Re: [Discuss-gnuradio] What is the LO Offset?

[Josh Blum]

On 07/08/2012 08:52 AM, Michael Hill wrote:
> Hi All,
> 
> I've toyed around a fair bit with the UHD_sink parameters for the target
> Centre Frequency, and in particular using the request command to set the
> centre freq and the LO Offset.
> But i can't seem to see any impact from the LO offset!
> 
> E.g.
> IF = 5 MHz
> Target RF = 100MHz
> LO thus would equal 95MHz.
> 
> But if I want to get a target RF of 100MHz with an LO of 105MHz.. how do I
> do this?
> Is the LO offset = 5 MHz, or do I state 105MHz?
> 

You can read more here:
http://files.ettus.com/uhd_docs/manual/html/general.html#tuning-notes
http://files.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__request__t.html

Be careful, XCVR2450 has a shared LO. If you have a source and sink
block, the tune from one block can "stomp" on the other.

Also:
http://files.ettus.com/uhd_docs/manual/html/dboards.html#xcvr-2450

-josh