US5367200A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring the duty cycle of a digital signal
Assignee: Nortel Networks Ltd
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Filing: 1993-11-29
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Granted: 1994-11-22
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Expires: 2013-11-29
Abstract
Abstract The technique of measuring the duty cycle of a digital signal of known repetition rate is disclosed. It makes use of the fact that the probability of the digital signal being at the high level is related to its duty cycle when the signal is sampled at a frequency incoherent with the repetition rate. The apparatus in one embodiment includes a random sampler for sampling the digital signal under measurement, and digital counters which count the total number of samples and the number of samples whose values are at one of the two digital levels.
Inventors
- 👤 Dan Leonida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 01:19
CPC Classifications
G; G01; G01R; G01R29/00; G01R29/02
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
79 words
A method of measuring the duty cycle of a digital signal of a fixed repetition rate, comprising steps of: sampling the digital signal at a sampling frequency which is incoherent with the fixed repetition rate; producing a total number of samples N t of the digital signal; counting a number of samples N 1 which are at one of two digital levels; and calculating a ratio of N 1 to N t which is indicative of the duty cycle.
Claim 2
Independent Claim
79 words
A method of measuring the duty cycle of a digital signal of a fixed repetition rate, comprising steps of: sampling the digital signal at a sampling frequency which is incoherent with the fixed repetition rate; producing a total number of samples N t of the digital signal; counting a number of samples N 1 which are at one of two digital levels; and calculating a ratio of N 1 to N t which is indicative of the duty cycle.
Claim 3
Dependent Claim
32 words
The method of measuring the duty cycle of a digital signal of a fixed repetition rate according to claim 1, wherein the step of sampling is performed at randomly variable sampling frequency.
Claim 4
Dependent Claim
53 words
The method of measuring the duty cycle of a digital signal of a fixed repetition rate according to claim 2, wherein the step of randomly sampling the digital signal comprises further steps of: generating a random noise; and modulating a voltage controlled oscillator by the random noise to produce a random sampling signal.
Claim 5
Dependent Claim
77 words
A method of measuring a time delay of a digital system by measuring the duty cycle of a digital signal of a known repetition rate, according to claim 3, comprising further steps of: applying the digital signal of the known repetition rate to the digital system under test and a flip-flop; and generating a digital output signal of the known repetition rate whose duty cycle is indicative of the time delay of the digital system under test.
Claim 6
Dependent Claim
97 words
A digital duty cycle measuring apparatus for measuring a digital signal of a fixed repetition rate having two digital levels, comprising: sampling means for sampling the digital signal at a sampling frequency which is incoherent with the fixed repetition rate; divider means for producing a total number of samples N t of the digital signal; counter means for counting a number of samples N 1 which are at one of two digital levels; and calculation means for generating a ratio of N 1 to N t which is indicative of the duty cycle of the digital signal.
Claim 7
Dependent Claim
97 words
A digital duty cycle measuring apparatus for measuring a digital signal of a fixed repetition rate having two digital levels, comprising: sampling means for sampling the digital signal at a sampling frequency which is incoherent with the fixed repetition rate; divider means for producing a total number of samples N t of the digital signal; counter means for counting a number of samples N 1 which are at one of two digital levels; and calculation means for generating a ratio of N 1 to N t which is indicative of the duty cycle of the digital signal.
Claim 8
Dependent Claim
58 words
The digital duty cycle measuring apparatus according to claim 5, wherein the sampling frequency is a randomly variable frequency and the sampling means comprises a random noise generator connected to a voltage controlled oscillator to generate a sampling signal of randomly variable frequency, and a flip-flop to receive the sampling signal and the digital signal to be measured.
Claim 9
Dependent Claim
19 words
The digital duty cycle measuring apparatus according to claim 6, wherein the random noise generator is a Zener diode.
Claim 10
Dependent Claim
39 words
The digital duty cycle measuring apparatus according to claim 5, wherein the counter means comprises an n-bit counter for counting N 1 , and the divider means resets the n-bit counter after N t samples, N t being adjustable.
Claim 11
Dependent Claim
28 words
The digital duty cycle measuring apparatus according to claim 5, wherein the calculating means comprises a flip-flop to generate a digital output signal indicative of the duty cycle.
Claim 12
Dependent Claim
22 words
The digital duty cycle measuring apparatus according to claim 8, wherein the counter means and the divider means are a programmed microprocessor.
Claim 13
Dependent Claim
18 words
The digital duty cycle measuring apparatus according to claim 9, wherein the calculating means is a programmed microprocessor.
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) | 1997-11-21 | 1998-05-23 | 1998-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-11-21 | 2002-05-23 | 2002-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-11-21 | 2006-05-23 | 2006-11-22 | $7700.00 | Window Closed / Lapsed |