SU1406801A1 - Device for compensating for noise in double radio signal reception - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to reduce the level of interference residuals when receiving an additive mixture of multi-frequency radio signals with relative phase manipulation with arbitrary type of interferences, with the exception of interferences imitating the useful signal, and also increase

Description

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The ratio of signal-to-noise ratio at the output of the device with deep frequency-selective signal fading. The device contains delay delays 1 and 2, bandpass filters (PF) 3, compensation blocks (BC) 9, and adders 24, 25, 28, and 29. The interference compensation device for dual reception of radio signals is designed to suppress external any kind, except for signal-like interferences, having a repetition period exactly coinciding with T, is the interval between the sets. In this case, the interference affects simultaneously both spatially separated antennas that are equally oriented, and the relative phase shift of the interference components to the cich in the input diversity signals differs from the phase shift of the signal components. In the device, interference components are compensated, and the useful components remain, i.e. purification of useful signals from interference occurs. The device according to Claim 1 is characterized by the introduction of el-delays 1 and 2. FFZ, BC 9 and adder 25, which reduces the level of interference residuals. The apparatus according to claim 2, is characterized by the introduction of adders 28 and 29, which increases the signal-to-interference ratio. An example of fulfillment is given. BK 9. 1 z.p. f-ly, 2 pcs.

The invention relates to radio engineering and can be used to receive multi-frequency radio signals with relative phase shift along tropospheric communication channels under the conditions of external interference.

The purpose of the invention is to reduce the level of interference residuals when receiving an additive mixture of multi-frequency radio signals with relative phase manipulation with random-type interference, with the exception of interference simulating a harmful signal, as well. also an increase in the signal-to-noise ratio at the device output during deep frequency-selective signal fading.

Figure 1 shows the structural electrical circuit of the compensation device, interference with dual radio reception in Figure 2 are graphs explaining the principle of operation of the interference compensation device with dual radio reception.

The device for compensating interference with dual radio reception contains the first 1 and second 2 N-tap delay elements, N pairs of bandpass filters 3, the first 4 and second 5 amplitude detectors, the integrating filter 6, the gating unit 7, the multiplier 8, the first and je (j 2 , 3, ..., N), compensation blocks 9, the first 10 and second 11 control blocks

amplifiers transfer coefficients, second 12, first 13, fifth 14, sixth 15, third 16 and quarter 17 delay elements, first to fourth mixers 18-21, first 22 and second 23 adders, first 24 and second 25 output adders, third to sixth adders 26-29, phase shifter 30 by 90 °, reference local oscillator 31, first 32 and second 33 amplifiers with adjustable transmission coefficients, the first 34 and second 35 blocks of phasing, the first 36 and second 37 switches, the first 38 and second 39 keys , the first 40 and second 41 subtractors, the first 42 and the second 43 threshold blog ki, the first 44 and second 45 square pulse shapers, first 46 and second 47 variable signal component filters, and element 48 And.

The device works as follows.

The operation of the proposed device is based on a special time-frequency structure of the spectrum of composite signals: Indeed (see Fig. 2a), despite the fact that the signal is different from zero, almost the entire interval T between the transmissions, during this interval, it takes at each instant of time relatively a narrow band of the spectrum within a common band f. Indeed, during each partial

15

interval T, / N signal exists only in one of the partial bands of width f, and inside the other bands at this time point the signal level is negligible. Therefore, if we consider a composite signal in a certain coordinate system, on whose axis the frequency f and time t (Fig. 2a) are plotted, then we can conclude that a small local region A in this coordinate system corresponds to each partial radio pulse. The aggregate of all partial signals forming a composite signal is aggregate. There are a number of such contiguous local areas. This set also forms a certain region B, describing the composite signal in the whole of the total interval f during period T, this region occupies a relatively small area, approximately equal to 1 / N.

External interference that affects the communication system can also be represented in a similar coordinate system. So the area corresponding to the high-speed impulse noise C is stretched along the vertical axis (f). The area corresponding to the continuous narrowband interference D is stretched along the horizontal axis (t). Interference of an arbitrary structure in a similar coordinate system may have an area of arbitrary shape.

