Coded data generation or conversion – Sample and hold – Having variable sampling rate
Reexamination Certificate
1999-10-12
2001-10-30
Wamsley, Patrick (Department: 2819)
Coded data generation or conversion
Sample and hold
Having variable sampling rate
C341S061000
Reexamination Certificate
active
06310566
ABSTRACT:
FIELD OF THE INVENTION
This invention is related to the sample rate conversion of digital data for data processing applications including video and audio among others.
BACKGROUND OF THE INVENTION
There are a variety of applications requiring conversion of digital data samples occurring at a first data rate to digital data samples occurring at a different second data rate. In these applications, data sampled at one rate is interpolated to provide estimates of data at a different rate or sampling phase. Sample rate conversion applications include, for example, conversion between different video standards such as between High Definition TV (HDTV) data and CCIR601 standard data and conversion between different video display formats such as between interlace and progressive display formats. Other applications include, for example, multi-media composite image formation and display e.g. for Picture-in-Picture (PIP) presentation, and data processing for digital data storage such as for CDROM or DVD applications and digital demodulation involving digital sample rate conversion for establishing frequency, phase or symbol timing synchronization. The widespread use of sample rate conversion in cost sensitive applications means that there is a need to optimize configurations for both sample rate converters and their interpolator and digital filter sub-components.
Known, classical interpolator configurations have been thought to be optimal in terms of maximizing performance and minimizing the hardware complexity involved, i.e., the numbers of adders, multipliers, registers etc. that are used. However, the sample rate converter, interpolator and digital filter systems and the methods of their derivation presented herein provide improvements over the known filter designs in both performance and reduced complexity.
SUMMARY OF THE INVENTION
A sample rate conversion system converts data of a first sample rate to data of a different second sample rate. The system uses an interpolator, operating at the first sample rate and includes a first interpolation network and a delay network. The first interpolation network interpolates the first sample rate data to provide upsampled interpolated data samples according to a first sample spacing. The delay network interpolates the upsampled interpolated data to provide delayed upsampled interpolated data samples, according to a second sample spacing of higher resolution than the first sample spacing, and preceding and succeeding an original sample position. The system also includes a digital filter operating at the second sample rate for filtering the higher resolution data samples to provide the second sample rate data.
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Eriksen Guy H.
Kurdyla Ronald H.
Thomson Licensing S.A.
Tripoli Joseph S.
Wamsley Patrick
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