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Fix KiwiSDR CW BFO offset so a tuned carrier produces an audible tone (#4423) #1

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Fix KiwiSDR CW BFO offset so a tuned carrier produces an audible tone (#4423) #1

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49fc50e
Offset KiwiSDR CW sound-stream BFO by the passband center (#4423)
wa2n-code Jul 24, 2026
54ee886
Use the radio's actual CW pitch for KiwiSDR BFO offset, not passband …
wa2n-code Jul 24, 2026
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13 changes: 6 additions & 7 deletions src/core/KiwiSdrClient.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -975,7 +975,7 @@ void KiwiSdrClient::disconnectFromEndpoint()
void KiwiSdrClient::setTrackedSlice(int sliceId, double frequencyMhz,
const QString& mode, int filterLowHz,
int filterHighHz, const QString& panId,
const QString& bandName)
const QString& bandName, int cwPitchHz)
{
const QString normalizedBandName = bandName.trimmed();
if (m_trackedSliceId == sliceId
Expand All @@ -984,7 +984,8 @@ void KiwiSdrClient::setTrackedSlice(int sliceId, double frequencyMhz,
&& m_trackedFilterLowHz == filterLowHz
&& m_trackedFilterHighHz == filterHighHz
&& m_trackedPanId == panId
&& m_trackedBandName == normalizedBandName) {
&& m_trackedBandName == normalizedBandName
&& m_trackedCwPitchHz == cwPitchHz) {
return;
}

Expand All @@ -998,6 +999,7 @@ void KiwiSdrClient::setTrackedSlice(int sliceId, double frequencyMhz,
m_trackedFilterLowHz = filterLowHz;
m_trackedFilterHighHz = filterHighHz;
m_trackedPanId = panId;
m_trackedCwPitchHz = cwPitchHz;
if (bandChanged) {
resetWaterfallAutoScaleHistory();
}
Expand Down Expand Up @@ -1391,11 +1393,8 @@ void KiwiSdrClient::sendTrackedSliceToServer()
<< "high_cut=" << highCutHz;
return;
}
sendSoundCommand(QStringLiteral("SET mod=%1 low_cut=%2 high_cut=%3 freq=%4")
.arg(mode)
.arg(lowCutHz)
.arg(highCutHz)
.arg(freqKhz, 0, 'f', 3));
sendSoundCommand(KiwiSdrProtocol::formatSoundTuneCommand(
mode, lowCutHz, highCutHz, freqKhz, m_trackedCwPitchHz));
}

