pa-calculator/mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QString>
#include <QtMath>
#include <QMessageBox>
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_ComboBox_selectSensUnit_currentIndexChanged(int index)
{
    double oldValue=ui->doubleSpinBox_ampInputSens->value();
    if (index==0){
       ui->doubleSpinBox_ampInputSens->setSuffix(QString(" V"));
       ui->doubleSpinBox_ampInputSens->setDecimals(2);
       ui->doubleSpinBox_ampInputSens->setValue(0.7746*qPow(10,oldValue/20));
    }else{
       ui->doubleSpinBox_ampInputSens->setSuffix(QString(" dBu"));
       ui->doubleSpinBox_ampInputSens->setDecimals(1);
       ui->doubleSpinBox_ampInputSens->setValue(20*std::log10(oldValue/0.7746));
    }

}


void MainWindow::on_pushButton_requestLimiter_clicked()
{
    qreal vMaxSpeakerInRMS=20*std::log10(qSqrt(ui->spinBox_speakerImp->value()*ui->spinBox_speakerRMSPower->value())/0.7746);
    qreal vMaxSpeakerInPeak=20*std::log10(qSqrt(ui->spinBox_speakerImp->value()*ui->spinBox_speakerPeakPower->value())/0.7746);

    qreal vAmpSens_volt=0;
    qreal vAmpsens_dBu=0;
    if(ui->ComboBox_selectSensUnit->currentIndex()==0){
        vAmpSens_volt=ui->doubleSpinBox_ampInputSens->value();
        vAmpsens_dBu=20*std::log10(vAmpSens_volt/0.7746);
    }else{
        vAmpSens_volt=qPow(10,ui->doubleSpinBox_ampInputSens->value()/20)*0.7746;
        vAmpsens_dBu=ui->doubleSpinBox_ampInputSens->value();
    }

    qreal voltageGain=20*std::log10(qSqrt(ui->spinBox_AmpImp->value()*ui->spinBox_AmpPower->value())/vAmpSens_volt);
    qreal vMaxAmpInRMS=vMaxSpeakerInRMS-voltageGain;
    qreal vMaxAmpInPeak=vMaxSpeakerInPeak-voltageGain;

    qreal thresholdRMS=-18-(ui->spinBox_digitalNominalLevel->value()-vMaxAmpInRMS);
    qreal thresholdPeak=-18-(ui->spinBox_digitalNominalLevel->value()-vMaxAmpInPeak);
    qreal attackTimeRMS=(double)1000/ui->spinBox_speakerHPF->value();
    qreal releaseTimeRMS=attackTimeRMS*8;
    qreal releaseTimePeak=attackTimeRMS;

    if (vAmpsens_dBu<vMaxAmpInRMS){
        QMessageBox msgBox(QMessageBox::Warning,"Amplifier can't deliver maximum RMS power","The maximum power level of the amplifier is below the maximum RMS power level of the speaker. To protect the speaker from a distorted signal the amplifier might deliver, a peak limiter is required with the amplifiers input sensitivty set as its threshold.");
        msgBox.exec();
        ui->label_thresholdRMS->setText(QString("not required"));
        ui->label_attackTimeRMS->setText(QString::number(attackTimeRMS,'f',2)+QString(" ms"));
        ui->label_releaseTimeRMS->setText(QString::number(releaseTimeRMS,'f',2)+QString(" ms"));
        ui->label_UMaxSpeakerInRMS->setText(QString::number(vMaxSpeakerInRMS,'f',2)+QString(" dBU (")+QString::number(qSqrt(ui->spinBox_speakerImp->value()*ui->spinBox_speakerRMSPower->value()),'f',2)+QString(" V)"));
        ui->label_UMaxAmpInRMS->setText(QString("not applicable"));


