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PostPosted: Sat Nov 23, 2013 12:57 pm 
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Joined: Fri Apr 17, 2009 7:52 am
Posts: 379
Location: Boden, Sweden
Hi,
I have been receiving requests recently for 32-bit data control systems. For some reasons it seems to be
that it is very hot topic on the GPR community, at least for some anyway. I have been thinking a bit about
it and I have come to some conclusions about the whole thing. I'll try to explain a bit here in a hope that
probably somebody else can contribute a little bit on this.

So, the first and very important topic is, 32-bit data storage systems or on a completely
different level 32-bit hardware acquisition systems. See, the difference is very important,
a 24-bit ADC will indeed output out 32-bit data, but it is in no way a 32-bit resolution device. To be honest,
most of the time is not a 24-bit neither but a 19-20-bit effective resolution system. The upper 8-bit from
24 to 32 are an extraordinary challenge to get for many reasons and the analog part being the worse.

There are a couple of companies offering 32-bit ADC chips, ESS technology has the SABRE ES9102 and AKM
has the AK5397, but in both cases these are Audio ADC, probably going up to 192kHz in the best case
scenario not a great thing. But, even if they cope well with GPR data, the electronics in the antennas are
still the same and therefore it would be the bottle neck.

But, OK, you got your 32-bit data in, effective bits or not that's another story, but you got it. Now what?
Going from 8-bit to 16-bit data was a great thing back in the day because all the power the DSP techniques
could offer. Probably going even higher would give a better possibilities for processing the data, although I'm
not so sure about it, perhaps some one here can explain that better. At the end of the day the data even
a 32-bit one contains information only about an amplitude at a particular moment in time. When presenting
the data for interpretation on a computer it still needs to be presented in some kind of color map. Even if
you use different colors for mapping different kind of amplitudes, that would mean 32-bit color palettes.

I had the opportunity to watch in real live one of those systems working and I was impressed that the palette
being used was an 8-bit one. So, what's all the fuzz about?

Hopping to get some feedback on this.

Regards,

_________________
Reinaldo Alvarez Cabrera
Geoscanners AB
Sweden
http://www.geoscanners.com


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