Re: [Discuss-gnuradio] xlating filter will introduce phase shift

[Tom Rondeau]

On Fri, Aug 12, 2011 at 3:50 AM, Page Jack <address@hidden> wrote:
> I use xlating filter to down convert signal. after I down convert signal it
> I decode it.
> however the data decoded is still the signal in 0 frequency before down
> convert.
> I check the xlating filter code it will change the signal phase to avoid
> aliasing, yeah
> it avoid aliasing but it is not the data I want how can I recover the data's
> phase after
> xlating filter?
>
> Regards!

Those filters are implemented as FIRs, which means they will have
linear phase in the passband and constant (and known) group delay.

In general, though, you will never know the phase of the incoming
signal received over the air. If you have a signal where you require
the phase, you'll have to figure out a way to recover it, anyways.

Tom