SU1224983A2 - Adaptive filter - Google Patents

Abstract

The invention relates to radio engineering. In relation to the main auth. N 1008888 increases noise immunity. Adaptive filter contains multichannel simulator I (MM), shaper 2 weight of new functions: (functions), adders 3, 5 and 11, threshold element 4, LPF 6, comparator 12, two additional keys 13, 15 and a waiting multivibrator 14. Input the signal is an additive mixture of an unknown repetitive signal and fluctuation interference arrives at the information input MM 1, and its control inputs are supplied with the voltage of the weight functions generated in the SPF 2. The output signals MM 1, passed the adder 3 and the threshold element 4, the trigger threshold which automatically re uliruets are input to the switch 15. If the output of the adder 11 the voltage is not zero, then the adaptive filter output from the adder 5, the LPF 6 and the key 13 enters voltage proportional to the envelope of the modulated sequence B - pulses. If the input signal contains only noise, then in the presence of adder II, comparator 12, key 15 and standby multivibrator 14 the key 13 is locked and the noise voltage from the output of the low-pass filter 6 does not reach the output of the adaptive filter. 1 silt I (O .I f 6 13

Description

one

The invention relates to radio engineering, can be used in signal processing systems of unknown shape and is an improvement of the Invention according to the author. No. 1008888,

The purpose of the invention - povyshenie-. mechanical stability.

. The drawing shows a structural electrical circuit of the adaptive filter.

The adaptive filter contains a multi-channel 1st model 1, a former 2 weight functions, the first adder 3, the threshold element 4, the second adder 5, the low-pass filter 6. Former 2 weight functions consists of a master oscillator 7, M amplitude modulators 8, M memory blocks 9 and M keys 0, as well as an additional adder 1I, comparator 12, the first additional key 13, the waiting multivibrator G4 and the second additional key 15.

Adaptive filter works as follows.

The input signal U, (t), which is an additive mixture of an unknown repeating signal and. (T) and a fluctuation noise (noise) U (t),

U, (t) U (t) + U (t)

enters the integrated information input of the multichannel model 1.

The number of used channels of model 1 is determined by the expression

.

,

c (t);

where B is the base of the received signal

Uc (t) j. F - upper frequency spectrum

 The cop

signal U, (t); T is the signal duration U The control inputs of all the M channels of model 1 from the corresponding outputs of the driver 2 are applied to the voltage of the weighting functions.

The formation of the stresses of the weight functions in the driver 2 is performed as follows,

From the M outputs of the master oscillator 7 of the driver 2, to the second inputs of the corresponding amplitude modulators 8 of the driver 2, short pulses of constant amplitude 222483a are received

amplitudes (pulses), the duration selected from the conditions

l xd 8 v

where is X.

V is the size of one element of the conductive layer of model 1 along the direction of recording the weight function; recording speed of the weight function on the inertia-free photoresistive layer of the model torus,

The interval of following S pulses at each of the outputs of the master oscillator 7 of driver 2 must not exceed the duration of the signal U (t) and the pulses at the output of the master oscillator 7 () are shifted relative to the pulses at the (i-1) th output of the master oscillator 7 for the interval ut; determined by the Katelnikov theorem

4tji

2F

Max

T In

The first input of each of the amplitude modulators 8 of the driver 2 from the corresponding storage unit 9 receives the voltage U. (t) (where) modulating in amplitude S-pulses supplied to the amplitude modulators 8 from the master oscillator 7. Modulated in amplitude 5 - pulses from the outputs of the amplitude modulators B of the imaging unit 2 are fed to the corresponding control inputs of the multichannel model 1,

At the moment the adaptive filter is turned on at the output of the model I, and therefore, at the input of the first adder 3, the voltage is almost zero, t, e, which is certainly below the initial threshold voltage of the threshold element 4, and the control voltage U4 at the output of the threshold element 4 is missing, the keys 10 of the imaging unit 2, the control inputs of which are interconnected and connected to the output of the threshold element 4, are closed. The voltages U, j (t) on the storage blocks 9 of the former 2 are absent. In this case, unmodulated S-pulses are fed to the control inputs of all the M channels of model I. Through the ID interval (time of signal processing in the model) at the output of each

model I torus channels for Vits output voltage -T), defined by the expression

(t

Ol

-TO)

U ((to;).

