EP0498022A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Timing recovery method and system for a receiver with A/D conversion
Assignee: Industrial Technology Research Institute
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Filing: 1991-03-23
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Granted: —
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Expires: 2011-03-23
Abstract
Abstract At a receiver in a digital communications system, an arriving analog signal is sampled using a local clock. To correct for asynchronous timing between the local receiver clock and the remote transmitter clock, the sample values obtained using the local clock are processed by a timing adjuster. The timing adjuster corrects the sample values obtained by the local clock by evaluating at a particular time a convolution of a plurality of the samples obtained by the local clock with a raised cosine function. The particular time at which the convolution is evaluated is determined by filtering the output samples of the timing adjuster with a narrow bandpass filter. A timing difference detector is utilized to evaluate certain samples output by the filter to adaptively adjust the time at which the timing adjuster evaluates the convolution.
Inventors
- 👤 Sammy Shyue
- 👤 Ching-Hsiang Lin
- 👤 Ji-Shang Yu
- 👤 Yen-Chun Lin
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 02:46
CPC Classifications
H; H04; H04L; H04L7/00; H04L7/0016; H04L7/002; H04L7/0029; H04L7/0054; H04L7/007; H04L7/02; H04L7/027
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
144 words
A method for digitizing an analog signal transmitted to a receiver comprising the steps of: at said receiver, sampling said analog signal using a local clock to obtain digital samples, inputting said digital samples into a first filter which evaluates at a particular value of a time variable the convolution of a plurality of said samples obtained with said local clock and an impulse response function to obtain corrected output samples, filtering said corrected output samples with a second narrow bandpass digital filter, adapting the particular value of said time variable at which said convolution is evaluated by said first filter in response to said samples outputted by said second filter, the values of said time variable being adjusted so that the corrected output samples produced by said first filter are corrected for any asynchronism between said local clock and a remote transmitter clock.
Claim 2
Dependent Claim
15 words
The method of claim 1 wherein said impulse response function is a raised cosine function.
Claim 3
Independent Claim
157 words
A method for sampling an analog signal transmitted from a transmitter to a receiver, said method comprising the steps of sampling said analog signal at said receiver using a local clock to obtain digital samples, correcting each of said digital samples to account for any asynchronism between said local clock and a remote clock at said transmitter by evaluating a convolution of a plurality of said samples obtained from said local clock and an impulse response function at a particular value of a time variable, said particular value of said time variable being obtained by filtering the corrected digital samples with a narrow bandpass digital filter and adapting the value of the time variable used to correct the digital samples in response to the output of said band-pass digital filter until the output of said band-pass digital filter indicates that the said sample values are corrected for any discrepancy between said local clock and said remote clock.
Claim 4
Dependent Claim
14 words
The method of claim 3 wherein said convolution is evaluated using a digital filter.
Claim 5
Independent Claim
143 words
A system for digitizing a received analog signal comprising, an analog-to-digital converter for receiving said analog signal and for sampling said analog signal in accordance with a local clock to obtain digital samples, adjustment means for receiving said digital samples produced by said analog-to-digital converter and for correcting said digital samples to account for any asynchronism between said local clock and a remote transmitter clock so as to produce corrected output samples, a narrow bandpass digital filter for filtering the corrected output samples, and timing detection means for detecting information about the remote clock from the output of said narrow bandpass filter and for providing the information about the remote clock to said adjustment means so that said adjustment means can correct said digital samples produced from said analog-to-digital converter to account for any asynchronism between said local clock and said remote clock.
Claim 6
Dependent Claim
68 words
The system of claim 5 wherein said adjustment means is a filter which evaluates a convolution of a plurality of digital samples obtained from said analog-to-digital converter with an impulse response function at a particular value of a time variable, and wherein said timing detector means supplies said particular value of said time variable to said adjustment means in response to the output of said narrow bandpass filter.
Claim 7
Dependent Claim
66 words
The system of claim 5 wherein adjustment means evaluates a convolution of the form where f(nT) are the digital samples obtained by said analog-to-digital converter, where T is the sampling interval, where n is an integer which takes on the values -N,....,+N, where f(t) is an analog signal, where t is determined by said timing detection means, and where In'( ) is a raised cosine function.
References Cited (Backward Citations)
No citation records indexed.
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