I'm not an expert on the matter, but I suspect that the XCVR2450 board requires some sort of command to select the 5GHz band, which would need to be implemented in the sounder's FPGA code. At a chip rate of 32MHz, you have a resolution of 3e8/32e6 meters. The length of the PN sequence determines the maximum unambiguous distance at which multipaths can be detected. So with a degree-12 sequence, you have (2^12 - 1)*3e8 meters to work with. With long sequences, however, you are limited by the capabilities of the USRP. Depending on your DBoard, you have ~20mW of output. Your antenna also makes a big difference. Especially if you want to do any work outside, I would use something like a log-periodic antenna. If you can get your hands on an amplifier, you can significantly boost your range. In my experience (with a sounder of my own design), averaging multiple IR's appreciably reduces the noise.
While I'm at it, can anyone explain why a complex correlation vector is coming out of the sounder FPGA? Doesn't a mathematical correlation return real values? Jordan On Fri, Jul 10, 2009 at 5:49 AM, Martin Braun <br...@int.uni-karlsruhe.de>wrote: > Hi, > > I was wondering if there's a way to use the channel sounder (gr-sounder) > with the XCVR d'boards at 5 GHz. I gave it a try, but the channel > impulse responses only popped up +-1s and zeros. Well, I wasn't > expecting it to work since the XCVR is not mentioned in the README, but > can it be tweaked? > > Plus, does anyone have any experience with the sounder they'd share? > If so, there's a couple of things I'd be interested to know: > > - What's a sensible distance for getting useful results without any > additional hardware? > - Can I tune the amp/gain settings to increase my SNR without distorting > the result? > - Assume the channel's stationary. In that case, every IR vector > should contain the same data (up to some phase shift, probably). I'm > figuring I could further increase the SNR by averaging > (phase-correctly) over several IRs, right? > > If anyone has any interesting stories on channel sounding with GR/USRP, > I'd be grateful for any info. > > Cheers, > MB > > -- > Dipl.-Ing. Martin Braun Phone: +49-(0)721-608 3790 > Institut fuer Nachrichtentechnik Fax: +49-(0)721-608 6071 > Universitaet Karlsruhe (TH) http://www.int.uni-karlsruhe.de/ > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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