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RTE Announce FTA Saorsat service
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Your posts are in the main superb and stunningly intelligent.
Aw Shucks, thanks
There were a few simple questions i wanted to ask in the last few months but went elsewhere for the answers as people can't be sure if they are going to get a smack in the gob if the mood takes You's!
To paraphrase the Duke of Wellington and Voltaire - Post and be Damned. ("I may disagree strongly with what you say but I will defend to the death your right to say it.")0 -
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Surely though, the original proposal must have come from someone with a strong technical/engineering background? How many people are likely to have been familiar with the Kasat multiple spotbeam footprint and its suitability as a FTA transmission route?
No prior knowledge or Satellite expertise required
ANYONE in RTE talking to Sat suppliers trying to get a handle on Real Digital payTV card scheme and trying to find out how on earth to supply the 2% to 10% that won't get DTT (51 TX sites when there should be 90 to 180?) would VERY quickly be told about Kasat.
I knew about Kasat two years ago. One day or two trying to find capacity for the entire Saorview for late 2010 or early 2011, that is inexpensive. Getting told you don't need encryption would have knocked them back!
See http://www.lyngsat.com/launches/ka.html
It's a satellite intended for only Internet (VSAT). But using a transponder or part transponder (multiple carriers per transponder possible nowadays, sort of like 3 or 4 "logical" transponders) for TV/Radio/Data is no bother.0 -
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No prior knowledge or Satellite expertise required
That's simply not true. How many people, without prior knowledge or expertise, would have been familiar with the suitability of the Kasat spotbeams?ANYONE in RTE talking to Sat suppliers trying to get a handle on Real Digital payTV card scheme and trying to find out how on earth to supply the 2% to 10% that won't get DTT (51 TX sites when there should be 90 to 180?) would VERY quickly be told about Kasat.
I knew about Kasat two years ago. One day or two trying to find capacity for the entire Saorview for late 2010 or early 2011, that is inexpensive. Getting told you don't need encryption would have knocked them back!
See http://www.lyngsat.com/launches/ka.html
It's a satellite intended for only Internet (VSAT). But using a transponder or part transponder (multiple carriers per transponder possible nowadays, sort of like 3 or 4 "logical" transponders) for TV/Radio/Data is no bother.
And that's the key thing. Kasat has been always been marketed by Eutelsat for the provision of satellite internet services. The use of the Ka-band for the provision of DTH programming is an alien concept in Europe, so the proposal that Kasat could be used as an obvious solution to the copyright issues for RTÉ is plain wrong.0 -
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Agreed 100%Someone from Eutelsat (with prior knowledge/expertise!) proposing Kasat to RTÉ seems perfectly plausible to me. The whole thing rings of a technical solution to a legal/economic problem i.e copyright issues wrt to FTA and cost of providing universal coverage via DTT alone.
However from RTE's point of view no other solution can even come within x10 in cost, so a no-brainer for the folks that write cheques.
You'd think so. But probably on NDA basis and quietly with top RTENL boffin(s) only, not the guys that actually do stuff out on site.But following that, then surely management in RTÉ would have run the proposal past their technical people to check if it was feasible or not? Assuming, of course, that it wasn't RTÉNL who were approached by Eutelsat initially.
Also of course it's 100% feasible. There will be very loud gnashing of teeth and wailing from RTE if the Launch or Satellite commissioning fails. Even louder from Viasat & Eutelsat of course.
[edit, side note]
Interesting that over 20 years ago (April 1989 BBC Engineering Information: BBC TV TX stations pg.5) BBC/ITV had 99.3% coverage and after years of claiming universal coverage (when they want the cheque for a Sat service of their own) they now admit to 80% to 90%. IMO the 80% no doubt corresponding to 64dBuV/m to 70dBuV/m of the BBC/IBA 99.3% 0 -
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Originally One Satellite Transponder = One physical Transmitter, implemented with a TWT fed direct via a filter from an LNA and Down Mixer from 14GHz to 18GHz band (uplink). Very little on board intellegence ("Pirate protection" simply by making it insensitive so you needed 20W+ TX and 5m+ dish for uplink!)
