PROGRAMMABLE DIGITAL FILTER Russian patent published in 1994 - IPC

FIELD: computer engineering. SUBSTANCE: samples of input signal are stored in registers 1, 5, 8. Signal is scaled by multiplication unit 2. Vector of filter mode is stored in register 12. Code of transmission function enters input of decoder 11 and weight coefficients which are encoded in direct parallel code enter inputs of code converters 13, 14, 15. Multiplexers 6 and 9 switch connections between units corresponding to non-recursive part of system for difference equations. Recursive part of system of equations has multiplication units 16, 17, controlled inverter units 18 and 19 and adder 20. Two parts of difference equations are combined by adder 3. Values of output signals are computed by adder 10. Double feedback for quantization error elimination is implemented due to delay of low information bits by means of registers 22 and 24 and due to multiplication of this bits by factors divisible by two. Then adders 23 and 25 shift these bits toward lower bits by one and two bits correspondingly. Outputs of adders 23 and 25 are connected to corresponding inputs adder 3. EFFECT: decreased overall variation of quantization noise at filter output due to introduction of double feedback for quantization error, increased quality of signal filtering, increased functional capabilities due to efficient transformation of transmission function and changed weight coefficients. 4 dwg