RU198305U1 - ADAPTIVE DIGITAL FILTER FOR THE SUPPRESSION OF NON-FLUCTUATION INTERFERENCE - Google Patents

Abstract

The utility model relates to the field of radio engineering and can be used in devices for digital processing of signals passing through communication channels, in which there is a possibility of signal distortion associated with the presence of external non-fluctuation interference in the channels. The claimed adaptive digital filter for suppressing non-fluctuation interference, comprising a first converter of the complex envelope of the signal into the complex conjugate envelope; the first register delay, consisting of series-connected first, second, third delay elements; the second register delay, consisting of serially connected fourth, fifth, sixth delay elements; the first, second and third multipliers of the outputs of the first delay register with weights; first adder; first, second and third integrators; the fifth, sixth and seventh multipliers of the output signals of the second delay register with the signal of the first adaptive weight adjustment circuit consisting of a series-connected derivative calculating unit, a first modulus calculating unit, a second adder with a voltage -G and a fourth multiplier with a voltage -d1, the proposed filter is characterized by by the fact that it includes the second converter of the complex envelope of the signal into the complex conjugate envelope, the input of which is connected to the output of the first adder and to the input of the third delay register, consisting of serially connected seventh, eighth, ninth delay elements, the outputs of which are connected to the first inputs of the eighth, ninth and the tenth multipliers of the output signals of the third delay register with weighting factors, while the outputs of these multipliers are connected to the inputs of the third adder, the output of which is the output of the device and at the same time - the input of the second adaptive tuning circuit ki of weight coefficients, containing in series a second unit for calculating the module, a squaring unit, a fourth adder, to the second input of which a constant voltage -1 is applied, and the output is connected to the input of the eleventh multiplier, the second input of which is connected to the output of the third adder, and the third input is designed to supply a constant voltage -d2, which determines the degree of inertia and stability of the adaptation process, and the output of the eleventh multiplier is connected to the first inputs of the twelfth, thirteenth, fourteenth multipliers with the output signals of the fourth delay register, the second inputs of which receive the output signals of the corresponding series-connected tenth, eleventh , the twelfth delay elements of the fourth delay register, while the input of the fourth delay register is connected to the output of the second converter of the complex signal envelope into the complex conjugate envelope, and the outputs of the twelfth, thirteenth o and the fourteenth multipliers with the output signals of the fourth delay register are connected through the fourth, fifth and sixth integrators with the second inputs of the eighth, ninth and tenth multipliers of the output signals of the third delay register with weight coefficients, provides a decrease in the level of non-fluctuation noise at the output of the adaptive digital filter by providing the possibility implementation of the method of adjusting the vector of weight coefficients taking into account the known information about the phase structure of the signal (the shape of the phase pulse) and its constant amplitude, as a result of which non-fluctuation noise is suppressed, which has a phase and amplitude structure different from the signal. 2 ill.

Description

The technical field to which the utility model relates.

The utility model relates to the field of radio engineering and can be used in digital signal processing devices passing through communication channels in which there is the possibility of signal distortion associated with the presence of external non-fluctuation interference in the channels.

State of the art

As you know, interference is any effect superimposed on a useful signal and making it difficult to receive. The interference is very diverse both in its origin and in physical properties [Electronic resource: https://koralexand.ru/?page_id=105].

At the input of the receiver, along with fluctuation (noise) interference, various non-fluctuation (non-noise, structural) interference is often present, the most typical of which are the following: harmonic signal, phase-shift signal, relay signal [Electronic resource: https://www.osp.ru / nets / 2000 / l0 / 141420 # 1].

An effective way to combat non-fluctuation noise in communication channels is to use adaptive filters (AF), which are usually implemented as non-recursive digital filters with adjustable weight coefficients (VC), included at the input of the signal demodulator.

An element of the output sequence of a non-recursive filter of length N in the space of complex envelopes can be written as follows

where X _i = [x _i , x _i-1 , ... x _{i-N + 1} ] ^T is the vector of the sequence of input samples;

- вектор ВК в i-й момент времени; т - символ транспонирования.

