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
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