Patent US4868774A successfully refreshed from Google Patents.
US4868774A
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Digital waveform generator and associated method
Assignee: Safran Data Systems SAS
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Filing: 1988-12-28
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Granted: 1989-09-19
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Expires: 2008-12-28
Abstract
Abstract The present invention relates to synthesis of an analog waveform representative of digital input words but subject to band limiting. In a device for performing such a synthesis a plurality of samples, obtained from the input words by accessing them in memory at a sampling frequency are filtered by a programmable digital filter to yield a plurality of output words which may be fed to a digital to analog converter at a conversion frequency, the converter producing an analog output representative of the input words.
Inventors
- 👤 Ferial Beukara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:27
CPC Classifications
G; G06; G06F; G06F1/00; G06F1/02; G06F1/03; G06F1/0321
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
184 words
A method for producing from a given series of digital input words, an output in the form of an analog waveform approximating, in analog amplitude with respect to time, values of a notional digital signal that would be formed by stepping through each of said digital input words at a stepping frequency selectable over a range of frequencies between a lower stepping frequency limit and an upper stepping frequency limit, said analog waveform having frequency components not exceeding a limiting frequency, comprising the steps of: deriving a plurality of digital samples from said digital input words, said samples being equivalent to a sampling of said notional digital signal at a sampling frequency which exceeds said stepping frequency; applying said samples to a programmable digital filter arranged to filter said samples to produce a sequence of digital output words, at a predetermined conversion frequency, said conversion frequency being at least twice said limiting frequency and independent of said selected stepping frequency; and converting said output words from digital form to analog form at said conversion frequency to thereby yield said analog waveform as said output.
Claim 2
Independent Claim
184 words
A method for producing from a given series of digital input words, an output in the form of an analog waveform approximating, in analog amplitude with respect to time, values of a notional digital signal that would be formed by stepping through each of said digital input words at a stepping frequency selectable over a range of frequencies between a lower stepping frequency limit and an upper stepping frequency limit, said analog waveform having frequency components not exceeding a limiting frequency, comprising the steps of: deriving a plurality of digital samples from said digital input words, said samples being equivalent to a sampling of said notional digital signal at a sampling frequency which exceeds said stepping frequency; applying said samples to a programmable digital filter arranged to filter said samples to produce a sequence of digital output words, at a predetermined conversion frequency, said conversion frequency being at least twice said limiting frequency and independent of said selected stepping frequency; and converting said output words from digital form to analog form at said conversion frequency to thereby yield said analog waveform as said output.
Claim 3
Dependent Claim
35 words
A method according to claim 1 including the step of arranging said digital filter to provide digital output words having a number of bits greater than the number of bits of said digital input words.
Claim 4
Dependent Claim
24 words
A method according to claim 1 and including the step of selecting said conversion frequency to be at least four times said stepping frequency.
Claim 5
Dependent Claim
19 words
A method according to claim 1 including the step of arranging said digital filter as a low pass filter.
Claim 6
Dependent Claim
29 words
A method according to claim 1 and including the step of selecting the number of said digital samples to be greater than the number of digital output words converted.
Claim 7
Dependent Claim
32 words
A method according to claim 1 including, as said step of deriving samples, storing said digital input words in a memory and accessing said memory at a later time prior to sampling.
Claim 8
Dependent Claim
29 words
A method according to claim 1 including the step of storing the digital output words in a memory and accessing said stored words to repeatedly generate said analog waveform.
Claim 9
Dependent Claim
44 words
A method according to claim 1 including the step of, during said step of applying said samples to said digital filter, applying a weighing to said digital samples said weighing being selected to compensate for distortion introduced in conversion of said digital output words.
Claim 10
Dependent Claim
15 words
A method according to claim 1 and including the step of smoothing said analog waveform.
Claim 11
Independent Claim
191 words
A device for producing, from a given series of digital input words, an output in the form of an analog waveform approximating, in analog amplitude with respect to time, values of a notional digital signal that would be formed by stepping through each of said digital input words at a stepping frequency selectable over a range of frequencies between a lower stepping frequency limit and an upper stepping frequency limit, said analog waveform having frequency components not exceeding a limiting frequency, said device comprising: sampling means for deriving a plurality of digital samples from said digital input words, said samples being equivalent to a sampling of said notional digital signal at a sampling frequency, said sampling frequency exceeding said stepping frequency; a programmable digital filter arranged to filter said samples to produce a sequence of digital output words, at a predetermined conversion frequency, said conversion frequency being at least twice said limiting frequency and independent of said selected stepping frequency, and a digital to analog converter for converting said output words from digital form to analog form at a said conversion frequency to thereby yield said analog waveform as said output.
Claim 12
Independent Claim
191 words
A device for producing, from a given series of digital input words, an output in the form of an analog waveform approximating, in analog amplitude with respect to time, values of a notional digital signal that would be formed by stepping through each of said digital input words at a stepping frequency selectable over a range of frequencies between a lower stepping frequency limit and an upper stepping frequency limit, said analog waveform having frequency components not exceeding a limiting frequency, said device comprising: sampling means for deriving a plurality of digital samples from said digital input words, said samples being equivalent to a sampling of said notional digital signal at a sampling frequency, said sampling frequency exceeding said stepping frequency; a programmable digital filter arranged to filter said samples to produce a sequence of digital output words, at a predetermined conversion frequency, said conversion frequency being at least twice said limiting frequency and independent of said selected stepping frequency, and a digital to analog converter for converting said output words from digital form to analog form at a said conversion frequency to thereby yield said analog waveform as said output.
Claim 13
Dependent Claim
26 words
A device according to claim 10 comprising a memory for containing said digital input words and programmable means for accessing said words at a stepping frequency.
Claim 14
Dependent Claim
17 words
A device according to claim 11 and wherein said sampling frequency is greater than said conversion frequency.
Claim 15
Dependent Claim
38 words
A device according to claim 12 wherein said digital filter produces output words at said sampling frequency and comprising a buffer circuit for supplying selected digital output words to said digital to analog converter at said conversion frequency.
Claim 16
Dependent Claim
31 words
A device according to claim 10 wherein said digital to analog converter has a resolution, expressed in number of bits, greater than the number of bits of said digital input words.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-18 | 1993-03-20 | 1993-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-18 | 1997-03-20 | 1997-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-18 | 2001-03-20 | 2001-09-19 | $7700.00 | Window Closed / Lapsed |