The device is designed to suppress external interference of any kind, except for signal-like interference.

those. having a repetition period exactly coinciding with T. In addition, the interference affects simultaneously both space-spaced antennas (not shown), which occurs in almost all cases, since both space-spaced antennas are equally oriented, the relative phase shift The components in the input diversity signals are different from the phase shift of the signal components.

In this case, the interference occupying the same common band of the spectrum f (as the useful signal and coexisting with it in time may not coincide at all with the region B occupied by the useful components, or only partially overlap it. Nevertheless also affects

14068014

receiver demodulators (not shown) and can lead to a significant degradation of the communication immunity. .

Consider the general case of interference (Fig. 2b). It has part E overlapping the area of the useful signal and part F lying outside of it.

In a device, both parts of the interference are variously neutralized in the useful signal.

Part F is simply excluded from the signal. For this, at the moments when there is no useful signal (partial radio pulse) on this band-pass filter 3, its output is disconnected from subsequent circuits, the E part of the interference is compensated inside the hour-20.

The input signals in the N-tap elements 1 and 2 are separated by tap with relative delays T, / N and pass through the corresponding band-pass filters 3. At the outputs of a pair of band-pass filters 3 of the same number, identical compensation blocks 9 are connected. In the absence of interference, the input of each block 9 receives a sequence of radio pulses of duration T, / N and the period following T, (if there is multipath, then instead of each radio impulse there are several). With the help of amplitude detectors 4 and 5, their envelope is selected, which is a sequence of video pulses. With its help, two sequences of rectangular gating pulses are formed which coincide in time with the received video pulses of each diversity signal. To this end, in order to reduce the effect of additive thermal noise, the accumulation g is applied in the edirculators formed by adders 26 and 27 and elements 16 and 17, having a delay time equal to T. Adders 26 and 27 provide a summation of signals with such weights that there was no self-excitation and, in addition, the level of additive noise at their outputs was reduced. The imagers 44 and 45 of the video pulses form the gating rectangular pulses necessary for cutting out interference. Filters 46 and 47 exclude the constant component, as well as the influence on the formers 44 and 45 of the continuous component of the interference.

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51406801

constant level (if it is the summation present). The keys 38 and 39 are opened only at the moments when the gate T arrives with gates from the formers 44 and 45. At other times they are closed.

To control the compensation, gating pulses from both drivers 44 and 45 are applied to element 48, which produces control voltage only when gating pulses from both drivers 44 and 45 are present at its inputs, i.e. when the partial-- central frequency. The pulses of a given pair of band-pass In phase shifter 30, after-filter 3 occurs in time (phase turn 90, the voltage across it would be partially).

The delay of elements 14 and 15 is also equal to T ,. Therefore, if there is no external interference, then there are no signals at the outputs of the subtractors 40 and 41. If the input has interference, then (since it is uncorrelated with the signal) on

The interference components are thereby compensated.

The amplitude-phase adjustment is made using the reference local oscillator 31. It produces a sinusoidal voltage Ug with a frequency Q og UpCostOr-t. In mixer 18, a difference frequency voltage of 10 UrU, (t) Cos (Wr, - Wr) t + (f, +

+ (|; | (t), where Un (t) (t) is the amplitude and phase of the interfering component of the first diversity signal transmitted through the given bandpass filter 3.00 - its

Ugo output Uj-sincOpt. Amplifiers 32 and 33 provide gain factors K and K (both coefficients can change sign). In this case, the voltage at the output of the adder 22} K, UrCoscOrt + + K Uj-sinQ t U AcosOlo t -Y. ,

The outputs of the subtractors 40 and 41 are equal to 25 where A is K + K,, oi, arctg; -. it

with voltage. The threshold blocks 42 and 43 fix this voltage and form the pulses controlling the switches 36 and 37 from the H o;

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the voltage is fed to the input of the mix- ers 19, where the signal of the differential frequency is formed.

