Slightly OT: Reginal News TV transmissions in HD

[Andy Burns]

Are there regional variants of COM7/COM8?

Since the recent changes they show up as belonging to a network of "Com78 National"

[Bill Wright]

I now have a Pythonesque image of some of our culturally diverse gangland brethren whispering to each other in dark alleyways about playout centres and multiple router salvos.

Bill

[SimonM]

Does it introduce substantial time delays?

ITV rarely, if ever do OBs into their local output here (Bristol), but Points West do. I realise cue "circuits" travel via different routes, but surely off-air (or the equiv of programme out) is still used occasionally, if only for checking.

I imagine there are "entertaining" issues with live cueing...

On the operational aspect to "opting", I went for a job interview at Central South way back in the late 1980s. I sat in on their evening programme, the "opt" being done by BT on a timeswitch. It was rather unnerving, as you couldn't match levels or anything like that - no subtlety whatsoever. You just watched the second hand reach the minute, and bang, you were live.

OTOH, it was easier for the PA doing the timing, as the programme duration was always exactly the same - no worrying about London over- or (worse) under-running the official opt-back time.

[Scott]

At least I've got a decent transmitter then (Blackhill). :-)

[Woody]

Er, (cough cough) - there's no U in Arqiva. Its pronounced Ar-key-va, not Ar-kwee-va.

[J. P. Gilliver (John)]

In message , Woody writes: []

Silly name then: why not spell it Arkiva or Arkeva. Same as that car model the Cash Kai, and many other similar examples. Fair enough if the word derives from another language where there's some difficulty because English doesn't quite have the sounds (Qatar, for example, is pronounced something very close to gatar, but not quite), but using letters in an unconventional way just for the hell of it is extremely irritating.

(, sorry. But Arkiva irritates me every time I see it.)

[Scott]

Is it not to make the name into a registered trade mark, such as Coca-Cola® or Irn-Bru® ?

[J. P. Gilliver (John)]

No. There aren't lots of people queuing up to register either Arkiva or Arkeva - and those aren't words. So it could have been registered as either of those. If Coke had called itself Coqa-couailla, I'd have had the same reaction, but Coca-cola is spelt as it is pronounced, not in a silly way. (Irn Bru is supposed, I think, to represent a robust Glasgow accent, it isn't just a funny spelling for its own sake. "Irn Bru - made from girrrrders!")

[Mark Carver]

Because 55 and 56 have yet to be cleared (of the other 6 muxes) in some areas. All 30 COM 7/8 sites will be on the SFN by the end of 2020

Err yes. DAB works fine with it, as does the PSB 1 DTT mux in The Netherlands, as it does for some small clusters in the UK. For instance the PSB muxes at CP and Reigate since April.

Because for a viable geographical sized SFN, it's a trade off against mux payload. That's why BBC 4 HD had to move from COM 7 to 8, reduce COM

7's total bandwidth requirement, so both muxes could adopt SFN working.

The main 6 muxes are too jam packed with stuff, (and the PSBs are regional) to allow large scale SFN operation

[Mark Carver]

Not really, the circuits between the regional studios, and the central playout facility are high bandwidth/low latency

'off air' DTT or D-Sat is not suitable for OB cueing, both have significant latency, so it's a moot point.

See above. Since DSO off air cueing isn't really viable.

Abingdon's output went back (via a BT circuit) to Central's MCR in Birmingham, and from there to the Oxford and Ridge Hill txs. I don't think it was on a time switch, but probably on a salvo from the Pres Mixer. The Brum, Nottingham, and Abingdon programmes all had to finish (and start) at the same time. No different to HTV, Meridian, YTV, Tyne Tees who all had similar split regions.

Isn't that why we have standards ? :-)

[Dave Liquorice]

Then up the bandwidth of the channels left to something that produces a watchable picture.

[Scott]

How many years from DSO would you need to wait to cater for people who purchased equipment in good faith?

[Dave Liquorice]

Ok but that's fudging it by making BBC CBR.

The round trip time between the Mark 1 eyeball seeing somthing at a "live", fibre connected OB and then seeing the same thing on an offair DSAT fed house monitor is around 8 *seconds*...

Pointers has a SNG truck, so the cue delay is mostly the satellite hop.

Having said that IP based systems are becoming more common and remote production keeps rearing it's head. The latentcy in the fibre circuits isn't a problem but then each (compressed) UHD camera uses

10 Gbps link. Sounds like a lot of bandwidth but in the great scheme of things 10 Gbps is but a drop in the ocean.

The BBC UHD streaming trials had around 40,000 streams running at 36 Mbps each or about 1,500 Gbps. Akamai say they peaked around 22,600 Gbps during the World Cup France v Belgium game...

There is a certain amount of "taking your own cue", ie during line up the PA and pres check clocks and the contribution delay and they then run things from the clock starting things a second or so "early".

Delays and sync is a nightmare these days and it's getting worse. AIUI UHD cameras are a frame late at the output of the CCU! And of course any bit of picture "fairy dust" that a picture goes through adds more delay. Unless you are very careful its all to easy to get into deep dodo...

[Bill Wright]

Pres Trump has the right idea. Fences. Quite high ones. But no need to be as high as you might at first think... An interesting thought experiment.

Bill

[J. P. Gilliver (John)]

I didn't make myself clear - I meant why only COM 7/8. But others have answered that - regional variations. (Though I'd have thought it could work with local relays.)

Ah, I didn't know it was already being used in small areas.

You mean SFN limits bitrate.

[J. P. Gilliver (John)]

Very sticky problem. There _is_ an implied contract with consumers, though it's not written down anywhere. In practice it's less of a problem than it might be because modern equipment on the whole doesn't last nearly as long, but there probably _are_ sufficient people who've been lucky with equipment failures (or rather lack thereof) for it to at least mean bad press.

[J. P. Gilliver (John)]

[]

"You are in a maze of twisty standards, all alike."

[Bill Wright]

It's a rule in English that a q is always followed by a u. No matter how big the company they cannot change this. If they want to have a spelling mistake as their company name that's up to them, as long as they know they're wrong. Bill

[Andy Burns]

At least Qantas has an excuse.

[Mark Carver]

The larger the SFN is geographically (in terms of separation of receivable transmitters at a given Rx point), the lower the payload of the mux.

It's a trade off