-Dl

t is the current moment of reference of the input signal in the i-th channel of the model torus, running through all values with the speed of movement of the weight function over the weight layer of the i-ro channel of model 1,

H;

to -

 to (H) t

t is the coefficient of proportionality, depending on the type of model 1 and its design features; the processing time of the input signal in model 1. Thus, at the time at the output of all M channels of model 1, the voltage Ugj ,,, (t g; -T), which is a sample of the instantaneous values of the input signal taken through interval At. All samples of the input signal from the outputs of the modulator 1 are fed to the first adder 3, the output voltage of which is determined by the ratio

CL1

ut

about

(

and. (t.)

Voltage U is applied to threshold element 4, where it is equal to the varying threshold voltage.

and

pore

() and, “op„ + li 4p „p (t),

where, p (s)

por f

the component of the threshold voltage generated from the signal applied to the input of the threshold element 4 At the time of switching on the adaptive filter, the threshold voltage „f, p (t) is equal to the initial value U..

During the whole time of receiving a repetitive signal, the voltage and, formed as the sum of the samples of the input signal U, (t), is applied to the threshold element 4. This voltage varies over time as due to the change in the input signal level and (t) which is a mixture of the useful signal and noise, and due to the adaptive approximation of the filter parameters on the model to the optimal ones,

to

five

20

25

thirty

- 35

- 40. ) five

50 55 If the voltage U (t) at the input of the first adder 3 does not exceed (t), then the voltage U at the output of the threshold element 4 is missing, the keys 10 in the driver 2 are closed, the voltage on the storage blocks 9 is missing, and the control The inputs of the model torus 1 and the second adder 5 are fed unmodulated 5 pulses. From the second adder 5, the unmodulated sequence of O pulses shifted relative to each other by it is fed to filter 6, the limiting frequency of which is chosen to be equal. In this case, the output voltage of the filter 6 is separated by a constant voltage, which is the envelope of the unmodulated sequence of F pulses, which is fed to the information input of the first key 13. Since the voltage on the storage blocks 9 is absent in this case, the output voltage additional adder 11 is zero.

The threshold of operation of the comparator 12 is selected optimally by the noise immunity criterion.

and ".or,.

where U, j y is the effective voltage of fluctuation noise at the input of the adaptive filter. Since in the case under consideration the voltage at the input of the comparator 12 is zero, i.e. threshold U, op is not exceeded, at its output a logical zero signal acts. In this case, the logical zero signal will be at the output of the second key 15 and the standby multivibrator 14. First key 13, to the control input of which a signal is sent from the standby multivibrator 14, is locked, and there is no signal at the output of the adaptive filter.

In the case when the voltage at the output of the first adder 3 exceeds the threshold voltage (t) of the threshold element 4, at the output of its voltage, the voltage U4 unlocks the keys 10 of the driver 2 and the second key 15. In the very same threshold element occurs at This automatically adjusts the threshold voltage.

When unlocking the keys 10 driver 2 on the storage units 9

the generator 2 is transferred to the input signal U, (t) from the output of model 1, modulating {, in amplitude modulators 8) -impulses coming from the reference oscillator 7. From the output of amplitude modulators 8 formatter 2 moduli amplitude amplitude S pulses are fed to the control inputs of channel model 1 and to adder 5, from which the amplitude-modulated sequence of signals is fed to low-pass filter 6, you are targeting a voltage proportional to the envelope of this sequence, koto The swarm is fed to the information: input of the first key 13. The voltage and from the storage blocks 9 of the generator 2, proportional to the readings of the input signals, are fed to the additional adder I15, the output of which is separated by the voltage

M.

and 9,

i

If this voltage exceeds the threshold of the comparator 12, then the output of the comparator I2 is a signal of a logical unit, which through the second key 15 is fed to a standby multivibrator 14. At the same time, the multivibrator 14 generates a signal of a logical unit, dA T, unlocking the first a key 13 through which the output of the adaptive filter puts a voltage proportional to the bending modulated sequence of S-pulses from the output of the filter 6,

If the input signal U, (t) contains only noise Uy (t), then the moments of operation of threshold element 4 will be completely random and the values of samples of the input signal transferred from the outputs of the multichannel model 1 through the keys 10 in the Omi a {other blocks 9 Former 2 will also be random. As a result of the voltage U. (t) on the storage units 9 will randomly fluctuate, remaining on average close to zero. In this case, from the imaging unit 2, the control inputs of the model 1 and the second adder 5 receive 8 pulses, the amplitude of which (pulses relative to the average value fo fo 0

five

about j

0

five

0

not in very small limits. At the output of the filter 6, the noise voltage and ,, „(t), which feed YOU X

On the information input of the first key 13.

