US3746848A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fft process and apparatus having equal delay at each stage or iteration
Assignee: AT&T Inc
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Filing: 1971-12-27
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Granted: 1973-07-17
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Expires: 1991-12-27
Abstract
Abstract Methods and apparatus for performing a sequential or cascaded version of the fast Fourier transform are described. A uniform set of delays are introduced in the described methods and apparatus, thereby permitting substantially identical apparatus to be used for each iteration. Unique data formatting and channeling arrangements permit high circuit efficiency and minimized overall complexity.
Inventors
- 👤 J Clary
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:40
CPC Classifications
G; G06; G06F; G06F17/00; G06F17/10; G06F17/14; G06F17/141; G06F17/142
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
105 words
Apparatus for generating Fourier series coefficients corresponding to N ordered samples of a time varying signal comprising a plurality of cascaded processing stages, each of which comprises input means for accepting sequential pairs of samples, means for selectively multiplying said input samples by predetermined trigonometric function values, means for generating output signals comprising means for adding the products of said multiplications selectively to others of said input values and for subtracting the products of said multiplications selectively from others of said input values, and means for selectively imposing a fixed delay on the resulting output signals, said delay being of equal value at each stage.
Claim 2
Dependent Claim
105 words
Apparatus for generating Fourier series coefficients corresponding to N ordered samples of a time varying signal comprising a plurality of cascaded processing stages, each of which comprises input means for accepting sequential pairs of samples, means for selectively multiplying said input samples by predetermined trigonometric function values, means for generating output signals comprising means for adding the products of said multiplications selectively to others of said input values and for subtracting the products of said multiplications selectively from others of said input values, and means for selectively imposing a fixed delay on the resulting output signals, said delay being of equal value at each stage.
Claim 3
Dependent Claim
38 words
Apparatus according to claim 1 wherein each of said processing stages further includes means for detecting when the magnitude of said output signals exceeds a predetermined value and means responsive to said determination for rescaling said output signals
Claim 4
Dependent Claim
27 words
first connecting means for applying alternate ones of successive pairs of said set of N input signals to respective ones of said pair of input terminals, and
Claim 5
Dependent Claim
27 words
first connecting means for applying alternate ones of successive pairs of said set of N input signals to respective ones of said pair of input terminals, and
Claim 6
Dependent Claim
57 words
second connecting means for applying pairs of signals formed at said pairs of output terminals to said pair of input terminals, said second connecting means comprising delay means for selectively delaying said pairs of signals appearing at said pair of output terminals in accordance with a fixed time relation prior to their application to said input terminals.
Claim 7
Dependent Claim
57 words
second connecting means for applying pairs of signals formed at said pairs of output terminals to said pair of input terminals, said second connecting means comprising delay means for selectively delaying said pairs of signals appearing at said pair of output terminals in accordance with a fixed time relation prior to their application to said input terminals.
Claim 8
Dependent Claim
51 words
Apparatus according to claim 2 wherein each of said processing stages further comprises means for selectively delaying one complex component of each output value signal such that the real and imaginary components of each of said output signals is presented substantially simultaneously to said input means for the immediately following stage.
Claim 9
Dependent Claim
60 words
Apparatus according to claim 3 wherein said means for multiplying and means for adding and subtracting include means for forming signals representing the function A'' + iB'' A + iB + (C + iD)ei and C'' + iD'' A + iB - (C + id)ei, where (A + iB) and (C + iD) represent a pair of complex input values.
Claim 10
Dependent Claim
17 words
Apparatus for generating Fourier series coefficientS corresponding to a set of N 2m ordered input signals comprising
Claim 11
Dependent Claim
17 words
Apparatus for generating Fourier series coefficientS corresponding to a set of N 2m ordered input signals comprising
Claim 12
Dependent Claim
36 words
Apparatus according to claim 5 wherein said delay means for selectively delaying comprises first and second serial delay units each selectively connected between one of said pair of output terminals and one of said input terminals.
Claim 13
Dependent Claim
58 words
Apparatus according to claim 7 wherein said first delay unit comprises means for delaying said signals appearing at said first output terminal by an amount equal to 2m 1-1 units of delay, and said second delay unit comprises means for delaying said signals appearing at said second output terminal by an amount equal to 2m-1 units of delay.
Claim 14
Dependent Claim
26 words
Apparatus according to claim 8 wherein said second connecting means further comprises means for alternately selecting between the output of said first and second delay units.
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) | 1976-07-16 | 1977-01-15 | 1977-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-16 | 1981-01-15 | 1981-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-16 | 1985-01-15 | 1985-07-17 | $7700.00 | Window Closed / Lapsed |