BBC White Paper Claims HD Over Low Bandwidth Signal 88
Kelten Miynos writes "According to CNet, the BBC has written a white paper in which they claim it's possible to double the available Freeview TV bandwidth by using some clever technologies. 'Doubling the space would mean we could easily have HD channels on Freeview, although everyone would need to buy a new receiver and aerial to pick them up. The key to all this is something called MIMO, which stands for multiple-input multiple-output. MIMO works using two transmitters, and two receivers. The two transmitters mean the two sets of data — sent on the same frequency — will arrive at the receivers at different times. Different arrival times are what allow the receiver to differentiate between the two separate signals and subsequently decode them.' These procedures could then be transplanted abroad to other countries with similar services."
Usage (Score:2, Interesting)
MIMO isn't exactly news though, but it's of course interesting to see it being used in this context.
I wonder how long this new found bandwidth will be enough, as we tend to expand usage right along side available resources at a disturbingly linear rate.
Fascinating technology, but useless for Freeview (Score:5, Interesting)
As the article says, a far simpler solution to the badwidth issues of freeview would be to ditch the huge number of junk channels and use the bandwidth to provide a HD signal for the ones that people actually watch.
Re:Fascinating technology, but useless for Freevie (Score:1)
Re:Fascinating technology, but useless for Freevie (Score:1)
Anyone care to tell us yanks wtf freeview is?
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http://www.freeview.co.uk/home [freeview.co.uk]
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I'm not sure I should even bother to type this, since your UID is much lower than mine.
If you read this far in fact, I'll reward you with this top tip: Avoid the "hard to open" jars in the cabinet in your bath
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Re:Fascinating technology, but useless for Freevie (Score:5, Informative)
Digital TV via an aerial. [wikipedia.org]
Previously there'd been two competing digital TV providers: Sky, selling digital via satellite, and ITV Digital, selling digital via aerial. Although both carried the same basic menu of free-to-air channels, they were basically pay-TV providers trying to push subscription services, and didn't really achieve much. Sky Digital inherited the viewers from Murdoch's existing satellite operation, but didn't really expand the market AFAIK, and ITV Digital did very poorly, being a second-best offering as a pay-TV platform, and again failing to win over the majority who aren't really interested in pay-TV. ITV Digital folded after a while.
At this point a BBC-led group established the Freeview standard, which is based around a set-top box made as cheap and simple as possible, and which provides a comparatively small number of free-to-air channels. There's an expansion that allows encrypted pay-TV channels, but few exist and hardly anyone bothers. Because the box was very cheap and it was a one-off expense - no subscriptions, no registration - it became the standard very quickly. These days it's being built in to most new TV sets as standard, and supposedly we're on course to be able to switch off the old analogue broadcasts on schedule.
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It's because there's more than 9 channels... (Score:4, Informative)
As anyone with a cable or satellite remote control already knows, multi-digit channel numbering means that if you want to hop non-sequentially between channels and the channel numbers are only one or two digits, then the set-top box will pause for a second or so to see if you are adding the second or third digit. If you don't, then it assume that the digits entered so far are the complete channel number and then jump to it.
This is why many Freeview remotes have a "channel plus" and "channel minus" button to get around this problem for channel surfers - just press that to cycle sequentially through the Freeview channels with no digit-delays. I find channel changing to be about one second on the Freeview and IDTV sets using the +/- buttons on the remote, which is OK (but I could believe slower boxes might take 2 seconds, but certainly not 5).
Channels not nicely numbered to allow such +/- surfing? Again, many Freeview boxes/sets allow you to reorder the channel numbering to your preference (e.g. I can only get Welsh Freeview, which insists on putting S4C on channel 4 and English Channel 4 on channel 8, so I swap those over!) and, even better, let you delete channels completely, which I do for all the pay channels, shopping channels etc.
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Actually, the GP may just have been referring to the fact that pretty much all Freeview boxes apparently have crappy firmware/hardware (at least I haven't found one that doesn't), and changing c
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Take one HD channel to transmit scaled down versions of all available channels for some given area. Keep one tuner constantly on this channel. When switching, briefly show the scaled down version while the main tuner switches over.
I'm sure this isn't the best solution however.
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Take one HD channel to transmit scaled down versions of all available channels for some given area. Keep one tuner constantly on this channel. When switching, briefly show the scaled down version while the main tuner switches over.
Hey, maybe you could also use that channel as a video channel guide - simultaneously see all available channels, tiled onto one screen in low-res, then pick the one you want...
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Re:Fascinating technology, but useless for Freevie (Score:2)
And who decides what the 'junk' channels are? Not everyone wants to watch mainstream reality-TV and soaps. If I was watching some obscure sci-fi programme or documentary I wouldn't want it cancelled so they could show Washed-Up Celebrities Dancing and Singing Badly on Ice in HD.
