[time-nuts] DHS Resilient PNT Conformance Framework

[Poul-Henning Kamp]

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Bob kb8tq writes:

> I have seen cases of “goes away until power cycled”. I have not seen any cases of 
> “goes away forever” other than the obvious  ( = feed it an insane almanac that prevents
> if from ever locking up ). Even with that said, I have not seen an example ot that sort of
> thing living through a hard reset … ( which isn’t quite the same thing as a power cycle ).

I have: An corrupt alamanac in NV storage contained something which
made a particular GPS receiver divide by zero, shit its pants and
wedge during startup.

The post mortem report said that the alamanac passed the "technical
consistency checks", by which I suppose they mean the Hamming code,
but it still caused a divide by zero.

This incident is the reasons why GPS receivers in some critical
applications are not allowed to have NV storage for "operational
purposes" and get the almanac downloaded from the attached systems
at startup.

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