SU1095419A1 - Interference suppression device - Google Patents

Abstract

1. DEVICE FOR ADDING INTERFERENCE by author. St. No. 675382, characterized in that, in order to reduce the distortion of the useful signal in the absence of concentrated interference, a signal analysis unit, i- and (, 2 ..., A /), is inputted into the input of which is connected to the output of the first limiting amplifier i th self-adjusting filter, N switching control blocks, the initial setup inputs of which are the input of the initial setup of the device, and their enabling inputs are connected to the output of the command to analyze the signal analysis block, the information input of the i-ro junction switching control block With the i-th output of the signal analysis unit, the input of each subsequent self-tuning filter is connected to the first output of the previous self-tuning filter through a switch whose other input is connected to the input of the previous self-adjusting filter, the control input of each switch is connected to the output of the corresponding control unit. switching. WITH SL 42k with

Description

2, The apparatus according to claim 1, wherein the signal analysis unit comprises a generator and a command generator connected in series with the orders, a first switch connected in series, the inputs of which are the inputs of the signal analysis unit and the control input connected to the driver output commands, a period meter, the other two inputs of which are connected to the output and another output of the master oscillator, respectively, the driver of the reference voltage, and the other inputs of which are connected to another output of the master oscillator Ator and other way out

the period meter, respectively, a synchronous drive, the other two inputs of which are connected to the output of the master oscillator and the output of the first switch, respectively, and the other output is the output of the command for analyzing the signal analysis block, the threshold element, the other input of which is connected to the output of the generator back, the switch, the control input of which is connected to the output of the command driver, and the outputs of the second switch are the outputs of the sinal analysis unit.

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The invention relates to radio engineering, in particular, to devices for suppressing narrowband interference and can be used in communication systems and navigation systems when working with 5 pulse signals.

According to the main author. St. No. 675382, a device for suppressing noise, comprising N series-connected self-tuning filters, each of which contains a series-connected notch filter, a first limiting amplifier phase, and an integrator whose output is connected to the first input of the notch filter, the second input and the second output of the notch filter are respectively the input and the first output of each of the N self-tuning filters, and the N -and self-tuning filter contains a second amplifier-limited itel connected between the second input of the notch filter and the second input of the phase detector, in each of the N-t self-tuning filters there are entered a series-connected adder and a second amplifier-limiter whose output is connected to the second input of the phase detector, and the second input of the 30 the detector filter is connected to the first input of the adder, the second output of each of the N self-adjusting filters, except for the first one, is connected to the corresponding N-K 35

the additional input of all previous self-adjusting filters (where K is the sequence number of the self-adjusting filter), N -K as additional inputs and the second output of which are respectively the (N-K + 1) -th inputs of the accumulator and the first output of the notch filter SP.

The disadvantages of this device (It is that in the absence of concentrated interference, the interference suppressors are tuned to the maximum of the spectrum within the bandwidth of the receiving path, i.e. to the carrier frequency of the signal, which distorts its envelope. the carrier frequency of the signal leads to a shift of the maximum in the interference spectrum, and the notch filter tunes to the frequency of interference, and if it disappears, it is tuned to the carrier frequency of the signal).

The purpose of the invention is to reduce the distortion of the useful signal in the absence of concentrated interference.

