sdrx:
Currently Sdrx is mainly a project intended for teaching my self the development of Software Defined Radio functions and Digital Signal Processing. I have built into sdrx an FFT-based Spectrum Display and de-modulators for Frequency Modulated and Amplitude Modulated radio transmissions, detectors for Single Sideband (USB/LSB) signals and for CW (Morse code) transmissions. Sdrx has controls for setting up RTL2832x-based SDR dongles via the librtlsdr, Mirics-based SDR dongles via the libmirisdrapi-rsp library and Perseus receivers via libperseus-sdr. These controls include the Tuner Center Frequency, RTL2832x Digital AGC, Tuner Gain Mode (Manual or Auto), Manual Tuner Gain Setting and Sampling Rate and Buffer Size for async streaming from the SDR dongle. Sdrx includes a Chebyshev Low Pass Filter which is used as the "roofing filter" of the sample stream from the SDR dongle and for the Low Pass filters needed by the Weaver SSB and CW de-modulator. Play Back of demodulated signals is via the computer's Sound Card and by using the ALSA sound system API.

As of version 0.9-beta, Sdrx includes functions for receiving and decoding Time Signal stations on VLF and Long Wave. Currently Sdrx can receive time and date data from MSF on 60kHz, RBU on 66.667kHz, DCF77 on 77.5kHz and TDF/Allouis on 162kHz. The detection of data bits and the synchronization signals is done by pattern matching rather than hard threshold-ing, so that Sdrx can successfully copy weak time station signals even well outside the official range. For example, the MSF signal on 60kHz can quite often be received and decoded even though it is about 3500km away! Development of time station receiving and decoding functions was done using a Perseus SDR receiver and a 1/4l GP antenna for the 30m amateur band (7.5m high).