Hi,
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.