The goal is achieved by the fact that in a noise suppression device containing N series-connected self-tuning filters, each of which contains a series-connected notch filter, a first amplifier-limiter, a phase detector and an integrator, the output of which is connected to the first input 310 of the notch filter, the second input and the second output of the notch filter are respectively the input and the first output of each of the N self-adjusting filters, and the Nth self-adjusting filter contains the second th amplifier-limiter connected between the second input of the notch filter and the second input of the phase detector, each of the N -1 self-tuning filters contains a series-connected adder and a second amplifier-limiter, the output of which is connected to the second input of the phase detector, and the second input of the notch filter is connected with the first input of the adder, the second output of each of the S self-tuning filters, with the exception of the first one, is connected to the corresponding NK by an additional input of all the pre-self-tuning filters (where K is the sequence number of the self-tuning filter), the 1H-K are the additional inputs and the second output of which are respectively (N-K + 1) -e inputs of the adder and the first input of the notch filter, a signal analysis block, {- The (, 2 ...,) input of which is connected to the output of the first limiter of the ith self-adjusting filter, N switching control blocks, the initial installation inputs of which are the input of the initial installation of the device, and their enabling inputs are connected to the output of the command end of analysis the signal analysis block, the information input of the i-th switching control block is connected to the i-th output of the signal analysis block, the input of each subsequent self-adjusting filter is connected to the first output of the previous self-tuning filter through a switch, the other of which is connected to the input of the previous self-adjusting filter, the control input of each switch is connected to the output of the corresponding transceiver control unit. The signal analysis unit contains a sequentially connected task generator and a command generator, which are successively connected to the first switch-tor, whose inputs are the inputs of the signal analysis unit, and the control input connected to the output of the command generator, a period meter, two other inputs of which are connected to the output and other output of the master oscillator, respectively, the driver of the reference voltage, the other two inputs of which are connected to another output of the generator and the other output of the period meter respectively, a synchronous storage, the other two inputs of which are connected to the output of the master oscillator and the output of the first switch, respectively, and the other output is the output of the command to complete the analysis of the signal analysis unit, the threshold element, the other input of which is connected to the output of the master oscillator, and the second switch The control input of which is connected to the output of the command driver, and the outputs of the second switch are the outputs of the signal analysis unit. FIG. 1 is a block diagram of the proposed interference suppression device; in fig. 2 - voltage diagrams for the operation of the proposed device; in fig. 3 is a block diagram of a signal analysis unit, which shows examples of the implementation of the nodes included in it. The interference suppression device contains notch filters 1, switches 2, adders 3, second limit amplifiers 4, integrators 5, first limit amplifiers 6, phase detectors 7, self-tuning filters 8, signal analysis unit 9 and switching control blocks 10. The signal analysis unit 9 comprises a synchronous storage device 11, a threshold element 12, a second switch 13, a first switch 14, a master oscillator 15, a driver 16, a period meter 17, a driver 18, a reference frequency, a first frequency divider 19, an element 20, delays, element AND-NE 21, element OR 22, D-trigger 23, first element AND 24, second frequency divider 25, second element AND 26, third frequency divider 27, code comparison inverter 29, pulse shaper 30, fourth frequency divider 31, phase shifter by 90 32, time discriminators 33, pack equal integrators 34, keys 35, first fi-5 -trigger 36, third element And 37, fifth frequency divider 38, threshold decoder 39, second P5-tripler 40, and reference oscillator 41. The interference suppressor works as follows, B the initial time after switching on the equipment according to the initial installation signal for some time required to configure notch filters 1, block 10 is in a state where switches 2 turn on all notch filters 1. At the same time, the operation of noise suppressors is similar about the prototype. The input mixture of atmospheric noise, sinusoidal lumped (spectrum) interference and the useful pulse signal is fed to the input of the device. Each of the notch filters 1 is tuned to the frequency of the most powerful interference from its input. The control element is the phase detector 7, the input of which receives signals (through the first 6 and second 4 amplifiers-limiters from the input and inverse band output) of the notch filter 1. When tuning the notch filter 1 to the frequency of the phase interference of the signals at both inputs of the phase detector 7 coincide and the control signal at its output disappears. The integrator 5 serves to improve noise immunity and acts as a memory | Control voltage circuit. After tuning to the interference of all notch filters 1, the outputs of the adders 3 will only receive the signal of the interference that is suppressed by this rejection filter G, since the rest of the input mixture interference received by the following notch filters t to the remaining inputs of the adder 3 and subtracted from the input mixture. Thanks to this, the notch filter 1 is tuned to the interference frequency more precisely (since both inputs of the phase detector 7 receive the signal of only one interference). By the time all notch filters t are set up for interference, the setup signal is turned off. Using the master oscillator 1, the driver 16 is installed in one of the NHix states, whereby the first 14 and second 13 switches synchronously connect to one of the notch filters 1. From the band output of the selected notch filter 1 through the first limiting amplifier 6, the first switch 14 is introduced by the notch filter 1, the noise enters the period meter 17 (Fig. 2). The output signals of the latter (the code defining the measured interference period and the measurement end signal) control the driver 18 of the reference voltage, at the output of which a sequence of gating pulses is formed, the period of which is equal to the interference period. The pulse sequence and the amplified, limited disturbance signal are fed to the synchronous storage device 11. In this case, if the interference phase of the stable i at the output of the synchronous storage device 11 appears voltage. If oyo exceeds a predetermined amount, threshold element 12 is triggered, the command from the output of which goes through the second switch 13 to the corresponding block 10, which controls the switch; tele 2, turns on this header light 1. If the interference phase is unstable (white noise), then the accumulation at the output of the synchronous accumulator 11 does not exceed the threshold level and the injector filter 1 is automatically turned off. Block 10 may be, for example, a B-trigger, to the input of which information comes from threshold element 12, and information is written into the memory of block 10 on the front of the analysis end command from synchronous accumulator 11. Then, following a command from, the imager of 16 commands passes: causes the first 14 and second 13 switches to be switched to the tracker filter 1, and so on. At the same time, 15 gauges of the synchronous storage unit 11 and the threshold element 12 are reset by the command of the 15 pulses, after which the analysis cycle repeats. If at the moment of switching on the device the amount of concentrated noise was less than the number of notch filters 1, all