Digital transmission delays

Jan 01, 2016 53 Replies

Isn't there a standard ~10s delay inserted into all nominally live but uncontrolled broadcasts these days in case something bad happens.

Delay on digital vs FM is typically 1-2s depending on the chipset and the route the signal takes - satellite feeds obviously being slowest.

In message , Dave Liquorice writes

Boring fireworks? Here in Aberdeenshire we had Jackie Bird and the Bay City Rollers on BBC1. I kid you not. The BCR are alive and kicking. Well, alive, anyway.

Question:

What is the typical delay on a Virginmedia cable TV feed? Assume worst-case distance from feed.

Advertorial:

Late this week, Apple managed to get several "news" sources to report that their iWatches are accurate to within 50 milliseconds. So two watches put next to each other always appear to be exactly in step. Apparently, if you have one of these fangled devices, everyone in the room will turn to YOU to know when it is new year.

[Gah! Why I am repeating this drivel...]

Happy New Year.

That's surprisingly short. Most people put I frames in one per second, and it's hard to make your compression latency less than that.

Andy

The way you put it, that sounds like time travel - hearing the clock in your headphones before you heard it live!

If you don't mind me asking, what sort of work did you do on tv broadcasts?

Yes. Our bedside radio-alarm is VHF, and so old it has red LEDs in the display ;)

Andy

Bill Wright scribbled

How do they know it's a majority, when they never express their views?

pamela scribbled

Flight engineer on the Tardis.

We always watch the Scottish programme. We like Ally Bain.

Bill

A silent majority that is obviously incapable of voting.

Not you, space cadet. I meant Dave.

That's nothing. I've just watched it on the BBC iPlayer catch up and it's nearly 34 hours later than when my RDS clock said it was midnight on New Years eve.

Turnip, I was referring to the FreeView system. Try looking at the EPG clock and see how far out that is. If you need help on how to do that I'd be pleased to advise.

It would be obvious to anyone that an individual broadcast could have a variation in the delay. Many have several years.

Bollocks. It would make 'live' interviews etc impossible, where the cue feeds are taken off air. The existing couple of seconds make things bad enough.

Yup. FreeView plus your set. Jools is recorded, and I assume they make it 'spot on' at their end.

Remember you're talking to Turnip. Who is never wrong.

Perhaps he only has one TV. Those with two may just have noticed they are never exactly in sync.

Simple answer. Big Ben has microphones close to the bells. The speed of an electrical signal is nearly the speed of light. Sound is relatively slow through the air.

Sound. Just about every job in it over the years.

Ever come across a guy called Chick Antony?

Just checked the FreeView dongle in the PC. About a second behind that FreeView TV in the same room.

Oh yes. Superb sound supervisor at the BBC, who specialised in drama. Very nice guy too.

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required