SU700919A2

SU700919A2 - Acoustical band-pass filter

Info

Publication number: SU700919A2
Application number: SU782631313A
Authority: SU
Inventors: Сергей Николаевич Кондратьев; Владимир Ильич Речицкий
Original assignee: Предприятие П/Я Г-4097
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1979-11-30

Description

(54) АКУСТИЧЕСКИЙ ПОЛОСОВОЙ ФИЛЬТР(54) ACOUSTIC STRIP FILTER

Изобретение относитс к области радиоэлектроники и может использоватьс в устройствах обработки сигналов.The invention relates to the field of radio electronics and can be used in signal processing devices.

В основном изобретении по авт. св. № 585589 описан акустический полосовой фильтр, в котором входной аподизованный преобразователь имеет прот женность в половину произведени длительности импульсного отклика фильтра на скорость акустических поверхностных волн на звукопроводе , а выходные преобразователи расположены по обеим сторонам входного на разных рассто ни х от него с разницей, составл ющей половину произведени длительности импульсного отклика фильтра на скорость акустических поверхностных волн.In the main invention of auth. St. No. 585589 describes an acoustic bandpass filter in which the input apodized transducer has a length of half the product of the filter impulse response time to the speed of acoustic surface waves on the acoustic duct, and the output transducers are located on both sides of the input at different distances from it with a difference of half the product of the filter's impulse response time to the speed of acoustic surface waves.

В этом фильтре может быть реализована только симметрична частотна характеристика .This filter can be implemented only symmetric frequency response.

Существует целый р«д устройств, где примен ютс фильтры с несимметричной частотной характеристикой, например фильтр УПЧ телевизионного приемника. Известный фильтр не позвол ет синтезировать несимметричную характеристику.There are a number of devices that use filters with asymmetric frequency response, such as an IFA filter for a television receiver. The known filter does not allow the synthesis of an asymmetric characteristic.

Целью изобретени вл етс получение несимметричной частотной характеристики.The aim of the invention is to obtain an asymmetrical frequency response.

Это достигаетс тем, что акустический полосовой фильтр по авт. св. № 585589 содерж .ит дополнительный аподизованный входной преобразователь, сдвинутый относительно линии симметрии выходных преобразователей на четверть длины акустической волны, при этом закон аподизации одного из входных преобразователей соответствует преобразованию Фурье четной составл ющей частотной характеристики фильтра, а другого - ее нечетной составл ющей.This is achieved by the fact that the acoustic bandpass filter according to ed. St. No. 585589 contains an additional apodized input transducer, shifted relative to the line of symmetry of the output transducers by a quarter of the acoustic wavelength, and the law of apodization of one of the input transducers corresponds to the Fourier transform of the even component of the frequency response of the filter, and the other its odd component.

На чертеже показано устройство фильтра.The drawing shows a filter device.

Claims

It consists of a piezoelectric chute 1, an input main 2 and an additional 3 converters, and output converters 4 and 5 located on the edges of the sound duct. The main input converter 2 and the additional input converter 3 have apodization laws that are proportional to the Fourier even and odd components required frequency response filter. The additional transducer 3 is shifted relative to the line of symmetry of 6 output transducers 4 and 5 by a quarter of the acoustic wavelength. The device works similarly to the device according to the main author. St. No. 585589. The frequency response of the converter is determined by the relation, Yak®, where 4 is the charge on the th electrode; d is the lattice period; N is the number of electrodes; VOL - the speed of acoustic surface waves. The task of transformer synthesis is solved with the help of the theory of Fourier series. The function F (ω) for a given number N has the smallest root-mean-square deviation from a given function H (ω) if f dK, 4π o-I; Chk A | H (w) e where f 0 g; j - j central frequency; A is the proportionality coefficient. Any asymmetric function F (cj) can be decomposed into an even Fj. (Co) and odd n (n) composition. To implement an even frequency response Ffi (co), you can use a system of electrodes located symmetrically relative to the central electrode. In this case, F.C6u), 4R "s (f" I). To implement the odd function, one can use a system of electrodes located symmetrically with respect to the line that divides the transducer across the array. Herewith (FH (O) 2 |; qHsin d (K -) l. A filter with such converters has an asymmetrical frequency response. Claims of the invention Acoustic band-pass filter according to aut. St. No. 585589, characterized in that asymmetric frequency response, it contains an additional apodized input transducer, shifted relative to the line of symmetry of the output transducers by a quarter of the acoustic wave, while the law of apodization of one of the input transducers corresponds to the Fourier transform of even Avl Yush, her frequency response of the filter, and the other, its odd composition Yush, her.