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[aprssig] Clarification of APRS weather station data flow.

Tapio Sokura oh2kku at iki.fi
Thu Mar 17 20:39:34 UTC 2011


Hi,

On 03/17/2011 05:29 AM, Scott Miller wrote:
> Also, unsurprisingly, there's been a big surge of interest in Geiger
> counter interfacing.  Bob, can we get a standard for sending ionizing
> radiation levels in weather reports?

I'm not Bob, but I'm sticking my spoon into the soup anyway after a 
little IRC chatting.. so here goes: Anyone who's familiar with radiation 
levels knows they can hugely vary in scale. So using a plain, say 
three-digit, number isn't going to scale very well (i.e. 001 = 1 uSv/h, 
999 = 999 uSv/h).

I'm suggesting the following: three digits, where the first two are the 
significant digits (mantissa) and the last one is an exponent. Base unit 
could be nSv/h, nanosieverts per hour (Sievert is the SI-unit for 
ionizing radiation dose equivalent).

If abc represents the digits, the resulting radiation level would be 
calculated using the formula ab * 10^c nSv/h. A few examples:

000 = special case for "reading unavailable"
010 = special (theoretical) case of 1 nSv/h or under
020 = 2 nSv/h
150 = 15 nSv/h
990 = 99 nSv/h
321 = 320 nSv/h
123 = 12 uSv/h
654 = 650 uSv/h
456 = 45 mSv/h
987 = 980 mSv/h
989 = 98 Sv/h
999 = special case for 99 Sv/h or over

So that's the digit part sorted out, now we just need a letter 
identifier/tag for it..

   Tapio



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