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Discussion Groups | Comp.DSP | is there easy way to know which decimation phase got selected?

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is there easy way to know which decimation phase got selected? - bharat pathak - 2010-09-30 09:45:00

Assume that i am doing decimation by 64, first by filtering and
then throwing. This is implemented the same way in RTL and C.

But there might be a data shift in input. Maybe one more or one less.
This would essentially be same as selecting a different phase of the
filter. Assuming that the input I feed is sine wave, is there a
way to know which phase got selected? Observability points are only
outputs.

-Bharat

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Re: is there easy way to know which decimation phase got selected? - Dirk Bell - 2010-09-30 11:08:00

On Sep 30, 9:45=A0am, "bharat pathak" <bharat@n_o_s_p_a_m.arithos.com>
wrote:
> Assume that i am doing decimation by 64, first by filtering and
> then throwing. This is implemented the same way in RTL and C.
>
> But there might be a data shift in input. Maybe one more or one less.
> This would essentially be same as selecting a different phase of the
> filter. Assuming that the input I feed is sine wave, is there a
> way to know which phase got selected? Observability points are only
> outputs.
>
> -Bharat

A data shift:

1) from the beginning?  OR
2) dropping or repeating a sample after the filtering has started? OR
3) dropping or repeating a sample  after the transient has died out?

Would this happen once or multiple times?

Dirk