Methods and apparatus for estimating clipped samples during analog to digital conversion

A circuit, comprising:

• an analogue to digital converter for digitising an analogue signal to form digitised samples;
• a clip processor, adapted to determine estimated values for clipped digitised samples;
• and
• means for replacing said clipped digitised samples with said estimated values, thereby mitigating effects of clipping in an output from said circuit;
• wherein said clip processor is adapted to measure a number of consecutive samples in a first group of said clipped digitised samples;
• and
• wherein said clip processor is adapted to determine an estimated value for each sample in said first group from the number of consecutive samples in said first group, values of consecutive digitised samples in a second group of digitised samples immediately preceding said first group, and values of consecutive digitised samples in a third group of digitised samples following said first group.

A circuit, comprising:

• an analogue to digital converter for digitising an analogue signal to form digitised samples;
• a clip processor, adapted to determine estimated values for clipped digitised samples;
• and
• means for replacing said clipped digitised samples with said estimated values, thereby mitigating effects of clipping in an output from said circuit;
• wherein a digital signal output from said circuit has a higher bit resolution after processing by said clip processor than it had prior to processing by said clip processor,
• wherein said clip processor is adapted to measure a number of consecutive samples in a first group of said clipped digitised samples and is further adapted to determine an estimated value for each sample in said first group from:
• the number of consecutive samples in said first group;
• values of consecutive samples in a second group of samples immediately preceding said first group;
• and
• values of consecutive samples in a third group of samples immediately following said first group.

A method of digitising an analogue signal, comprising acts of:

• sampling, quantising, and digitising the analogue signal to form samples of a digitised signal;
• buffering said samples of said digitised signal;
• detecting whether said samples are clipped;
• determining a number of consecutive clipped samples, constituting a group of clipped samples;
• reading a first plurality of unclipped samples preceding said group of clipped samples into a buffer, reading said group of clipped samples into said buffer and reading a second plurality of unclipped samples into said buffer;
• determining estimated values of the consecutive clipped samples of said group of clipped samples;
• and
• overwriting said group of clipped samples in said buffer with the estimated values.

A method of analogue to digital conversion, comprising acts of:

• determining estimated values for clipped digitised samples;
• replacing said clipped digitised samples with said estimated values, thereby mitigating effects of clipping;
• dynamically storing a plurality of digitised samples, produced by an analogue to digital converter, in a buffer;
• reading digitised samples from said buffer into a clip processor;
• and
• determining if any of the digitised samples is a clipped digitised sample;
• wherein said buffer has a length sufficient to store:
• a first plurality of unclipped digitised samples occurring before a group of said clipped digitised samples;
• said group of said clipped digitised samples;
• and
• a second plurality of unclipped digitised samples following said group of said clipped digitised samples, and wherein the method further comprises an act of dynamically storing the first plurality of unclipped digitised samples, the group of said clipped digitised samples, and the second plurality of unclipped digitised samples in the buffer.

A method of analogue to digital conversion, comprising acts of:

• determining estimated values for clipped digitised samples;
• replacing said clipped digitised samples with said estimated values, thereby mitigating effects of clipping;
• dynamically storing a plurality of digitised samples, produced by an analogue to digital converter, in a buffer;
• reading digitised samples from said buffer into a clip processor;
• determining if any of the digitised samples is a clipped digitised sample;
• measuring a number of samples in a first group of consecutive clipped digitised samples;
• and
• determining an estimated value for each sample in said first group from the number of consecutive samples in said first group, values of consecutive digitised samples in a second group of digitised samples immediately preceding said first group, and values of consecutive digitised samples in a third group of digitised samples immediately following said first group.

A method of analogue to digital conversion, comprising acts of:

• determining estimated values for clipped digitised samples;
• replacing said clipped digitised samples with said estimated values, thereby mitigating effects of clipping;
• dynamically storing a plurality of digitised samples, produced by an analogue to digital converter, in a buffer;
• reading digitised samples from said buffer into a clip processor;
• determining if any of the digitised samples is a clipped digitised sample;
• inputting to said clip processor a first digital signal comprising said clipped digitised samples;
• and
• outputting from said clip processor a second digital signal comprising said estimated values;
• wherein said second digital signal has a higher bit resolution than said first digital signal.

A method of analogue to digital conversion, comprising acts of:

• determining estimated values for clipped digitised samples;
• replacing said clipped digitised samples with said estimated values, thereby mitigating effects of clipping;
• dynamically storing a plurality of digitised samples, produced by an analogue to digital converter, in a buffer;
• reading digitised samples from said buffer into a clip processor;
• determining if any of the digitised samples is a clipped digitised sample;
• inputting to said clip processor a first digital signal comprising said clipped digitised samples;
• outputting from said clip processor a second digital signal comprising said estimated values, wherein said second digital signal has a higher bit resolution than said first digital signal;
• and
• measuring a number of samples in a first group of consecutive clipped digitised samples and determining an estimated value for each sample in said first group from:
• the number of consecutive samples in said first group;
• values of consecutive samples in a second group of samples immediately preceding said first group;
• and
• values of samples in a third group of samples immediately following said first group.

A circuit, comprising:

• an analog to digital converter for digitizing an analog signal;
• a clip processor adapted to determine estimated values for clipped digital signal samples;
• and
• means for replacing said clipped digital signal samples with said estimated values, said means for replacing including a buffer adapted to dynamically store a plurality of digitized samples produced by said analog to digital converter,
• wherein:
• said clip processor is adapted to read the digitized samples from said buffer and replace said clipped digital signal samples, in the buffer, with the estimated values;
• and
• said clip processor is adapted to process at least some digitized samples following said clipped digital signal samples to determine the estimated values.