Re:Fascinating technology, but useless for Freevie (Score:1)
Of course we will have to buy new boxes to watch HD anyway.
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Indoor aerials suck.
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Thing is that these along with the quiz (lottery) channels are likely to cost nothing to the broadcaster, possibly they even pay to be broadcast...
Re:Fascinating technology, but useless for Freevie (Score:2)
Quite right. Why do I have to put up with that BBC1/2/3/4, ITV1/2/3, Channel4 and Five junk when I never watch it?
Re:Fascinating technology, but useless for Freevie (Score:1)
We could start by only having one channel that plays friends and scrubs all day, instead of three.
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We could start by only having one channel that plays friends and scrubs all day, instead of three.
Which would free up a channel for all the various flavors of "Law and Order" and another for "CSI-wherever", and I could program out both.
Of course what I really want is for anything to do with Donald Trump (and I mean anything, including any mention of him by others) to be confined to one particular channel, and then I can install a notch filter right where the cable hits the grounding block at the demarcation point.
The upgrade cost means it will never happen (Score:5, Informative)
Anyway, if you are going to have a new box, why not move to MPEG4 as well? That would double the number of available channels again.
Re:The upgrade cost means it will never happen (Score:5, Interesting)
You aren't being forced to switch all frequencies to MIMO. You could just as well leave half the spectrum in-place for standard definition, and just broadcast MIMO on the other half.
The PDF mentioned this test was done using h.264.
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In other news... (Score:5, Funny)
Who cares? (Score:1)
Because we can't all install satellite dishes (Score:2)
Being in a town is great as I can get my Freeview reception and speedy ADSL2 - unfortunately I'm not allowed to slap a satellite dish on the outside of my building and as even the f'in pavement outside is listed, it was considered too expensive to lay cable. If I'm ever to get HDTV it's going to be using MIMO, after switchover, or IPTV.
Now I know I'm probably in a somewhat rare position, but loads of people find they can't re
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Sky HD isn't up to much at the moment, so don't feel like you're missing out
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What is MIMO (Score:5, Informative)
The most exciting MIMO technology is also known as "space multiplexing," which lets a system with N transmit and N receive antennas transfer data at N times the rate of a system with just 1 transmit and receive antenna. The marketing departments like to use MIMO to refer to any old system with multiple antennas, because technically the definition is correct. However, most of the time those systems can't get this kind of performance gain. I believe most of the pre-n hardware out there just does fancy antenna selection; the language is usually careful to say that "802.11n supports space multiplexing," even though it is optional, and there are no performance numbers yet. Someone please correct me if I'm wrong, which I'd love to be!
The way space multiplexing works is counterintuitive: each transmit antenna sends an independent stream of data on the same frequency. The "magic" that makes it work is the fact that multiple receiving antennas observe the combined signal at different times (the article summary got it surprisingly right here); specifically, the phase offsets observed at different RX antennas should be random. This can happen when the signals bounce off a lot of objects like walls indoors, or buildings etc. outdoors.
Here is a simplified example that illustrates how this can work. Suppose we have 2 transmit antennas. Suppose at a given time we send two signals a and b. If we only had one receive antenna, we would observe (a+b), and there would be no way to extract the individual signals. However, if we have a second antenna, AND the phase offset happens to be such that the other antenna gets (a-b), we can clearly extract the original signals.
There are environments such as open outdoor fields with line-of-sight, where the received phase offsets are not random and don't happen to be "nice" like in the above example; in that case MIMO performance falls back to 1x1, or a little better if the phase offsets have some degree of randomness.
Re:What is MIMO (Score:5, Informative)
The correct summary would be "BBC White Paper Claims HD By Efficient Use of Existing Bandwidth".
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Re:What is MIMO (Score:4, Informative)
A good example - When listening to an old analog FM radio station in your car, you stop at a traffic light or a traffic jam and the station basically fades out to the point that it is static. For whatever reason, you move your car a few feet, and the station is now coming in strong. (Or when driving along the road, the signal quality "flutters" rapidly). What is happening here is that the signal between the radio station and your antenna isn't necessarily traveling in a straight line - more likely the signal is being reflected off of objects near the radio station or near you. In some cases, the path lenghs of these signals are such that they all add in-phase (constructive interference) and the signal is strong. In other cases, they are out of phase and cancel each other (destructive interference) and you get static.
Now imagine that your car had two antennas with some physical distance between them. Then your radio could choose the signal with the strongest signal, with two antennas there is a significantly reduced probability that BOTH will be experiencing multipath fade at once. This is generally called receive diversity. Some companies now call this MIMO even though it really isn't. Some diversity systems user fancier combining algorithms, but most just use selection diversity. It is also possible to have transmit diversity, although it is somewhat more difficult. Usually the transmit modulation scheme and the transmitters themselves need to be modified to do this, unless the transmitter is aware of the path from it to a receiver (i.e. a point-to-point link with some sort of feedback channel from the receiver back to the transmitter). For a scheme that works without knowledge of the channel, search Google of Wikipedia for Alamouti space-time multiplexing. Such systems provide no benefit in line-of-sight situations, but reduce penalty in multipath situations.
