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Improve spectrum analyzer

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- revert LO2 shift mechanism (restores previous SA speed)
- allow tracking generator to reach all(?) frequencies with sufficient accuracy
This commit is contained in:
Jan Käberich 2025-01-04 16:50:20 +01:00
parent 8df7d1b7be
commit b77ba278de
3 changed files with 68 additions and 60 deletions
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26
Software/PC_Application/LibreVNA-GUI/Device/LibreVNA/librevnadriver.cpp
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@ -501,32 +501,6 @@ bool LibreVNADriver::setSA(const DeviceDriver::SASettings &s, std::function<void
p.spectrumSettings.syncMode = (int) sync;
p.spectrumSettings.syncMaster = syncMaster ? 1 : 0;
if(p.spectrumSettings.trackingGenerator && p.spectrumSettings.f_stop >= 25000000) {
// Check point spacing.
// The highband PLL used as the tracking generator is not able to reach every frequency exactly. This
// could lead to sharp drops in the spectrum at certain frequencies. If the span is wide enough with
// respect to the point number, it is ensured that every displayed point has at least one sample with
// a reachable PLL frequency in it. Display a warning message if this is not the case with the current
// settings.
auto pointSpacing = (p.spectrumSettings.f_stop - p.spectrumSettings.f_start) / (p.spectrumSettings.pointNum - 1);
// The frequency resolution of the PLL is frequency dependent (due to PLL divider).
// This code assumes some knowledge of the actual hardware and probably should be moved
// onto the device at some point
double minSpacing = 25000;
auto stop = p.spectrumSettings.f_stop;
while(stop <= 3000000000) {
minSpacing /= 2;
stop *= 2;
}
if(pointSpacing < minSpacing) {
auto requiredMinSpan = minSpacing * (p.spectrumSettings.pointNum - 1);
auto message = QString() + "Due to PLL limitations, the tracking generator can not reach every frequency exactly. "
"With your current span, this could result in the signal not being detected at some bands. A minimum"
" span of " + Unit::ToString(requiredMinSpan, "Hz", " kMG") + " is recommended at this stop frequency.";
InformationBox::ShowMessage("Warning", message, "TrackingGeneratorSpanTooSmallWarning");
}
}
return SendPacket(p, [=](TransmissionResult r){
if(cb) {
cb(r == TransmissionResult::Ack);