- VC vector at the i-th moment of time; t is the symbol of transposition.

With the same structure, filters of this type differ in the ways of tuning the VC vector, aimed at minimizing a given objective function.

From the prior art [copyright certificate SU 1707740 A1, publ. 01/23/1992] a digital non-recursive filter is known, which includes a delay register, seventeen delay recorder blocks, sixteen adders and a computer connected to the corresponding binary switching.

A disadvantage of the known device is that it does not have the ability to adapt to the signal parameters, that is, the filter uses the initially set signal correction parameters, which are independent of changes in the noise parameters.

The prior art [patent RU 99623 U1, publ. November 20, 2010] an adaptive signal filter is known, consisting of an input device block, an adaptation loop block, a dynamic error compensator block, and an identifier block. The blocks of this device, by means of the electric and / or electronic elements included in them, implement the principle of filtering a scalar message with a random noise dispersion identification block, which allows you to compensate for the a priori unknown noise stream of the processed signal caused by an a priori unknown flow of measurement errors and / or source state error signal, and / or external noise.

A disadvantage of the known device is that it only filters noise interference, and filtering non-fluctuation interference is impossible in it.

The prior art [copyright certificate SU 1764145 A1, publ. 09/23/1992] an adaptive filter is known that contains two digital filters, an adder, a threshold block, a unit for setting weight coefficients, a single signal source, a division block, which serves to isolate a constant component of current or voltage in a transient process.

The disadvantage of this device is the inability to allocate alternating current or voltage against non-fluctuation interference.

From the prior art [Treichler J.R. et ah A new approach to multipath correction of constant modulus signals / IEEE Transactions on Acoustics, Speech, and Signal Processing, 1983, V. 31, N. 2, pp. 459-472] there is a known adaptive filter that suppresses non-fluctuation interference, focused on the reception of signals with a constant envelope. It contains the first and second delay lines, consisting of series-connected delay elements, multipliers of the output signals of the first delay line with weighting coefficients, the outputs of which are connected to the inputs of the adder, the output of which is the output of the device and at the same time, the input of the adaptive adjustment circuit of the weighting factors, consisting of a block computing a module, a subtractor, a gain block, multipliers with the output signals of the second register and integrators.

The disadvantage of this device is the inability to suppress non-fluctuation interference, which, like the useful signal, has a constant envelope.

The closest in technical essence analogue (prototype of the proposed utility model) [patent RU 194496 U1, publ. 12.12.2019] is an adaptive filter, comprising: a converter of a complex envelope of a signal into a complex conjugate envelope; a first delay register, consisting of series-connected first, second, third delay elements; a second delay register, consisting of series-connected fourth, fifth, sixth delay elements; first, second and third multipliers of the output signals of the first delay register with weighting factors; first adder; first, second and third integrators; the fifth, sixth and seventh multipliers of the output signals of the second delay register with the signal of the adaptive adjustment scheme of the weight coefficients, consisting of a derivative calculation unit, a module calculation unit, a first adder and a fourth multiplier.

In the closest analogue, a method that implements the procedure is used to fine-tune the vector of weight coefficients of a non-recursive filter:

where d1 is the coefficient determining the degree of inertia and process stability

adaptation; y _i - discrete samples of the complex envelope; (⋅) 'is the sign of the derivative; G is the module of the derivative of the information component of the phase (slope of the phase pulse) of the signal; (⋅) * is the sign of complex conjugation.

As a result of the adaptive filter (AF), the phase trajectory of the useful signal is aligned and, as a result, the interference effect on the signal is reduced.

The disadvantage of the prototype device is the fact that only the phase trajectory of the signal is aligned, but its envelope is not aligned, which is also distorted due to interference, which means that the accuracy of noise suppression is limited.