Also, a car with two or more receive antennas could instead combine the signals in such a way as to form a single virtual antenna that was directional, rejecting some of the paths causing interference. Such techniques are known as a phased array antenna. Phased arrays can be fixed (directionality governed by wiring harnesses), and steerable (directionality controlled by configurable phase shifters and configurable delays), and this category can be either manually steered (operator steers the antenna) or adaptively steered (receiver guesses the best way to steer the antenna to maximize the received signal.) Again, some companies now call this MIMO. For example, the "MIMO" system used by Ruckus Wireless (and licensed to Netgear of their RangeMax WPN824) is just an adaptive phased array system. (Not that this is necessarily bad - it's the best way to improve performance with "legacy" endpoints that don't understand true MIMO techniques, but can't achieve the full capacity of a true MIMO system.) Phased array systems provide a Log(N) improvement in capacity in line-of-sight situations, and also a reduction in multipath penalties.
A true MIMO system can analyze the paths between all transmit and receive antennas, and effectively transmit different data on each path. In reality, most such systems do it in a more abstract manner - a matrix is formed in which there is one row for each transmit antenna, and one column for each receive antenna, and each element of the matrix is the gain between the transmit and receive antennas associated with that row/column, the singular value decomposition of this matrix is calculated, and the singular values (which are related to the matrix's eigenvalues by the way) represent the gains of the possible "virtual" channels formed by the MIMO system. (I have a link on my work machine to a VERY good d
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Yes, quite. The independence between antenna pairs arises from delay spread, caused by signals traveling different distances.
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Early television receivers suffered something similar when airplanes flew overhead and bounced back the signal, which arrived at the antenna slightly later than that which was coming straight from the transmitter.
True MIMO 802.11n exists (Score:2)
I am almost as certain that other implemen
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Wouldn't better/DVD quality at the same framerate at a lower bitrate simply meant a more efficient compression scheme is being used, meaning lower signal frequency and thus power usage for the same decompressed results?
And what makes you think a digital signal means you can't use an analog display, like all TVs and CRTs have been for years while playing back DVDs and PC content?
Re:Fuck DVB-T (Score:4, Insightful)
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DVB-T in Australia transmits the SD TV (non-HD) channels at a rate of about 3 Gbyte/hour, which should provide a picture at least as good as your average DVD.
Assuming the realtime MPEG-2 encoders at the TV stations aren't junk.
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Yes, I too hate pixelization, but the decode box should really have options to smooth that out/filter process it.
One thing they could do is perhaps offer a SD-HI mode on the HD channel like 7 does. If there is no HD content, then just offer
a 576p SD version at HD bandwidth rates on the HD channel, rathern than just upscaling an SD signal to HD format.
They should also do proper HD
Cable companies did something similar (Score:2)
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When I lived in the Comcast service area, they actually had two coax wires entering the house. Without a cable box you would get one channel line up on A and a different line up on B. Both wires went into the cable box. The cable box assigned these signals to a different set of cable channels. IIRC I somet
Using just 2 is not all we could do (Score:2)
Complete Rubbish (Score:1)
Basically once you add a second transmitter on the same frrequency the noise floor increases. Basically the first transmitter adds noise to the second transmitter, and vice vera. Some people will argue that if you know what the first signal is then you can subtract it to find out the second signal. Things do not work like this since the first signal is distorted in the ether, meaning that you cannot properly subtract it.
If there was the bandwidth available to have the two different
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Re:Complete Rubbish (Score:4, Interesting)
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Does it still work in marginal reception areas (like on the borders of 3 regions) and in unfavorable weather (either heavy rain reducing signal levels or high pressure allowing interference from very long ranges)?
Present Freeview has problems in places not 30 miles from the centre of London - especially
on the ITV channels that use the higher symbol rate.
Andy
(Rayleigh, Essex - on the fringes of London, Meridian, and Anglia areas)
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I've seen MIMO before... (Score:1)
I had a MIMO Netgear wireless card and router once. They claimed it doubled the bandwidth and range of your WLAN on the same principle. I thought using two signals was kind of cheating, but it worked.
Here's one of the routers [netgear.com].
Just like The BS of BluRay or HDDVD (Score:5, Interesting)
You can get HD content on standard HD discs. a dual layer standard DVD can hold incredible 1080i content that looks fantastic on all HD displays available, but then it does not have DRM up the wazoo and is not making several companies morbidly rich with royalties.
