Rusty Dekema schreef: > > The reason CDMA reference clocks are so popular is that CDMA systems > require a tremendous degree of accuracy and precision in the > synchronization of time between base transmitter sites and mobile > units, and that the CDMA (IS-95) spec calls for the entire network to > be synchronized to UTC as opposed to any other time base. > Last time a leap second was inserted they had issues, though... but they of course were not alone. It had been so long after the previous leap second that programmers became sloppy and testing was difficult. > Of course, most GSM operators do maintain some sort of time-of-day > standard, otherwise they wouldn't be able to set the clocks on > subscribers' handsets to meaningful values. They aren't! Apparently, subscribers are supposed to set their own clocks. I'm amazed by this as well, but the original GSM system does not transmit the time-of-day to the handsets, and the handsets just include a time setting menu option and wander away from correct time like a watch. I think a major manufacturer (Nokia?) has added a nonstandard message to carry time-of-day, but it only works when both the base station equipment and the handset are from that manufacturer, or at least support that additional message. Indeed it is probably not wise to use this message as a clock reference. The network may be running on wristwatch time as well.
There is precise timesync within the network to facilitate accurate handovers and to synchronize the TDMA system it uses, but the designers apparently did not think it was worthwile to carry accurate time-of-day to the user interface seen by the subscribers. (of course a network technically does not require absolute time, as long as it maintains internal sync. it may be that the easiest way to specify this is to require sync to UTC, but that does not mean it is required. The GPS system is a good example) Rob _______________________________________________ timekeepers mailing list [email protected] https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
