[Hackrf-dev] Sensitivity

[McDonald, J Douglas]

I have not measured numerically the sensitivity of these tyoe devices, but
have comapred them.  In actual use the seinsitivity of the HackRF and 
the RTL dongles are similar, using both SDR$ and Gnuradio. 

Both devices are limited by a too-low number of digitized bits. 
It is extremely important that the gains be set correctly. You have to
have the HackRF's multiple gains split correctly or it can limit even in an
early stage, resulting in all sorts of image problems, etc. 

Try experimenting with widely varying signal levels and gain settings. 

I find that for signals well prefiltered performance is extremely similar,
but if not, the HackRF is  vastly (no exaggeration) inferior. Note that
"well" implies really great rejection of unwanted signals from 0.3
to 10,000 Mhz. I have no idea what is happening above the
max frequency spec of either, but for HackRF I suspect the
worst in terms of intermodulation problems. Computers with the current rage RF networking 
running can seriously overload these gizmos. So use prefilters and
be SURE that they are rejecting all the microwave stuff you are 
actually using. Test them. If you are working below a GHz, your filter
may not be killing enough up in the upper reaches.




Doug McDonald