WHY G90 – PC Control, Waterfall and DSP Tool for the Xiegu G90

WHY G90 is currently an early Beta version.

The program is under active development and should be seen as an experimental ham-radio project rather than finished software. The goal is to provide a useful PC-side operating aid with audio spectrum display, waterfall, CAT control, DSP audio tools, CW support, recording and firmware-update helper functions.

The program does not replace the G90 front panel, and it is not the same type of interface as the Xiegu GSOC. WHY G90 uses normal PC audio input and the standard G90 CAT/CI-V serial interface.

An early Beta: 

why-g90-beta-2.zip

 

Main Purpose

WHY G90 is intended to make operation of the Xiegu G90 more visual and convenient from a Windows PC.

It provides a larger audio spectrum and waterfall display, basic CAT control, audio monitoring, recording, CW tools and a clearer desktop interface for some common operating tasks.

The program is especially useful as a visual audio companion when using the G90 with an external sound card, headphone output, line output or a DE-19/CE-19 style interface.

Important Technical Note

The spectrum and waterfall in WHY G90 are based on the received audio signal, not on a true RF/IQ spectrum from the radio.

This means:

  • The waterfall shows audio frequency content from the selected Windows audio input.
  • The displayed radio frequency is the G90 VFO/dial frequency.
  • Clicking in the waterfall moves the radio VFO by the audio-frequency difference, so the selected signal is moved to the wanted audio tone.
  • The waterfall should not be interpreted as a full RF spectrum around the VFO unless a suitable I/Q source is used.

This is different from a true SDR panadapter or the Xiegu GSOC concept.

Spectrum Display

The program includes a real-time FFT spectrum display based on the selected PC audio input.

Features include:

  • Real-time audio spectrum display
  • Audio-frequency scale
  • Click tuning support
  • Marker display
  • Zoom modes
  • Peak detection
  • Auto peak function
  • Find next signal function

The display is intended as an operating aid for visually locating signals in the received audio passband.

Waterfall Display

WHY G90 includes a WSJT-style waterfall display. The waterfall gives a visual overview of received audio signals over time.

Waterfall functions include:

  • Real-time scrolling waterfall
  • Adjustable waterfall gain
  • Automatic level handling
  • WSJT-like colour palette
  • Signal marker overlay
  • Zoom support
  • Wide audio display span

The program currently uses a 48 kHz audio sample rate. Depending on the audio source, this gives a wide audio view, but it is still an audio-domain display.

Audio Input and Monitor

The program can select the wanted Windows audio input device directly from the GUI.

Audio functions include:

  • Audio device selection
  • Input level meter
  • Clipping indication
  • Audio monitor function
  • Adjustable monitor gain
  • Simple DSP noise reduction
  • Recording to WAV file

The input meter helps avoid too low audio level or clipping. This is especially important when using the G90 headphone output, since the level is affected by the radio volume setting.

A cleaner and more stable audio connection is expected when using a DE-19/CE-19 style interface.

Filter Display

WHY G90 includes a graphical filter display.

At the moment the program treats the G90 radio filter as read-only. The program reads the G90 IF filter bandwidth using the documented CAT command 1A 03 and displays the reported bandwidth as a B-value, for example:

  • B50
  • B100
  • B300
  • B500
  • B2700
  • B3000

For CW, the G90 normally reports B500 in the tested setup. The program therefore displays the radio filter as B500 and draws a local audio representation around the selected CW audio tone.

The G90 front panel allows lower and upper filter edge adjustment, but these lower/upper edge values have not been found to be readable or writable through the normal G90 CAT interface in the current tests. Therefore WHY G90 does not claim to control the G90 F-L/F-H filter edges from the PC.

CW Decoder Support

WHY G90 includes an experimental built-in CW decoder.

CW functions include:

  • Selectable CW audio tone
  • CW signal locking
  • CW text display
  • Clear CW text button
  • Peak-assisted CW signal selection
  • Narrowband DSP support

The CW decoder is intended as an aid, not as a guaranteed decoder. Performance depends heavily on audio quality, signal-to-noise ratio, correct tuning, keying quality and input level.

At this stage the CW decoder should be considered experimental.

Frequency Display and Click Tuning

The main frequency display shows the current G90 VFO/dial frequency.

The waterfall itself is audio-based. When clicking on a signal in the waterfall, the program calculates the audio-frequency difference between the clicked signal and the wanted target tone, then moves the G90 VFO accordingly.

