What is the LO Offset?

GNU Radio
1

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?

Thanks in advance!

-Michael

2

On 07/08/2012 08:52 AM, Michael H. wrote:

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

3

Ah that makes sense!

Thanks guys!

-Michael