void KiwiSdrClient::sendReceiverControlsToServer()
Expand Down
3 changes: 2 additions & 1 deletion src/core/KiwiSdrClient.h
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Original file line number Diff line number Diff line change
Expand Up @@ -105,7 +105,7 @@ public slots:
void setTrackedSlice(int sliceId, double frequencyMhz,
const QString& mode, int filterLowHz,
int filterHighHz, const QString& panId,
const QString& bandName);
const QString& bandName, int cwPitchHz);
void setWaterfallView(const QString& panId, double centerMhz,
double bandwidthMhz);
void setWaterfallLineDurationMs(int lineDurationMs);
Expand Down Expand Up @@ -278,6 +278,7 @@ public slots:
QString m_trackedMode;
int m_trackedFilterLowHz{0};
int m_trackedFilterHighHz{0};
int m_trackedCwPitchHz{600};
QString m_trackedPanId;
bool m_userDisconnecting{false};
bool m_secureWebSocket{false};
Expand Down
24 changes: 14 additions & 10 deletions src/core/KiwiSdrManager.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -440,7 +440,7 @@ void KiwiSdrManager::connectProfile(const QString& id)
m_clientHasTrackedSlice.insert(id, false);
invokeClient(id, [](KiwiSdrClient* client) {
client->setTrackedSlice(-1, 0.0, QString(), 0, 0, QString(),
QString());
QString(), 0);
});
emit profileNeedsInitialTracking(id);
}
Expand Down Expand Up @@ -521,7 +521,8 @@ void KiwiSdrManager::primeProfileTracking(const QString& id, int sliceId,
double centerMhz,
double bandwidthMhz,
int lineDurationMs,
const QString& bandName)
const QString& bandName,
int cwPitchHz)
{
if (!hasProfile(id) || sliceId < 0 || frequencyMhz <= 0.0) {
return;
Expand All @@ -532,10 +533,10 @@ void KiwiSdrManager::primeProfileTracking(const QString& id, int sliceId,
m_clientHasTrackedSlice.insert(id, true);
invokeClient(id, [sliceId, frequencyMhz, mode, filterLowHz,
filterHighHz, panId, lineDurationMs,
centerMhz, bandwidthMhz, bandName](
centerMhz, bandwidthMhz, bandName, cwPitchHz](
KiwiSdrClient* client) {
client->setTrackedSlice(sliceId, frequencyMhz, mode, filterLowHz,
filterHighHz, panId, bandName);
filterHighHz, panId, bandName, cwPitchHz);
client->setWaterfallLineDurationMs(lineDurationMs);
if (!panId.isEmpty() && centerMhz > 0.0 && bandwidthMhz > 0.0) {
client->setWaterfallView(panId, centerMhz, bandwidthMhz);
Expand All @@ -549,7 +550,8 @@ void KiwiSdrManager::assignSliceToProfile(int sliceId, const QString& profileId,
const QString& mode,
int filterLowHz, int filterHighHz,
const QString& panId,
const QString& bandName)
const QString& bandName,
int cwPitchHz)
{
if (sliceId < 0 || !hasProfile(profileId)) {
clearSliceAssignment(sliceId);
Expand Down Expand Up @@ -597,10 +599,11 @@ void KiwiSdrManager::assignSliceToProfile(int sliceId, const QString& profileId,
const bool connected =
KiwiSdrClient::stateHasReceiveAudio(state(profileId));
invokeClient(profileId, [sliceId, frequencyMhz, mode, filterLowHz,
filterHighHz, panId, bandName, connected](
filterHighHz, panId, bandName, connected,
cwPitchHz](
KiwiSdrClient* client) {
client->setTrackedSlice(sliceId, frequencyMhz, mode, filterLowHz,
filterHighHz, panId, bandName);
filterHighHz, panId, bandName, cwPitchHz);
client->setAudioActive(connected);
});
}
Expand Down Expand Up @@ -639,7 +642,8 @@ void KiwiSdrManager::updateSliceTracking(int sliceId, double frequencyMhz,
const QString& mode,
int filterLowHz, int filterHighHz,
const QString& panId,
const QString& bandName)
const QString& bandName,
int cwPitchHz)
{
const QString profileId = m_sliceAssignments.value(sliceId);
if (profileId.isEmpty()) {
Expand All @@ -650,10 +654,10 @@ void KiwiSdrManager::updateSliceTracking(int sliceId, double frequencyMhz,
m_clientHasTrackedSlice.insert(profileId, sliceId >= 0 && frequencyMhz > 0.0);
invokeClient(profileId, [sliceId, frequencyMhz, mode,
filterLowHz, filterHighHz, panId,
bandName](
bandName, cwPitchHz](
KiwiSdrClient* client) {
client->setTrackedSlice(sliceId, frequencyMhz, mode, filterLowHz,
filterHighHz, panId, bandName);
filterHighHz, panId, bandName, cwPitchHz);
});
}
}
Expand Down
6 changes: 3 additions & 3 deletions src/core/KiwiSdrManager.h
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Original file line number Diff line number Diff line change
Expand Up @@ -97,17 +97,17 @@ public slots:
int filterLowHz, int filterHighHz,
const QString& panId, double centerMhz,
double bandwidthMhz, int lineDurationMs,
const QString& bandName);
const QString& bandName, int cwPitchHz);
void assignSliceToProfile(int sliceId, const QString& profileId,
double frequencyMhz, const QString& mode,
int filterLowHz, int filterHighHz,
const QString& panId,
const QString& bandName);
const QString& bandName, int cwPitchHz);
void clearSliceAssignment(int sliceId);
void updateSliceTracking(int sliceId, double frequencyMhz,
const QString& mode, int filterLowHz,
int filterHighHz, const QString& panId,
const QString& bandName);
const QString& bandName, int cwPitchHz);
void updateWaterfallView(int sliceId, const QString& panId,
double centerMhz, double bandwidthMhz,
int lineDurationMs);
Expand Down
29 changes: 29 additions & 0 deletions src/core/KiwiSdrProtocol.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1585,6 +1585,35 @@ QString formatAgcCommand(bool enabled, bool hang, int thresholdDb,
.arg(clampedManualGain);
}