Today there is more complex circuits on Satellite with ability to re-map different uplinks to different downlinks. Also one physical Transmitter can be several 10MHz, 20MHz or 25MHz channels or even maybe a single 75MHz or larger channel.
On 28.2E €1.5M a year would only buy maybe one or two SD channel's worth of bitrate. On Kasat it might be enough bandwidth for 24Mbps or 50Mbps. DVB-S2 uses less bandwidth than DVB-s (30Mbps on 28.2E might need 25MHz bandwidth). The amount of bitrate you can fit in bandwidth depends on dish size at Satellite, dish size at Home user and the Power.
The "best" usage is to simply use the exact same MPEG2-TS (Multiplex's Transport stream) for DVB-t and Satellite. It doesn't matter if it doesn't fill a physical transponder. So one stream per terrestrial Multiplex. It might take 40MHz to 50MHz depending on FEC, Modulation (no longer just QPSK on DVBs-2) and power for 2 x 8MHz Terrestrial Mux. It's possible to have the same transport stream content on Terrestrial and Satellite and it be compatible with both receivers. The DVB-s2 and DVB-t are different modulation schemes that can carry the same Transport Stream content.
Then the only cost is uplink. The €1.5M p.a. would not include uplink. Ideally they would do their own uplink and then it's a maintence and operation cost after the €85K+ install cost (4.8m dish + 20W power amp at Ka uplink frequency).
Then at each DTT site a single sat receiver that has an entire transport stream simply feeds a DVB-t modulator direct if terrestrial feed lost. Otherwise you need one receiver per channel (this is how Analogue from Sky box works) and a very expensive local encoder and Multiplex (About €95,000 to €200,000 per mux). So using same MPEG_TS on satellite as DTT saves 51 x 2 x €200,000, approx €10M. It means Sat viewers in the 2% to 10% not covered get an exact copy of DTT.
All we know about kasat is:- It's Ka band
- 80 spot beams. Probably spots x2 to x3 size shown, but frequency reuse allows some overlap and prevents further out of area as per Astra 2D with giant dishes
- Apparently N=4 frequency reuse of spots
- Four dishes on that basic model of Satellite, so same technique as one dish + multiple LNBs. Each dish must have 20 slightly differently offset feeds, 20 x 4 = 80 spots.
- There might be slightly more than 20 feeds. Redundancy.
- It's not likely it uses 80 TWTs? Many "Transponders" are likely sharing one physical (TWT). There are satellites with 70 "transponders". Even if multiple "virtual" transponders per TWT, that would be 80, if one per spot. Maybe it doesn't use TWT and is all solid state, in which case there could be maybe 8 real transponders per spot = 640 Transponders. Really we have no idea how many physical transponders its got!
- Probably launch Dec 2010 or Jan 2011 on Proton (Russian Launcher)
- Project is jointly between Viasat and Eutelsat
- Satellite mostly EADS Astrium design/Build, Based on the EUROSTAR Eurostar-3000 platform.
- Main application is Viasat's Tooway DOCSIS based VSAT using surfbeam modem. (Almost Broadband by Satellite. Main limitation is 790ms latency)
- Location to be 9E on "Clarke Belt"
- Total throughput of over 70 Gigabits per second.
- Design life 15+ years (could be less or more, some satellites working after 30+ years (badly).
- Launch mass of 5.8 tons (Ariane can launch 2 x sats simultaneously, Proton one this size)
- Payload consuming more than 11 kW of power, with solar arrays generating 15 kW of power. Thus less than 100W per spot. Many Satellites are about 20W per spot! The Dish has a lot of gain, maybe 50dB!
Irish Spot and corresponding French on same frequency, blocking English reception (see red line)
Spots same colour are same polarisation/Frequency band
This shows shape slightly better.
