[USRP-users] Capturing signals at the carrier

Marcus D. Leech mleech at ripnet.com
Mon Sep 30 18:18:45 EDT 2013

On 09/30/2013 04:47 PM, Cochenour, Brandon M CIV NAWCAD, 4.5.6 wrote:
> After some further experimentation...I notice that not all carrier frequencies result in the DC component being removed.
> For example....using the N210 with WBX...
> At a 50 MHz carrier...I can modulate a single tone all the way down to about 200 Hz with no issue.  Between 100-200 Hz...I observe all sorts of weird harmonics.  At 100 Hz...everything is fine.  Between 1-100 Hz...strange harmonics. And then a 0 Hz...a clear spectral peak at DC.
> However at certain other frequencies....I'll get no DC through at all.
> I also note that it doesn't matter if I use the TX side of the WBX as my input...or if I try to tune an external source to get as close to the USRP LO as I can.  Some center frequencies work.  Others don't.
> There doesn't seem to be much rhyme or reason as to why certain frequencies work, and others don't.  Should there be?
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
The amount of DC offset and gain and IQ imbalance produced in the PLL is 
highly dependant on the tuned frequency.

Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20130930/3273ac16/attachment-0002.html>

More information about the USRP-users mailing list