diff --git a/plugins/samplesink/fileoutput/fileoutput.cpp b/plugins/samplesink/fileoutput/fileoutput.cpp
index d00c38f66..735fab4ca 100644
--- a/plugins/samplesink/fileoutput/fileoutput.cpp
+++ b/plugins/samplesink/fileoutput/fileoutput.cpp
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////////////
-// Copyright (C) 2016-2023 Edouard Griffiths, F4EXB <f4exb06@gmail.com>          //
+// Copyright (C) 2016-2026 Edouard Griffiths, F4EXB <f4exb06@gmail.com>          //
 // Copyright (C) 2021 Andreas Baulig <free.geronimo@hotmail.de>                  //
 //                                                                               //
 // This program is free software; you can redistribute it and/or modify          //
@@ -45,6 +45,7 @@ MESSAGE_CLASS_DEFINITION(FileOutput::MsgReportFileOutputStreamTiming, Message)
 FileOutput::FileOutput(DeviceAPI *deviceAPI) :
     m_deviceAPI(deviceAPI),
 	m_settings(),
+    m_spectrumVis(SDR_TX_SCALEF),
 	m_deviceDescription("FileOutput"),
 	m_masterTimer(deviceAPI->getMasterTimer())
 {
@@ -77,7 +78,7 @@ void FileOutput::openFileStream()
     header.centerFrequency = m_settings.m_centerFrequency;
     m_startingTimeStamp = QDateTime::currentMSecsSinceEpoch();
     header.startTimeStamp = (quint64)m_startingTimeStamp;
-    header.sampleSize = SDR_RX_SAMP_SZ;
+    header.sampleSize = SDR_TX_SAMP_SZ;
 
     FileRecord::writeHeader(m_ofstream, header);
 
@@ -91,8 +92,6 @@ void FileOutput::init()
 
 bool FileOutput::start()
 {
-	QMutexLocker mutexLocker(&m_mutex);
-
     if (m_running) {
         return true;
     }
@@ -103,13 +102,13 @@ bool FileOutput::start()
 
 	m_fileOutputWorker = new FileOutputWorker(&m_ofstream, &m_sampleSourceFifo);
     m_fileOutputWorker->moveToThread(&m_fileOutputWorkerThread);
+    m_fileOutputWorker->setSpectrumSink(&m_spectrumVis);
 	m_fileOutputWorker->setSamplerate((int) m_settings.m_sampleRate);
 	m_fileOutputWorker->setLog2Interpolation(m_settings.m_log2Interp);
 	m_fileOutputWorker->connectTimer(m_masterTimer);
 	startWorker();
     m_running = true;
 
-	mutexLocker.unlock();
 	qDebug("FileOutput::start: started");
 
     if (getMessageQueueToGUI())
@@ -123,8 +122,6 @@ bool FileOutput::start()
 
 void FileOutput::stop()
 {
-	QMutexLocker mutexLocker(&m_mutex);
-
     if (!m_running) {
         return;
     }
@@ -298,8 +295,8 @@ bool FileOutput::handleMessage(const Message& message)
 void FileOutput::applySettings(const FileOutputSettings& settings, const QList<QString>& settingsKeys, bool force)
 {
     qDebug() << "FileOutput::applySettings: force:" << force << settings.getDebugString(settingsKeys, force);
-    QMutexLocker mutexLocker(&m_mutex);
     bool forwardChange = false;
+    bool needRestart = false;
 
     if (force || settingsKeys.contains("centerFrequency"))
     {
@@ -308,19 +305,13 @@ void FileOutput::applySettings(const FileOutputSettings& settings, const QList<Q
 
     if (force || settingsKeys.contains("sampleRate"))
     {
-        if (m_fileOutputWorker != nullptr) {
-            m_fileOutputWorker->setSamplerate((int) settings.m_sampleRate);
-        }
-
+        needRestart = true;
         forwardChange = true;
     }
 
     if (force || settingsKeys.contains("log2Interp"))
     {
-        if (m_fileOutputWorker != nullptr) {
-            m_fileOutputWorker->setLog2Interpolation(settings.m_log2Interp);
-        }
-
+        needRestart = true;
         forwardChange = true;
     }
 
@@ -339,6 +330,12 @@ void FileOutput::applySettings(const FileOutputSettings& settings, const QList<Q
         m_settings.applySettings(settingsKeys, settings);
     }
 
