Re: [amsat-bb] Time references (UT vs. GPS) Whoa, there!

[Phil Karn <karn@xxxxxxxx>]

Bill Jones wrote:

>    After 45 minutes of studying, I checked my GPS again, and NOW, it is 
> correct relative to UTC.  ????
>    My guess is that before the GPS can display UTC correctly, it needs to 
> receive a message from the satellites telling it the current number of leap 
> seconds, and when I initially got my GPS running, although it had a fix, 
> perhaps it hadn't had time to collect a complete almanac of data including 
> leap seconds???  However after leaving it running for 45 minutes, it 
> apparently had all the data it needed to display UTC correctly???

This is almost certainly correct. The almanac "page" that gives the 
GPS-UTC offset is sent only once every 15 minutes, so it could take that 
long for a receiver to get that information if it's been off for a long 
time.

Phil


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