QString formatSoundTuneCommand(const QString& mode, int lowCutHz, int highCutHz,
double freqKhz, int cwPitchHz)
{
int tunedLowCutHz = lowCutHz;
int tunedHighCutHz = highCutHz;
double tunedFreqKhz = freqKhz;
if (mode == QStringLiteral("cw") && cwPitchHz != 0) {
// Flex reports the CW passband symmetric about the carrier (e.g.
// low_cut=-400 high_cut=400) — the sidetone pitch is a DSP shift
// Flex applies AFTER that filter, not something baked into it. The
// Kiwi has no such post-filter shift: 'freq' is the BFO/mixdown
// point and low_cut/high_cut are an audio passband relative to it.
// Sending freq=carrier with the passband as reported puts the
// carrier at 0 Hz (audible only as a DC thump, not a tone) — #4423.
// Reproduce the Flex behavior by shifting the whole receive chain
// by the pitch: move the BFO down so the carrier demodulates to
// +cwPitchHz, and slide the passband up by the same amount so that
// frequency is still inside it.
tunedLowCutHz += cwPitchHz;
tunedHighCutHz += cwPitchHz;
tunedFreqKhz -= cwPitchHz / 1000.0;
}
return QStringLiteral("SET mod=%1 low_cut=%2 high_cut=%3 freq=%4")
.arg(mode)
.arg(tunedLowCutHz)
.arg(tunedHighCutHz)
.arg(tunedFreqKhz, 0, 'f', 3);
}

