SU570981A2 - Digital filter - Google Patents

Description

multipliers 3 and accumulating adders of 4 quadrature channels, the outputs of which are connected to the inputs of the adder 5. The first inputs of the binary multipliers 3 are combined, and the second are connected to the outputs of the binary-quantized reference signals of the 6 reference frequencies. In addition, to the second input of the multiplier 2 are connected in series generator 7 clock pulses, reversible counter 8, a storage device 9 and a register 10, the output of which through the amplifier 11 overwriting connected to the second input of the storage device 9, and the second output of the generator 7 clock pulses connected one of the inputs of the analog-to-digital converter 1.

In addition, the digital filter contains a shaper 12 single pulses, the first input of which is connected to one of the generator outputs 6 reference frequencies, the second input - to the generator output 7 clock pulses, and the output to the clock inputs of accumulating adders 4 quadrature channels.

The digital filter works as follows.

A clock generator 7, which determines the frequency of operation of the analog-digital converter 1 and the weighting processing circuit consisting of multiplier 2, register 10, reversible counter 8 and memory 9, samples the input signal with the maximum achievable frequency.

The shaper of single pulses 12 selects from a sequence of pulses arriving at its second input from generator 7 by one pulse per period of the frequency of the signal fed to the first input of the shaper of single pulses 12. This frequency is a multiple of the reference frequency / oni of this digital filter (for example, 4 / op,), sets the sampling rate in this filter. The shaper of 12 single impulses gives out

the first whole pulse from the breeding sequence after crossing the threshold level with a positive derivative by the selection signal, which ensures the normal operation of accumulating adders

4 quadrature channels, since the addition pulse arrives synchronously with the information and has a predetermined duration in each accumulating adder 4, which ensures the accumulation of information arriving through

equal (up to a period of the oscillator frequency of 7 clock pulses), the time intervals corresponding to the sampling period in this filter. The distortion of the frequency response of a digital filter due to the mentioned discreteness of the reference time is negligible if the frequency of the clock generator is much higher than any of the reference frequencies. Thus, the proposed digital

the filter allows, at low instrumental costs, to construct a set of Doppler filters with a small amount of side lobes of the amplitude-frequency characteristics.

Claims (1)

Invention Formula Digital filter auth. St. No. 443458, characterized in that, in order to reduce the side lobes of the amplitude-frequency characteristic, a single pulse shaper was additionally introduced, the first input of which is connected to the output of the reference frequency generator, the second input - to the output of the clock generator, and the output - to the clock inputs of the accumulating adders quadrature channels. P