#include <atsc_equalizer.h>
Inheritance diagram for atsc_equalizer:
Public Member Functions | |
atsc_equalizer () | |
virtual | ~atsc_equalizer () |
virtual void | reset () |
reset state (e.g., on channel change) | |
virtual void | filter (const float *input_samples, const atsc::syminfo *input_tags, float *output_samples, int nsamples) |
produce nsamples of output from given inputs and tags | |
virtual int | ntaps () const =0 |
how much history the input data stream requires. | |
virtual int | npretaps () const =0 |
how many taps are "in the future". | |
Protected Member Functions | |
virtual void | filter_normal (const float *input_samples, float *output_samples, int nsamples)=0 |
virtual void | filter_data_seg_sync (const float *input_samples, float *output_samples, int nsamples, int offset)=0 |
virtual void | filter_field_sync (const float *input_samples, float *output_samples, int nsamples, int offset, int which_field)=0 |
Private Attributes | |
bool | d_locked_p |
int | d_offset_from_last_field_sync |
int | d_current_field |
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produce This is the main entry point. It examines the input_tags and local state and invokes the appropriate virtual function to handle each sub-segment of the input data.
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Input range is known to consist of only a data segment sync or a portion of a data segment sync.
Implemented in atsc_equalizer_lms, atsc_equalizer_lms2, and atsc_equalizer_nop.
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Input range is known to consist of only a field sync segment or a portion of a field sync segment.
Implemented in atsc_equalizer_lms, atsc_equalizer_lms2, and atsc_equalizer_nop.
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Input range is known NOT TO CONTAIN data segment syncs or field syncs. This should be the fast path. In the non decicion directed case, this just runs the input through the filter without adapting it.
Implemented in atsc_equalizer_lms, atsc_equalizer_lms2, and atsc_equalizer_nop.
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how many taps are "in the future". This allows us to handle what the ATSC folks call "pre-ghosts". What it really does is allow the caller to jack with the offset between the tags and the data so that everything magically works out. npretaps () must return a value between 0 and ntaps() - 1. If npretaps () returns 0, this means that the equalizer will only handle multipath "in the past." I suspect that a good value would be something like 15% - 20% of ntaps (). Implemented in atsc_equalizer_lms, atsc_equalizer_lms2, and atsc_equalizer_nop.
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how much history the input data stream requires. This must return a value >= 1. Think of this as the number of samples you need to look at to compute a single output sample. Implemented in atsc_equalizer_lms, atsc_equalizer_lms2, and atsc_equalizer_nop.
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reset state (e.g., on channel change) Note, subclasses must invoke the superclass's method too! Reimplemented in atsc_equalizer_lms, atsc_equalizer_lms2, and atsc_equalizer_nop.
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