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// smeter.cpp: implementation of the CS<eter class.
//
// This class takes magnitude data and detemines peak and average power
// for use in S Meter display
//
// History:
// 2010-12-22 Initial creation MSW
// 2011-03-27 Initial release
// 2013-07-28 Added single/double precision math macros
//////////////////////////////////////////////////////////////////////
//==========================================================================================
// + + + This Software is released under the "Simplified BSD License" + + +
//Copyright 2010 Moe Wheatley. All rights reserved.
//
//Redistribution and use in source and binary forms, with or without modification, are
//permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other materials
// provided with the distribution.
//
//THIS SOFTWARE IS PROVIDED BY Moe Wheatley ``AS IS'' AND ANY EXPRESS OR IMPLIED
//WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
//FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL Moe Wheatley OR
//CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
//CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
//SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
//ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
//NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
//ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
//The views and conclusions contained in the software and documentation are those of the
//authors and should not be interpreted as representing official policies, either expressed
//or implied, of Moe Wheatley.
//==========================================================================================
#include "smeter.h"
#include <QDebug>
#define ATTACK_TIMECONST .01 //attack time in seconds
#define DECAY_TIMECONST .1 //decay time in seconds
#define SMETER_CALIBRATION 5.0 //S-Meter calibration offset added to make reading absolute dBm
#define MAX_PWR (32767.0*32767.0)
CSMeter::CSMeter()
{
m_PeakMag = 0;
m_SampleRate = 1.0;
m_AttackAlpha = 1.0;
m_DecayAlpha = 1.0;
m_AttackAve = -120.0;
m_DecayAve = -120.0;
}
////////////////////////////////////////////////////////////////////////////////////
// Process magnitude data and set S-Meter power variables
////////////////////////////////////////////////////////////////////////////////////
void CSMeter::ProcessData(int length, TYPECPX* pInData, TYPEREAL SampleRate)
{
if(SampleRate != m_SampleRate)
{ //need to recalculate any values dependent on sample rate
m_SampleRate = SampleRate;
m_AttackAlpha = (1.0-MEXP(-1.0/(m_SampleRate*ATTACK_TIMECONST)) );
m_DecayAlpha = (1.0-MEXP(-1.0/(m_SampleRate*DECAY_TIMECONST)) );
//qDebug()<<"SMeter vals "<<m_AttackAlpha << m_DecayAlpha << SampleRate;
}
for(int i=0; i<length; i++)
{
//calculate instantaeous power magnitude of pInData which is I*I + Q*Q
TYPECPX in = pInData[i];
//convert I/Q magnitude to dB power
TYPEREAL mag = 10.0*MLOG10((in.re*in.re+in.im*in.im)/ MAX_PWR + 1e-30);
//calculate attack and decay average
m_AttackAve = (1.0-m_AttackAlpha)*m_AttackAve + m_AttackAlpha*mag;
m_DecayAve = (1.0-m_DecayAlpha)*m_DecayAve + m_DecayAlpha*mag;
if(m_AttackAve>m_DecayAve)
{ //if attack average is greater then must be increasing signal
m_AverageMag = m_AttackAve; //use attack average value
m_DecayAve = m_AttackAve; //force decay average to attack average
}
else
{ //is decreasing strength so use decay average
m_AverageMag = m_DecayAve; //use decay average value
}
if(mag > m_PeakMag)
m_PeakMag = mag; //save new peak (reset when read )
}
}
////////////////////////////////////////////////////////////////////////////////////
// returns Peak S-Meter power variable
////////////////////////////////////////////////////////////////////////////////////
TYPEREAL CSMeter::GetPeak()
{
TYPEREAL x = m_PeakMag;
m_PeakMag = 0;
return x+SMETER_CALIBRATION + m_CalibrationOffset;
}
////////////////////////////////////////////////////////////////////////////////////
// returns Average S-Meter power variable with attack and decay time averaging
////////////////////////////////////////////////////////////////////////////////////
TYPEREAL CSMeter::GetAve()
{
// qDebug()<<m_AverageMag << m_CalibrationOffset;
return m_AverageMag + SMETER_CALIBRATION + m_CalibrationOffset;
}
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