+    if (needRestart && m_running)
+    {
+        stop();
+        start();
+    }
+
     if (forwardChange)
     {
         qDebug("FileOutput::applySettings: forward: m_centerFrequency: %llu m_sampleRate: %llu m_log2Interp: %d",
diff --git a/plugins/samplesink/fileoutput/fileoutput.h b/plugins/samplesink/fileoutput/fileoutput.h
index 7c405d888..84e30703d 100644
--- a/plugins/samplesink/fileoutput/fileoutput.h
+++ b/plugins/samplesink/fileoutput/fileoutput.h
@@ -2,7 +2,7 @@
 // Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
 // written by Christian Daniel                                                   //
 // Copyright (C) 2014 John Greb <hexameron@spam.no>                              //
-// Copyright (C) 2015-2017, 2019-2022 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
+// Copyright (C) 2015-2017, 2019-2026 Edouard Griffiths, F4EXB                   //
 // Copyright (C) 2021 Andreas Baulig <free.geronimo@hotmail.de>                  //
 //                                                                               //
 // This program is free software; you can redistribute it and/or modify          //
@@ -32,6 +32,7 @@
 #include <fstream>
 
 #include "dsp/devicesamplesink.h"
+#include "dsp/spectrumvis.h"
 #include "fileoutputsettings.h"
 
 class QNetworkAccessManager;
@@ -231,11 +232,14 @@ public:
             const QStringList& deviceSettingsKeys,
             SWGSDRangel::SWGDeviceSettings& response);
 
+	SpectrumVis *getSpectrumVis() { return &m_spectrumVis; }
+    void setSpectrumGUI(Serializable *spectrumGUI) { m_settings.setSpectrumGUI(spectrumGUI); }
+
 private:
     DeviceAPI *m_deviceAPI;
-	QMutex m_mutex;
     bool m_running = false;
 	FileOutputSettings m_settings;
+	SpectrumVis m_spectrumVis;
 	std::ofstream m_ofstream;
 	FileOutputWorker* m_fileOutputWorker = nullptr;
     QThread m_fileOutputWorkerThread;
diff --git a/plugins/samplesink/fileoutput/fileoutputgui.cpp b/plugins/samplesink/fileoutput/fileoutputgui.cpp
index e90d9b972..8770e9400 100644
--- a/plugins/samplesink/fileoutput/fileoutputgui.cpp
+++ b/plugins/samplesink/fileoutput/fileoutputgui.cpp
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////////////
-// Copyright (C) 2015-2022 Edouard Griffiths, F4EXB <f4exb06@gmail.com>          //
+// Copyright (C) 2015-2026 Edouard Griffiths, F4EXB <f4exb06@gmail.com>          //
 // Copyright (C) 2018 beta-tester <alpha-beta-release@gmx.net>                   //
 // Copyright (C) 2020, 2022-2023 Jon Beniston, M7RCE <jon@beniston.com>          //
 //                                                                               //
@@ -31,6 +31,7 @@
 #include "gui/basicdevicesettingsdialog.h"
 #include "gui/dialogpositioner.h"
 #include "dsp/dspcommands.h"
+#include "dsp/spectrumvis.h"
 
 #include "device/deviceapi.h"
 #include "device/deviceuiset.h"
@@ -54,6 +55,7 @@ FileOutputGui::FileOutputGui(DeviceUISet *deviceUISet, QWidget* parent) :
     setAttribute(Qt::WA_DeleteOnClose, true);
     ui->setupUi(getContents());
     sizeToContents();
+    setMinimumSize(m_MinimumWidth, m_MinimumHeight);
     getContents()->setStyleSheet("#FileOutputGui { background-color: rgb(64, 64, 64); }");
     m_helpURL = "plugins/samplesink/fileoutput/readme.md";
     ui->centerFrequency->setColorMapper(ColorMapper(ColorMapper::GrayGold));
@@ -66,6 +68,15 @@ FileOutputGui::FileOutputGui(DeviceUISet *deviceUISet, QWidget* parent) :
 
 	ui->fileNameText->setText(m_settings.m_fileName);
 
