Curious: OTA TV signal delays

[Chuck(G)]

This is just one of those things that makes for brain worms...

I've got a couple of TVs that are wired for OTA signals. What's interesting is the delay in the audio between the two, when both are tuned to the same station. On some days, the delay is only a few milliseconds, manifesting as a reverberation on the two audio signals. On other days, the delay can extend to a few seconds.

Since both sets are getting the identical signal, why the extremes in delay between the two?

 

[Agent Orange]

This is just one of those things that makes for brain worms...

I've got a couple of TVs that are wired for OTA signals. What's interesting is the delay in the audio between the two, when both are tuned to the same station. On some days, the delay is only a few milliseconds, manifesting as a reverberation on the two audio signals. On other days, the delay can extend to a few seconds.

Since both sets are getting the identical signal, why the extremes in delay between the two?

I have 5 tv's connected to a chimney mounted antenna (not unsightly). No lags and video/audio always seems sync'd. Maybe you need to take a look at you splitter(s) or just replace it.

 

[jlang]

I've seen a similar thing....
I think is a combination of buffering and errored frames.
I've seen one OTA TV lag by minutes on wet mornings (high error rate)

joe

 

[Chuck(G)]

What's a "splitter'? I can look out of my window and see the transmission towers on the next hill. Rain, wind and tree movement do have an effect--something that we were told on the rollout of DTV would be less noticeable.

 

[Agent Orange]

What's a "splitter'?

 

[maxtherabbit]

The decoders in the TV have quite a bit of design variance. The RF propagation has nothing to do with this

 

[Eudimorphodon]

ATSC video is MPEG-2 video carried by a digital transport stream incorporating error correction data at a maximum rate at... something like 20 megabits per second? A given decoder might have several megabytes (or tens of megabytes) of RAM to buffer both the incoming “raw” stream and the decoded frames in order to apply the various special effects most higher end TVs support these days so... sure, I imagine there’s a lot of room for two ATSC TVs sitting next to each other to run out of sync. Never tried it but kind of itching to now.

 

[Chuck(G)]

View attachment 67216

Tongue in cheek query. I'd get the same reception with a wire coat-hanger.

 

[Chuck(G)]

ATSC video is MPEG-2 video carried by a digital transport stream incorporating error correction data at a maximum rate at... something like 20 megabits per second? A given decoder might have several megabytes (or tens of megabytes) of RAM to buffer both the incoming “raw” stream and the decoded frames in order to apply the various special effects most higher end TVs support these days so... sure, I imagine there’s a lot of room for two ATSC TVs sitting next to each other to run out of sync. Never tried it but kind of itching to now.

It's interesting in that it can vary so widely between two sets on the same day and channel.

 

[Agent Orange]

Tongue in cheek query. I'd get the same reception with a wire coat-hanger.

You're not gong to run 2 tv's off the same coat hanger without a signal splitter.

 

[Chuck(G)]

I own more than two wire coat hangers. Besides, why attenuate a signal unnecessarily, when you can simply use a separate antenna?

 

[Agent Orange]

I own more than two wire coat hangers. Besides, why attenuate a signal unnecessarily, when you can simply use a separate antenna?

Well, for one thing 5 antennas for 5 tv's would look kind of dumb on my roof. I'd wager that a splitter is a bit more tidy. Also, you never indicated that you had multiple antennas.

 

[Chuck(G)]

Why would I need an antenna on my roof when I can see the transmitter? I'm on top of a ridge and the transmitter farm is on the next ridge.

 

[Agent Orange]

Why would I need an antenna on my roof when I can see the transmitter? I'm on top of a ridge and the transmitter farm is on the next ridge.

Most folks that I know with OTA have an antenna. In your case maybe 1950's rabbit ears would do. So, how many channels do you get off the farm? I get everything that's blasted out in about a 40-45 mile radius.

 

[Chuck(G)]

Since we're pretty much the only OTA broadcaster within about 100 miles, let me count them (not including repeaters, 24x7 advertising and Bible-thumpers):

3 ABC channels (ABC, MeTV, Ion)
3 CBS channels (CBS, TBD,ChargeTV)
2 local independents (COZI, TimelessTV)
3 NBC channels ( NBC, CW, Comet)
3 FOX channels ( Fox, MyTV, DABL)
4 PBS channels ( OPB, OPBplus, OPB kids, OPB FM)

So not exactly a desert, but nothing to be enthusiastic about. Recently grabbed one of those FireTV sets, so Internet content as well via WiFi.