[time-nuts] Question about SoundCard stability?

[Jim Lux]

On Oct 13, 2010, at 12:32 AM, David McClain <dbm at refined-audiometrics.com> wrote:

> Hello John,
> 
>> Well, not entirely -- it's common enough to see FFT applications that
>> compute frequency readings at sub-bin precision by tracking atan(Q,I) across
>> multiple time records.  That is a well-defined thing to do, since the
> 
> 
> Yes, indeed, I am familiar with that technique from my SIGINT days... however, what you are really doing is extending the sampling period by looking at multiple scans. And so that isn't really any different at its base than just taking a longer period FFT.
> 
> The only way I have ever seen super-resolution is when you do AR deconvolution, bearing in mind that wherever there are instrumental induced zeros in the spectrum, you will get nonsense values in the result. AR, aka maximum-entropy, attempts to produce a minimum norm estimate, akin to that from SVD analysis.
> 

That's but one way.   There's also music and esprit as well of a host of other similar methods.

>