eli5: In a world of instant communication via satellite, why does news anchors connecting with field reporters live still involve a 3 second silent pause?
In: Physics
As far as I know that is the delay they add in for real time editing to avoid things that shouldn’t be shown or said being shown or said
Communication via satellite is not instant — many communications satellites fly at an altitude high enough that their orbital speed is equal to the rotation of the earth — in other words a fixed antenna on the ground can point to the same position in the sky, day and night (geostationary orbit). Roughly, this is an altitude of 35,000km. The speed of light is 300,000km/s. To bounce a signal from earth, to the satellite, back to earth is 70,000km, or ~250ms, a quarter of a second.
The three second delay is more a discipline of the broadcaster to wait for that much pause to ensure they don’t speak over each other. You’d be surprised how much difficulty a quarter of a second delay adds to a conversation.
Hey, I did my thesis on something relevant!
Basically if you go the satellite way then the signal.has to travel all the way to the satellite and then be relayed all the way back to earth. This process alone takes almost half a second.
The instant communications we are used to usually are communication where the signal doesn’t have to leave the earth. For example the cellular networks that our phones use.
There is the option for news agencies to go this way, but sending a high definition video and with enough frames to look good on those big TVs we have demands a lot more data than an average video call does and ends up being quite costly.
Apart from satellite, there is a device called LiveU that utilizes 4G connectivity for live links. Each camera gets connected directly to this device that will encode the signal. You can fit up to 8 SIM cards os each such device and it will use the combined speed of all to send picture back to a server on premises.
You can set the delay manually, shorter delay means the picture might crack and drop and it will have significantly lower quality. Most channels put the delay on 2.5 seconds as it seems this is the optimal.
News anchors have to always have this in mind when speaking with a reporter live, and they have some code words to steer the conversation. For example in Greece and Cyprus the word “malista” (roughly translates to aha/yes/ok) signifies that the news anchor wants you to wrap it up and end the discussion.
Source: I was working in the media industry for years.
They don’t want to be dependent on the internet because it’s beyond their control. They may lose quality or could even be sensored or controlled by the government through the internet in extreme cases. So they have their own equipment that goes through satellites which are far away and therefore add a delay to the signal. In exchange they have full control over the entire process.
It really depends on the system that is being used. Essentially it is the mercy of the networks. Satellite can have 250ms or more of latency, local radio broadcast can be much quicker (depending on the technology) and even wired copper/fiber can have some latency associated with it. To add, nowadays everything is digital (which adds DSP encoding and decoding latencies to it all).
Long story short…just because we call it instant…doesn’t mean physics allows for “instant”.
In high school I worked for the town’s local radio conglomerate, and though it was many years ago, I wouldnt be surprised if they still patched remotes through the telephone line like we were doing 20 some years ago.
Especially because once I graduated and got to college, my first work study gig was cueing up and playing the sponsor’s advertisements… from their 8-tracks!
It wasn’t THAT long ago…
My only point being that stations get fixed in their ways, both equipment and protocol. You’d be surprised just how few people work at any given station, especially locally. Those station managers know what they’ve been forced to change, what they fought to keep in place, and what method has been most reliable for them over the years. Usually they aim for live air above all, but they must follow fcc rules and what has become important to that guy and his audience isn’t necessarily the driving factor in a stations business model anymore.
So it all depends on the comm equipment and protocol being used – and while it may not be dialed in anymore, what one station uses isn’t necessarily indicative of another station’s methods.
Speaking from a news person’s POV, aside from satellites we also use a technology known as ‘bonded cellular’. Basically, we have a little computer that uses multiple cellular modems to send video back via the cellphone network.
I, as a photographer in the field, can change the delay settings which will affect the video quality. When doing live shots in an urban area I will usually have the system set to a 1.5-second delay, which is basically the ‘fastest’ setting for the device (Dejero in our case) to process the video, transmit it back to the station, allow the decoders at the station to process it and to get it on air.
If I have a weak cell signal, I will increase the delay as that reduces the video quality and reduces the bandwidth required to send the video.
A lot of news outlets use this technology now as it is far cheaper than satellite trucks (which require their own independent operator). Sat trucks still have a use – e.g. disaster areas where there will be limited to no cellular service, remote areas with limited to no cellular service, points where it’s really, really important to make sure there’s no disruption in signal (like sporting events, 8 hours of live shots during major breaking news, etc.), but they’re becoming rarer and rarer for everyday use.
In Slash’s Biography, he says that the 3 second delay is a direct result of Guns n Roses getting an award they weren’t expecting at a televised event.They were massively drunk, and cursed up a storm when accepting the award.
The 3 seconds is necessary (aside from all the technical reasons) as it gives the production people time to bleep out the slurs.
It sounds like a good reason, but Slash’s biography is my only reference for it, so I’m not sure how true it is.
Ground stations are static whilst satellites are zipping past in a constellation/mesh network, meaning the ground station is constantly having to reconnect with satellites and having to negotiate terms of communication with them, otherwise known as a handshake.
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