[ntp:questions] NTP over DRM: RDS on FM only accurate to 100ms and no tracability mechinsim exists
mikehack at u.washington.edu
Wed Mar 21 07:38:08 UTC 2007
NPR stations that use RDS are only accurate to within 100ms, due to RDS's
time transmission design flaws.
No accuracy or traceability mechanism exists for RDS-TC (Time Clock, or TS:
Time Service) service.
IP packets are of no meaning here, RDS cannot really encapsulate them.
This is a non-TCP_IP use of NTP.
NTP is a data transmission format for time separate of its IP4 and IP6
multihop measurement mechanisms.
NTP over DRM: http://hireme.geek.nz/NTP.html
> NPR currently uses NTP to synchronize the local broadcast time to the
> satellite feed. The crucial issue is to encapsulate the compressed audio
> in IP packets, not the other way around. I suspect PBS might do the same
> thing as well, as their programs start time deltas are be in the low
> milliseconds relative to UTC. The DRM page cited is riddled with errors.
> Somebody (me?) should send a comprehensive bug report.
>> Yes, but a BCD Time and Date is t deltasansmitted -- not NTP.
>> NTP is a proven workhorse for time signal distribution -- and can be
>> implemented beyond the WWW.
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