Warner Losh <[email protected]> wrote: > Also, these systems were not on the internet, so downloading one of the many > sources of TAI-UTC differences wasn't an option.
OK, obviously asking every system to be connected to the Internet would be a non-starter, for security etc reasons, but what's wrong with dedicated, special-purpose narrowband non-Internet channels? Why not have an old-fashioned modem (as in 9600 baud or slower) dial a service such as ACTS that would provide the necessary Earth Correction information? (I realize that ACTS in its present form does not provide this information - I'm referring to a hypothetical ACTS-like service here.) There is a huge difference in terms of security etc exposure between a full-blown general purpose TCP/IP stack connected to the public Internet and a special-purpose low baud rate serial line. If you have a serial port in your system, and the only piece of code that touches this serial port (and even knows about its existence) is the single- purpose code that retrieves Earth Correction information, expecting just one specific (hard-coded) data format and accepting nothing else, where is the risk? > We had a requirement that cold spares had to sit on the shelf for up to 5 > years, and come up in a new system with the correct UTC time within 3 minutes > of power being applied. It seems to me that the correct solution to a problem like this one is that whoever came up with such an unreasonable requirement should be removed from office, and replaced with someone who would be more reasonable. Why was this solution not considered? In other words, was there any true, genuine justification for the "requirement" you have stated, other than someone's whimsical say-so? Why did it have to produce "UTC" time, and not something like TAI or GPS? UTC should be for displaying *civil* times only, i.e., a user interface or presentation issue, with all internal things done on a timescale like TAI instead. And if the correct *civil* time is only for the convenience of human operators, why is it so critical to get it right within 3 minutes of powering up a cold spare? Surely the world won't come to an end because of some LCD on some control panel showing the wrong time for 25 min instead of 3 min after a technician swapped out a module. VLR, SF _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
