Digital filter employing serial arithmetic

Claim 2

Digital filtering apparatus for processing successively applied digital input words by algebraically combining each input word with at least two recirculating data words, comprising: first and second serially connected storage units; first and second arithmetic units; means for selectively applying the output of said first storage unit to said first arithmetic unit; means for selectively applying the output of said second storage unit to said second arithmetic unit; means for selectively applying the output of said second arithmetic unit to said first arithmetic unit; means for selectively applying said input word to said first arithmetic unit including means for selectively applying said input word to said first storage unit; and means for selectively applying the output of said first arithmetic unit to said first storage unit.

Claim 3

Digital filtering apparatus for processing successively applied digital input words by algebraically combining each input word with at least two recirculating data words, comprising: first and second serially connected storage units; first and second arithmetic units; means for selectively applying the output of said first storage unit to said first arithmetic unit; means for selectively applying the output of said second storage unit to said second arithmetic unit; means for selectively applying the output of said second arithmetic unit to said first arithmetic unit; means for selectively applying said input word to said first arithmetic unit including means for selectively applying said input word to said first storage unit; and means for selectively applying the output of said first arithmetic unit to said first storage unit.

Claim 4

Digital filtering apparatus for processing successively applied digital input words by algebraically combining each input word with at least two recirculating data words, comprising: first and second serially connected storage units; first and second arithmetic units; means for selectively applying the output of said first storage unit to said first arithmetic unit; means for selectively applying the output of said second storage unit to said second arithmetic unit; means for selectively applying the output of said second arithmetic unit to said first arithmetic unit; means for selectively applying said input word to said first arithmetic unit including means for selectively applying said input word to said first storage unit; and means for selectively applying the output of said first arithmetic unit to said first storage unit.

Claim 5

The apparatus defined in claim 1 further comprising: a third storage unit serially connected to said second storage unit; a fourth storage unit; third and fourth arithmetic units; means for selectively applying the output of said first storage unit to said fourth storage unit; means for selectively applying the output of said second storage unit to said third arithmetic unit; means for selectively applying the output of said third storage unit to said fourth arithmetic unit; means for selectively applying to output of said fourth arithmetic unit to said third arithmetic unit; means for selectively applying the output of said fourth storage unit to said fourth arithmetic unit; and means for selectively applying the output of said fourth arithmetic unit to said fourth storage unit.

Claim 6

Digital filtering apparatus for processing successively applied digital input words by algebraically combining each input word with at least two preceding input words, comprising: first and second serially connected storage units; first and second arithmetic units; means for selectively applying the output of said first storage unit to said first arithmetic unit; means for selectively applying the output of said second storage unit to said second arithmetic unit; means for selectively applying the output of said second arithmetic unit to said first arithmetic unit; and means for selectively applying said input word to said first storage unit and to said first arithmetic unit.

Claim 7

Digital filtering apparatus for processing successively applied digital input words by algebraically combining each input word with at least two preceding input words, comprising: first and second serially connected storage units; first and second arithmetic units; means for selectively applying the output of said first storage unit to said first arithmetic unit; means for selectively applying the output of said second storage unit to said second arithmetic unit; means for selectively applying the output of said second arithmetic unit to said first arithmetic unit; and means for selectively applying said input word to said first storage unit and to said first arithmetic unit.

Claim 8

In a digital filter for processing successively applied digital input words to produce successive digital output words by algebraically combining each input word with at least two previously computed output words, said filter including first and second serially connected delay units for successively delaying said previously computed output words and first and second multipliers for multipyling the output of said first and second delay units by first and second filter coefficients to produce first and second product words respectively, said first and second multipliers each including an accumulator for accumulating successive partial products, the improvement comprising: means for applying said first and second product words to said accumulator of said first multiplier to produce a first sum word; means for applying said first sum word and said input word to said accumulator of said first multiplier to produce an output word; and means for applying said output word to said first delay unit.

