[USRP-users] Question about LO Locked

Ian Buckley ianb at ionconcepts.com
Fri Apr 10 13:09:29 EDT 2015


Frank,
The way N2x0 works is that it has an internal 10MHz TCXO which is used as the default 10MHz reference w.r.t the downstream PLL/100MHz VCXO. When you connect an external 10MHz reference (or an internal GPSDO, or a MIMO cable) this replaces the internal 10MHz as the source of the reference. As Martin indicates the LOCK indication comes from the PLL that all possible reference sources drive.

-Ian

On Apr 10, 2015, at 9:26 AM, "Wallace, Frank L CIV NSWCDD, Q41 via USRP-users" <usrp-users at lists.ettus.com> wrote:

> I have two N210 radios connected with the MIMO cable.  On the master  radio, I told it to use an external reference source.  I have the slave using the MIMO reference.
> This worked well until one day I forgot to turn on the 10 MHz external reference and didn't notice.  The "Ref Locked" sensor still reported true even though there was no signal on the input.  What is the "Ref Locked" supposed to tell me.  I thought it would tell me when it doesn't have an external reference.
> 
> Thanks,
> Frank
> 
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