SU1003339A2 - Non-linear digital filter - Google Patents

Description

. The invention relates to radio engineering and is intended to filter the measurement results of two functionally related parameters, such as range and speed, which are digitized with a digital code.

According to the main author. St. No. 813701 is a non-linear digital filter comprising two circuits, each of which consists of a series-connected comparison unit, a two-way limiter, an adder and a non-recursive filter, the output of which is connected to other inputs of the corresponding comparison unit and adder, as well as the measurement dispersion estimator, input which is connected to the output of the corresponding two-way limiter, the first output to the input of the corresponding two-way limiter, and the second output to the control inputs is non-recursive filters, and the output of the adder of each circuit is connected to another signal input of the non-recursive filter of another circuit tl3.

The shortcoming of the device is the relatively low filtration accuracy under the conditions of the time variable value of the correlation moment.

The purpose of the invention is to improve the filtration accuracy.

To achieve the goal, an OR element, two prohibition blocks, a multiplier and an additional non-recursive filter are introduced into the nonlinear digital filter, with the additional outputs of two-way terminators connected to the OR element inputs, the prohibition blocks controlling inputs, and the information input of each of which are connected to the output with the output of the corresponding two-sided limiter, the outputs of the inhibit blocks are connected to the multiplier, the output is the input of an additional non-recursive filter, the output of which is connected to an additional control inputs of non-recursive filters. . .

The drawing shows a structural electrical circuit of a non-linear digital filter.

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A non-linear digital filter contains two circuits, each of which consists of a series of connected 1-1 (1-2) comparison units, a two-way limiter 2-1 (2-2), a total of 30 torus 3-1 (3-2), and a non-recursive filter 4-1 (4-2), the output of which is connected to the other inputs of the corresponding block 1-1 (1-2) sar and adder 3-1 (3-2), as well as block 5-1 (5-2 ) estimates of variance and measurements, the input of which is connected to the output of the corresponding two-sided limiter 2-1 (2-2), the first output -1 to the input of the corresponding two-sided limiter 2-1 (2 second output - to control non-recursive filters 4-1 (4-2), with the output of the adder 3-1 (3-2), connected to the other signal input of the non-recursive filter 4-2 (4-1) of another circuit, and the same an OR 6 element, each of its two inputs is connected to the output of the corresponding two-way limiter 2-1 and 2-2, and the output to the control inputs of two prohibition blocks 7-1 and 7-2, the information input of each of which is connected to the signal output the corresponding bilateral limiter 2-1 (2-2), and the output - to the series-connected multiplier 8, add nomu nonrecursive fil py 9, the output of which is connected to the control inputs of the FIR filters 4-1 and 4-2. The device works as follows. In the untreated mode, when there are no anomalous distortions of the measured parameters, as well as constant dispersions of measurement errors and a correlation moment, the results of measuring velocity V and distance 5 V.m. time points t are fed to the digital filter inputs. Let us assume that the measurements of the range Sj and the velocity V at the instants of time t are unmarked and are carried out with error, characterized by their dispersions b | and bu respectively. In this case, the values of the velocity V and S through the corresponding block 1 (1-2) of the match, the two-way limiter 2-1 (2-2), the adder 3-1 (3-2 arrive at the inputs of non-recursive ohms filters 4-1 (4 -2). At the output of the non-cursive filter 4-1, the measurements of the velocity Y have a sliding estimate of the velocity of V, and at the output of the non-recursive filter 4-2 of the measurements of the range Sj, the estimated distance S In each circuit there is negative feedback from the non-recursive filter 4-1 (4-2) to block 1-1 (1-2) of the comparison is compensated by positive feedback from the non-recursive filter 4-1 (4-2) to the sum 3-1 (3-2). When anomalous measurement errors occur, the two-sided limiter 2-1 (2-2) limits them from above and below. Simultaneously, from the output of the two-way limiter 2-1 (2-2), the signal goes to the input of the unit 5-1 (5-2) of the measurement dispersion estimate, in which the interval slid estimate of the variance is made from the measurement source. This unit 5-1 (5-2) of the estimate can be a series-connected square and amplifier. The output signal from the evaluation unit 5-1 (5-2) of the evaluation is fed to the input of the two-way limiter 2-1 (2-2) of the corresponding filtering circuit and to the inputs of non-recursive filters 4-1 (4-2). If the variances of measurement errors change, the limiter limits of limiters 2-1 (2-2) also change accordingly, and the values of the output signals of the generators of standard non-recursive filters 4-1 (4-2) are also corrected, what. corresponds to a change in the constant coefficients that are a function of 3 |, d. K, t, -, where K is the correlation moment, tj is the current moment of time. At the same time, signals from the outputs of two-sided stops 2-1 (2-2), equal to () and (V - V), through normally open blocks 7-1 (7-2) of the ban, enter the multiplier 8, the output of which produces 3- (S - S (. The signals from the output of multiplier 8 are fed to an additional non-recursive filter 9, operating in a slip averaging mode, at which the estimate of the correlation moment F is generated) where m is the number of registers of the non-recursive filter 9, Evaluation K is applied to the control inputs of non-recursive filters 4-1 and 4-2, resulting in the filter parameters are adjusted and the filtering accuracy is increased under conditions of variable magnitude of the correlation moment. At the same time, if the signal at the input of one of the two-way limiters 2-1 and 2-2 exceeds the upper threshold of the restrictions or is less than the lower threshold , fo at the output of the corresponding two-way limiter 2-1 or 2-2, a signal appears that corresponds to the anomalous distortion of the measured parameter. The signal from the output of the element OR 6 closes the prohibition blocks 7-1 and 7-2, the signals through which the outputs of the two-way limit 2-1 and 2-2 do not arrive at the inputs of the multiply 8. Thereby, the correlation moment estimate is made only on the basis of processing undistorted measurement results.

In this way, the accuracy of the filtering in terms of the variable magnitude of the correlation moment, which is determined only by the undistorted results of measurements of both functionally related parameters, is increasing.

Valid at the same time: measuring speed V and range S to a moving object according to the results of speed and range measurements at discrete points in time (V, Sj), estimates of non-recursive filters 4 are obtained by the algorithm

f (K, 6; .62.t..n,); , (5.t ,, tt,),

where K is the correlation moment,

t; - moment of measurement, y, b - dispersion of measurements of speed and range V and S, m - number of measurements. The prototype device does not provide for the restructuring of non-recursive filters in accordance with changes in the magnitude of the correlation moment. Therefore, if the current value of K is different from the a priori value to which the non-recursive filters are tuned, then the estimates of V and S will be relatively coarse.

In the proposed device, the interval to the inputs of non-recursive illtr are directed to the gyre

time-dependent estimates of the correlation moment. As a result, non-recursive filters are rebuilt and thereby increase the accuracy of the filtering, since the estimates of V and S will be more accurate.

Claims (1)

1. USSR author's certificate No. 813701, cl. H 03 H 17/04, 1979 (prototype).