Claim 9

In a digital filter for processing successively applied digital input words to produce successive digital output words by algebraically combining each input word with at least two previously computed output words, said filter including first and second serially connected delay units for successively delaying said previously computed output words and first and second multipliers for multipyling the output of said first and second delay units by first and second filter coefficients to produce first and second product words respectively, said first and second multipliers each including an accumulator for accumulating successive partial products, the improvement comprising: means for applying said first and second product words to said accumulator of said first multiplier to produce a first sum word; means for applying said first sum word and said input word to said accumulator of said first multiplier to produce an output word; and means for applying said output word to said first delay unit.

Claim 10

The digital filter defined in claim 4 wherein said means for applying said first sum word and said input word to said accumulator of said first multiplier includes means for storing said input word in said first delay unit prior to its application to said accumulator.

Claim 11

In a digital filter for processing successively applied digital input words to produce successive digital output words by algebraically combining each input word with at least two previous input words, said filter including first and second serially connected delay units for successively delaying said previous input words and first and second multipliers for multiplying the output of said first and second delay units by first and second filter coefficients to produce first and second product words respectively, each of said first and second multipliers including an accumulator for accumulating successive partial products, the improvement comprising: means for applying said first and second product words to the accumulator of one of said multipliers to produce a first sum word; and means for applying said input word and said first sum word to the accumulator of said one of said multipliers to produce an output word.

Claim 12

In a digital filter for processing successively applied digital input words to produce successive digital output words by algebraically combining each input word with at least two previous input words, said filter including first and second serially connected delay units for successively delaying said previous input words and first and second multipliers for multiplying the output of said first and second delay units by first and second filter coefficients to produce first and second product words respectively, each of said first and second multipliers including an accumulator for accumulating successive partial products, the improvement comprising: means for applying said first and second product words to the accumulator of one of said multipliers to produce a first sum word; and means for applying said input word and said first sum word to the accumulator of said one of said multipliers to produce an output word.

Claim 13

Digital filtering apparatus for processing successively applied digitally coded input words to produce successive digitally coded output words by algebraically combining each input word with weighted versions of a plurality of previously computed recirculating data words, comprising: first and second serially connected delay devices for successively delaying said previously computEd recirculating data words; a first arithmetic unit for multiplying the data word produced by said first delay device by a first feedback filter coefficient to produce a first product word, said first arithmetic unit including an adder for accumulating successive partial product words; a second arithmetic unit for multiplying the data word produced by said second delay device by a second feedback filter coefficient to produce a second product word; means for applying said first and second product words to said adder of said first arithmetic unit for addition to produce a first sum word; means for applying said first sum word and said input word to said adder for addition to produce a recirculating data word; and means for applying said recirculating data word to said first delay device.

Claim 14

Digital filtering apparatus for processing successively applied digitally coded input words to produce successive digitally coded output words by algebraically combining each input word with weighted versions of a plurality of previously computed recirculating data words, comprising: first and second serially connected delay devices for successively delaying said previously computEd recirculating data words; a first arithmetic unit for multiplying the data word produced by said first delay device by a first feedback filter coefficient to produce a first product word, said first arithmetic unit including an adder for accumulating successive partial product words; a second arithmetic unit for multiplying the data word produced by said second delay device by a second feedback filter coefficient to produce a second product word; means for applying said first and second product words to said adder of said first arithmetic unit for addition to produce a first sum word; means for applying said first sum word and said input word to said adder for addition to produce a recirculating data word; and means for applying said recirculating data word to said first delay device.

Claim 15

The apparatus defined in claim 7 further comprising: a third delay device serially connected to said second delay device for further delaying said previously computed recirculating data words; a storage device for storing and reproducing an applied data word; means for applying the data word produced by said first delay device to said storage device; a third arithmetic unit for multiplying the data word produced by said second delay device by a first feedforward filter coefficient to produce a third product word, said third arithmetic unit including an adder for accumulating successive partial product words; a fourth arithmetic unit for multiplying the data word produced by said third delay device by a second feedforward filter coefficient to produce a fourth product word; means for applying said third and fourth product words to said adder of said third arithmetic unit for addition to produce a second sum word; and means for applying said second sum word and the data word produced by said storage device to said adder of said third arithmetic unit for addition to produce an output word.

