mirror of
https://github.com/DSheirer/sdrtrunk.git
synced 2026-11-12 08:37:25 -05:00
88 lines
2.8 KiB
Java
88 lines
2.8 KiB
Java
/*******************************************************************************
|
|
* SDR Trunk
|
|
* Copyright (C) 2014 Dennis Sheirer
|
|
*
|
|
* This program 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 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>
|
|
******************************************************************************/
|
|
package decode.nbfm;
|
|
|
|
import sample.real.RealSampleListener;
|
|
import source.Source.SampleType;
|
|
import decode.Decoder;
|
|
import decode.DecoderType;
|
|
import dsp.filter.DCRemovalFilter2;
|
|
import dsp.nbfm.FilteringNBFMDemodulator;
|
|
|
|
public class NBFMDecoder extends Decoder
|
|
{
|
|
/**
|
|
* This value determines how quickly the DC remove filter responds to
|
|
* changes in frequency.
|
|
*/
|
|
private static final double sDC_REMOVAL_RATIO = 0.000003;
|
|
|
|
private FilteringNBFMDemodulator mDemodulator;
|
|
private DCRemovalFilter2 mDCRemovalFilter;
|
|
|
|
public NBFMDecoder( SampleType sampleType )
|
|
{
|
|
super( sampleType );
|
|
|
|
/**
|
|
* Only setup a demod chain if we're receiving complex samples. If
|
|
* we're receiving demodulated samples, they'll be handled the same
|
|
* was as we handle the output of the demodulator.
|
|
*/
|
|
if( mSourceSampleType == SampleType.COMPLEX )
|
|
{
|
|
/**
|
|
* The Decoder super class is both a Complex listener and a float
|
|
* listener. So, we add the demod to listen to the incoming
|
|
* quadrature samples, and we wire the output of the demod right
|
|
* back to this class, so we can receive the demodulated output
|
|
* to process
|
|
*/
|
|
mDemodulator = new FilteringNBFMDemodulator();
|
|
this.addComplexListener( mDemodulator );
|
|
|
|
/**
|
|
* Remove the DC component that is present when we're mistuned
|
|
*/
|
|
mDCRemovalFilter = new DCRemovalFilter2( sDC_REMOVAL_RATIO );
|
|
mDemodulator.addListener( mDCRemovalFilter );
|
|
|
|
/**
|
|
* Route the demodulated, filtered samples back to this class to send
|
|
* to all registered listeners
|
|
*/
|
|
mDCRemovalFilter.setListener( this.getRealReceiver() );
|
|
}
|
|
}
|
|
|
|
@Override
|
|
public DecoderType getType()
|
|
{
|
|
return DecoderType.NBFM;
|
|
}
|
|
|
|
@Override
|
|
public void addUnfilteredRealSampleListener( RealSampleListener listener )
|
|
{
|
|
if( mDemodulator != null )
|
|
{
|
|
mDemodulator.addListener( listener );
|
|
}
|
|
}
|
|
}
|