US4472785A
Expired / Lapsed
US
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Sampling frequency converter
Assignee: Victor Company of Japan Ltd
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Filing: 1981-10-13
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Granted: 1984-09-18
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Expires: 2001-10-13
Abstract
Abstract A sampling frequency converter for converting a first signal sampled at a first sampling frequency f1 into a second signal sampled at a second sampling frequency f2 comprising an interpolation device supplied with the first signal, for inserting L-1 zeros (L is an integer) for every sampling time, a filter circuit for attenuating a frequency component over a frequency f/2 (f is a frequency) within an output signal of said interpolation device, where the filter circuit has a series circuit consisting of a finite impulse response digital filter and an infinite impulse response digital filter, and the frequency f is equal to the first sampling frequency f1 when f1<f2 and equal to the second sampling frequency f2 when f1>f2, and a decimation device for extracting every M-th (M is an integer) output signal of the filter circuit, to produce said second signal.
Inventors
- 👤 Masao Kasuga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:09
CPC Classifications
H; H03; H03H; H03H17/00; H03H17/02; H03H17/0283; H03H17/0286; H03H17/0288; H03H17/06; H03H17/0621; H03H17/0635; H03H17/0685
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
238 words
A sampling frequency converter for converting a first signal sampled at a first sampling frequency f1 into a second signal sampled at a second sampling frequency f2, said second sampling frequency f2 being equal to L/M times said first sampling frequency f1, where L and M are natural numbers satisfying L≠M, said sampling frequency converter comprising: an interpolation device supplied with said first signal as an input signal thereof, for inserting L-1 zeros for every sampling time; a filter circuit supplied with an output signal of said interpolation device as an input signal thereof, for attenuating a frequency component over a frequency f/2 within an output signal of said interpolation device, where f is a frequency, said filter circuit comprising a series circuit which includes a finite impulse response digital filter and an infinite impulse response digital filter which is coupled in series to an output stage of said finite impulse response digital filter, said frequency f being equal to said first sampling frequency f1 under a condition f1<f2 and being equal to said second sampling frequency f 2 under a condition f1>f2; and a decimation device supplied with an output signal of said filter circuit as an input signal thereof, for extracting sampled values in the output signal of said filter circuit at a rate of one sampled value for every M sampled values in the output signal of said filter circuit, to produce said second signal.
Claim 2
Dependent Claim
238 words
A sampling frequency converter for converting a first signal sampled at a first sampling frequency f1 into a second signal sampled at a second sampling frequency f2, said second sampling frequency f2 being equal to L/M times said first sampling frequency f1, where L and M are natural numbers satisfying L≠M, said sampling frequency converter comprising: an interpolation device supplied with said first signal as an input signal thereof, for inserting L-1 zeros for every sampling time; a filter circuit supplied with an output signal of said interpolation device as an input signal thereof, for attenuating a frequency component over a frequency f/2 within an output signal of said interpolation device, where f is a frequency, said filter circuit comprising a series circuit which includes a finite impulse response digital filter and an infinite impulse response digital filter which is coupled in series to an output stage of said finite impulse response digital filter, said frequency f being equal to said first sampling frequency f1 under a condition f1<f2 and being equal to said second sampling frequency f 2 under a condition f1>f2; and a decimation device supplied with an output signal of said filter circuit as an input signal thereof, for extracting sampled values in the output signal of said filter circuit at a rate of one sampled value for every M sampled values in the output signal of said filter circuit, to produce said second signal.
Claim 3
Dependent Claim
67 words
A sampling frequency converter as claimed in claim 1 in which said infinite impulse response digital filter is a digital filter described by a transfer function ##EQU12## satisfying an equation f1L=Mf2=i p Kf2 (or i p k=M) where K is a natural number, i p is a prime number, and a 0 , a 1 , a 2 , b 1 , and b 2 are coefficients.
Claim 4
Dependent Claim
37 words
A sampling frequency converter as claimed in claim 1 in which said filter circuit comprises a plurality of finite impulse response digital filters and a plurality of infinite impulse response digital filters which are coupled in series.
Claim 5
Dependent Claim
36 words
A sampling frequency converter as claimed in claim 1 in which the order of said infinite impulse response digital filter within said filter circuit is selected to four or six according to the value of M.
Claim 6
Dependent Claim
90 words
A sampling frequency converter as claimed in claim 1 in which said infinite impulse response digital filter has an amplitude characteristic in which an upper limit frequency of a passband thereof is in a vicinity of a roll-off frequency due to resonance, and has a phase characteristic which is substantially linear in the passband thereof, and said finite impulse response digital filter has an amplitude characteristic for cancelling a peak which is in the vicinity of the roll-off frequency in the amplitude characteristic of said infinite impulse response digital filter.
References Cited (Backward Citations)
US3997772A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-09-18 | 1988-03-19 | 1988-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-18 | 1992-03-19 | 1992-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-18 | 1996-03-19 | 1996-09-18 | $7700.00 | Window Closed / Lapsed |