[time-nuts] TV Signals as a frequency reference
John Marvin
jm-tnut at themarvins.org
Tue Apr 3 05:03:37 EDT 2018
Yeah, that's pretty much the story around the country. I also have some
monitoring software (monitoring PSIP, video and audio data, not
specifically for monitoring STT packets) that I run on the Denver and
Cheyenne stations 24 hours a day. Very few have set their GPS-UTC offset
to 18 seconds. None are set to 0 though. The values range from 14 to
18. Almost half of the stations are within 1-2 seconds of the actual
time (when taking their mostly wrong GPS-UTC offset into account). But
some are 10's of seconds off, some are 10's of minutes off, and one is
about an hour off, and another about 5 hours off (currently).
The amazing thing is that every once in a while, some stations make a
"correction". Sometimes it is to bring their error back down close to
zero. But some appear to make large changes in the wrong direction,
e.g. -88 seconds to -195 seconds. Looks like some stations have someone
setting the time based on their watch (if I had to guess), which is
really off.
Doesn't give me much hope that the ATSC 3.0 standard will be implemented
any better, given that the FCC has taken an even more hands off approach
to this transition than the transition from analog to digital. I highly
doubt we'll see many channels doing over the air 4K transmissions, i.e.
they'll just use the better compression to stuff more crappy subchannels
into their signal. But I'm getting pretty far away from time nuttery
here, so I'll stop now.
John
On 4/2/2018 11:15 PM, Mark Sims wrote:
> Here's a local guy's take on monitoring time and DST errors on the stations in the Dallas area:
> http://home.earthlink.net/~schultdw/atsc/
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