        thresholdPeak=-18-(ui->spinBox_digitalNominalLevel->value()-vAmpsens_dBu);
        ui->label_thresholdPeak->setText(QString::number(thresholdPeak,'f',1)+QString(" dBFS"));
        ui->label_releaseTimePeak->setText(QString::number(releaseTimePeak,'f',2)+QString(" ms"));
        ui->label_UMaxSpeakerInPeak->setText(QString::number(vMaxSpeakerInPeak,'f',2)+QString(" dBU (")+QString::number(qSqrt(ui->spinBox_speakerImp->value()*ui->spinBox_speakerPeakPower->value()),'f',2)+QString(" V)"));
        ui->label_UMaxAmpInPeak->setText(QString::number(vAmpSens_volt,'f',2)+QString(" V (= input sensitivity)"));
    }else if (vAmpsens_dBu<vMaxAmpInPeak){
        QMessageBox msgBox(QMessageBox::Warning,"Amplifier can't deliver maximum peak power","The maximum power level of the amplifier is below the maximum peak power level of the speaker. To protect the speaker from a distorted signal the amplifier might deliver, a peak limiter is required with the amplifiers input sensitivty set as its threshold.");
        msgBox.exec();

        ui->label_thresholdRMS->setText(QString::number(thresholdRMS,'f',1)+QString(" dBFS"));
        ui->label_attackTimeRMS->setText(QString::number(attackTimeRMS,'f',2)+QString(" ms"));
        ui->label_releaseTimeRMS->setText(QString::number(releaseTimeRMS,'f',2)+QString(" ms"));
        ui->label_UMaxSpeakerInRMS->setText(QString::number(vMaxSpeakerInRMS,'f',2)+QString(" dBU (")+QString::number(qSqrt(ui->spinBox_speakerImp->value()*ui->spinBox_speakerRMSPower->value()),'f',2)+QString(" V)"));
        ui->label_UMaxAmpInRMS->setText(QString::number(vMaxAmpInRMS,'f',2)+QString(" dBU (")+QString::number(qPow(10,vMaxAmpInRMS/20)*0.7746,'f',2)+QString(" V)"));

        thresholdPeak=-18-(ui->spinBox_digitalNominalLevel->value()-vAmpsens_dBu);
        ui->label_thresholdPeak->setText(QString::number(thresholdPeak,'f',1)+QString(" dBFS"));
        ui->label_releaseTimePeak->setText(QString::number(releaseTimePeak,'f',2)+QString(" ms"));
        ui->label_UMaxSpeakerInPeak->setText(QString::number(vMaxSpeakerInPeak,'f',2)+QString(" dBU (")+QString::number(qSqrt(ui->spinBox_speakerImp->value()*ui->spinBox_speakerPeakPower->value()),'f',2)+QString(" V)"));
        ui->label_UMaxAmpInPeak->setText(QString::number(vAmpSens_volt,'f',2)+QString(" V (= input sensitivity)"));
    }else{
        ui->label_thresholdRMS->setText(QString::number(thresholdRMS,'f',1)+QString(" dBFS"));
        ui->label_attackTimeRMS->setText(QString::number(attackTimeRMS,'f',2)+QString(" ms"));
        ui->label_releaseTimeRMS->setText(QString::number(releaseTimeRMS,'f',2)+QString(" ms"));
        ui->label_UMaxSpeakerInRMS->setText(QString::number(vMaxSpeakerInRMS,'f',2)+QString(" dBU (")+QString::number(qSqrt(ui->spinBox_speakerImp->value()*ui->spinBox_speakerRMSPower->value()),'f',2)+QString(" V)"));
        ui->label_UMaxAmpInRMS->setText(QString::number(vMaxAmpInRMS,'f',2)+QString(" dBU (")+QString::number(qPow(10,vMaxAmpInRMS/20)*0.7746,'f',2)+QString(" V)"));

        ui->label_thresholdPeak->setText(QString::number(thresholdPeak,'f',1)+QString(" dBFS"));
        ui->label_releaseTimePeak->setText(QString::number(releaseTimePeak,'f',2)+QString(" ms"));
        ui->label_UMaxSpeakerInPeak->setText(QString::number(vMaxSpeakerInPeak,'f',2)+QString(" dBU (")+QString::number(qSqrt(ui->spinBox_speakerImp->value()*ui->spinBox_speakerPeakPower->value()),'f',2)+QString(" V)"));
        ui->label_UMaxAmpInPeak->setText(QString::number(vMaxAmpInPeak,'f',2)+QString(" dBU (")+QString::number(qPow(10,vMaxAmpInPeak/20)*0.7746,'f',2)+QString(" V)"));
    }




}