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Ralph A. Schmid, dk5ras ralph at schmid.xxxHi, > Note that the USRP1-WBX combination does not support LO offset or IQ > imbalance compensation; those factors will be your largest source of overall > signal distortion. In regards to the harmonic distortion, it seems that the > concern is over spurious free dynamic range (SFDR) of front end > components, which is more of an issue of wideband RF design than SDR in > general. Similar issues can exist in any wireless system - SDR or not. Yes, sure, this is normal behavior. > I will certainly not deny that spurious signals exist in USRP-type boards or that > passband filters are used in commercial products. My only issue is the claim > that a narrow tuning range limited by front end filters is a mandatory > requirement for suitable spectrum compliance. A huge number of frequency I see more problems in the receiver stages, and there parameters are also mandatory during compliance tests. > bands is required by current and future wireless services and attaching a > fixed RF filter for every individual band in use is not a sustainable approach. > There has been a very significant amount of development in flexible RF > design over the past decade in order to address these issues, which I do not > think should be ignored. Of course, this is true, but do not forget the strong signals that come backwards, from other transmitters at a populated antenna site. Those can do nasty things in the PAs, so some filters and isolators can hardly be eliminated. A high power wideband system out in the wild is another beast than hooked to your lab setup. > -TT Ralph.