Utility Model Disclosure

The technical problem to be solved by the claimed utility model is to increase the accuracy of filtering non-fluctuation interference, taking into account known information about both the phase structure of the signal and its constant envelope, different from the phase and amplitude structure of the interference.

The technical result that is achieved in the proposed utility model is to reduce the level of non-fluctuation interference at the output of the adaptive digital filter by providing the possibility of implementing the method of tuning the vector of weight coefficients taking into account the known information about the phase structure of the signal (phase pulse shape) and its constant amplitude, in As a result, non-fluctuation interference with a phase and amplitude structure different from the signal is suppressed, and the filtering accuracy is increased.

The stated technical problem is solved and the technical result is achieved by the fact that an adaptive digital filter for suppressing non-fluctuation interference, comprising a first converter of the complex envelope of the signal into a complex conjugate envelope; a first delay register, consisting of series-connected first, second, third delay elements; a second delay register, consisting of series-connected fourth, fifth, sixth delay elements; first, second and third multipliers of the output signals of the first delay register with weighting factors; first adder; first, second and third integrators; the fifth, sixth and seventh multipliers of the output signals of the second delay register with the signal of the first adaptive adjustment of weight coefficients, consisting of series-connected derivative calculation unit, the first module calculation unit, the second adder with voltage -G and the fourth multiplier with voltage -d1, according to the claimed useful model includes a second converter of the complex envelope of the signal into a complex conjugate envelope, the input of which is connected to the output of the first adder and to the input of the third delay register, consisting of the seventh, eighth, ninth delay elements in series, the outputs of which are connected to the first inputs of the eighth, ninth and tenth multipliers of the output signals of the third delay register with weights, while the outputs of these multipliers are connected to the inputs of the third adder, the output of which is the output of the device and at the same time the input of the second adaptive adjustment scale of the coefficients, which contains the second block of module calculation, the squaring block, the fourth adder, the second input of which is supplied with a constant voltage of -1, and the output is connected to the input of the eleventh multiplier, the second input of which is connected to the output of the third adder, and the third input is for applying a constant voltage -d2, which determines the degree of inertia and stability of the adaptation process, the output of the eleventh multiplier connected to the first inputs of the twelfth, thirteenth and fourteenth multipliers with the output signals of the fourth delay register, the second inputs of which receive the output signals of the corresponding series-connected tenth, eleventh, the twelfth delay elements of the fourth delay register, while the input of the fourth delay register is connected to the output of the second converter of the complex envelope of the signal into a complex conjugate envelope, and the outputs of the twelfth, thirteenth and even The eleventh multipliers with the output signals of the fourth delay register are connected through the fourth, fifth, and sixth integrators to the second inputs of the eighth, ninth, and tenth multipliers of the output signals of the third delay register with weights.

Brief Description of the Drawings

The essence of the utility model is illustrated by the following drawings: in FIG. 1 presents a structural diagram of the inventive adaptive digital filter to suppress non-fluctuation (non-noise, structural) interference; in FIG. Figure 2 shows the dependences of the probability of error when receiving a signal against a background of harmonic interference.

The drawing in FIG. 1 contains the following items:

1 - the first converter of the complex envelope of the signal into a complex conjugate envelope;

2, 3, 4 - the first, second, third delay elements of the first delay register;

5, 6, 7 - the first, second, third multipliers of the output signals of the first delay register with weights;

8 - the first adder;

9 - block computing the derivative;

10 - the first block computing module;

11 - second adder;

12 - the fourth multiplier;

13, 14, 15 - the first, second and third integrators;

16, 17, 18 - the fifth, sixth, seventh multipliers of the output signals of the second delay register with the signal of the first adaptive adjustment of weight coefficients;

19, 20, 21 - the fourth, fifth, sixth delay elements of the second delay register.

