Amateur radio, space technology and other geeky stuff by Alexandru Csete
This video shows my first on-the-air tests with the WBX transceiver using the USRP (Universal Software Radio Peripheral) and GNU Radio.
The receiver was tested using wide band FM broadcast, APT signal from NOAA 17 satellite and Copenhagen VOLMET. I have also performed some tests using DVB-T signal and wireless sensor signals but I wanted to keep the video short so these were not included. I can post them in separate videos if there is interest.
I have been quite busy during the last weeks doing overtime at work, nonetheless, I have managed to carry out some small on the air tests of my newly acquired WBX transceiver boards for the USRP and GNU Radio. Tonight, I tuned in to Copenhagen VOLMET that transmits AM on 127.000 MHz.
I had a few hours to spare tonight and I decided to do a quick check of the WBX receiver. Didn’t have time for much so I just compared it to the TVRX tuner using a strong FM broadcast station. The software was a simple WFM receiver constructed in the GNU Radio Companion graphical editor. … Read more
Tonight I have been testing some ham radio transceiver code written in Python/GNU Radio. It is some student project published on SourceForge. You can find the code on the project page at Sourceforge: http://sourceforge.net/projects/sdr.
This page provides an overview of the various projects and experiments I am or have been doing with GNU Radio and the Universal Software Radio Peripheral (USRP). GNU Radio is a free, open source software development toolkit that provides the signal processing runtime and processing blocks to implement software defined radio. The USRP provides a … Read more
I made good progress with the portable S-band ground station this week.
I took the receiver to the OZ7SAT lab to measure its performance. Using the USRP+DBSRX and no LNA we could easily detect a -132 dBm CW signal with modest FFT integration (fraction of a second) in a GNU Radio spectrum scope. Using the LNA we could go down to about -138 dBm, i.e. an improvement in SNR of 6 dB. These figures were measured at an SNR ~5 dB. This is excellent, but please note that this is not real “sensitivity” in the traditional sense because we were not demodulating or decoding the signal. We were simply integrating the spectrum for a fraction of a second to detect the presence of the signal. The measurements were done by sampling a 250 kHz wide spectrum.
In this new video blog I am introducing a new project that has kept me occupied for a few weeks now: A low cost S-band ground station for receiving signals from NASA’s lunar spacecrafts LRO and LCROSS. More info at Receiving LRO and LCROSS. Based on the Universal Software Radio Peripheral (USRP) with DBSRX daughterboard, … Read more