Claim 16

Digital filtering apparatus for processing successively applied digitally coded input words to produce successive digitally coded output words by algebraically combining each input word with weighted versions of at least two previously applied input words comprising: first and second serially connected delay devices for successively delaying said previously applied input words; a first arithmetic unit for multiplying the data word produced by said first delay device by a first feed-forward filter coefficient to produce a first product word, said first arithmetic unit including an adder for accumulating successive partial product words; a second arithmetic unit for multiplying the data word produced by said second delay device by a second feed-forward filter coefficient to produce a second product word; means for applying said first and second product words to said adder for addition to produce a first sum word; and means for applying said first sum word and said input word to said adder for addition to produce said output word.

Claim 17

Digital filtering apparatus for processing successively applied digitally coded input words to produce successive digitally coded output words by algebraically combining each input word with weighted versions of at least two previously applied input words comprising: first and second serially connected delay devices for successively delaying said previously applied input words; a first arithmetic unit for multiplying the data word produced by said first delay device by a first feed-forward filter coefficient to produce a first product word, said first arithmetic unit including an adder for accumulating successive partial product words; a second arithmetic unit for multiplying the data word produced by said second delay device by a second feed-forward filter coefficient to produce a second product word; means for applying said first and second product words to said adder for addition to produce a first sum word; and means for applying said first sum word and said input word to said adder for addition to produce said output word.

Claim 18

Digital filtering apparatus for processing successively applied digitally coded input words to produce successive digitally coded output words by algebraically combining each input word with weighted versions of a plurality previously computed recirculating data words comprising: first and second serially connected shift registers for successively delaying said previously computed recirculating data words; a first serial multiplier for multiplying the data word produced by said first shift register by a first feedback filter coefficient to produce a first product word, said first multiplier including a first serial accumulator for accumulating successive partial product words; a second serial multiplier for multiplying the data word produced by said second shift register by a second feedback filter coefficient to produce a second product word; means for selectively applying said second product word to said first accumulator for serial addition to said first producT word to produce a first sum word stored in said first accumulator; means for selectively applying said input word to said first serial accumulator for serial addition to said first sum word to produce a recirculating data word; and means for selectively applying said recirculating data word to said first shift register.

Claim 19

Digital filtering apparatus for processing successively applied digitally coded input words to produce successive digitally coded output words by algebraically combining each input word with weighted versions of a plurality previously computed recirculating data words comprising: first and second serially connected shift registers for successively delaying said previously computed recirculating data words; a first serial multiplier for multiplying the data word produced by said first shift register by a first feedback filter coefficient to produce a first product word, said first multiplier including a first serial accumulator for accumulating successive partial product words; a second serial multiplier for multiplying the data word produced by said second shift register by a second feedback filter coefficient to produce a second product word; means for selectively applying said second product word to said first accumulator for serial addition to said first producT word to produce a first sum word stored in said first accumulator; means for selectively applying said input word to said first serial accumulator for serial addition to said first sum word to produce a recirculating data word; and means for selectively applying said recirculating data word to said first shift register.

Claim 20

The apparatus defined in claim 11 further comprising: a third shift register serially connected to said second shift register for further delaying said previously computed recirculating data words; a storage register for storing and reproducing an applied data word; means for selectively applying the data word produced by said first shift register to said storage register; a third serial multiplier for multiplying the data word produced by said second shift register by a first feed-forward filter coefficient to produce a third product word, said third multiplier including a second serial accumulator for accumulating successive partial product words; a fourth serial multiplier for multiplying the data word produced by said third shift register by a second feed-forward filter coefficient to produce a fourth product word; means for selectively applying said fourth product word to said second serial accumulator for serial addition to said third product word to produce a second sum word stored in said second accumulator; and means for selectively applying the data word produced by said storage register to said second serial accumulator for serial addition to said second sum word to produce an output word.