Re: [Discuss-gnuradio] can our USRP do this? --Help really needed from fellows gnuradioers :)

[Dominik Auras]

Hi!

If you experience strong distortions in your signal, then this could be
related to the cic interpolator and decimator in the usrp. I am
transmitting ofdm signals. When those signals occupy the whole sample
bandwidth, or a greater part of it, the frequency band at the border is
greatly attenuated. Especially when the complete bandwidth is used (i.e.
in your case 8 Mhz), the received signal looks similar to a gaussian
distribution.

At the moment, I bypass this problem by using filters on transmission
and receiving side. They interpolate/decimate by a constant factor, for
example 2x. The data rate sent to usrp is therefore doubled.

To test the filter and run some experiments, I have modified usrp_fft.py
and usrp_siggen.py. Maybe you want to have a look at these.

My hardware are two usrp's, revision 4.2, with Flex2400 daughterboard
installed.

Greetings
Dominik

patch_usrp_utils.tar.gz
Description: application/compressed-tar