On 22/10/11 10:56 PM, Bonee Soibam wrote: > Hi Marcus , > Sorry i did not explain to you my set-up , i have two usrpn200's with > RX2400 as the daughterboards . i have omnidirectional antennas . Its a > line of sight experiment . i used .benchmark_tx.py -f 2475M -m bpsk > --from-file=test.pdf -S 2 -s 50 --tx-amplitude=0.25 -v > and on the receiver side i ran ./uhd_fft.py and ./rx_ascii_art_dft.py . > the problem i get in uhd_fft.py is that , as i vary the transmit > powers from 0.25 to 0.85 , i am getting -20 dB constant peak at a > fixed distance . logically it should increase as you said but i am > getting constant received values . My suspicion, having not looked at the code, is that the magnitude of the signals arriving at the "amp" block in that flow-graph are already sufficiently larger than "1", that you're seeing clipping somewhere in the chain.
> > Please tell me what to do next . i read on your site that , you can > measure analog RSSI measurements using read_aux_adc(side,0) . > Can you explain a little bit on which file it is referring too . looks > like the repository has moved too so i am unable to find which app it > is referring to . > Eagerly anticipating your reply > Bonee > > o <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> > > You *could* read the RX-side aux_adc, but it would give you mis-leading results, since the power-detector is showing you the power across the entire post-mixer bandwidth. It really, really is better to calculate the RSSI from the incoming data, and since you'd have to modify your application anyway to read the aux_adc, you might as well add a couple of blocks to calculate received power properly. Also, not all cards *have* an RSSI detector available in hardware, so assuming that they do is non-portable to other types of cards. -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
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