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sdrangel/sdrbase/dsp/nco.cpp

71 lines
2.3 KiB
C++

///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
// written by Christian Daniel //
// //
// 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 as version 3 of the License, or //
// //
// 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 V3 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/>. //
///////////////////////////////////////////////////////////////////////////////////
#include <QtGlobal>
#include <stdio.h>
#define _USE_MATH_DEFINES
#include <math.h>
#include "dsp/nco.h"
Real NCO::m_table[NCO::TableSize];
bool NCO::m_tableInitialized = false;
void NCO::initTable()
{
if(m_tableInitialized)
return;
for(int i = 0; i < TableSize; i++)
m_table[i] = cos((2.0 * M_PI * i) / TableSize);
m_tableInitialized = true;
}
NCO::NCO()
{
initTable();
m_phase = 0;
}
void NCO::setFreq(Real freq, Real sampleRate)
{
m_phaseIncrement = (freq * TableSize) / sampleRate;
qDebug("NCO phase inc %d", m_phaseIncrement);
}
float NCO::next()
{
m_phase += m_phaseIncrement;
while(m_phase >= TableSize)
m_phase -= TableSize;
while(m_phase < 0)
m_phase += TableSize;
return m_table[m_phase];
}
Complex NCO::nextIQ()
{
m_phase += m_phaseIncrement;
while(m_phase >= TableSize)
m_phase -= TableSize;
while(m_phase < 0)
m_phase += TableSize;
return Complex(m_table[m_phase], -m_table[(m_phase + TableSize / 4) % TableSize]);
}