[time-nuts] Sneaky Errors

Hal Murray hmurray at megapathdsl.net
Thu Oct 20 08:19:36 UTC 2011

> If you are very conservative or if this is for some critical requirement then
> I'd get something other than another TB.

That's a good point.

There are 2 obvious single points of failure in using TBolts.  One is TBolt 
firmware (or obscure design error).  The other is the GPS system.

If you want to protect against things like firmware bugs, I think you have to 
get 3 independent designs.  If you have 2 TBolts and 1 other receiver, a bug 
in the TBolt firmware will out vote the sane 3rd receiver.

I don't know how much to worry about problems in the GPS system.  The 
military probably considers it to be very important so I expect they have 
thought hard about how to keep it going.  Politics might be important.  For 
example, somebody might decide to turn selective availability back on.

At the receiver, you obviously have to worry about things like a shared 
antenna with a splitter.  Even if you have separate antennas, the cables 
probably run near to each other and the antennas are probably close to each 
other where they might get knocked out by the same snowstorm, bird nest, or 
object falling from the sky.

These are my opinions, not necessarily my employer's.  I hate spam.

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