Uiq AUrUn, (t) cosr (0n-ar) t + Fp + Previously, the switches 36 n 37 connect + f. -oc

The signals of direct ,, (t) are the amplitude of the interfering signal from the outputs (from the 34 output units to the second wind35). After the control signal arrives from the threshold blocks 42 and 43, both switches 36 and 37 connect a signal from the output of mixer 20 to their outputs. This ensures neutralization of part E (fig.2b) of the interfering signal, since on the code of mixer 20 in the useful signal weft compensated.

v, vj - relative phase

35

interference offset between diversity branches.

The signals of mixers 18 and 19 are added to adder 23. With the help of cor, the corresponding K, and K provide 40 conditions Uq, AUnj; y - o n. At the same time, the noise components in the separated signals are compensated, and the useful components (since they are uncorrelated with the noise) remain, 45 Thus, the signal 7 is cleared from interference.

The keys 38 and 39 are opened by the corresponding gating pulses, which take place only at the moments of the presence of the partial pulses of the useful signal. The rest of the time they are closed. Thus, the output of the device passes signals only in the mixer 20 are allocated the total frequency Q (с „- Uo) + og

KO from region B (Fig. 2a). All the rest is - UP, i.e. the signal returns to the first part outside of them, regardless of the fact that it is in the initial region of the spectrum, it contains interference (region F, This cleared interference signal and

Fig. 2b) or only the thermal noise of the input circuits is clipped.

used in switches 36 and 37 at times when interference and input signal overlap each other.

Ko sine interference components 55 (area E in FIG. 26). the input signals are produced using amplitude-phase adjustment (so that the noise in them becomes equal and antiphase) and after blocks 34 and 35, the phase of this diversity signal (output element 12 or 13) is compared with the compensation signal phase

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central frequency. In phase shifter 30, the phase is rotated by 90, the voltage is on.

The interference components are thereby compensated.

The amplitude-phase adjustment is made using the reference local oscillator 31. It produces a sinusoidal voltage Ug with a frequency Q og UpCostOr-t. In mixer 18, a voltage difference voltage UU is generated, (t) Cos (Wr, - Wr) t + (f, +

+ (|; | (t), where Un (t) (t) is the amplitude and phase of the interfering component of the first diversity signal transmitted through the given bandpass filter 3.00 - its

central frequency. In phase shifter 30, the phase is rotated by 90, the voltage is on.

Ugo output Uj-sincOpt. Amplifiers 32 and 33 provide gain factors K and K (both coefficients can change sign). In this case, the voltage at the output of the adder 22} K, UrCoscOrt + + K Uj-sinQ t U AcosOlo t -Y. ,

v, vj - relative phase

interference offset between diversity branches.

The signals of mixers 18 and 19 are added in adder 23. With the help of cor, the corresponding K, and K provide the conditions Uq, AUnj; In this case, the noise components in the separated signals are compensated, and the useful components (since they are uncorrelated with the interference) remain. Thus, the signal from the interference is cleared.

In mixer 20, the total frequency Q (ω-Uo) + og is allocated.

--Up, i.e. the signal returns to the original spectral region. This cleared signal and

(area E in Fig.26).

In blocks 34 and 35, the phase of the separated signal (from the output of element 12 or 13) is compared with the phase of the compensation signal.

(from the output of the mixer 20) and the phase of each spaced signal is adjusted to the phase of the total compensation signal, which contains only the useful component). For this reason, when re-switching in switches 36 and 37, the phase of the useful signal does not occur sufficiently dangerous for OFT. The coefficients K ;, and K of controlled amplifiers are controlled by blocks 10 and 11. In each of them, the second separated signal is transferred to the frequency o - cpg with external noise (regardless of its position relative to the region B of the signal, fig.2a), B other blocks 9 perform similar operations. All partial pulses are fed to adders 24 and 25, where short radio pulses are generated, which are used in further processing. In terms of a relatively small level of the useful signal and significant selective frequency-fading, switching on adders 28 and 29 is used. Under such conditions, it can occur with the power of a mixer 21, then it is determined that the summation of the correct

Og

with the correlation coefficient of this signal with the input signal of the mixer 20 using a multiplier 8. This signal is integrated into the integrating

filter 6, the results of integration 20 that are insufficient for stable operation are proportional to the coefficients K, and K. formers 44 and 45. Under these conditions, the correct generation of gating pulses by formers 44 and 45, since the level of some of the partial and my may become small.

