Yesterday i used my HiQSDR frontend for transmitting a shortwave radio signal in digital DRM standard.
I had to use the FPGA firmware version 1.2 which contains enhanced filters that allow modulation of signals with a bandwidth of up to 22kHz in IQ mode (+-11kHz around the tuning frequency).
Stefan, DL2STG, did a great job creating support for the HiQSDR within the Gnuradio project. After noticing a IQ swap the 64QAM DRM signal was decodable. See the constellation diagram below.
Recently Jim, N2ADR released a new version of his FPGA code for the HiQSDR/N2ADR frontend. This brings improved TX filters that should now also support FM and DRM TX. Stefan, DL2STG ported his HiQScope extension to the new Verilog code. This made me want to give it a try. It is really impressive how this makes the HiQSDR a 60MHz Bandwidth spectrum analyzer with waterfall functionality. And it can run in parallel to the regular transceiver application.
The screenshots below show the unfiltered spectrum from a short mobile shortwave antenna. The big signals above 16MHz are images of the extreme strong FM radio stations that i have here. Below the shortwave radio bands can be seen.
during weekend i took a screenshot of the TX signal quality of my HiQSDR PCB. As example i put the IMD spectrum for 10m here.
Looks quite nice, doesn´t it ? Its the DAC signal amplified by MMIC. I think it was around 6dBm output power.
I tried QtRadio + the gHPSDR-server which now also supports the HiQSDR frontend. The server runs on the PC connected to the frontend. The QtRadio application can run on another PC and can also be connected via Internet. The server supports Softrock radios and the Perseus as well. TX support is in progress. It is also possible to share your radio with others this way.
The following video shows a reception test of a shortwave DRM station using the direct sampling frontend designed by N2ADR. The SDR software Quisk allows for adjustable filter bandwidth up to 21kHz from version 3.5.2.
The soundcard output was fed into another PC’s soundcard. There DREAM DRM software decoder was running.
DRM reception with N2ADR frontend and Quisk 3.5.2 and DREAM