In message <[email protected]>, Rob Seaman writes:
>Consider the iconic issue of timekeeping for trains, one of the >primary drivers for our current standard time zone system. Trains >clearly need to be synchronized with external clocks. Trains clearly >have some mechanism or set of procedures (imperfect or not) for doing >so. So they don't match the question asked. Modern trains run at speeds of roughly 100 m/s. They care very much about seconds and fractions thereof. In fact, they run so fast that a special version of the GSM mobile standard called "GSM-R", has been created for train-control applications. The main difference between plain GSM and GSM-R is that the latter allows for dopplershift up to 140 m/s, but now railway people have started bitching about that not being enough margin. If you want to know what non-antique rail-road control looks like, search for and study "ERTMS". Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [email protected] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
