I've been working on a system for observing cosmic radio noise, over a broad beamwidth, at the low-end of VHF (around 30-40MHz), using a USRP2 and a BASIC_RX. The application measures RMS power over a small bandwidth (between 100KHz and 750KHz, depending on user input).
Yesterday, I discovered that I at some point blew up one of more of my mini-circuits ZFL-500 amplifiers, so while I'm waiting for replacements, I thought I'd do a quick experiment. I plugged the crossed-dipole antenna directly into the USRP2, with a 5th-order Butterworth low-pass filter with a corner frequency of 48MHz between the antenna and the USRP2. I fully expected to get *nothing* when I plugged in the antenna, or perhaps a minor increase in output. But, quite the contrary, plugging in the antenna produced a roughly 15dB increase in detected power across a 250KHz selected bandwidth. So, I thought that the BASIC_RX had *zero* gain, but I'm surprised that the A/D in the USRP2 is sensitive enough to plug directly into a low-VHF antenna without any gain. Does this match other peoples observations of the Basic_RX? Have people been able to use the Basic_RX as an HF/low-VHF receiver with no gain at all? -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
