[Ground-station] 0 dBFS conventions?

[Stephen Hicks, N5AC]

At FlexRadio we use 0dBFS := sqrt (i^2+q^2) = max number space.  So for a
16-bit ADC, this would be sqrt(i^2) or sqrt(q^2) which is i or q at max
numerical value which would be 32767 for a converter in signed mode (most
converters can output in different number spaces).  I believe this comes
out to the same definition as Ettus.

When we convert to float in baseband, this value is assigned to 1.0F.
Google just told that this value is also 17.222C as I was typing, but I'm
pretty sure Google is wrong :-)

Steve

On Mon, Jul 9, 2018 at 06:46 Ground-Station
<ground-station at lists.openresearch.institute> wrote:

> Yes, full power in both I and Q. I assume the thinking was that the
> highest power single tone that can be represented was the most relevant
> full scale definition. A square wave is an interesting alternative since it
> (and any summation of sub tones) are the only higher power signals that
> don't encounter distortion.
>
> On Mon, Jul 9, 2018, at 3:39 AM, Ground-Station wrote:
>
> On 7/9/18 02:43, Ground-Station wrote:
>
> At Ettus we use a sine wave with peaks at the rails.
>
>
> So a rail-to-rail square wave would be +3dBFS?
>
> Does this include the power in both I and Q?
>
> Thanks,
>
> Phil
>
>
>
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-- 

Stephen Hicks, N5AC
VP Engineering
FlexRadio Systems™
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