In practical terms:

  • The G90 frequency display remains the radio VFO frequency.
  • The waterfall shows audio frequency.
  • Click tuning moves the radio so the selected signal lands near the selected audio tone.

This is the most honest model when using normal audio from the G90.

CAT Control for Xiegu G90

WHY G90 uses the G90 CI-V compatible CAT interface.

Currently working or partly working CAT functions include:

  • Connect/disconnect to the G90
  • Read active VFO frequency
  • Read active operating mode
  • Set active VFO frequency
  • Read S-meter
  • Read configured TX power setting
  • Read IF filter bandwidth
  • Start ATU tuning
  • Firmware update helper, using an external updater tool

Known CAT limitations found during testing:

  • Live TX power could not be read reliably through normal CAT.
  • Live SWR could not be read reliably through normal CAT.
  • Radio supply voltage did not behave as a useful dynamic CAT value in the tested setup.
  • During TX the G90 may stop responding to normal CAT polling.
  • CW filter lower/upper edge control was not found through the tested CAT commands.
  • The program therefore avoids pretending that unavailable CAT values are real live radio measurements.

The status line and meter display should therefore be interpreted carefully. S-meter and VFO/mode readback are useful. TX power is shown only as configured/selected power when available, not as measured RF output power.

G90 Meter Display

The right-hand meter panel is mainly intended to show radio-related information in a visual form.

Currently:

  • S-meter is read from the radio in RX.
  • Configured TX power may be shown during TX as PSET.
  • SWR is not shown as a live CAT value.
  • VCC is not shown unless a reliable dynamic readout is found.

This avoids displaying misleading fixed or fake values.

ATU Control

The program includes an ATU Tune button for the Xiegu G90 internal antenna tuner.

The intended sequence is:

  1. Enable the internal ATU.
  2. Start automatic tuning.
  3. Temporarily pause normal CAT polling while tuning is running.
  4. Resume normal CAT polling afterwards.

The program does not currently try to read live power or SWR during the tuning process, because the tested CAT interface does not provide reliable live TX meter data.

Firmware Update Support

WHY G90 includes a firmware update helper intended to start the external G90 firmware update tool from the program folder.

The firmware update helper is designed to:

  • Check that the updater executable exists
  • Let the user select a firmware file
  • Show a clear warning before starting
  • Close the CAT port before firmware update
  • Show update log output in a separate window

This function should be used with care and only with the correct firmware file for the correct G90 unit.

Recording

WHY G90 can record received audio to WAV files.

Recording functions include:

  • Start/stop recording
  • Automatic filename with frequency and timestamp
  • Recordings saved in a local recordings folder

This is useful for later analysis, CW practice, signal comparison or documentation.

Noise Reduction

A simple DSP noise reduction function is included.

Noise reduction settings include:

  • NR OFF / ON
  • Mild / Normal / Aggressive style settings
  • Reset of noise estimate when settings are changed

This is intended as a practical listening aid rather than a replacement for the radio’s own DSP functions.

Band Presets

The program includes band presets for quick operation on common amateur bands.

The selected band updates local frequency handling and can also be used with CAT frequency control when the G90 is connected.

Current Beta Status

This is an early Beta version.

Currently useful/tested areas include:

  • Audio input selection
  • Spectrum display
  • Audio waterfall display
  • Input level meter
  • Recording
  • Monitor audio
  • Simple DSP noise reduction
  • Basic CAT connection
  • G90 frequency read/write
  • G90 mode readback
  • G90 S-meter readback
  • G90 ATU start command
  • G90 IF bandwidth readback
  • Firmware update helper

Known limitations:

  • The waterfall is audio-based, not true RF/IQ unless a suitable I/Q source is used.
  • Live PWR/SWR via normal CAT has not been found to work reliably.
  • G90 CAT may become silent during TX.
  • VCC readout is currently disabled because it was not useful as a dynamic value.
  • G90 CW F-L/F-H filter edge control is not currently available through the tested CAT commands.
  • CW decoding is experimental and depends strongly on audio quality and tuning.

Planned Improvements

Planned development includes:

  • Cleaner DE-19/CE-19 audio support
  • Better audio calibration and level handling
  • Improved click tuning behaviour
  • More robust CAT logging
  • Cleaner separation between radio CAT values and local DSP values
  • Improved CW decoder performance
  • Better documentation
  • More robust error handling
  • Optional debug tools for CAT command testing

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