US4569075A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of coding voice signals and device using said method
Assignee: International Business Machines Corp
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Filing: 1982-07-19
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Granted: 1986-02-04
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Expires: 2002-07-19
Abstract
Abstract The baseband portion x(t) of a voice signal is first applied to a complex filter which provides a couple of signal components y and y in quadrature with each other. Each of the components y and y is then fed to a bank of QMF filters which split the spectra of y and y into N subbands providing subband components y i and y i (with i=1, 2, . . . , N), respectively. The subband components y i and y i are combined together to generate information representative of the phase (φ i ) and amplitude (ρ i ) of the contents of each subband, which information is then transcoded by a coder which dynamically distributes the available bit resources to the various subbands.
Inventors
- 👤 Henri Nussbaumer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:27
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66; H04B1/667
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
218 words
A coding device for coding a low frequency band limited portion of a voice signal, said coding device including: sampling means for sampling the band limited voice signal fed thereto at its Nyquist frequency (fs) to generate a decimated series of samples; complex filtering means connected to said sampling means for deriving therefrom for each sample of said decimated series of samples a couple of signal components in quadrature with each other, said complex filtering means comprising: first and second modulation means alternatively connected to said sampling means for multiplying said couple of signal components by the cyclic sequence (1, 0, -1, 0) and (0, 1, 0, -1), respectively, and low-pass filter means connected to said modulation means, said low-pass filtering means deriving therefrom said couple of signal components in quadrature with each other; filtering means connected to said complex filtering means for splitting the frequency spectrum of said couple of signal components in quadrature with each other into a given number of subbands through the use of Quadrature Mirror Filter techniques; phase-amplitude means connected to said filtering means to derive from the contents of each of said subbands a phase information and an amplitude information; and coding means connected to said phase-amplitude means for coding said phase information and said amplitude information within each of said subbands.
Claim 2
Dependent Claim
218 words
A coding device for coding a low frequency band limited portion of a voice signal, said coding device including: sampling means for sampling the band limited voice signal fed thereto at its Nyquist frequency (fs) to generate a decimated series of samples; complex filtering means connected to said sampling means for deriving therefrom for each sample of said decimated series of samples a couple of signal components in quadrature with each other, said complex filtering means comprising: first and second modulation means alternatively connected to said sampling means for multiplying said couple of signal components by the cyclic sequence (1, 0, -1, 0) and (0, 1, 0, -1), respectively, and low-pass filter means connected to said modulation means, said low-pass filtering means deriving therefrom said couple of signal components in quadrature with each other; filtering means connected to said complex filtering means for splitting the frequency spectrum of said couple of signal components in quadrature with each other into a given number of subbands through the use of Quadrature Mirror Filter techniques; phase-amplitude means connected to said filtering means to derive from the contents of each of said subbands a phase information and an amplitude information; and coding means connected to said phase-amplitude means for coding said phase information and said amplitude information within each of said subbands.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-03 | 1989-08-05 | 1990-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-03 | 1993-08-05 | 1994-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-03 | 1997-08-05 | 1998-02-04 | $7700.00 | Window Closed / Lapsed |