On 1 Jan 2011 at 10:37, Poul-Henning Kamp wrote: > In message <[email protected]>, "Daniel R. Tobias" > writes: > > >I just watched the ball drop in Times Square (on TV, not in person!), > >and noticed that my watch (auto-synced daily via radio signal) was > >about 15 seconds fast [...] > > In difference from analog tv/radio, digital transmission of broadcast > signals almost begs to be delayed.
As I recall, a few years ago (before the U.S. digital TV transition was completed and the analog broadcasts stopped), when I had the same program turned on with both a digital high-definition TV and an analog one, the digital one was delayed a few seconds from the analog one (because, I guess, my cable company was getting the analog feed directly with no delay [beyond whatever delay was imposed by the network for bleeping out bad words] while the digital one had delays for encoding/decoding). However, at some point in the intervening years, things flipped over so that now it's the analog TV that has a few seconds delay from the digital one, I guess because the cable company has to create the analog versions of the channels themselves (now that it's no longer broadcast that way) by decoding the digital transmission and that takes longer than simply sending the digital signal directly. Either way, it's a bit of a nuisance when I have TVs on in several rooms, some of them ancient analog ones while the main TV in the living room is digital/HD. Anyway, if there's one time that the average person (not the specialized techies on this list) actually notices and cares about time down to the second, it's New Years Eve, but it seems that the time they see when they count down to the TV is actually shifted somewhat from the real time. The network techies, however, do need to concern themselves with being precisely synced to whatever time standard the Times Square people use; it would be embarrassing if the ball dropped a second early or late compared to their countdown. This means that if there was a leap second at UTC midnight (a few hours before New York midnight), they'd better all be on the same page with regard to applying it (or not). -- == Dan == Dan's Mail Format Site: http://mailformat.dan.info/ Dan's Web Tips: http://webtips.dan.info/ Dan's Domain Site: http://domains.dan.info/ _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