MeterReading meterUnavailable(MeterSource source, const QString& notes)
{
MeterReading reading;
Expand Down
2 changes: 2 additions & 0 deletions src/core/KiwiSdrProtocol.h
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Original file line number Diff line number Diff line change
Expand Up @@ -325,6 +325,8 @@ QString formatSquelchCommand(bool enabled, int thresholdDb,
int agcDecayMsForMode(const QString& mode);
QString formatAgcCommand(bool enabled, bool hang, int thresholdDb,
int manualGainDb, int decayMs);
QString formatSoundTuneCommand(const QString& mode, int lowCutHz, int highCutHz,
double freqKhz, int cwPitchHz);
MeterReading meterUnavailable(MeterSource source, const QString& notes = {});
MeterReading extractMeterFromSndVerifiedLayout(const QByteArray& frame,
const MeterContext& context);
Expand Down
9 changes: 6 additions & 3 deletions src/gui/MainWindow_KiwiSdr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -602,7 +602,8 @@ void MainWindow::setKiwiSdrVirtualAntennaForSliceInternal(int sliceId,
m_kiwiSdrManager->assignSliceToProfile(
sliceId, profileId, slice->frequency(), slice->mode(),
slice->filterLow(), slice->filterHigh(), slice->panId(),
BandSettings::bandForFrequency(slice->frequency()));
BandSettings::bandForFrequency(slice->frequency()),
m_radioModel.transmitModel().cwPitch());
updateKiwiSdrVirtualTrackingForSlice(slice);
updateKiwiSdrVirtualAudioControlsForSlice(slice);
updateKiwiSdrVirtualReceiverControlsForSlice(slice);
Expand Down Expand Up @@ -1035,7 +1036,8 @@ void MainWindow::updateKiwiSdrVirtualTrackingForSlice(SliceModel* slice)
m_kiwiSdrManager->updateSliceTracking(
slice->sliceId(), slice->frequency(), slice->mode(),
slice->filterLow(), slice->filterHigh(), slice->panId(),
BandSettings::bandForFrequency(slice->frequency()));
BandSettings::bandForFrequency(slice->frequency()),
m_radioModel.transmitModel().cwPitch());
if (SpectrumWidget* spectrum = spectrumForSlice(slice)) {
m_kiwiSdrManager->updateWaterfallView(
slice->sliceId(), slice->panId(), spectrum->centerMhz(),
Expand Down Expand Up @@ -1674,7 +1676,8 @@ void MainWindow::wireKiwiSdr()
spectrum ? spectrum->centerMhz() : slice->frequency(),
spectrum ? spectrum->bandwidthMhz() : 0.2,
spectrum ? spectrum->wfLineDuration() : 100,
BandSettings::bandForFrequency(slice->frequency()));
BandSettings::bandForFrequency(slice->frequency()),
m_radioModel.transmitModel().cwPitch());
});
if (m_audio) {
connect(m_kiwiSdrManager, &KiwiSdrManager::decodedAudioReady,
Expand Down
5 changes: 5 additions & 0 deletions src/gui/MainWindow_Wiring.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4688,6 +4688,11 @@ void MainWindow::wireVfoWidget(VfoWidget* w, SliceModel* s)
connect(s, &SliceModel::panIdChanged, this, [this, s](const QString&) {
updateKiwiSdrVirtualTrackingForSlice(s);
});
// Re-send the tracked-slice command when the radio's CW pitch changes so
// an already-active KiwiSDR CW session's BFO offset stays in sync (#4423)
// instead of going stale until the next frequency/mode/filter edit.
connect(&m_radioModel.transmitModel(), &TransmitModel::phoneStateChanged,
this, [this, s]() { updateKiwiSdrVirtualTrackingForSlice(s); });
connect(s, &SliceModel::audioGainChanged, this, [this, s](float) {
updateKiwiSdrVirtualAudioControlsForSlice(s);
updateAetherDspModePolicy();
Expand Down
18 changes: 18 additions & 0 deletions tests/kiwi_sdr_protocol_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -294,6 +294,24 @@ int main()
return fail("AGC command formatting is wrong");
}

// #4423: Flex reports the CW passband symmetric about the carrier (e.g.
// -400..400, confirmed from a real session log) and applies the sidetone
// pitch as a DSP shift AFTER that filter. The Kiwi has no such shift:
// 'freq' is the BFO and low_cut/high_cut are relative to it, so sending
// freq=carrier with an unshifted passband puts the carrier at 0 Hz (a DC
// thump, not a tone). Both the BFO and the passband must move by the
// pitch so the carrier lands audibly inside it.
if (formatSoundTuneCommand(QStringLiteral("cw"), -400, 400, 7000.0, 600)
!= QStringLiteral("SET mod=cw low_cut=200 high_cut=1000 freq=6999.400")
|| formatSoundTuneCommand(QStringLiteral("cw"), -400, 400, 7000.0, 0)
!= QStringLiteral("SET mod=cw low_cut=-400 high_cut=400 freq=7000.000")
|| formatSoundTuneCommand(QStringLiteral("usb"), 100, 2900, 7000.0, 600)
!= QStringLiteral("SET mod=usb low_cut=100 high_cut=2900 freq=7000.000")
|| formatSoundTuneCommand(QStringLiteral("lsb"), -2900, -100, 7000.0, 600)
!= QStringLiteral("SET mod=lsb low_cut=-2900 high_cut=-100 freq=7000.000")) {
return fail("sound tune command formatting is wrong");
}

const QVector<MsgToken> msgTokens = parseMsgTokens(
QStringLiteral("MSG wb_only password_timeout inactivity_timeout=15 "
"kiwi_kick=1%2coperator%20request badp=5 =ignored"));
Expand Down
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