Re: [Discuss-gnuradio] Channel Model omits first 3 samples

[Tom Rondeau]

On Tue, Jul 9, 2013 at 8:38 PM, Gregory Warnes <address@hidden> wrote:
> Hi All,
>
> I've been working on calculating BER for simulated transmitter/recieved pair
> and have noticed that the channel_model eats the first 3 samples.  Thus to
> correctly align the data input and output from channel_model (e.g. for
> calculating BER), it is necessary to account for the 3-sample offset.
>
> Perhaps it would be worth adding a note to this effect to the channel_model
> documentation.
>
> -Greg

It's not that the channel model 'eat's 3 samples. This is group delay
of your filters that you're seeing. The transmitter, receiver, and
channel model may all have filters in them and each has a group delay.
You always have to adjust for this. Not sure we can put it into the
documentation except to say that you need to calculate the total group
delay of your system if you want to align the data.

Tom