XDR-GTK v0.2

Changelog:

• user settings
• calibrated signal meter
• rewritten spectral scanning
• antenna pattern plotting
• frequency presets
• sound volume control
• antenna switching
• network connection
• improved look (Windows)
• new GTK+ libraries (Windows)
• rewritten serial port handling (Windows)
• other bug-fixes / improvements

Upload the latest XDR-I2C using Arduino IDE to your Seeeduino board. Antenna input alignment function is now divided into a separate file (align.ino), so don’t forget to update it with your own values. The network connection requires a dedicated server. I’m working on a Linux version, but final version is not available at the moment. Antenna switching is one of the features requested by users. An external RF switch is required. I haven’t built one myself. Petr Vozár uses four antennas and Mike Fallon uses two antennas. Check the Modified tuners page for more info.

The antenna pattern plotting function requires a rotator (full 360°). For best results (i.e. a linear response) a signal attenuator between XDR and antenna may be necessary to keep the signal below 60 dBf.

Many thanks to Przemysław Korpas (SQ7JHV) from Warsaw University of Technology for help with signal meter calibration using a professional signal generator. I compared two XDR tuners and they seem to give very close results. Maximum signal strength reported by XDR is around -36dBm or 84 dBf /75Ω/ (known previously as 102 dB value). For valid signal level set AGC threshold to highest, turn off RF and IF +6dB gain and make sure that antenna input is properly aligned. For local stations with very high signals over 80 dBf use an attenuator.

For more info, source code and download see: XDR-GTK