[LEAPSECS] Crunching Bulletin B numbers (POSIX time)

[Warner Losh]

On 02/22/2011 16:19, Steve Allen wrote:

> On Tue 2011-02-22T18:01:00 -0500, Keith Winstein hath writ:

>> If you just need GPS-CC time, you're right. Adding 19 seconds gets you

>> within 1 microsecond of "TAI(USNO,MC)".

> Correct me if I'm wrong, but I think if you

>

> 1) buy a Meinberg NTP server

> 2) configure it to emit GPS time instead of UTC

> 3) get the zoneinfo source code files

> 4) edit the "leapseconds" file and delete all leaps before 1980

> 5) compile the zoneinfo files yourself, asking for the "right" ones

> 6) install the resulting zoneinfo files

> 7) set the system to use the "right" timezone

> 8) set the system to use your Meinberg stratum 1 NTP server

>

> then you have a system which is running its time_t based on GPS time,

> therefore does not have issues with leap seconds resetting the clock,

> and which produces a correct local time string for every time zone.

>

> The trick being that you are not POSIX-compliant and cannot exchange a

> time_t value with any POSIX-compliant system.


You could do that, but you still have the wait for UTC and the 'cold 
spare' problem of a unit bing on the shelf for years and not having the 
proper zoneinfo files.

The machine in question that I keep referring to is a stratum 1 GPS 
receiver that also outputs a PPS for top of second of GPS time (in some 
models 'more or less' thanks Motorola)...

Warner