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US 4,691,293 AGranted
High frequency, wide range FIR filter
AssigneeFord Aerospace & Communications Corporation
InventorLeo W. Conboy
Life of this patent
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Abstract
The operating speed and dynamic input range of a digital FIR filter are markedly improved by encoding the signal by powers of two and using the thus encoded signal to shift (rather than multiply) the coefficient at each tap of the filter. A multiplexed shifter for simultaneously shifting all digits of the coefficient is also disclosed.
Claims5
A digital FIR filter, comprising:
- (a) a source of time-spaced analog samples of a signal to be filtered;
- (b) encoding means for converting said samples into a digital code representative of signal levels differing from each other by powers of two;
- (c) first storage means for storing a predetermined sequence of said digitally encoded signal samples;
- (d) second storage means for storing a plurality of predetermined coefficients;
- (e) shifting means for multiplying each sample of said sequence by one of said coefficients through shifting the digits of said coefficient by a number of positions determined by said digital code;
- and
- (f) accumulator means for producing a digital value representative of the sum of said multiplications.
4 more elements
Dependencies are inferred from the claim text.