Seems to be about 2-3 seconds before the remote guy gets the full question from the studio guy and he can start to respond.
Heck, it’s 2021 and musicians and gamers are interacting in real time. My company’s zoom meeting have no discernable lag with participants internationally… what’s the deal with CNN, NBC, and my local news?
If they’re using a satellite link it has to go way, way up in the air, hit the satellite, then come way, way back down again. The speed of light is not infinite even if it is very fast and that’s a very long way to go.
Shoot messages over lines on the surface of the Earth or relay them through cell towers it’s not nearly the same distance.
Geosynchronous satellite altitude is about 35,800 km over the equator. The distance is further from around 40 degrees latitude, but that only would increase it to maybe 42,000 Km. That’s around .14 light seconds. Doubling it for both direction travel, it’s still less than half a second. There must be delays elsewhere in the system.
Digital compression of video introduces delays - partly because frames in digital video are not complete independent images - they are dependent on frames preceding them. so typically there is a buffer - it can introduce noticeable (like up to 1 second) latency on the decoding end.
Edit: this also exists in the video technologies used in things like Zoom, which the OP mentioned. There is definitely latency in these teleconference services too - if you don’t believe it, get all the participants to sing someone happy birthday together. It will collapse in an utter mess because of latency.
Latency can also be added by compression and forward error correction.
In a bandwidth-limited situation, you’ll need to apply compression to each frame, packetize the result and apply forward error correction to the packets because you can’t wait around for a retransmission. Generally speaking, the better the compression, the more time it takes to compress, and the better the error correction, the more data overhead it will take.
I suspect that there’s a human factor involved as well, as an anchor talking to a reporter over a satellite link isn’t going to use “over” to signify the end of their part of the communication. I’d guess that reporters are trained to wait a beat or two after the anchor is finished both to gather their thoughts and to ensure that the anchor’s side of the conversation is, in fact, over.
edit: ninja’ed in part by Mangetout
I don’t like how the reporters smile and nod their heads while waiting to hear the question. It makes them look foolish, IMHO.
They should pick there noses? Now that’s entertainment.
Samantha Bee would mock that on the Daily Show
Because you canna change the laws of physics, laws of physics, laws of physics…
lly Ballou missed that memo…
Yes, and often, the truck doesn’t have the satt gear so it has to connect to a local site that does. There’s one more point of lag.
It’s funny that you say that. A little while ago I saw some non-TV-talking-head in a live cross. Perhaps a scientist or sportsperson. They simply stood there looking alert while listening to the question being asked, via an earpiece, by the studio. I remarked to the people that I was watching with how much better it looked.
Your zoom videos are “best effort”, they try to get the data to you through shared pipes which can suffer from momentary congestion, dropped packets and other network mishaps that lead to stuttering video and corruption. It’s the same as driving a car on public roads, you’re sharing with all the other cars so traffic can lead to unpredictability.
News channels can’t deal with such instability so they rent virtual circuits on satellite feeds instead. They have exclusive, non-contentious use of the channel for the duration of the broadcast and one packet sent in one end will always emerge out the other side at the exact same time. It’s closer to renting out an entire train track to send just your train across the country. But because you don’t get to amortize the costs across billions of users, there’s far fewer train tracks than there are city streets. This means they have to go far into space and back for a signal rather than using the fiber internet backbone that your zoom call is using.
But as I pointed out in post #3, going to the satellite and back takes less than half a second. The delay is always much longer than that, so it’s mostly the compression and perhaps other things causing most of the delay.
satellite traditionally had a large buffer system, there’s no upgrading the transponder in the satellite thats already up there…
There may have been a reason they switched the feed back to some high latency system, as used for live sport. Maybe it was there on site.
Don’t forget you’re seeing the total delay - there is latency on the return path too - so the field reporter typically started answering about halfway through the delay you see on screen - the other half is the latency of their response getting back to the studio.
I do wonder if Chronostasis could be a compounding issue with this too - our perception of time is variable - if you glance at a clock, it may appear that the second hand takes more than a second to ‘tick’ the first time it moves.
The half second was a pretty large overestimate. It’s actually under a third of a second. The total delay of going up and down twice would be about .6 sec. Still way shorter than the delay we see.
Agreed - it’s just important to remember that some of the things causing the delay are happening twice - once on the transmission of the studio out to the field and once again on the return path, but we have a tendency to interpret it as a single monolithic delay, experienced by the field reporter.
Although I am not sure how often the studio would be transmitting video out to the field rather than just the spoken question, so I guess the video compression might not be a thing outbound.
I had C band satellite and small dish satellite. It involved being able to watch “The Walking Dead”. I could receive network feeds on C-Band. The delay on a program on small dish which went from the network to a local studio to small dish to me and C-band, which went from the studio to me, was about two seconds.