When integrated, both measured correlation coefficients are minimized at the same time. If the influence of the useful signal is eliminated, then the achievement of correlation coefficients of zeros means simultaneously compensating for the interference at the input of the mixer 20.

The effect of the useful signal of the systems, the output of the adder 26 is also connected to one of the inputs of the adder 28, 25 outputs of the corresponding adders 26 of the other blocks 9 are connected to its other inputs. The output of the adder 28 is connected to one of their inputs of the adder 26 in each of the blocks 9 .

Similarly, the output of the adder 27 is a block 7, It is controlled by the construction of each of the blocks 9 connected to one biasing square impulses from the inputs of the adder 29, and the output of the sum of the output of the element 48 and opens upon their arrival. Hazardous (for measuring interference parameters) are only the results of multiplying the useful components of both separated after all band-pass filters 3 already

coincide in time, then in the formation of the total video impulse at the outputs of adders 26 and 27, used in imaging devices 44 and 45, video impulses, formed immediately from all partial, are now involved. Therefore, even if the level of any parti35,

Mator 29 is connected to the input of the adder 27 in each block 9.

one .

Because partial pulses

40

signals. These times take place only with the simultaneous presence of partial pulses at the output of this pair of filters 3, but just at these moments the result of multiplication is excluded from accumulation by the integrator using block 7. This neutralizes the effect of the useful signal on the control of the adjustable amplifiers.

Elements 12 and 13 are used to neutralize the delay time for the formation of gating pulses. Their value is chosen such that, in block 7, the gating pulse from AND 48 arrives simultaneously with the result of multiplying the partial pulses in the multiplier B.

As a result of the implementation of all the described operations, the outputs of block 10 contain the same partial pulses as the outputs, respectively; 3 bandpass filters, but without

50

55

Since it becomes small (because of the selective frequency frequencies), then the work of the corresponding block 9 does not affect it.

Claims (1)

