It's likely that initialization of the board gain and frequency settings will take some finite but non-zero amount of time to settle. It's always a good idea to toss the first few samples until things settle down. The settling time will be different for each daughterboard and should be experimentally determined in your application.
--n On Tue, 2010-09-28 at 15:15 +0200, Patrik Eliardsson wrote: > Dear List, > > We have made a test program using a source and a file sink (see fg.jpg) where > we are receiving a fixed number of samples (with UHD and USRP2 and WBX-card) > from an AWGN-generator (constant power -19dB). If we plot the abs value of > the received signal we always see a "spike" in the 10 first samples (see > fig1) before the abs value settles to a more expected value. Sometimes > (seldom) there is no "spike" but the result is still not as expected, the > received data starts at a higher level and slopes down during a quite long > time before settling to a stable level (see fig 2). > > Have we missed something or why does this "spike" occur? Is there some > initialization time in the hardware that we need to take into consideration > before we start to receive samples (recv) after setting all parameters? > > Br, > Patrik > _______________________________________________ Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