Averaged noise and voltage voltage readings; arrive at an additional91 adder

life and .. Zl 12., from which eg - Ugj is fed to the comparator

Since the voltage and „; in this case, close to zero, then the threshold and, 2, „„ of comparator 12 will not be exceeded by voltage U ,,, at the output of comparator 12, the logical zero signal is in effect. The signal will also be output at the outputs of the second key 15 and the waiting multivibrator 14.

The first key 13 is locked at the same time, and the noise voltage from the output of the filter 6 does not reach the output of the adaptive filter,

When the input signal is the sum of the noise voltages Uy (t) and the useful signal Uj (t), the likelihood of the triggering of the threshold element 4 increases due to an increase in the energy of the input signal U, (t), and therefore and the total voltage of samples of the input signal Ug (t) applied to the threshold element 4. The higher the signal-to-noise ratio at the input of the adaptive filter, the more likely the triggering of the threshold element 4 at the moments of the appearance of the useful signal U (t).

But even with small signal-to-noise ratios, threshold element 4 will be triggered — more often with a useful signal at the input of the adaptive filter than with its absence.

After several repetitions of the useful signal that triggered the threshold element 4, the values of the voltages U. (t) on the storage units 9 of the imaging unit 2, the values of the samples of the useful signal are approximated. This is due to the averaging of the Ug- (t) voltage surges caused by noise, with the accumulation of samples of the input signal on the storage blocks 9.

On the UE. Uo. (T), modulate the S pulses applied to the amplitude modulators 8 of the master oscillator 7. At the same time, the voltage values of the weighting functions supplied from the generator 2 approach the optimum ones, which correspond to the readings of the instantaneous values of the useful U signal (t). By approximating the weighting factors to the optimum, the frequency of correct (when a useful signal appears) triggering of threshold element 4 will increase, as the response of each model I channel to the useful signal starts to increase, which will lead to an increase in voltage Jj (t) at the output of the first adder 3

The adaptation process will accelerate. In order to simultaneously reduce the random triggering of the threshold element 4 under the influence of noise at intervals when the useful signal U, (t) is absent, the threshold of the threshold element 4 automatically increases with increasing voltage at the output of the first adder 3.

A sample of the useful signal U ((t)), a sequence of S-pulses from the output of the former 2, through the second adder 5 is fed to a filter 6, which isolates the voltage, which more accurately replicates the form of the useful signal. the input of the first key 13.

The voltage on the storage units 9 of the driver 2 in this case significantly exceeds the noise voltage, so the voltage U ,,, coming to the input of the comparator 12 from the additional adder 1 1, higher than its threshold of operation U, 2 then At the output of the comparator 12 acts a signal of a logical unit that arrives at the information input of the second key 15.

If the total voltage of the input signal samples. (T) exceeds the threshold of the threshold element 4 (fixing the appearance of the useful signal U (, (t)), the output of the threshold element 4 is the voltage U based on the second key 15. The signal of the logical unit from the comparator 12 through the second key 15 is fed to the waiting multivibrator 14, the generating signal of the logical unit for the length T, which unlocks the first key 13. The voltage of the useful signal from the filter 6 through the first key 13 output adaptive If the threshold element 4 did not work when the voltage Ug (t) arrived at its input (which happens when there is no useful signal at the input), the second key 15 is locked, the logic zero signal acts on the standby multivibrator 14 signal the key 13 and the voltage formed at the output of the filter 6 is not fed to the output of the adaptive filter.

Thus, when in the input voltage U, (t) of the adaptive filter there is no repetitive signal U (t), random triggering of the threshold element 4 occurs, the average values of the voltages on the storage units 9 of the driver 2 remain zero, the threshold) threshold element 4 remains The value is close to, and the first key 13 is locked and there is no signal at the output of the adaptive filter.

With the occurrence of a repeating signal and (t) the percentage of random triggering of the threshold element 4 gradually decreases, the voltage on the storage units 9 more and more approaches the optimal values modulated by this voltage 5 - the pulses applied to the second adder 5 samples of the output signal, rushing to the value of samples of the useful signal, the threshold voltage at the output of filter 6 more and more accurately repeats the form of the useful signal Uc (t), since it is an envelope collection of samples of the useful signal U, -, taken cut ingtch

interval utr -, which allows you to accurately restore the shape of this signal.

Claims (1)

Formula invented and Adaptive filter on auth. No. 1008888, characterized in that, in order to improve noise immunity, the input of the first additional key is included between the outputs of the low-pass filter and the adaptive filter, and between the outputs M of memory blocks of the weighting function and the control input of the first additional switch 9122498310 In series, the connected lines of which are connected to the input are an additional adder, a comparator, a driver of weighting functions, and a second additional key is waiting, an input is a multiplicative multivibrator.