Note: It's likely all Irish spot is same polarisation and band. Even if you have the Tooway Internet, it's likely you can just split the receive coax for modem and Feed any number of sat receivers without a Quad LNB etc. Only longer cable or more that 4 tuners is likely to need an amp.
All known spots
(There may actually be more than 80, I have not counted how many are shown)
Artist's mockup of Eurostar-3000 (believed to be what Kasat is based on )0 -
Has the idea of Ka band spotbeam TV delivery been around RTÉ since 2008 or maybe someone in RTÉ read this Rapid TV News report last March.
No idea.
But I've worked with this kind of stuff for years, even designing systems. Never ever was there any suggestion that Ka Band or Kasat could not be used for DTH TV. It's just that the main market for next 5 to 10 years is obviously the installed base of Ku. Only a Niche product was ever going to use Ka or Kasat for TV. If Scotland got Independence and their own real equivalent of RTE (not just ITV content rebranded STV) then the top two spots would have to have the Scottish Mux. They could neither afford English Rights nor Encryption
Top two spots for real STV?
If the Welsh got independence and wanted an English Channel (some folks do speak English there:) ) then there is a handy Welsh Spot. I suppose the "Rights Holders" wouldn't charge them too much more for Cornwall, Devon and Somerset/Bristol.
German, French, Italian, Spanish, Sky, Freesat and pay TV generally isn't going to be interested in ka spots for a good number of years.0 -
Found this interesting 'stack plan' or 'stacking plan' for Ka to IF downconversion on DirectTV...DirectTV LNB IF outputs by frequency.
While the Ku IF norms are observed , look what they do with the Ka frequencies FFS
Some are sent down on DTT or VHF Band III frequencies and some are sent down above the Ku band IFs . Damned if I know a receiver that will tune into them though.
This forum contains lots of data and much anorakage abounds thereupon. However DirectTV ( the biggest Ka user ) tucks Ka down conversion around the standard Ku IF ...above and below .
Were a DVB-T 'mux' payload broadcast in the Ka Lo band as Watty intimated then a DirectTV LNB would output it between 250mhz and 750mhz ...locating the 'mux' precisely in the upper part of the Ka Lo band would correspond to a DTT mux frequency meaning that a sat receiver would not be required at all, a Saorview receiver would do it.
You would have a Ka Lo LNB input into a DTT box.
Some 18v style power injection and current return blockage would be required to the LNB at some stage....evidently not from the DTT box of course
Bit more data in this multiswitch data sheet
http://www.prosatellitesupply.com/PDF_Files/WB616manual.pdf
Can anyone tell me if a Ka LNB switched to H or V and transponder and with power then disconnected would work as a passive unpowered LNB thereafter...ie would it only require power to set transponder frequency and polarity....once...or does it require continous power and if so how much ?!!??0 -
Never ever was there any suggestion that Ka Band or Kasat could not be used for DTH TV.
Surely no one would be daft enough to make such a suggestion.Sponge Bob wrote: »While the Ku IF norms are observed , look what they do with the Ka frequencies FFS Some are sent down on DTT or VHF Band III frequencies and some are sent down above the Ku band IFs . Damned if I know a receiver that will tune into them though.
They use receivers with standard L-band tuners, but with a B-band to L-band upconverter in between. As outlined previously here. The receivers originally were similar to the Quali-TV MPEG2 HD receivers which were mostly used in Europe for their 4:2:2 capability.Sponge Bob wrote: »Can anyone tell me if a Ka LNB switched to H or V and transponder and with power then disconnected would work as a passive unpowered LNB thereafter...ie would it only require power to set transponder frequency and polarity....once !!
I don't quite get what you're after, but the LNB needs to be powered at all times to downconvert (and amplify) from Ka-band to L-band. The receiver tunes to a specific frequency, not the LNB.
[edit] The use of the term 'Ka-Hi' in the 'Output Frequencies' in the pic above is somewhat misleading. A satellite tuner with 950-2150MHz range is standard. But the Americans are a little different in the way they approach the Ku-band - universal Ku-band LNBFs are still something of rarity in the US.0 -
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