Reference : http://gnuradio.4.n7.nabble.com/USRP-transient-peak-from-lock-unlock-set-decim-freq-tt11240.html#a11243
Each time the daughterboard is re-tuned, there is a transient as the VCO settles. A smaller (and much shorter) transient is expected during rate changes as well due to different filters being switched in and out. It's best to throw away the first few samples after changing frequency or rate.
Most modern digital consumer-appliance tuners tend to mute the audio during re-tune, precisely because PLL settling takes a finite time, and typically produces glitches.
Any real communications system will necessarily have to "cope" with glitches on the channel. Very few RF channels are completely clean and free of RFI and other artifacts of nature.
Each time the daughterboard is re-tuned, there is a transient as the VCO settles. A smaller (and much shorter) transient is expected during rate changes as well due to different filters being switched in and out. It's best to throw away the first few samples after changing frequency or rate.
Most modern digital consumer-appliance tuners tend to mute the audio during re-tune, precisely because PLL settling takes a finite time, and typically produces glitches.
Any real communications system will necessarily have to "cope" with glitches on the channel. Very few RF channels are completely clean and free of RFI and other artifacts of nature.
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