+    m_deviceSampleSink = (FileOutput*) m_deviceUISet->m_deviceAPI->getSampleSink();
+
+    m_spectrumVis = m_deviceSampleSink->getSpectrumVis();
+    m_spectrumVis->setGLSpectrum(ui->glSpectrum);
+    ui->glSpectrum->setCenterFrequency(m_settings.m_centerFrequency);
+    ui->glSpectrum->setSampleRate(m_settings.m_sampleRate*(1<<m_settings.m_log2Interp));
+    ui->spectrumGUI->setBuddies(m_spectrumVis, ui->glSpectrum);
+    m_deviceSampleSink->setSpectrumGUI(ui->spectrumGUI);
+
 	connect(&(m_deviceUISet->m_deviceAPI->getMasterTimer()), SIGNAL(timeout()), this, SLOT(tick()));
 	connect(&m_updateTimer, SIGNAL(timeout()), this, SLOT(updateHardware()));
 	connect(&m_statusTimer, SIGNAL(timeout()), this, SLOT(updateStatus()));
@@ -75,7 +86,6 @@ FileOutputGui::FileOutputGui(DeviceUISet *deviceUISet, QWidget* parent) :
     makeUIConnections();
     m_resizer.enableChildMouseTracking();
 
-    m_deviceSampleSink = (FileOutput*) m_deviceUISet->m_deviceAPI->getSampleSink();
     connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
     connect(this, SIGNAL(customContextMenuRequested(const QPoint &)), this, SLOT(openDeviceSettingsDialog(const QPoint &)));
 }
@@ -256,6 +266,7 @@ void FileOutputGui::updateStatus()
 void FileOutputGui::on_centerFrequency_changed(quint64 value)
 {
     m_settings.m_centerFrequency = value * 1000;
+    ui->glSpectrum->setCenterFrequency(m_settings.m_centerFrequency);
     m_settingsKeys.append("centerFrequency");
     sendSettings();
 }
@@ -263,6 +274,7 @@ void FileOutputGui::on_centerFrequency_changed(quint64 value)
 void FileOutputGui::on_sampleRate_changed(quint64 value)
 {
     m_settings.m_sampleRate = value;
+    ui->glSpectrum->setSampleRate(m_settings.m_sampleRate*(1<<m_settings.m_log2Interp));
     m_settingsKeys.append("sampleRate");
     sendSettings();
 }
@@ -274,6 +286,7 @@ void FileOutputGui::on_interp_currentIndexChanged(int index)
     }
 
     m_settings.m_log2Interp = index;
+    ui->glSpectrum->setSampleRate(m_settings.m_sampleRate*(1<<m_settings.m_log2Interp));
     m_settingsKeys.append("log2Interp");
     updateSampleRateAndFrequency();
     sendSettings();
diff --git a/plugins/samplesink/fileoutput/fileoutputgui.h b/plugins/samplesink/fileoutput/fileoutputgui.h
index 7fde1a4ee..7c349e20e 100644
--- a/plugins/samplesink/fileoutput/fileoutputgui.h
+++ b/plugins/samplesink/fileoutput/fileoutputgui.h
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////////////
-// Copyright (C) 2015-2017, 2019-2022 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
+// Copyright (C) 2015-2017, 2019-2026 Edouard Griffiths, F4EXB                   //
 // Copyright (C) 2022 Jon Beniston, M7RCE <jon@beniston.com>                     //
 //                                                                               //
 // This program is free software; you can redistribute it and/or modify          //
@@ -31,6 +31,7 @@
 
 class DeviceSampleSink;
 class DeviceUISet;
+class SpectrumVis;
 
 namespace Ui {
 	class FileOutputGui;
@@ -58,7 +59,7 @@ private:
     QList<QString> m_settingsKeys;
 	QTimer m_updateTimer;
     QTimer m_statusTimer;
-	DeviceSampleSink* m_deviceSampleSink;
+	FileOutput* m_deviceSampleSink;
     int m_sampleRate;
     quint64 m_deviceCenterFrequency; //!< Center frequency in device
     bool m_generation;
@@ -67,6 +68,9 @@ private:
 	std::size_t m_tickCount;
 	int m_lastEngineState;
 	MessageQueue m_inputMessageQueue;
+	SpectrumVis* m_spectrumVis;
+    static const int m_MinimumWidth = 370;
+    static const int m_MinimumHeight = 470;
 
