of the first compression unit of the frequency spectrum connected to each other, and n the outputs of the narrowband interference suppression elements of the second group from n / 2 + 1 to n are connected to the n inputs of the second parallel to serial code converter, the output of which is connected to the second inputs of the second coincidence blocks interconnected The first unit of compression of the frequency spectrum.

 The synchronized inputs of the first and second parallel code to serial converters are connected to each other and to the first output of the clock generator. In the first and second compression blocks of the frequency spectrum, each of which contains n / 2 parallel channels, the inputs of the triggers of the first, second,. . . and n / 2 channels are interconnected in pairs and each pair is connected to one of the corresponding K outputs of the decoder. In addition, the trigger output is connected to the first input of the coincidence unit, the output of which is connected to the input of the second counter, K outputs of which are connected to the first heterodyne input of the mixer, the output of which is connected to one of the n inputs of the adder.

In FIG. 3 shows a functional diagram of the proposed device, where the following notation is introduced:
1 - broadband amplifier of intermediate frequency (UPCH);
2 - narrowband jammer (narrowband jammer);
3 - adder
4 - matched filter,
5 ₁ -5 _n - narrow-band amplifier of intermediate frequency (UPCH);
6 ₁ -6 _n - elements for suppressing narrowband interference;
7 - multiplier;
8 - integrator;
9 - reference signal generator;
10 - clock generator;
11 - the first counter;
12 - decoder;
13 ₁ and 13 _n - the first and second converters of parallel code into serial;
14 ₁ -14 _{n / 2} - triggers,
15 ₁ -15 _{n / 2} - coincidence blocks;
16 ₁ -16 _{n / 2} - second counters;
17 ₁ -17 _{n / 2} - local oscillators;
18 ₁ -18 _{n / 2} - mixers;
19 ₁ and 19 ₂ - the first and second blocks of compression of the frequency spectrum.

 The proposed device has the following functional relationships.

A broadband intermediate frequency amplifier (IFA) 1, the input of which is the input of the device, is connected by an output to the input of a narrowband interference suppressor 2, containing n parallel channels, each of which consists of a series-connected narrowband intermediate frequency amplifier 5 ₁ and a narrowband interference suppression element 6 ₁ , wherein all the inputs of narrow-band amplifiers of intermediate frequency 5 ₁ -5 _n are interconnected; in addition, the outputs of the first group of narrow-band amplifiers of intermediate frequency 5 ₁ -5 _{n / 2 are} connected to the second, signal, inputs of mixers 18 ₁ -18 _{n / 2 of the} first compression unit of the frequency spectrum 19 ₁ , and the outputs of the second group of narrow-band amplifiers of intermediate frequency 5 _{n / 2 + 1} -5 _{n are} connected to the second, signal, inputs of the mixers l8 ₁ -18 _{n / 2 of the} second compression unit of the frequency spectrum 19 ₂ ; n outputs of narrowband interference suppression elements 6 ₁ -6 _{n / 2 of the} first group are connected respectively to n inputs of the first parallel-to-serial code converter 13 ₁ , and n outputs of narrowband interference suppression elements 6 _{n / 2 + 1} -6 _{n of the} second group are connected respectively to n inputs of the second parallel to serial code converter 13 ₂ .

The synchronized inputs of the first 13 ₁ and second 13 ₂ parallel-to-serial code converters are connected to each other and to the first output of the clock generator 10, the second output of which is connected to the input of the first counter 11, the K outputs of which are connected to the K inputs of the decoder 12; in the first 19.1 and second 19.2 frequency spectrum compression blocks, each of which contains n / 2 parallel channels, trigger inputs from 14 ₁ to 14 _{n / 2} and from 14 ₁ ¹ to 14 _{n / 2} ^{1 of the} first, second, ... and n / 2 channels are interconnected in pairs (trigger input 14 ₁ with trigger input 14 ₁ ¹ ; trigger input 14 ₂ with trigger input 14 ₂ ¹ , trigger input 14 _{n / 2} with trigger input 14 _{n / 2} '), and each pair connected to one of the corresponding K outputs of the decoder 12; in addition, the trigger output 14 _{1 is} connected to the first input of the matching block 15 ₁ , the output of which is connected to the input of the second counter 16 ₁ , the K outputs of which are connected to the K inputs of the local oscillator 17 ₁ , the output of which is connected to the first heterodyne input of the mixer 18 ₁ , the output which is connected to one of the n inputs of the adder 3; the second inputs of the matching blocks 15 ₁ -15 _{n / 2 of the} first compression unit of the frequency spectrum 19 _{1 are} connected to each other and with the output of the first parallel-to-serial code converter 13 ₁ , and the second inputs of the matching blocks 15 ₁ -15 _{n / 2 of the} second compression block of the frequency spectrum 19 ₂ are interconnected and with the output of the second parallel-to-serial code converter 13 ₂ .

