Digital TV

Dynamic Time Warping. This provides spectrum for the subliminal government messages to be transmitted to the masses.

Powdered Toast Man

I'm curious, why you still use open system rather than cctv? live in the outpost?

async is not caused by digitalized, most of situation is at front port, when they produce, this is also occurring in the analogy ages. especially in NGE, or microwave transmission, becaue the video signal and audio is transmitted saperatly in differnent lines.as I knowl

there is a time delay between them and then modify them at TV station by time base adjustor. so called frame sync. etc.

On the Analog vs Digital time difference, are you certain that they are being broadcast simultaneously or is there a delay between them? I can pick up two different analog signals of the same network through different local affiliates, and they sometimes are a source of amusement for me when I switch back and forth and they are not in sync - I'm easily amused.

Ah the wonderful world of digital signals...

Our government is forcing this upon us in the UK, having worked on TV test instrumentation I can tell you its a con...

Although digital TV has the picture/sound quality built in, what it does not have is the ability to understand 'noise'. An analogue TV will display a weak/noisy signal MUCH better than a digital one.

As for the time delay YES!!! it takes time for a digital TV to decode the signal and display it - about 1½ seconds.

A pub I frequent has numerous TV displays, but one is connected to the analogue input while the others are connected to the digital to analogue convertor... Its fun to watch the analogue TV and see everything happening 1½ seconds before everyone else!!!!

Exactly..

I am glad that I am not the only one living in an outpost or behind the times as one poster mentioned. But then, maybe Brecksville, OH is the middle of nowhere.

Haha, someone who lives in a so-called higher level city, but still acts as a peasant in the country.

To see a tv program that has a async video and audio by a same cable is caused by the front port of produce, but when took place this phenomena is caused by converter's time difference in a same room is very different concept.

just like something when you see program show you in different station. there are always time different existing.

any engineer who has only a little electronic knowdege will well know it.

USA is of an advance tech country, but it s not everyone who lives in the country is educated.

We have digital TV in Japan for a while better quality, wide-screen, i am quite pleased with it.

And the delay would not surprise me, we don't want another shocking Nipple Gate!

Yes need good antenna to receive vid/aud in sync- old antenna would tolerate corrosion, wind movement- yet still provide good pic/audio in analogue- just won't work with digital!- I invented a new compact antenna that not only receives analogue perfectly but also digital- we are talking band 1 to band 5!. Hint- I use 300 ohm twin lead cable!. Any one could do this sort of thing- especially as set-top boxes have readouts of signal level/signal quality- it's not rocket science!- but experimentation!. I still watch analogue- while it's here- why not!?- we have till about 2013 before Big Brother switches analogue off for good!.

There are two distinct issues here, 1) overall delay and 2) audio/video sync.

1) The overall delay is much greater with digital TV because of the way the signal is compressed and decompressed combined with a smaller delay involved in creating the multiplex of several TV channels on one carrier. (The latter applies in Europe/UK but may not in the USA as the system is different.) The compression ratio is very high compared with that used for professional purposes and this leads to longer delay. Even analogue TV is delayed by the studio transmitter links and the delay will vary according th the path to the transmitter site and the number of links which is why AnhydrousBob notices different delays from one analogue station to another.

2) The audio and video signals do not travel by different routes as they are embedded in the same data stream. The antenna design will not have a direct influence on the synchronisation. (Even with analogue broadcasts the signal is sent digitally to the transmitter sites with the audio embedded and the digital Nicam stereo signal is embedded in the video signal itself.) The only place where the audio and video tend to get separated is in remote broadcasts where they do take separate paths and in production studios and master control rooms.

The problem arises with the inherent delay in converting from one digital video system to another which happens several times in the production chain. This delay is much greater than the delay caused by trans-coding the audio so the audio will get ahead of the video unless it is delayed to compensate. The problem for a master control room is that material is coming in a variety of formats with differing delays and it is very difficult to keep on top correcting this in a busy environment.

I see fewer lip sync errors on the BBC than a few years ago when the digital broadcasts began so it seems that with experience broadcasters are getting on top of this problem.

I agree with Electroman that digital TV is more prone to interference from RF noise but it is much more resistant to co-channel interference. I live on the South coast of England and when there is a high pressure ridge in the English Channel there is very bad ducting with French TV stations making the analogue TV unwatchable. The digital system has totally eliminated this problem.

The only effect of an antenna on delay is where the digital signal is so marginal that massive error correction is taking place. The system is designed to favour the audio as breaks in the audio are more disturbing than glitches to the video. This is why the image may occasionally freeze or fall behind whilst the audio continues.

This may not apply, so I apologise if true, but are you comparing the same TV channel over analog terrestrial (or even DABT) and Digital (DABS) satellite? There will always be a significant time difference due to the distance the Sat signal has to travel, around 44,600 miles in all.

But if the Digital signal you are comparing with is DABT (as against DABS), then the previous comments from other posters are surely the correct answer(s).

So keep the old set