 	void blockApplySettings(bool block) { m_doApplySettings = !block; }
 	void displaySettings();
diff --git a/plugins/samplesink/fileoutput/fileoutputgui.ui b/plugins/samplesink/fileoutput/fileoutputgui.ui
index c36dbb4e6..26c13dea8 100644
--- a/plugins/samplesink/fileoutput/fileoutputgui.ui
+++ b/plugins/samplesink/fileoutput/fileoutputgui.ui
@@ -6,26 +6,20 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>360</width>
-    <height>126</height>
+    <width>370</width>
+    <height>470</height>
    </rect>
   </property>
   <property name="sizePolicy">
-   <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
+   <sizepolicy hsizetype="Expanding" vsizetype="Ignored">
     <horstretch>0</horstretch>
     <verstretch>0</verstretch>
    </sizepolicy>
   </property>
   <property name="minimumSize">
    <size>
-    <width>360</width>
-    <height>126</height>
-   </size>
-  </property>
-  <property name="maximumSize">
-   <size>
-    <width>380</width>
-    <height>144</height>
+    <width>370</width>
+    <height>470</height>
    </size>
   </property>
   <property name="font">
@@ -226,13 +220,6 @@
      </item>
     </layout>
    </item>
-   <item>
-    <widget class="Line" name="line_rate">
-     <property name="orientation">
-      <enum>Qt::Horizontal</enum>
-     </property>
-    </widget>
-   </item>
    <item>
     <layout class="QHBoxLayout" name="rateControlLayout">
      <property name="topMargin">
@@ -361,29 +348,91 @@
        </property>
       </widget>
      </item>
-     <item>
-      <widget class="Line" name="linePlay2">
-       <property name="orientation">
-        <enum>Qt::Vertical</enum>
-       </property>
-      </widget>
-     </item>
     </layout>
    </item>
+   <item>
+    <widget class="Line" name="line_rate">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QWidget" name="spec" native="true">
+     <property name="sizePolicy">
+      <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+       <horstretch>0</horstretch>
+       <verstretch>0</verstretch>
+      </sizepolicy>
+     </property>
+     <layout class="QVBoxLayout" name="spectrumLayout">
+      <item>
+       <widget class="GLSpectrum" name="glSpectrum" native="true">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+        <property name="minimumSize">
+         <size>
+          <width>354</width>
+          <height>200</height>
+         </size>
+        </property>
+        <property name="font">
+         <font>
+          <family>Liberation Mono</family>
+          <pointsize>8</pointsize>
+         </font>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="GLSpectrumGUI" name="spectrumGUI" native="true">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+        <property name="minimumSize">
+         <size>
+          <width>354</width>
+          <height>30</height>
+         </size>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
   </layout>
  </widget>
  <customwidgets>
+  <customwidget>
+   <class>ButtonSwitch</class>
+   <extends>QToolButton</extends>
+   <header>gui/buttonswitch.h</header>
+  </customwidget>
+  <customwidget>
+   <class>GLSpectrum</class>
+   <extends>QWidget</extends>
+   <header>gui/glspectrum.h</header>
+   <container>1</container>
+  </customwidget>
+  <customwidget>
+   <class>GLSpectrumGUI</class>
+   <extends>QWidget</extends>
+   <header>gui/glspectrumgui.h</header>
+   <container>1</container>
+  </customwidget>
   <customwidget>
    <class>ValueDial</class>
    <extends>QWidget</extends>
    <header>gui/valuedial.h</header>
    <container>1</container>
   </customwidget>
-  <customwidget>
-   <class>ButtonSwitch</class>
-   <extends>QToolButton</extends>
-   <header>gui/buttonswitch.h</header>
-  </customwidget>
  </customwidgets>
  <resources>
   <include location="../../../sdrgui/resources/res.qrc"/>
diff --git a/plugins/samplesink/fileoutput/fileoutputsettings.cpp b/plugins/samplesink/fileoutput/fileoutputsettings.cpp
index 4a3a4a042..ce5364fc4 100644
--- a/plugins/samplesink/fileoutput/fileoutputsettings.cpp
+++ b/plugins/samplesink/fileoutput/fileoutputsettings.cpp
@@ -1,7 +1,7 @@
 ///////////////////////////////////////////////////////////////////////////////////
 // Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
 // written by Christian Daniel                                                   //
-// Copyright (C) 2015-2017, 2019-2022 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
+// Copyright (C) 2015-2017, 2019-2026 Edouard Griffiths, F4EXB                   //
 //                                                                               //
 // 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          //
@@ -18,6 +18,7 @@
 ///////////////////////////////////////////////////////////////////////////////////
 
 #include "util/simpleserializer.h"
+#include "settings/serializable.h"
 #include "fileoutputsettings.h"
 
