[time-nuts] TBolt self survey

[Charles P. Steinmetz]

Raj wrote:

>My GPS reading is about 850 +- 1
>The "official" height ASL = 920
>This calculator gives me ~936
>So what should I use ?

Use the self-survey result.  The GPS isn't wrong, it's just reporting 
your altitude in a different system than you are used to.  The 
calculator allows you to check the GPS-reported altitude in the 
system that you are familiar with.

Specifically, the calculator translates the GPS altitude (which is 
specified not with respect to actual mean sea level, but rather to an 
abstract, calculated "geoid") to one more familiar to you (specified 
with respect to mean sea level).  In your case, 936 is in pretty good 
agreement with 920, telling you that the GPS-reported value is plausible.

Best regards,

Charles