22 - the second converter of the complex envelope of the signal into a complex conjugate envelope;

23, 24, 25 - the seventh, eighth, ninth delay elements of the third delay register;

26, 27, 28 - the eighth, ninth, tenth multipliers of the output signals of the third delay register with weighting factors;

29 - the third adder;

30 is a second block computing module;

31 - block squaring;

32 - the fourth adder;

33 - the eleventh multiplier;

34, 35, 36 — fourth, fifth, and sixth integrators;

37, 38, 39 - twelfth, thirteenth, fourteenth multipliers with output signals of the fourth delay register;

40, 41, 42 — tenth, eleventh, twelfth delay elements of the fourth delay register.

Utility Model Implementation

The adaptive digital filter of non-fluctuation interference (Fig. 1) contains the first converter of the complex envelope of the signal into a complex conjugate envelope 1, the input of which is the input of the device, and this input is connected to the input of the first delay register, consisting of the first, second, third delay elements of the first delay register 2, 3, 4, the outputs of which are connected to the first inputs of the first, second, third multipliers of the output signals of the first delay register with weights 5, 6, 7. The outputs of these multipliers 5, 6, 7 are connected to the inputs of the first adder 8, output which is connected to the input of the second transducer of the complex envelope of the signal into a complex conjugate envelope 22, the input of the third delay register and at the same time to the input of the first adaptive adjustment of weighting coefficients containing the derivative 9, the first unit 10, the second adder 11, WTO the swarm input of which is supplied with a constant voltage -G proportional to the derivative of the phase pulse of the signal, and the output is connected to the input of the fourth multiplier 12, the second input of which is connected to the output of the first adder 8, and the constant voltage -d1 is applied to the third input, which determines the degree of inertia and process stability adaptation. Moreover, the output of the fourth multiplier 12 is connected to the first inputs of the fifth, sixth, and seventh multipliers of the output signals of the second delay register with the signal of the first adaptive adjustment circuit of the weight coefficients 16, 17, 18, to the second inputs of which the output signals of the corresponding fourth, fifth, and sixth elements are connected in series the delay of the second delay register 19, 20, 21, while the input of the second delay register is connected to the output of the first converter of the complex envelope of the signal into a complex conjugate envelope 1, and the outputs of the fifth, sixth, seventh multipliers of the output signals of the second delay register with the signal of the first adaptive weight adjustment circuit coefficients 16, 17, 18 are connected through the first, second and third integrators 13, 14, 15 with the second inputs of the multipliers of the output signals of the first delay register with weighting factors 5, 6, 7. Moreover, the input of the second converter of the complex envelope of the signal in complex conjugate The envelope 22 is connected to the input of the third delay register, consisting of the seventh, eighth, and ninth delay elements 23, 24, 25 connected in series, the outputs of which are connected to the first inputs of the eighth, ninth, and tenth multipliers of the output signals of the third delay register with weighting factors 26, 27 , 28. The outputs of these multipliers 26, 27, 28 are connected to the inputs of the third adder 29, the output of which is the output of the device and at the same time, the input of the second adaptive adjustment of the weight coefficients circuit, containing the second block of calculation of the module 30 connected in series, the squaring unit 31, the fourth an adder 32, the second input of which is supplied with a constant voltage of -1, and the output is connected to the input of the eleventh multiplier 33, the second input of which is connected with the output of the third adder 29, and a constant voltage -d2 is applied to the third input, which determines the degree of inertia and stability of the adaptation process. Moreover, the output of the eleventh multiplier 33 is connected to the first inputs of the twelfth, thirteenth, fourteenth multipliers with the output signals of the fourth delay register 37, 38, 39, the second inputs of which receive the output signals of the corresponding series-connected tenth, eleventh, twelfth delay elements of the fourth delay register 40, 41 , 42, while the input of the fourth delay register is connected to the output of the second converter of the complex envelope of the signal into a complex conjugate envelope 22, and the outputs of the twelfth, thirteenth, fourteenth multipliers with the outputs of the fourth delay register 37, 38, 39 are connected through the fourth, fifth, and sixth integrators 34, 35, 36 with the second inputs of the multipliers of the output signals of the third delay register with weights 26, 27, 28.