 FileOutputSettings::FileOutputSettings()
@@ -31,6 +32,7 @@ void FileOutputSettings::resetToDefaults()
     m_sampleRate = 48000;
     m_log2Interp = 0;
     m_fileName = "./test.sdriq";
+    m_spectrumGUI = nullptr;
     m_useReverseAPI = false;
     m_reverseAPIAddress = "127.0.0.1";
     m_reverseAPIPort = 8888;
@@ -49,6 +51,10 @@ QByteArray FileOutputSettings::serialize() const
     s.writeU32(6, m_reverseAPIPort);
     s.writeU32(7, m_reverseAPIDeviceIndex);
 
+    if (m_spectrumGUI) {
+        s.writeBlob(8, m_spectrumGUI->serialize());
+    }
+
     return s.final();
 }
 
@@ -82,6 +88,13 @@ bool FileOutputSettings::deserialize(const QByteArray& data)
         d.readU32(7, &uintval, 0);
         m_reverseAPIDeviceIndex = uintval > 99 ? 99 : uintval;
 
+        if (m_spectrumGUI)
+        {
+            QByteArray bytetmp;
+            d.readBlob(8, &bytetmp);
+            m_spectrumGUI->deserialize(bytetmp);
+        }
+
         return true;
     }
     else
diff --git a/plugins/samplesink/fileoutput/fileoutputsettings.h b/plugins/samplesink/fileoutput/fileoutputsettings.h
index 83fbb16d9..26f8de404 100644
--- a/plugins/samplesink/fileoutput/fileoutputsettings.h
+++ b/plugins/samplesink/fileoutput/fileoutputsettings.h
@@ -1,7 +1,7 @@
 ///////////////////////////////////////////////////////////////////////////////////
 // Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
 // written by Christian Daniel                                                   //
-// Copyright (C) 2015-2017, 2019-2022 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
+// Copyright (C) 2015-2017, 2019-2026 Edouard Griffiths, F4EXB                   //
 //                                                                               //
 // 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          //
@@ -20,11 +20,14 @@
 #ifndef PLUGINS_SAMPLESINK_FILEOUTPUT_FILEOUTPUTSETTINGS_H_
 #define PLUGINS_SAMPLESINK_FILEOUTPUT_FILEOUTPUTSETTINGS_H_
 
+class Serializable;
+
 struct FileOutputSettings {
     quint64 m_centerFrequency;
     quint64 m_sampleRate;
     quint32 m_log2Interp;
     QString m_fileName;
+    Serializable *m_spectrumGUI;
     bool     m_useReverseAPI;
     QString  m_reverseAPIAddress;
     uint16_t m_reverseAPIPort;
@@ -36,6 +39,7 @@ struct FileOutputSettings {
     bool deserialize(const QByteArray& data);
     void applySettings(const QStringList& settingsKeys, const FileOutputSettings& settings);
     QString getDebugString(const QStringList& settingsKeys, bool force=false) const;
+    void setSpectrumGUI(Serializable *spectrumGUI) { m_spectrumGUI = spectrumGUI; }
 };
 
 #endif /* PLUGINS_SAMPLESINK_FILEOUTPUT_FILEOUTPUTSETTINGS_H_ */
diff --git a/plugins/samplesink/fileoutput/fileoutputworker.cpp b/plugins/samplesink/fileoutput/fileoutputworker.cpp
index 158e2d857..908f94ef7 100644
--- a/plugins/samplesink/fileoutput/fileoutputworker.cpp
+++ b/plugins/samplesink/fileoutput/fileoutputworker.cpp
@@ -1,5 +1,5 @@
 ///////////////////////////////////////////////////////////////////////////////////
-// Copyright (C) 2016-2017, 2019-2020 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
+// Copyright (C) 2016-2017, 2019-2026 Edouard Griffiths, F4EXB                   //
 //                                                                               //
 // 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          //
@@ -21,6 +21,7 @@
 #include <QDebug>
 
 #include "dsp/samplesourcefifo.h"
+#include "dsp/basebandsamplesink.h"
 #include "fileoutputworker.h"
 
