[aprssig] APRS Runner Tracking

AC kf4lvz at yahoo.com
Wed Aug 7 16:35:47 CDT 2013


 >
 >
 >>> Set your position to your checkpoint.  Then each time you want to
 >>> report a particular runner number, just change the MYCALL of the radio
 >>> to the runner number...
 >
 >> Interesting idea but you won't catch me doing it and
 >> that's because you're forgetting that the radio stores data
 >>  in flash memory which has a finite lifetime.  I prefer
 >>  not to wear out the flash memory in my radio prematurely
 >
 > Hummh.  I have about 8 or so D7's between my oriingal prototype and all
 > the ones at work, and so the age is from 15 years old to about 10 years
 > old, and not one of them has failed for anything, though  several have no
 > control knob from having bounced on concrete numerous times.
 >
 >> It all gets stored in flash which wears out.
 >
 > Yes, but 100,000 cycles is sure a long long time.  Let say 20 entries per
 > marathon 5 marathons a year, that is about 1000 years life.  I doubt even
 > Kenwood will be around then...
 >
 >

The cycles are usually referenced to a chip and that assumes mitigation 
methods like wear-leveling.  A typical flash memory cell (not the whole 
chip, just one memory bit location) can't handle that many writes (it's 
usually 10,000 or less).  Kenwood likely didn't use a smart chip in the 
memory module but instead used a simple flash device to act like an 
EEPROM (direct addressing).  That means a specific set of cells gets 
rewritten every time a particular parameter changes instead of the 
writes being distributed across all the cells as would be the case in a 
wear-leveled device.

Now the calculation says 100 years instead of 1000, which is still quite 
a while, but that also assumes the chip is in excellent health (and we 
know what happens when assumptions are made).



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