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US 7,599,451 B2Granted
Sample rate conversion module and applications thereof
AssigneeSigmatel, Inc.
InventorMichael R. May
Life of this patent
Estimating the term…
Abstract
A sample rate converter includes an upsampling module, a low pass filter, and a linear sample rate conversion module. The upsampling module is operably coupled up-sample a digital input signal having a first rate to produce a digitally up-sampled signal. The low pass filter is operably coupled to low pass filter the digitally up-sampled signal to produce a digitally filtered signal at an up-sampled rate. The linear sample rate conversion module is operably coupled to convert the digitally up-sampled signal into a sample rate adjusted digital signal having a second rate based on an control feedback signal and a linear function, wherein a relationship between the first rate and the second rate is a non-power of two.
Claims18
A sample rate converter comprising:
- an upsampling module operable to up-sample a digital input signal having a first rate to produce a digitally up-sampled signal;
- a low pass filter operably coupled to low pass filter the digitally up-sampled signal to produce a digitally filtered signal at an up-sampled rate;
- and
- a linear sample rate conversion module operably coupled to convert the digitally up-sampled signal into a sample rate adjusted digital signal having a second rate based on a control feedback signal and a linear function, wherein a relationship between the first rate and the second rate is a rate other than a power of two;
- wherein the linear sample rate conversion module further functions to:
- pass, as a sample of the sample rate adjusted digital signal, a sample of the digitally up-sampled signal when, for the sample of the sample rate adjusted digital signal, the control feedback signal has a value that is within a first value range;
- and
- determine, as the sample of the sample rate adjusted digital signal, a sample value based on a current sample of the digitally up-sampled signal and a previous sample of the digitally up-sampled signal when, for the sample of the sample rate adjusted digital signal, the control feedback signal has a value that is outside the first value range.
5 more elements
A sample rate converter comprising:
- a sampling module operably coupled to sample, at a sampling rate, an input signal to produce a digital sampled signal at the sampling rate;
- a determining module operably coupled to determine whether, for a given sample of a sample rate conversion digital signal at a second rate, a sample of the digital sampled signal has an error term within a first value range, wherein a relationship between the sampling rate and the second rate is a non-power of two;
- and
- an outputting module operably coupled to:
- pass the sample of the digital sampled signal as the given sample when the error term is within the first value range;
- and
- determine a value for the given sample based on the sample of the digital sampled signal, a previous sample of the digital sampled signal, and the error term when the error term is not within the first value range.
4 more elements
A digital Frequency Modulation (FM) decoder comprising:
- a low noise amplifier operably coupled to amplify a received FM signal to produce an amplified FM signal;
- a mixing module operably coupled to convert the amplified FM signal into a low intermediate frequency (IF) signal based on a local oscillation;
- an analog to digital conversion module operably coupled to convert the low IF signal into a digital low IF signal;
- a digital baseband conversion module operably coupled to convert the digital low IF signal into a digital baseband signal;
- a sample rate converter operably coupled to adjust the digital baseband signal from a first rate to a second rate based on a feedback error signal to produce a digital FM encoded signal;
- a demodulation module operably coupled to demodulate the digital FM encoded signal to produce a digital FM composite signal;
- a channel separation module operably coupled to separate a left channel signal and a right channel signal from the digital FM composite signal;
- and
- an error sensing module operably coupled to produce the feedback error signal based on the digital FM composite signal;
- wherein the sample rate converter comprises:
- an upsampling module operably coupled to up-sample a digital baseband signal having a first rate to produce a digitally up-sampled signal;
- a low pass filter operably coupled to low pass filter the digitally up-sampled signal to produce a digitally filtered signal at an up-sampled rate;
- and
- linear sample rate conversion module operably coupled to convert the digitally up-sampled signal into the digital FM encoded signal having the second rate based on a control feedback signal and a linear function, wherein a relationship between the first rate and the second rate is a non-power of two.
11 more elements
A digital Frequency Modulation (FM) decoder comprising:
- a low noise amplifier operably coupled to amplify a received FM signal to produce an amplified FM signal;
- a mixing module operably coupled to convert the amplified FM signal into a low intermediate frequency (IF) signal based on a local oscillation;
- an analog to digital conversion module operably coupled to convert the low IF signal into a digital low IF signal;
- a digital baseband conversion module operably coupled to convert the digital low IF signal into a digital baseband signal;
- a sample rate converter operably coupled to adjust the digital baseband signal from a first rate to a second rate based on a feedback error signal to produce a digital FM encoded signal;
- a demodulation module operably coupled to demodulate the digital FM encoded signal to produce a digital FM composite signal;
- a channel separation module operably coupled to separate a left channel signal and a right channel signal from the digital FM composite signal;
- and
- an error sensing module operably coupled to produce the feedback error signal based on the digital FM composite signal;
- wherein the sample rate converter comprises:
- a sampling module operably coupled to sample, at a sampling rate, the digital baseband signal to produce a digital sampled signal at the sampling rate;
- a determining module operably coupled to determine whether, for a given sample of the digital FM encoded signal, a sample of the digital sampled signal has an error term of the feedback error signal within a first value range, wherein a relationship between the sampling rate and the second rate is a non-power of two;
- and
- an outputting module operably coupled to:
- pass the sample of the digital sampled signal as the given sample when the error term is within the first value range;
- and
- determine a value for the given sample based on the sample of the digital sampled signal, a previous sample of the digital sampled signal, and the error term.
14 more elements
A sample rate converter comprising:
- a sampling module operably coupled to sample a digital input signal having a first rate to produce a sampled digital signal having a second rate;
- a low pass filter operably coupled to filter the sampled digital signal to produce a filtered digital signal;
- a linear sample rate conversion module operably coupled to sample the filtered digital signal in accordance with a control feedback signal to produce a sample rate adjusted digital signal having a third rate;
- and
- a sigma-delta modulator operably coupled to produce the control feedback signal based on the first and third rates;
- wherein the linear sample rate conversion module further functions to:
- pass, as a sample of the sample rate adjusted digital signal, a sample of the digitally up-sampled signal when, for the sample of the sample rate adjusted digital signal, the control feedback signal has a value that is within a first value range;
- and
- determine, as the sample of the sample rate adjusted digital signal, a sample value based on a current sample of the digitally up-sampled signal and a previous sample of the digitally up-sampled signal when, for the sample of the sample rate adjusted digital signal, the control feedback signal has a value that is outside the first value range.
6 more elements
A linear interpolator comprising:
- a linear sample rate conversion module operable to sample a digital signal in accordance with a control feedback signal;
- and
- a sigma-delta modulator operably coupled to produce the control feedback signal based on an interpolation ratio that is based on an input data rate and an output data rate;
- wherein the linear sample rate conversion module further functions to:
- pass, as a sample of a sample rate adjusted digital signal, a sample of a digitally up-sampled signal when, for the sample of the sample rate adjusted digital signal, the control feedback signal has a value that is within a first value range;
- and
- determine, as the sample of the sample rate adjusted digital signal, a sample value based on a current sample of the digitally up sampled signal and a previous sample of the digitally up-sampled signal when, for the sample of the sample rate adjusted digital signal, the control feedback signal has a value that is outside the first value range.
4 more elements
Dependencies are inferred from the claim text.