SU1495978A1 - Digital quadrature filter - Google Patents

Abstract

The invention relates to radio engineering and m. used to filter the signals specified by digital quadrature samples with a shift in the signal spectrum. The purpose of the invention is to improve the filtration accuracy while simplifying the reorganization of its frequency characteristics. The filter contains four transducers 1-4 samples, two adders 7 and 8, two multipliers 11 and 14, input 15 and output 16 of the real part of the signal, input 17 and output 18 of the imaginary part of the signal. Four adders 8, 5, 10, 6, respectively, and two multipliers 12 and 13 are additionally introduced into the filter. Synchronously changing the values of the multipliers of multipliers 11 and 14, you can control the band, synchronously changing the values of the multipliers of multipliers 12 and 13, you can control the frequency And by changing the multiplication factors of the converter multipliers, it is possible to shift the signal spectrum. 2 Il.

Description

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The invention relates to radio engineering. And can be used to illustrate signals defined by digital quadrature samples with a shift in the signal spectrum.

The purpose of the invention is to improve the filtration accuracy while simplifying the reorganization of its frequency characteristics.

FIG. Figure 1 shows the electrical structure of a digital quadrature filter; in fig. 2 is a sample converter circuit.

Digital quadrature filter (Fig. 1) contains the first 1, second 2, third 3, and fourth 4 sample converters, fourth 5, sixth 6, first 7, second 8, third 9 and fifth fifth adders, first 11, third 12, quarters 13 and 14 second decelerators, input 15 and output 16. the real part of the signal, input 17 and output 18 of the imaginary part of the signal.

The first 1, second 2, third 3, and fourth 4 sample converters (Fig. 2) contain the first 19 and second 20 delay elements, the first 21, the second 22, the third 23, and the fourth 24 um- Owners. .thirty

Digital quadrature filter works as follows.

Reports of the real part of the input signal are fed to the input 15.

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rum 22, third 23 and fourth 24 multipliers.

The counts of the real part of the input signal, the counts from the outputs of the fourth converter 4, the third converter 3 and the third multiplier 12 are fed to the inputs of the fourth adder 5, where they are added and fed to its output. They are then weighted in the first multiplier 11 and fed to the input of the first adder 7, where they are added to the samples from the outputs of the first converter 1, the third converter 2 and the third multiplier 12. The counts at the output of the second multiplier 12 are formed as follows.

. The inputs of the third adder 9 receive samples from the outputs of the first 1, second 2j third 3 and fourth 4 converters. The counts, paramilitary as a result of the summation, are fed to the input of the third multiplier 12, where they are weighed and fed to its output. ., -.

The samples obtained at the output of the first adder 7 are fed to the input of the second converter 2 and the output 16, where a real part of the samples is formed, the output signal. The samples of the imaginary part of the input signal are fed to the input 17 and the imaginary part of the output signal is formed at the output 18

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These readings are delayed in the first 19-35.

and the second 20 delay elements, then they are weighed in the first 21, second

((q, g- / V) (3-J ° m) KfJ

- (4-ib, J.Cz- / jfb.-jbJ- -4b ,, jb, J

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where the coefficients cosu) cAT ;.

a4 b j cos2Wc. , sin2 ..

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determine the magnitude of the shift w of the signal spectrum, the coefficient o (is the band, and the coefficient 5 is the center frequency of synchronizing the values of the multipliers of the first 11 and second 14 multipliers; you can control the band by synchronously changing the values of the multipliers of the third 12 and fourth 13 multipliers , you can control the frequency, and by changing the values of the multipliers of the first 21, second 22, third 23 and fourth 24 multipliers, you can shift the signal spectrum.

The transfer function of a digital quadrature filter is

2m

.-jbJ- -4b ,,

Claims (1)

Invention Formula A digital quadrature filter containing the first sample converter, whose input is the input of the real part of the digital quadrature filter signal, the first multiplier connected in series, the first adder, the output of which is the output of the real part of the signal, the digital quadrature filter, and the second sample converter - p. sampler, the input of the co. is the input of the imaginary part of the digital quadrature filter signal, connected in series to the second the multiplier, the second adder, the output of which is the output of the imaginary part of the digital quadrature filter signal and the fourth sample converter, the first, second, third and fourth sample converters made in the form of serially connected first delay element, whose input is the input of the converter samples, the second delay element and the first multiplier, the output of which is the first output of the sample converter, the second multiplier, the input of which is connected to the output of the first element delays, and the output is the second output of the sample converter, the third multiplier, whose input is connected to the output of the first delay element, and the output is the third output of the sample converter, and the fourth multiplier, whose input is connected to the output of the second delay element, and A fourth output of the sample converter, characterized in that, in order to improve the filtration accuracy while simplifying the tuning of its frequency characteristics, the third connected in series are introduced the adder, the first, second, third and fourth inputs of which are connected respectively to the second output of the first sample converter, to the third output of the third sample converter, to the second output of the second sample converter and to the third output of the fourth sample converter, the third multiplier, the output of which is connected to the second input the first adder, and even The lateral adder, the output of which is connected to the input of the first multiplier, the fifth adder connected in series, the first, second, third and fourth inputs of which are connected respectively to the third output of the second sample converter, to the second output of the fourth sample converter, with the third output of the first sample converter and c the second output of the third sample converter, the fourth multiplier, the output of which is connected to the second input of the second adder, and the sixth adder, the output of which is connected to the input v In this case, the first output of the second transducer is VL of samples and the fourth output of the fourth sample converter is connected respectively to the second and third inputs of the fourth summer, the fourth input of which is combined with the input of the first sample converter, the fourth output of the second sample converter and the first output of the fourth the sample converter is connected respectively to the second and third inputs of the sixth adder, the fourth input of which is combined with the input of the second sample converter, the fourth output of the first sample converter and the first output of the third sample converter are connected respectively to the third and fourth inputs of the second adder, and the first output of the first sample converter and the fourth output of the third sample converter are connected respectively with the third and fourth inputs of the first adder. Figg