Re: [Discuss-gnuradio] Optimum decimation for maximizing dynamic range

[Matt Ettus]

Yes, you are thinking about it correctly.  You should decimate as
little as possible in hardware, and do the rest in software in
floating point.

Matt

On Thu, Jul 16, 2015 at 10:44 AM, madengr <address@hidden> wrote:
> Is there an optimum hardware decimation to maximize receiver dynamic range?
>
> For example, if I have an X310 at 200 Msps with 14 bit ADC receiving a low
> frequency tone (LFRX board), those samples are truncated to 16 bits prior to
> Ethernet.  If I'm decimating by 800 (from 200 Msps to 250 ksps) in the
> hardware, then I have gained an ~5 additional bits for a total of 19 ENOB.
> Thus I lose 3 bits from the truncation.
>
> If I hardware decimate by 16 (from 200 Msps to 12.5 Msps) then I have gained
> just 2 bits for a total of 16 ENOB.  I could then decimate to 250 ksps in GR
> where it's floating point, and possibly preserve the full 19 ENOB.
>
> Am I thinking this out correctly, or is it not worth the trouble?  I assume
> the 32-bit floating point decimation in GR will have the range to preserve
> 19 ENOB?
>
> Thanks,
> Lou
>
>
>
>
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