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/* -*- c++ -*- */
/*
* Copyright 2002 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef _ATSC_FS_CHECKER_H_
#define _ATSC_FS_CHECKER_H_
#include <atsci_syminfo.h>
/*!
* \brief abstract base class for ATSC field sync checker
*
* Processes input samples one at a time looking for
* an occurence of either the field sync 1 or field sync 2 pattern.
*
* Note that unlike atsci_fs_correlator, this class uses the symbol_num in
* input_tag to avoid having to test each symbol position.
*
* For each sample processed, an output sample and an output tag are produced.
* The output samples are identical to the input samples but are delayed by
* a number of samples given by \p delay(). The output tag associated with
* the the given output sample indicates whether this sample is the beginning
* of one of the field syncs or is an ordinary sample. The tags are defined in
* atsci_sync_tag.h.
*
* For ease of use, the field sync patterns are defined to begin with the
* first symbol of the 4 symbol data segment sync pattern that immediately
* proceeds the actual PN 511 code. This makes it easier for downstream code
* to determine the location of data segment syncs merely by counting. They'll
* occur every 832 samples assuming everything is working.
*/
class atsci_fs_checker {
public:
// CREATORS
atsci_fs_checker ();
virtual ~atsci_fs_checker () = 0;
// MANIPULATORS
virtual void reset () = 0;
virtual void filter (float input_sample, atsc::syminfo input_tag,
float *output_sample, atsc::syminfo *output_tag) = 0;
// ACCESSORS
//! return delay in samples from input to output
virtual int delay () const = 0;
};
#endif /* _ATSC_FS_CHECKER_H_ */
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