The outputs of the parallel n channels of the first and second compression blocks of the frequency spectrum 19 ₁ and 19 _{2 are} connected to the corresponding inputs of the adder 3, the output of which is connected to the input of the matched filter 4, consisting of a series multiplier 7 and an integrator 8, the output of which is the outputs of the device, the second the input of the multiplier 7 is connected to the output of the reference signal generator 9.

 The proposed device works as follows.

 The frequency spectrum of the received signal in the presence of disconnected cells is compressed to the middle frequency on the right and left (see figure 2). Denote by n the number of cells (partial channels) of the narrow-band interference protection unit (n is most often even, since the spectrum of the FM signal is symmetric with respect to the center frequency). In this case, cells with numbers ≤n / 2 are shifted to the right along the frequency axis, and cells with numbers> n / 2 are shifted to the left along the frequency axis. If the number of disabled cells of the protection unit is more than one, then the average frequencies of each of the cells must be moved to a different number Δf (Δf is the frequency bandwidth of each cell of the protection unit). Thus, it is necessary to calculate the quantity α (i) Δf, by which the frequency spectrum of the cell of the protection unit (BS) should move, i = 1,2 ... n.

где i - исходный номер частотной ячейки БЗ,
i' - номер ячейки БЗ после перенумерации.The calculation algorithm (i) is as follows:
1. Renumbering of individual cells of the KB according to the law:

where i is the initial number of the frequency cell BZ,
i 'is the cell number of the KB after renumbering.

Ячейки БЗ перенумерованы с помощью (1) в виде 1,2,3...n/2 от центральной частоты влево и вправо соответственно. Просматриваются номера i' в порядке возрастания. До первой отключенной ячейки БЗ средние частоты ячеек с номерами i' остаются без изменения, после первой отключенной ячейки частот изменяются на Δf в соответствии с (2), после второй отключенной ячейки - на 2 Δf и т.д. влево и вправо от центральной частоты.The local oscillator frequency is calculated using the formula:

BS cells are renumbered using (1) in the form of 1,2,3 ... n / 2 from the center frequency to the left and right, respectively. The numbers i 'are scanned in ascending order. Until the first disconnected BS cell, the average frequencies of the cells with numbers i 'remain unchanged, after the first disconnected cell, the frequencies change by Δf in accordance with (2), after the second disconnected cell, by 2 Δf, etc. left and right of the center frequency.

 The block diagram of the algorithm is shown in figure 3.

The adopted SHPS after frequency conversion is fed to broadband amplifier 1, where it is amplified to the required value and then fed to the narrowband interference protection unit 2, consisting of n narrowly connected amplifier narrowband amplifiers 5 ₁ -5 _n and n narrowband interference suppression elements 6 ₁ -6 _n .

где Δf - ширина полосы одного парциального канала;
ΔF - ширина полосы принятого ШПС,
n - число парциальных каналов.With the help of filters included in narrow-band UPCh5 ₁ -5 _{n, the} entire NWB band is divided into n narrow bands - partial channels:

where Δf is the bandwidth of one partial channel;
ΔF is the bandwidth of the received SHPS,
n is the number of partial channels.

 Moreover, the bandwidth of all n partial channels should be the same and, in addition, the frequency bands of the partial channels should not overlap. Therefore, the amplitude-frequency and phase-frequency characteristics of the frequency response and phase response of the noise suppressor are presented as the sum of the frequency response and phase response of individual channels.

 In each partial channel, in addition to the narrow-band filter, there is an amplifier with which the attenuation in the filter of its partial channel is compensated. The bandwidth of each partial channel is selected so that no more than one narrow-band interference gets into each partial channel.

If there is narrowband interference in any of the partial channels, it is suppressed in the suppression elements 6 ₁ -6 _n . The narrowband interference suppression elements 6 ₁ -6 _n are non-linear elements operating either in the input mixture restriction mode or in the key mode (the channel is open at low levels of interference and closed at high levels of interference).

From the outputs of the suppression elements of narrow-band interference 6 ₁ -6 _{n / 2, the} signal is sent in parallel binary code to the n inputs of the first converter of the parallel code in serial 13 ₁ , and from the outputs of the suppression elements 6 _{n / 2 + 1} -6 _n to the n inputs of the second parallel to serial converter 13 ₂ .

