spectrogram for viewing frequency-shift keyed (FSK) signals in real time


FSKview is a high-resolution spectrogram for viewing narrowband frequency-shift keyed (FSK) signals in real time. FSKview can be used as a QRSS viewer, and if WSJT-X is running FSKview can label WSPR spots directly on the spectrogram as they are decoded.


💡 Feature requests and bug reports are welcome on the FSKview issues page.

Latest Version

If FSKview fails to launch, ensure you have the .NET Framework runtime 4.7.2 or newer

All Versions

  • FSKview-1.1.7.zip
    • Improved spectral AGC
    • Added option to customize AGC power
  • FSKview-1.1.6.zip
    • Improved spectral AGC symmetry
  • FSKview-1.1.5.zip
    • Added experimental spectral normalization AGC option
    • FT4/FT8 dial frequencies are now hidden by default
  • FSKview-1.1.4.zip
    • FT4/FT8 spot labels are now placed directly on the spot
  • FSKview-1.1.3.zip
    • FT4/FT8 spots now display full message
  • FSKview-1.1.2.zip
    • additional options for vertical compression
  • FSKview-1.1.0.zip
    • corrected 160m WSPR dial frequency
  • FSKview-1.0.10.zip
    • improved alignment for FT4/FT8 spots
    • improved support for systems where language settings do not treat a period as decimal separator
  • FSKview-1.0.9.zip
    • improved frequency labeling of FT4/FT8 spots WSJT-X logs
  • FSKview-1.0.8.zip
    • added support for WSJT-X logs containing FT4/FT8 spots
    • improved parsing of WSPR logs from different programs
    • fix bug introduced in 1.0.7 that truncated 7-character callsigns
    • log parsing errors fail silently (rather than launching an error message)
  • FSKview-1.0.7.zip
    • support multiple WSPR log formats (classical WSPR, WSJT-X 2.1.2, and WSJT-X 2.2.2)
    • recall brightness on startup
  • FSKview-1.0.6.zip
    • saved images now display 1-minute time ticks
    • updated 80m WSPR dial frequency
    • improved FTP test dialogue
  • FSKview-1.0.5c.zip
    • Spectrogram width and saved image height is customizable
    • Integrated FTP uploader
    • All settings persist through program restarts
    • Images saved to the grabs-all folder no longer have a scale bar (useful for stitching)
    • Display now has a "scroll" option as an alternative to the scroll/wipe behavior
    • Only in-band WSPR spots are shown (useful if frequency hopping)
    • Frequency offset adjustment for fine-tuning calibration
  • FSKview-1.0.4c.zip
    • Increased autosave image resolution from 930x670 to 1130x914
  • FSKview-1.0.4b.zip
    • More informative error messages
    • Improved support for FTP server address
    • Added .jpg to default list of images files (previously only .jpeg)
  • FSKview-1.0.4.zip
    • New option to customize autosave filename
    • Remove seconds from UTC timestamp on saved grabs
  • FSKview-1.0.3.zip
    • Improved time alignment
    • FTP Uploader produces quieter error messages
  • FSKview-1.0.2.zip
    • Fixed bug that stopped Spectrogram when switching audio devices
  • FSKview-1.0.1.zip
    • Improved colormaps
  • FSKview-1.0.0.zip
    • Initial release

Configure as a QRSS Grabber

FSKview can serve as a QRSS grabber, saving the latest grab every 10 minutes. Saved images are stamped with the date, time, and station information, and can be automatically uploaded to a web server using FTP. The settings button on the main screen launches an extended settings window, allowing the user to customize settings useful for fine-tuning behavior of a QRSS grabber.

QRSS and WSPR Example

This video shows my system listening to the 30m WSPR band over a 24 hour period. I don't have a great antenna, but it gets the job done well enough to demonstrate how this software works. The task manager is left open so you can see FSKview is not particularly resource intensive.

Why Viridis is Superior to Other Colormaps

Viridis is a carefully-designed colormap specifically created to maximize human perception while visualizing scientific data. Unlike many common colormaps, Viridis demonstrates a smooth increase in perceived visual intensity from low values through high values (it is perceptually uniform) and it uses intentionally-chosen color palette desined to maximize human perception (even in colorblind individuals). For these reasons, Viridis is the default colormap used for visualizing spectrograms in FSKview.

Source Code

This software is open-source on GitHub:

Linux Support

FSKview seeks to be a simple click-to-run spectrogram similar to Argo, but open-source and developed using modern programming techniques. FSKview uses Windows-specific code to interact with audio hardware and it does not support Linux. Excellent QRSS spectrogram software exists for Linux, including LOPORA, QRSSpig, and Baudline.