Re: [Discuss-gnuradio] dboard lock detect bit?

[Brian Padalino]

On Sun, May 4, 2008 at 2:56 AM, George Nychis <address@hidden> wrote:
> Hi all,
>
>  I was wondering what the lock detect bit actually is:
>
> http://gnuradio.org/trac/browser/gnuradio/trunk/gr-usrp/src/db_flexrf.py#L133
>
>  In the C++ tuning code that I have, sometimes when trying to initialize the
> board, I find that the bit is 0, then I do what it does and try again, and I
> find it's still 9 and so I exit.  I often have to unplug the board to get it
> to unset.
>
>  What exactly is the bit?  I can obviously read the comment "the value of
> the VCO/PLL lock detect bit" ... but I don't understand exactly what that is
> :)

This is getting more onto the hardware side of things.  I am assuming
you're working with the 2.4GHz board, so the part you're interested in
is the ADF4360 Integrated Synthesizer and VCO.  The product
information page can be found here:

    http://www.analog.com/en/prod/0,,770_850_ADF4360%252D0,00.html

The lock bit just ensures that the PLL is, indeed, locked to the
desired frequency (within some tolerance).  If this bit is not set,
the transmit frequency cannot be guaranteed.

Reading that entire datasheet should help you understand how the
tuning of the RF front ends works.

Brian