The clock generator 10 generates pulses with a clock frequency of processing the serial code, which are fed to the clock inputs of the first 13 ₁ and second 13 ₂ converters, and from the other output to the clock input of the first counter 11, which gives the number of the clock to the K outputs with a binary code, which on K inputs it goes to the decoder 12. At one of the n / 2 outputs of the decoder 12 a single pulse appears, which changes the state of the corresponding trigger 14 ₁ -14 ₁ ^{1 of} both compression blocks of the frequency spectrum 19.1 and 19.2 to the active state, the outputs of which are fixed logical unit at specified points in time in accordance with the numbers of the frequency channel BZ.

From the outputs of the triggers 14 ₁ -14 _{n / 2} and the first and second compression units of the frequency spectrum 19.1 and 19.2 are fed to the first inputs of the coincidence units 15 ₁ -15 _{n / 2} , the second inputs of which receive signals from the outputs of the first and second converters 13 ₁ and 13 ₂ respectively. If there are logical units at both inputs of one of the coincidence blocks 15 ₁ -15 _{n / 2} , a logical unit appears at the output. Matching blocks can be performed on AND gates.

From the outputs of the coincidence blocks 15 ₁ -15 _{n / 2, the} signal goes to the inputs of the second counters 16 ₁ -16 _{n / 2,} respectively, from the outputs of which the code of the number of permutations of special components goes to tunable local oscillators 17 ₁ -17 _{n / 2} . This code determines how many partial channels the local oscillator frequency should shift in one direction or another. This frequency of the local oscillator 17 ₁ -17 _{n / 2 is} fed to the heterodyne input of the mixer 18 ₁ -18 _{n / 2} , the signal input of which receives the signal from the corresponding output of the narrow-band amplifier 5 ₁ -5 _n .

In mixers 18 ₁ -18 _{n / 2,} partial channels that were disabled by narrow-band interference suppression elements 6 ₁ -6 _n are excluded, and the remaining channels are moved to the center of the frequency spectrum, as a result of which the frequency spectrum is compressed, gaps are eliminated in it and it becomes uniform (see Fig. 2), which leads to a significant decrease in lateral components, and this, in turn, leads to increased noise immunity.

Claims (1)

 A noise suppression device comprising a broadband intermediate-frequency amplifier, the input of which is the input of the device, and the output of the intermediate-frequency amplifier is connected to the input of the narrow-band noise suppressor, containing n parallel channels, each channel consisting of a narrow-band intermediate-frequency amplifier and a suppression element narrow-band interference, and all inputs of narrow-band amplifiers of intermediate frequency are interconnected and with the output of the broadband power intermediate frequency, as well as a series-connected adder and a matched filter, consisting of series-connected multiplier, the first input of which is connected to the input of the matched filter and integrator, the output of which is the output of the device, and a reference signal generator, the output of which is connected to the second input of the multiplier, different the fact that the first and second converters of the parallel code into a serial, sequentially connected clock generator, the second output to orogo connected to the input of the first counter, K outputs which are connected to the K inputs of the decoder, and first and second compression blocks of the frequency spectrum; moreover, the outputs of the first group of narrow-band amplifiers of intermediate frequency from the first to n / 2 are connected respectively to the second signal inputs of the mixers of the first compression unit of the frequency spectrum, and the outputs of the second group of narrow-band amplifiers of intermediate frequency from n / 2 + 1 to n are connected respectively to the second signal inputs of the mixers a second frequency spectrum compression unit; the outputs of the narrowband interference suppression elements of the first group from the first to n / 2 are connected to the n inputs of the first parallel code to serial converter, the output of which is connected to the second inputs of the matching blocks of the first compression unit of the frequency spectrum connected to each other, and the outputs of the narrowband interference suppression elements of the second group from n / 2 + 1 to n are connected to the n inputs of the second parallel to serial code converter, the output of which is connected to the second inputs of the matching blocks of the second interconnected th block of compression of the frequency spectrum; the synchronized inputs of the first and second parallel code to serial converters are connected to each other and to the first output of the clock generator; in the first and second compression blocks of the frequency spectrum, each of which contains n / 2 parallel channels, the inputs of the triggers of the first, second, ... and n / 2 channels are paired together and each pair is connected to one of the corresponding K outputs of the decoder; in addition, the trigger output is connected to the first input of the coincidence unit, the output of which is connected to the input of the second counter, the K outputs of which are connected to the K inputs of the local oscillator, the output of which is connected to the first heterodyne input of the mixer, the output of which is connected to one of the n inputs of the adder.

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