DIGITAL FILTER

PROBLEM TO BE SOLVED: To achieve operations in combination of filtering and timing restora tion in a digital demodulator. SOLUTION: This invention provides methods and apparatus for variable-rate down-sampling filters for discrete-time sampled systems using a fixed sampling rate. The variable Rate D...

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Bibliographic Details
Main Authors STEPHEN KAREN J, GUPTA ALOK, CROMWELL JONATHAN
Format Patent
LanguageEnglish
Published 07.03.2003
Edition7
Subjects
BASIC ELECTRONIC CIRCUITRY
ELECTRICITY
IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS
RESONATORS
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Summary:PROBLEM TO BE SOLVED: To achieve operations in combination of filtering and timing restora tion in a digital demodulator. SOLUTION: This invention provides methods and apparatus for variable-rate down-sampling filters for discrete-time sampled systems using a fixed sampling rate. The variable Rate Down-Sampling Filter allows a continuous range of sample rates to be derived from input samples at a fixed rate. The output rate does not have to be related to a fixed input rate using an integer or a rational number. A fixed sampling rate at the A/D converter greatly simplifies the design of the analog front end. A single ant-aliasing filter can be designed and precisely matched to the fixed sampling rate. Used with a frequency- modulated numerically controlled oscillator (NCO), the Down-Sampling Filter keeps the entire frequency-synthesis and time-tracking loop in the digital domain. The need for an analog time-tracking loop to adjust the sampling instant at the A/D converter is eliminated.
Bibliography:Application Number: JP20020186246