SU396812A1 - MULTI-CHANNEL DOPPLER FILTER - Google Patents

Description

one

The invention relates to the field of radio engineering and can be used in radio engineering and radar devices for determining the Doppler shift of the frequency of received signals.

Known multichannel Doiler filters on ultrasonic delay lines with multi-element electroacoustic transducers located on a common single-crystal anisotropic sound duct do not provide sufficient accuracy in the relative frequency distribution of the filter channels.

The aim of the invention is to eliminate this drawback.

For this purpose, all equidistant lattices of the counter-transducers of all filter channels are identical, and the longitudinal axes of converters are developed in the plane of the anisotropic acoustic duct at an angle to one another, so that the velocity of the surface wave propagates in the direction of the longitudinal axis of any converter the center frequency of the channel formed by this transducer is a constant value equal to the spatial location of the electrodes.

FIG. Figure 1 shows the proposed filter with three multi-element transducers on the sump "from piezoquartz";

in fig. 2, a, b - dependences of the velocity of propagation of the surface wave in piezoquartz.

The main element of a multichannel Doppler filter is a duct / cut from a piezoelectric mono-crystal with input and output multielement converters 2 and 3, respectively, forming independent frequency

channels. The longitudinal axes of the converters aaa, bb, and cc are rotated with respect to one K to another in such a way that the angles between the axes of the adjacent converters are equal to A6, chosen from the given

frequency detuning according to the formula: D / -L

TO

where K is spatial

the period of the gratings of converters;

D / - frequency detuning of two

adjacent channels;

K - steepness of characteristic.

The formula was obtained under the assumption of a linear dependence of the change in the velocity of the ultrasonic wave on the angle of the AE, which is valid for small values of A9 (Fig. 2).

Signal in the form of a radio pulse with a frequency

the filling, lying in the limit x of the band of working frequencies, is fed to the input of electrically connected; input converters 2. Signals with different amplitudes are not connected to the output PreObrashthree x 3, which do not have an electrical contact between the speaker. In this case, the signal will have the highest value. At the output of the converter, for which the relation

;; (e)

Xnz

where CdE is the propagation velocity of the surface wave in the direction 9; f is the channel setting frequency.

Subject invention

A multichannel Doppler filter on ultra-ultrasound: X delay lines with multi-element electroacoustic transducers located on a common monocrystalline anisotropic sound duct, characterized in that, in order to increase the accuracy of the relative frequency distribution of the filter channels, all equidistant lattices of retro-pin converters of all channel channels have all of the channel channels used in all channel channels. identical, and the longitudinal axes of the transducers are rotated in the plane of the anisotropic sound conductor at an angle to one another, so that the ratio velocity of propagation of the surface wave in the direction of the longitudinal axis of each transducer to the central frequency of the channel formed by these preobrazo1vatelem, is a constant value equal to the spatial period of the arrangement of electrodes.

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