non-working notch filters 1 are automatically switched off. When a new noise appears, one of the notch filters 1 adjusts to it, an interference signal appears at its inverse (band-pass) output and the corresponding block 10 includes this notch filter 1. Consider specific examples of the implementation of individual units of the device when using it in the receiver-indicator of a pulse-phase radionavigation system emy (IFRNS) Loran-C type. The IFRNS stations emit bundles of eight radio pulses, with a period of 30–100 thousand microns. with. The frequency of filling of radio pulses is 100 kHz, and the duration is 0.5 to 100 microns, c. With such a duty cycle, the useful signal, even with a large level, does not cause the shutdown of the notch filters 1, although its phase is stable. Indeed, the measurement of the period of interference is performed nonper-horizontally for a sufficiently long period of time, and the duration of the signal is short compared with the analysis time. Therefore, if synchronous interference is present, the carrier frequency of the signal will not introduce a significant error in the measurement of the interference period. In the absence of synchronous interference, the phase of atmospheric noise interference is random and does not give a significant accumulation in synchronous accumulator 11 (despite the presence of even a powerful useful signal with a stable phase). As a reference generator, a quartz oscillator with 5 MHz with frequency doubling can be used as part of the IFRNS receiver for which the inventive device was developed. A 10 MHz square wave is applied to the first frequency divider 19, the output of which produces pulses determining the switching period of the notch filters 1. These pulses are fed to the command generator (frequency divider), whose division ratio is equal to the number of notch filters 1. The binary code from the output of the generator 16 controls the switches 14, 14 and 13, which switch one notch filter 1. The measurement of the period of interference from the output of the notch filter, 1 that is currently connected, is performed as follows. A 10 98 P-trigger 23 is set to O pulse of the output of the first frequency divider (Fig; 24). The pulses go to the P-input of D-trigger 23 through the element OR 22. Then to the counting input. In the trigger 23, several I-NOT 21 elements pass through the implementation constraints from the output of the notch filter 1 (Fig. 2a), at this moment the second input element AND-NOT 21 receives the enabling pulse from the output of the element 20 of the delay (Fig.25). D-trigger 23 is transferred to the D-input state (i.e., 1), at the moment of a positive differential, the output from the notch filter 1 is supplied to the counting input and to the input of the second frequency divider 25 through the first And 24 element. periods of this implementation (for example, 2,256) at the output of the second frequency divider 25 appears pulse- which through the OR element 22 enters the input of the P-trigger 23 and sets it to 0. The first element 24 is locked before switching to the next notch filter (until the input element AND-NOT 21 the next resolution impulse will not come). Thus, at the output of the B flip-flop 23, a pulse of equal duration is formed, for example, 256 implementation periods (Fig. 2e). This pulse and the frequency of the reference oscillator 41 (Fig. 2e) are fed to the input of the second element I 26, the output of which thus forms a burst of pulses, the number of which is strictly proportional to the length of the pulses (Fig. 2). This burst of pulses goes to the third frequency divider 27 and is stored on it before switching to the next notch filter 1. E. the binary code at the output of the third divider 27 frequency is uniquely associated with the pulse duration of the D-trigger 23 (or with a duration of, for example, 256 realization periods from the output of the notch filter 1). To determine the duration of one period of interference, you need to divide this code into the corresponding number of times. To do this, discard the corresponding number of bits of the third frequency divider 27. The formation of pulses, following a period equal to the measured period of interference, can be done as follows. 91 The code from the outputs of the third 27 and fourth 31 frequency dividers feeds to block 29 of the code comparison, at the output of which a pulse appears with equal, both codes. This impulse goes through the shaper 30 to the fourth division of the 31 frequency frequency to 0. The fourth frequency divider 31 counts the pulses arriving at its input until the frequency equalizes with the third frequency divider 27, etc. the period following the output pulses of driver 18 is uniquely associated with the code at the output of the third frequency divider 27, i.e. with a period of interference, (Fig. 2h). In order for the pulses (FIG. 2h) not to be generated during the measurement of the period of the disturbance, the input from the code comparison unit 29 is prohibited from going to the D-trigger 23 (via inverto 28). The mutual temporary position of the interference phase and the generated pulse sequence can be Different, since it depends on what number was recorded. in the fourth frequency divider 31 at the time of admitting them, the pulse to the code comparison block 29 (although the period x is the same). Therefore, it is necessary to resort to quadrature analysis of the synchronization of interference. Synchronous drive 11 can be performed by different algorithms, for example lz,; where 12-, I - the module of accumulation of the results of signal gating and interference; the same for gating the implementation shifted by 1/4 of the r.t. filling threshold. Thus, the synchronous accumulator 11 can be two links of the serially connected time discriminator 33 and the controlled integrator 34. The control inputs of the temporary discriminators 33 are pulsed from the output of the former 18 through the third element I 3 at the time of arrival of which the time discriminators 33 open up. The signal of one of them is delivered directly from the output of one of the notch filters 1, and the signal input of the second through the phase shifter, If there is no synchronous interference, then the phase of atmospheric interference between the received radio pulses is random and the accumulative accumulators 34 do not exceed the threshold value . In the presence of a concentrated spectrum disturbance at the output of at least one of the controlled integrators 34, the accumulation exceeds the specified threshold. If the strobe pulses on one of the time discriminators 33 ows fall in time with the phase transition point of interference through O, then in the second channel they gate the top of the half wave of the interference. The analysis time is fixed and is determined by the division factor of the fifth frequency divider 38, which generates a setup pulse after passing a predetermined number of gating pulses. The installation pulse resets the first trigger 36 into O, which prohibits further passage of the gating pulses through the third element 37. At the moment of transition to the next notch filter, the master oscillator 15 generates a pulse closing the keys 35 (for zeroing control number 1X of the integrators 34) is simultaneously reset the first R5 trigger 36 and the fifth frequency divider 38 zero. Thus, the synchronous drive 11 is again prepared for the following analysis cycle. After the completion of the next measurement period of the interference period, the pulse at the output of the D-trigger 23 disappears and pulses appear at the output of the forger 18. The process is repeated. Information from controlled integrators 34 is fed to a threshold decoder 39, which is triggered when a threshold level arrives at its input and cokes the second RS flip-flop 40. The output level of the second P5 flip-flop 40 through the second switch 13 is fed to the input of the corresponding block to, which can Be a 2 trigger (information is sent to its D input). A pulse from the output of the fifth divider 38 is generated at its counting input, which is generated at the end of the analysis. On the front of this pulse, block 10 is triggered,

