DBSRX

No Mars Express experiment this time

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It was a difficult decision to accept, but the Mars Express experiment with the USRP and GNU Radio is not going to happen this time! It’s a shame because the link budget looked quite promising. An optimistic estimate gives almost 20 dB signal to noise ratio, which is more than we need, so the problem … Read more

Aiming for planetary science with GNU Radio and the USRP

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Thanks to the European Space Agency (ESA) and the Mars Express mission, we might have an opportunity just around the corner for doing big science with GNU Radio and the USRP!

On March 3, 2010, Mars Express will visit the Martian moon Phobos by performing a close flyby. According to ESA, the ESOC ops team is working with a number of possible scenarios, including one that would take the spacecraft to just 50 km above Phobos. At that distance the orbit of the spacecraft is expected to be influenced by the gravitational pull of Phobos. I knew this already for about a week when I first read it on the Mars Express Blog but it was first today that I realized the opportunities this event offers.

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Portable S-band Ground Station Update

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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.

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New vLog: Introducing the S-band Ground Station Project for LRO/LCROSS Reception

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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