Digital filter for filtering time-division-multiplexed signal
OwnerMasahiro Shiozawainventor
Life of this patent
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Abstract
A digital filter is provided for simultaneously filtering different components of a time-division-multiplexed signal. The digital filter comprises an odd number of a plurality of taps. A center tap and odd-numbered taps counted from the center tap all have coefficients equal to zero. The remaining taps, i.e., even-numbered taps counted from the center tap have coefficients for defining the filtering characteristic.
Claims19
A digital filter having a plurality of taps, wherein:
- every (i+1)−th taps from a predetermined tap have coefficients for defining the characteristic of filtering, where i is an arbitrary positive integer;
- and
- the remaining taps have coefficients equal to zero.
A digital filter having an odd number of a plurality of taps, wherein:
- a center tap, and odd-numbered taps counted from said center tap of said plurality of taps all have coefficients equal to zero;
- and
- the rest of said plurality of taps have coefficients for defining a characteristic of filtering.
A half band filter having an odd number of a plurality of taps, wherein:
- a center tap of said plurality of taps has a coefficient equal to zero.
A double interpolation circuit for generating a first double interpolated signal sequence and a second double interpolated signal sequence from an input signal which comprises a first and a second signal sequence being alternately time-division-multiplexed, each of said first and second signal sequences comprising discrete signal components, said double interpolation circuit comprising:
- a digital filter having an input for receiving said input signal, and an output for generating a filter output on which a first and a second filtered signal sequence are alternately time-division-multiplexed;
- separating means connected to receive said filter output for separating said first filtered signal sequence and said second filtered signal sequence from said filter output;
- delay means connected to receive said input signal for generating a delayed input signal;
- and
- combining means for combining said first filtered signal sequence with said first signal sequence in said delayed input signal to generate said first double interpolated signal sequence, and for combining said second filtered signal sequence with said second signal sequence in said delayed input signal to generate said second double interpolated signal sequence.
A filtering method for simultaneously filtering an input signal which comprises a first and a second signal sequence being alternately time-division-multiplexed, said first and second signal sequences each comprising discrete signal components, said method comprising the steps of:
- providing a digital filter, said digital filter having an odd number of a plurality of taps, wherein a center tap and odd-numbered taps counted from said center tap of said plurality of taps have coefficients equal to zero, and the rest of said plurality of taps have coefficients for defining a filtering characteristic of said digital filter;
- applying said input signal to said digital filter for executing said same filtering on each of said first and second signal sequences to generate a first and a second filtered signal sequence in a time-division multiplexed form to be output from the digital filter.
A double interpolation method for generating a first double interpolated signal sequence and a second double interpolated signal sequence from an input signal which comprises a first and a second signal sequence being alternately time-division-multiplexed, said first and second signal sequences each comprising discrete signal components, said method comprising the steps of:
- applying said input signal to a digital filter for outputting in response to said input signal a filter output comprising a first and a second filtered signal sequence being alternately time-division-multiplexed;
- separating said filter output into said first filtered signal sequence and said second filtered signal sequence;
- delaying said input signal to generate a delayed input signal;
- and
- combining said first filtered signal sequence with said first signal sequence in said delayed input signal to generate said first double interpolated signal sequence, and combining said second filtered signal sequence with said second signal sequence in said delayed input signal to generate said second double interpolated signal sequence.
Dependencies are inferred from the claim text.