The operation of the device is based on the use of known data on the shape of the phase pulse and the constant envelope of the received signal.

The inventive device sequentially implements two methods for adjusting the vectors of weights:

the first is controlling the shape of the phase pulse of the received signal in accordance with the equation:

, где М{⋅} - знак математического усреднения;where d1 is a coefficient determining the degree of inertia and stability of the first adaptation process, while the objective functional is minimized

where M {⋅} is the sign of mathematical averaging;

the second - controlling the constant envelope of the received signal:

where d2 is the coefficient determining the degree of inertia and stability of the second adaptation process, while the objective functional M {(| z _i | ² -1) ² } is minimized.

As a result of the AF operation, the phase pulse and the envelope of the received signal are aligned and, as a result, the influence of noise is reduced and the filtering accuracy is increased.

The input discrete samples of the complex envelope x _i go to the input of the first delay register, consisting of the first, second and third delay elements 2, 3, 4, connected in series, and from their outputs go to the inputs of the multipliers of the output signals of the first delay register with weight coefficients 5, 6 , 7 sample vectors X _i with weighting factors W ¹ _i generated by the first, second and third integrators 13, 14, 15. The signals from the outputs of the multipliers of the output signals of the first delay register with weighting factors 5, 6, 7 are fed to the inputs of the first adder 8, the output of which is the output of the device. This structure is a non-recursive filter that implements the procedure for adjusting the vector of weight coefficients, which controls the shape of the phase pulse of the received signal and generates samples of the signal y _i .

In the process of adaptation, the correction of the weight coefficients W ¹ _i occurs in accordance with equation (I). For this, the output signal of the adaptive digital filter is differentiated by the derivative calculation unit 9, then the derivative module in the first calculation unit of the module 10 is calculated, and the signal is supplied to the second adder 11, the second input of which is supplied with a constant voltage -G proportional to the derivative of the signal phase pulse. This allows you to compare the current value of the slope of the phase pulse of the signal with the ideal a priori specified value G.

If there is non-fluctuation (non-noise, structural) interference in the communication channel, these values will differ, and the second adder 11 will generate a control voltage proportional to their difference, which will be used to adjust the vector of weight coefficients in accordance with equation (I). For this, the signal from the output of the second adder 11 is fed to the input of the fourth multiplier 12, the adaptive filter signal y _{i is} supplied to the second input, and a constant voltage -d1 is applied to the third input, which determines the degree of inertia and stability of the first adaptation process. Then there is a multiplication of the vector of samples of the complex conjugate envelope X _i *, delayed in the second delay register on the fourth, fifth, sixth delay elements 19, 20, 21:

X _i * = [x _i *, x _i-1 *, ... x _{i-N + 1} *].

in the fifth, sixth, seventh multipliers of the output signals of the second delay register with the signal of the first adaptive adjustment circuit of the weighting factors 16, 17, 18.

The output signals of the fifth, sixth, and seventh multipliers of the output signals of the second delay register with the signal of the first adaptive adjustment scheme of the weight coefficients 16, 17, 18 are fed to the inputs of the first, second, and third integrators 13,14,15, which carry out the correction of the weight vector W ¹ _{i + 1} .

Next, discrete samples y _i go to the input of the third delay register, consisting of the seventh, eighth, ninth delay elements 23, 24, 25 connected in series, and from their outputs go to the inputs of the eighth, ninth, tenth multipliers of the output signals of the third delay register with weight coefficients 26, 27, 28 sample vectors Y _i with weighting factors W ² _i generated by the fourth, fifth and sixth integrators 34, 35, 36. Signals from the outputs of the eighth, ninth, tenth multipliers of the output signals of the third delay register with weighting factors 26, 27, 28 enter the inputs of the third adder 29, the output of which is the output of the device. This structure is a non-recursive filter that implements the procedure for adjusting the vector of weight coefficients, which controls the constant envelope of the received signal and generates samples of the signal z _i .