1 10954192

memorize information existing Positive effect while

at this moment. concluded that thanks

Thus, in the proposed auto-shutdown device

In comparison with the prototype preventive filter 1, when reducing the noise level of the rezhek-5s to avoid unwarranted, the source filters 1 automatically turn off the envelope of the useful sign.

Claims (2)

'1. DEVICE FOR SUPPRESSING INTERFERENCE by ed. St. No. 675382, characterized in that, in order to reduce distortion of the useful signal in the absence of concentrated noise, a signal analysis unit, i-th (i = 1,2.,., * /), The input of which is connected to the output of the first amplifier-limiter of the ΐ-th self-tuning filter, N switching control units, the initial setting inputs of which are the initial setting of the device, and their enable inputs are connected to the output of the signal analysis analysis analysis block, the information input of the i-th switching control unit is connected with i-th output of the signal analysis unit, the input of each subsequent self-tuning filter connected to the first output of the preceding self-tuning filter through a switch, the other input of which is connected to the input of the previous self-tuning filter, each switch control input coupled to an output of the respective switching control unit ^. , 50 .... 1095419 2. The device according to π. 1, characterized in that the signal analysis unit comprises a serially connected master oscillator and a command shaper, a first switch connected in series, the inputs of which are inputs of a signal analysis block, and the control input is connected to the output of the command shaper, a period meter, the other two inputs of which are connected to the output and another output of the master oscillator, respectively, a driver of the reference voltage, the other two inputs of which are connected to another output of the master oscillator and another output of the period, respectively, a synchronous drive, the other two inputs of which are connected to the output of the master oscillator and the output of the first one, the switch, respectively, and the other output is the output of the command to finish the analysis of the signal analysis unit, a threshold element, the other input of which is connected to the output of the master oscillator, and the second a switch, the control input of which is connected to the output of the command shaper, and the outputs of the second switch are the outputs of the signal analysis block.