 FileOutputWorker::FileOutputWorker(std::ofstream *samplesStream, SampleSourceFifo* sampleFifo, QObject* parent) :
@@ -180,7 +181,9 @@ void FileOutputWorker::callbackPart(SampleVector& data, unsigned int iBegin, uns
 
     if (m_log2Interpolation == 0)
     {
-        m_ofstream->write(reinterpret_cast<char*>(&(*beginRead)), chunkSize*sizeof(Sample));
+        m_interpolators.interpolate1(&beginRead, m_buf, 2*chunkSize);
+        m_ofstream->write(reinterpret_cast<char*>(m_buf), chunkSize*2*sizeof(int16_t));
+        feedSpectrum(m_buf, 2*chunkSize);
     }
     else
     {
@@ -209,5 +212,27 @@ void FileOutputWorker::callbackPart(SampleVector& data, unsigned int iBegin, uns
         }
 
         m_ofstream->write(reinterpret_cast<char*>(m_buf), chunkSize*(1<<m_log2Interpolation)*2*sizeof(int16_t));
+        feedSpectrum(m_buf, 2*chunkSize*(1<<m_log2Interpolation));
     }
 }
+
+void FileOutputWorker::feedSpectrum(int16_t *buf, unsigned int bufSize)
+{
+    if (!m_spectrumSink) {
+        return;
+    }
+
+    m_samplesVector.allocate(bufSize/2);
+    Sample16 *s16Buf = (Sample16*) buf;
+
+    std::transform(
+        s16Buf,
+        s16Buf + (bufSize/2),
+        m_samplesVector.m_vector.begin(),
+        [](Sample16 s) -> Sample {
+            return Sample{s.m_real, s.m_imag};
+        }
+    );
+
+    m_spectrumSink->feed(m_samplesVector.m_vector.begin(), m_samplesVector.m_vector.begin() + (bufSize/2), false);
+}
diff --git a/plugins/samplesink/fileoutput/fileoutputworker.h b/plugins/samplesink/fileoutput/fileoutputworker.h
index 44f44119c..45c6f7e3b 100644
--- a/plugins/samplesink/fileoutput/fileoutputworker.h
+++ b/plugins/samplesink/fileoutput/fileoutputworker.h
@@ -2,7 +2,7 @@
 // Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
 // written by Christian Daniel                                                   //
 // Copyright (C) 2014 John Greb <hexameron@spam.no>                              //
-// Copyright (C) 2015-2020 Edouard Griffiths, F4EXB <f4exb06@gmail.com>          //
+// Copyright (C) 2015-2026 Edouard Griffiths, F4EXB <f4exb06@gmail.com>          //
 //                                                                               //
 // 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          //
@@ -30,10 +30,12 @@
 #include <stdint.h>
 
 #include "dsp/interpolators.h"
+#include "util/incrementalvector.h"
 
 #define FILEOUTPUT_THROTTLE_MS 50
 
 class SampleSourceFifo;
+class BasebandSampleSink;
 
 class FileOutputWorker : public QObject {
 	Q_OBJECT
@@ -50,10 +52,18 @@ public:
 	bool isRunning() const { return m_running; }
     std::size_t getSamplesCount() const { return m_samplesCount; }
     void setSamplesCount(int samplesCount) { m_samplesCount = samplesCount; }
+	void setSpectrumSink(BasebandSampleSink *spectrumSink) { m_spectrumSink = spectrumSink; }
 
 	void connectTimer(const QTimer& timer);
 
 private:
+#pragma pack(push, 1)
+    struct Sample16
+    {
+        int16_t m_real;
+        int16_t m_imag;
+    };
+#pragma pack(pop)
 	volatile bool m_running;
 
 	std::ofstream* m_ofstream;
@@ -68,11 +78,14 @@ private:
     int m_maxThrottlems;
     QElapsedTimer m_elapsedTimer;
     bool m_throttleToggle;
+	BasebandSampleSink* m_spectrumSink;
+	IncrementalVector<Sample> m_samplesVector;
 
     Interpolators<qint16, SDR_TX_SAMP_SZ, 16> m_interpolators;
     int16_t *m_buf;
 
 	void callbackPart(SampleVector& data, unsigned int iBegin, unsigned int iEnd);
+	void feedSpectrum(int16_t *buf, unsigned int bufSize);
 
 private slots:
 	void tick();
diff --git a/plugins/samplesink/fileoutput/readme.md b/plugins/samplesink/fileoutput/readme.md
index 63007e351..2b5ddde62 100644
--- a/plugins/samplesink/fileoutput/readme.md
+++ b/plugins/samplesink/fileoutput/readme.md
@@ -22,6 +22,8 @@ The top and bottom bars of the device window are described [here](../../../sdrgu
 
 ![File output plugin GUI](../../../doc/img/FileOutput_plugin.png)
 
+Note: the associated spectrum in the independent spectrum window shows the baseband. The interpolated output that will go to the file appears in the attached spectrum view below the settings.
+
 <h3>1: Start/Stop</h3>
 
 Device start / stop button.