[USRP-users] Extended multipath (10 ms) at an indoor environment.

Ian Song ajsongs at gmail.com
Thu Apr 25 11:39:08 EDT 2013


I used USRPB100+WBX daughter board to transmit linear modulated frequency
(LFM) signals at the center frequency fc (fc=80 or fc=83 MHz). The LFM
signal sweeps from fc-16 kHz to fc+16 kHz in 0.05 or 0.5 s. The other
USRPB100 +WBX daughter board did the reception. The two devices were placed
in a large room, separated by variable distances (20 cm to a couple of
meters). I also changed the gain in both the source and the receiver
(varying gain from -5 to 20 dB for both).

Then I examined the received LFM signals through matched-filtering
operations. The part that I do not understand that the calculated impulse
responses also had extended multipath. I can see four or five strong
multipaths, always with one dominating path. The channel time span was 10
ms. To me, it seems impossible to have such a long mutlipath. Can everyone
explain the long delayed multipath? Is it real or due to the device
distortion? Any suggestions?


Many thanks,


Ian
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