SU1169149A1 - Recursive band-pass filter of discrete signals - Google Patents

Abstract

RECURSIVE STRIP FILTER OF DISCRETE SIGNALS containing a first adder connected in series, a first delay line, a second adder, a second delay line, a third adder, the non-inverting second input of which is connected to the non-inverting first input of the first adder, the first adapter whose output is connected to the second input, the second input whose output is connected to the second input, which is connected to the non-inverting first input of the first summer adder adder, and the second multiplier, the output of which is connected to the third input of the first adder, as well as the third multiplier and the fourth multiplier, the input of which is connected to the output of the perotli ayuvogo multiplier. the fact that, in order to adjust the filter frequency by changing one factor while maintaining the bandwidth unchanged, the outputs of the second and fourth multipliers are connected to the input of the third multiplier and the non-inverting input of the second adder, respectively, the second and fourth inputs of the first adder are combined and are non-inverting inputs, and the third input of the first adder and the first input of the third adder are inverting inputs, with the first input of the first adder and the output tego multiplier are input and output of the bandpass filter of the recursive digital signals, respectively.

Description

11169149 The invention relates to radio engineering and can be used in digital information processing systems. The purpose of the invention is the implementation of the filter frequency adjustment by changing one coefficient. FIG. 1 shows a structural electrical circuit of a recursive band-pass filter for discrete signals; figure 2 is its signal graph. The recursive bandpass filter of discrete signals contains the first adder 1, the first line 2 of the delay-is, the second adder 3, the second line 4 of the delay, the third adder 5, the first 6, the second 7, the third 8 and the fourth 9 multipliers. The recursive bandpass filter of disk signals operates as follows. The transfer function in the Z-plane for a recursive band-pass filter for discrete signals, based on its 25th graph (FIG. 2), is equal to H (Z). I - L lj2-; where p, SAH; p, f Z (-1) SAH; L, Z-; (-1) CB; . LZ zZ - (- l) CA (71); Bz rz-4-i) C2 B, A, C, K are the multiplication coefficients of the fourth 9, first 6, second 7 and third 8 smart inhabitants, and C 0 d "Produced all necessary extractions, we get MTvstSh Tstg-Dl evaluating the frequency properties of the filter, the resulting expression (2) should be transformed into the p-plane using the expression

(f) (WG

As a result, we get the square of the frequency response module "T. and then from

(|)

(6)

(2).

(7)

From expressions (4) and (6) it follows that the filter can be tuned in frequency with a constant band in a wide range of operating frequencies. According to expression (5), filter tuning by frequency can be possible if iulf. “Lg (f) 4 (e - ,, (,., R) we follow the obtained expression (3),. We find the dependence of the band (s) of the resonance frequency (MC from the A and B oscillators. Since | n (,) | k, according to the expression (3) (B-4) tg4f -) - (B + 4) O ud 2. 4 + In 4.p, J arctg- --g. in -4 cos (sotsre, T). By analogy to the bandwidth coordinates of the attenuation level n can be written down | H (J (.,) h Hn (l.M ,,) | a K li according to the extrusion (3) we have C ь d (2 Af (6P | 6 h g;; fUu, , T 2MnM- (7ftV4nMVBSi6 to I la - -. - 2 I. 6-4 Use tf (sf.-K) (tgot-tg /)) / 1 + tgoJ tg / i, then tg (-)

3116.91494

Only a change in the coefficient is thrown unchanged during the restructuring. 6 fourth multiplier 9. And. In this case, the adjustment of the bandwidth coefficient, specified by the co-transmission at the resonant frequency of the expression (7), can only be made by changing the A-factor of the first multiplier 6, the base 5 of the coefficient k of the third multiplier.

Code I; -,

. Z, -1 with fi (1Md

 Z .. & -

Claims (1)

RECURSIVE BAND FILTER OF DISCRETE SIGNALS, containing in series the first adder, the first delay line, the second adder, and the second one. delay, the third adder, the non-inverting second input of which is connected to the non-inverting first input of the first adder, the first multiplier, the output of which is connected to the second input of the first adder, and the second multiplier, the output of which is connected to the third input of the first adder, as well as the third multiplier and the fourth multiplier, the input of which is connected to the output of the first multiplier, characterized in that, in order to carry out the tuning of the filter in frequency by changing one coefficient while maintaining an unchanged prop band accelerations, the outputs of the second and fourth multipliers are connected to the input of the third multiplier and to the non-inverting input of the second adder, respectively, the second and fourth inputs of the first adder are combined and are its non-inverting inputs, and the third input of the first adder and the first Input of the third adder are inverting inputs, while the first the input of the first adder and the output of the third multiplier are the input and output of the recursive bandpass filter of discrete signals, respectively. FIG. /