In the process of adaptation, the correction of the weight coefficients W ² _i occurs in accordance with equation (II). For this, in the second block of the calculation module 30, the adaptive digital filter output signal module is calculated, which is then squared in the squaring block 31, and the signal is supplied to the fourth adder 32, the second input of which is supplied with a constant voltage of -1. This allows you to compare the current value of the envelope of the signal with an ideal constant value of 1.

If there is non-fluctuation (non-noise, structural) interference in the communication channel, these values will differ, and the fourth adder 32 will generate a control voltage proportional to their difference, which will be used to adjust the weight vector in accordance with equation (II). For this, the signal from the output of the fourth adder 32 is fed to the input of the eleventh multiplier 33, the output signal of the adaptive filter z _i is supplied to the second input, and a constant voltage -d2 is applied to the third input, which determines the degree of inertia and stability of the second adaptation process. The signal thus formed is multiplied in the twelfth, thirteenth, fourteenth multipliers with the output signals of the fourth delay register 37, 38, 39 with the sample vector of the complex conjugate envelope Y _i * delayed in the fourth delay register on the delay elements 40, 41, 42:

Y _i * = [y _i *, y _i-1 *, ..., y _{i-N + 1} *].

The output signals of the twelfth, thirteenth, fourteenth multipliers with the output signals of the second delay register 37, 38, 39 are fed to the inputs of the fourth, fifth and sixth integrators 34, 35, 36, which carry out the correction of the weight vector W ² _{i + 1} .

In FIG. Figure 2 shows the dependences of the probability Re of the erroneous reception of a phase-shifted signal against a background of harmonic interference with a relative intensity μ = 0.9. The solid line corresponds to the claimed device, the upper dashed line is constructed without an adaptive filter, the middle dashed line corresponds to a similar device (prototype). The effect of using the claimed device in terms of signal-to-noise ratio reaches 3 dB with a probability of error Pe = 0.01.

Claims (1)

An adaptive digital filter for suppressing non-fluctuation interference, comprising a first converter of the complex envelope of the signal into a complex conjugate envelope; a first delay register, consisting of series-connected first, second, third delay elements; a second delay register, consisting of series-connected fourth, fifth, sixth delay elements; first, second and third multipliers of the output signals of the first delay register with weighting factors; first adder; first, second and third integrators; the fifth, sixth and seventh multipliers of the output signals of the second delay register with the signal of the first adaptive adjustment of weight coefficients, consisting of series-connected derivative calculation unit, the first module calculation unit, the second adder with voltage -G and the fourth multiplier with voltage -d1, characterized in that it includes a second converter of the complex envelope of the signal into a complex conjugate envelope, the input of which is connected to the output of the first adder and to the input of the third delay register, consisting of the seventh, eighth, ninth delay elements connected in series, the outputs of which are connected to the first inputs of the eighth, ninth and tenth multipliers of the output signals of the third delay register with weighting factors, while the outputs of these multipliers are connected to the inputs of the third adder, the output of which is the output of the device and at the same time the input of the second adaptive adjustment of the weighting factors nt, containing in series the second block of the module calculation, the squaring block, the fourth adder, the second input of which is supplied with a constant voltage of -1, and the output is connected to the input of the eleventh multiplier, the second input of which is connected to the output of the third adder, and the third input is intended for applying a constant voltage -d2, which determines the degree of inertia and stability of the adaptation process, the output of the eleventh multiplier connected to the first inputs of the twelfth, thirteenth and fourteenth multipliers with the output signals of the fourth delay register, to the second inputs of which the output signals of the corresponding series-connected tenth, eleventh, twelfth delay elements of the fourth delay register, while the input of the fourth delay register is connected to the output of the second converter of the complex envelope of the signal into a complex conjugate envelope, and the outputs of the twelfth, thirteenth and fourteenth multipliers with the output signals of the fourth delay register are connected through the fourth, fifth and sixth integrators with the second inputs of the eighth, ninth and tenth multipliers of the output signals of the third delay register with weight coefficients.

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