Re: [Discuss-gnuradio] USRP DDC usage

[Achilleas Anastasopoulos]

Dear all,

although I agree that in the SPECIAL case when the CORDIC
frequency is set to 0 it is meaningful to assume a known
phase (set to 0 at power up or otherwise set externally to 0),
I think it is a bad engineering practice to design receivers that assume 
a known phase (ie, a coherent operation) when the CORDIC frequency is 
NON-ZERO. I wonder if you share this reservation with me.

Achilleas

Matt Ettus wrote:
> > Even if you set the frequency to 0, there is a "random" initial phase
> > that is unknown, and thus you cannot separate the two channels.
>
>
> The initial phase is always 0 at power up.  If you never set the
> frequency to something other than 0, it will always stay that way.  Its
> a simple change to make the phase go back to zero.  Patches welcome...
>
> Matt