1. A device for compensating interference in dual radio reception, containing a first output adder and a first compensation block, the output of which is connected to the first input of the first, output adder, the first compensation block contains the first and second threshold blocks, the first and second amplitude detectors, the first and insufficient for the stable operation of the formers 44 and 45. Under these conditions, the correct generation of the gating pulses by the formers 44 and 45, since the level of some of the partial and benefits may become small. Similarly, the output of the adder 27 of the DA of each of the blocks 9 is connected to one of the inputs of the adder 29, and the output of the sum after all of the band-pass filters 3 already 35, Mator 29 is connected to the input of the adder 27 in each block 9. one . Because partial pulses 0 five Since it becomes small (because of the selective frequency frequencies), then the work of the corresponding block 9 does not affect it. Invention Formula 1. A device for compensating interference in dual radio reception, containing a first output adder and a first compensation block, the output of which is connected to the first input of the first, output adder, the first compensation block contains the first and second threshold blocks, the first and second amplitude detectors, the first and the second phasing unit, the first and second switches, the first delay element, the second delay element, the And element, the first and second rectangular pulse shapers, the outputs of which are connected to the corresponding inputs of the And element, the first and second accelerator transmission control units, the first mixer, are connected in series, the reference local oscillator, the output of which is connected to the first input of the first mixer, the first amplifier with an adjustable transmission coefficient, the input of the regulating signal of which is connected to the output ohm the first amplifier gain control unit, the first adder, the second mixer, the second adder, the output of which is connected to the first inputs of the first and second amplifier gain control units, and the other input connected to the output of the first mixer, and the third mixer, the output of which is connected to the first inputs of the first and second switches, connected in series by a phase shifter with input 90 connected to the output of the reference local oscillator, and a second amplifier with an adjustable gain, in the course of which is connected to another input of the first adder, and the input of the regulating signal is connected to the output of the second amplifier gain control unit, characterized in that, in order to reduce the level of interference residues when receiving an additive mixture of multi-frequency radio signals with relative phase manipulation - Arrays of any kind, with the exception of interference imitating the useful signal, the first and second N-tap delay elements are inputted into it, whose inputs are the first and second inputs of the device, respectively. n pairs of bandpass filters, je compensation blocks (j 2,3, ..., N), identical to the first compensation block, the output of each of which is connected to the JM input of the first output adder, the second output adder, each input of which is connected to an additional output of the corresponding compensation block, ie (i 1,2, ... N) - the taps of the first and second N-tap delay elements are connected to the first and second inputs of the i-ro block 5 o o five five 0 five compensation, respectively, through the first and second bandpass filters of the i-th pair of bandpass filters; in each compensation block, the first and second keys are entered, whose outputs are the output and an additional output of the compensation block, the inputs are connected to the outputs of the first and second switches, respectively, and the control inputs connected, respectively, to the outputs of the first and second formers of rectangular pulses, connected in series by a first variable signal component of the signal, the input of which is connected to the output of the first an amplitude detector, a third adder, the output of which is connected to the input of the first square wave former, and a third delay element, the output of which is connected to the second input of the third adder, connected in series to the second F1 to тth variable of the signal component, the input of which is connected to the output of the second amplitude detector , the fourth adder, the output of which is connected to the input of the second driver of rectangular pulses, and the fourth delay element, the output of which is connected to the second input of the fourth an unmatch connected in series five delay elements, the input of which is connected to the output of the first amplitude detector, and the first subtractor, another input of which is connected to the output of the first amplitude detector, and the output connected to the input of the first threshold unit, connected in series to the sixth delay element, the input of which is connected to the output of the second amplitude detector, and the second subtractor, another input of which is connected to the output of the second amplitude detector, and the output connected to the input of the second threshold block ka, the outputs of the first and second threshold blocks are connected respectively to the control inputs of the first and second switches, the second inputs of which are connected respectively to the outputs of the first and second phase blocks, the output of the first delay element, whose input is connected to the input of the second amplitude detector and is second the input of the compensation unit, connected to the input of the second phasing unit and another input of the second mixer, another input of the second the phasing unit is connected to the output of the third mixer, the other input of which is connected to the output of the reference local oscillator, the first and second inputs of the first phasing unit are connected respectively to the output of the third mixer and another input of the first mixer, also connected to the output of the second delay element the amplitude detector is the first input of a compensation unit, each amplifier gain transmission control unit contains a fourth mixer connected in series, the first input of which is the second input of the control unit is coefficient which, in order to increase the signal-to-noise ratio at the output of the device with deep frequency selective fading of the signal, the fifth adder is entered into it, the inputs : The amplifier's transmission channel and connected to the output of the first delay element, 20 of which is connected to the third outputs and the second input is the third input of the adders, and the output is connected to the treater of the amplifier gain control unit, the multiplier, the other input of which is the first input the third inputs of the third adders, the sixth adder, the inputs of which are connected to the outputs of the fourth adder of the corresponding control unit of a cora 25 oV; and the output is connected to the third transfer gain of the amplifier, the block of the fourth adders. gating, the control input of which is connected to the output of the AND element and is the fourth input of the amplifier gain control unit, and the integrating filter whose output is the output of the amplifier gain control block, the third inputs of the first and second amplifier gain control blocks are connected respectively to the output of the reference local oscillator and the output of the phase shifter by 90 °. 2, The device according to claim 1, so that in order to increase the signal-to-noise ratio at the output of the device with deep frequency selective fading of the signal, a fifth adder is entered into it, the inputs which is connected to the outputs of the third adders, and the output is connected to the third which is connected to the outputs of the third adders, and the output is connected to the third the inputs of the third adders, the sixth adder, the inputs of which are connected to the outputs of the fourth combiners .2