This seems like something simple I half remember.. (Score:1)
They have 8 MHz! (Score:2)
Here in the U.S. we have 6 MHz channels for our terrestrial 8VSB DTV, we have 19 Mbps, and HD works just fine, thanks.
My understanding is that Freeview was SD only because the set-top-boxes had to be cheap.
Why not use more channels per station ..... duh (Score:2)
Give every tv station 3 channels each so they can have a HD channel, SD channel, Repeat Channel. Along with that there are sub channels for each of those, but
thats like a much easier solution, which costs zero dollars.
But I forget, in this world, no one likes solutions that cost $0, because then no one can feed of the system and make more money out of it.
This technology exists today (Score:1)
They already sell boxes that tansfer HD signals from 1 location to another. Yes, the context is different but the technology is already on sale.
MIMO (Score:2)
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> If Vista has such great scheduling and other improvements under its hood,
> why does it run slower than XP?
Because it's bigger, and so it swaps more unless you have loads of Ram.
Pity the consumer... (Score:5, Insightful)
To a first approximation, the technologies are each presently operated by a separate single supplier: DVB-S by Murdoch's Sky TV, DVB-C by Virgin Media (formerly NTL/Telewest) and DVB-T by Freeview (a consortium in which the BBC is a main player).
The principle advantage of "Freeview" is that it provides a very simple marketing message: you buy a £30 box which plugs into your existing aerial (mostly) and TV and that's it. In exchange you get both a wider range of channels and protection against the "analogue switch-off".
That message is getting progressively less simple, though. Freeview has subscription channels (entertainment and sport) as a result of the legacy of the collapsed On-Digital/ITV Digital service that preceded it (needs box with a card slot). There is also some limited PPV (mainly porn) which interestingly requires no card but an access code obtained by telephone.
Furthermore, there is a significant demand from broadcasters for additional Freeview slots - recently there have been auctions for broadcast rights which have reached millions of pounds per channel. In order to prevent interference to analogue signals, the number and power of DVB-T channels is artificially limited at present leading to a seriously-constrained supply of channels. Partly this has been addressed by improving the encoding and stat-muxing process, partly by compromising on quality (some services average below 2MBit/sec video rate) but basically the available spectrum is full. Sky TV (which is also a content provider as well as operating a DVB-S platform) has 3 channels on Freeview which it has contemplated pulling and replacing with 4 MPEG-4 channels which existing Freeview hardware cannot receive in order to increase the number of channels it can provide on DVB-T.
So, despite the current constraints, DVB-T has been a success. The danger is that the capacity constraints will cause the platform to fragment as different content-providers try to deal with this and the consequent increasing costs by invoking a range of incompatible technical solutions and payment mechanisms.
It was originally believed that the closure of analogue TV would enable a significant increase in the coverage and capacity of Freeview, but the government has since made it very clear that it intends to auction off the spectrum space rather than simply re-allocate it to Freeview as it becomes available. Consequently, the future expansion of Freeview is in doubt and the BBC in particular is concerned that it might only be able to provide HD programmes on DVB-T by sacrificing other channels.
This technical research by the BBC is very much a desperate bid to retain the future viability of DVB-T, in which it now has a significant stake, in the face of current government policy. So don't assume it's the BBC's preferred option: the recent DVB-T HD trials used rather more mundane and easily-deployable technology.
At the same time, there are consultations on switching off FM radio (about which there is a serious outcry as the DAB alternative is also seriously constrained by limited spectrum space meaning that the audio quality of FM is actually better; one possible consequence of which is that FM is switched off and DAB is enhanced incompatibly with current receivers) and trials replacing AM radio with DRM (that's Digital Radio Mondiale in this context!).
In almost 90 years of public broadcasting there has historically been only one major technology shift in Europe that has obsoleted consumer equipment - the move to colour TV (which led, after a decent interval, to the shutting down
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The BBC and ITV recently announced Freesat, beginning next year, that will deliver their channels in HD via satellite. Looks like a good solution for those happy to pay a premium for HD.
Personally I believe the government will have to rething their pl
Move to digital is bad enough (Score:2)
The tech savvy people might be willing to do so, therefore if this happens it should be in parallel to the existing system.
HD will be good news, but only if they don't compress it too much. The compression needs to deal with motion well too for sports events.
Er... (Score:1)
Oh Brother, I can see it now... (Score:1)
Martha: Oh Blimey Harold, you and your matches are gonna be the death of me.
Harold: Edwina, darling, are you ready for the game?
Edwina: Yes, Father, just climbing into position now.
Harold: Okay Martha, a little farther up and to the left..
Martha: (Mutters something unintelligible)
Harold: Now Edwina, my little flower, if you'll hold your antenna straight and turn ever so slightly towards the south, that would be lovely.
Edwi