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HD and Freesat questions and answers

Al posted some very good questions about HD and Freesat.

Al posted some very good questions about HD and Freesat.
published on UK Free TV

Al posted some very good questions about HD and Freesat.

"I know upscalers are not HD, they merely interpolate a SD signal to make it fit a HD screen"

It is very confusing that HD is used to mean several different technologies. High Definition refers to:

  • the resolution the number of picture cells of the screen;
  • the resolution of the encoded pictures;
  • the resolution of the source material;
  • as "HDMI" the digital connector between a set-top box and a display;

There are also a number of associated technologies, which come under the name MPEG4. These are used to encode the pictures, audio and data that you recognise as a TV signal.

Standard Definition (SD) is shorthand to refer to the resolution of PAL-type televisions. Technically this is called MP@ML, Main Profile at Main Level.

"My point was where a programme has been recorded in SD only, then it is still possible to have a HD only transmission service by the use of upscaling those programs to HD format - something I understand Sky do now with some of their content."

This is not necessary. MPEG 4 can work with sources at any of the defined resolutions. As a rule you should always transmit the material in the original format wherever possible. Interpolation before the data compression just results in unnecessary data, or a poor encoding.

"Point is it allows a HD only format channel in the interim between some programs and all programs being recorded in HD. "

This is exactly what you would expect from the history of television. BBC One started as BBC Television in monochrome, 405-line and moved first to 625-line colour and then to MPEG2 digital widescreen. This is true for all UK services.

You would expect the next transformation to be to HD.

"As for the hundreds of channels on Freesat currently, I understood that Sky Freesat and BBC Freesat were different entities."

The Eurobird 1 & Astra 2A/2B/2C/2D at satellites over the equator at 28.2E provide transmission services for the UK.

Broadcasters are quite free to upload any content to these satellites. Each transponder carries a digital stream in MPEG2 format that each has ten or more television channels.

Some of these services are free-to-air, some are encrypted. Anyone is free to point a dish at it and use a suitable decoder to watch the services.

The BBC and ITV channels are unencrypted and numerous. Each BBC and ITV region has to be carried on the satellites, as this is the only way to replicate the local services provided terrestrially.

To add to the confusion there are some services that are what is termed "soft encrypted", which means a card is required to decode them, but no subscription is required.

So, "Freesat From Sky" comprises all the free-to-air services PLUS a number of soft encrypted channels: Channel 4, five, five Life, five US and Sky Three. The Sky service also includes the Sky Electronic Programme Guide.

"The Sky Freesat being Sky's current free to air system and BBC Freesat being a BBC / ITV collaboration producing a new satellite service."

Sky's Digibox set-up is a special version of a satellite receiver. It contains a special Sky subscription card system, the Sky EPG and also a software system called "OpenTV".

The BBC/ITV Freesat service, called just "Freesat", will use all the existing free-to-air satellite broadcasts and provide a non-Sky EPG. There will be no subscription system and it will have the MHEG-5 software, as all Freeview boxes have.

In addition the boxes will be able to decode MPEG4 transmissions, which will allow high-definition services to be carried.

The Freesat boxes will be of various types, from a basic box to a high-end personal video recorder (PVR), like Sky+. Without the monthly fee, however.

"However, if they are the same, then the answer is still yes. If it is the same service then either way its done, those 9 million boxes will have to be changed one way or another."

This is always a dilemma of digital technology. If you make cheap, mass market decoders you have to fix the standard. All the Sky boxes out there are MPEG2, DVB-S.

So, all new HD services and any other SD services encoded with MPEG4 are totally invisible to anyone with an "old" box. So yes, over time, the whole system will move to MPEG4 in HD.

This provides an interesting question. If you have a SD channel, do you use MPEG4 or MEPG2?

"It's far better to set a defined changeover date and switch off the existing Freesat service on that date in favour of a new HD only service than to confuse consumers by having two parallel systems with intermixed programming of ever changing proportions that leaves people unsure about what, when and where to get HD content."

It might be, but it is not just Freesat from Sky people using the current free-to-air transmission, but all those Sky subscribers too. Until they have all got MPEG-4 boxes, you can't move to HD.

"I know you next reply will be what about the consumers who've only just bought a Sky Freesat SD box? Well the answer is: - exactly the same scenario will apply whether the switchover is made by gradual means, someone somewhere will have only just bought an SD Freesat box. "

I understand that the idea is that ALL Freesat boxes will be able to decode MPEG4, even if they output a downscaled version of HD channels on the SCART.

There is going to be many years of people moving from SD to HD satellite reception.

"If Sky wanted to soften the blow, then a simple trade in discount scheme for those who've bought boxes in the last 6 months would suffice I'm sure."

There's not much in this for Sky. Remember that Sky only provide a very few of their channels. They provide the subscription services, but they do not play-out, encode, multiplex, uplink most of the channels.

The only way that Sky will start swapping out boxes will be if they can make more money. At some point, as with the analogue satellite closedown, it becomes cheaper to force customers to have a new box than waste money on inefficient transmissions.

"All of this gradual rollout rubbish not only confuses consumers by blurring the issues of what programming is available where and when and what equipment is needed (2 parallel types) - this is quite contrary to the claims that it is avoiding confusing consumers."

You are right. Confusion isn't the half of it.

In the US, there has been a very simple transition from analogue, 4:3, SD to digital 16:9 HD. Each SD channel has simply transformed into a HD channel.

Whilst in the UK, we have transformed so slowly that the early start has meant that by the time we achieve terrestrial switchover, the technology will be out of date.

"The current analogue switch over is the slowest and most confusing thing out!! If that's the government's idea of helping consumers they should stick to politics."

To be honest, the government's policy is to not intervene. The satellites are provided by two companies, SES Astra and Eurobird. The uplinking by several UK companies, including BT. The channels by hundreds of broadcasters.

It is policy that the providers can do as they please.

"This current policy is also putting the UK behind the rest of the world."

Not really. Everyone in the EU is in the same kind of boat.

"I believe JVC has already announced that it's to start manufacturing test sets for the next generation of TV's dubbed 4k2K (4096x2160 pixel resolution) and that broadcasting trials of this format will commence in 2011 in Japan."

You can't measure other countries expectations against our current position. Also, other countries are more bothered about consumer choice than government income.

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Wednesday, 1 June 2016
1:44 PM

in light rain it doesn't affect signal level at all .##

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Den's 5 posts GB flag
4:19 PM

ITs raining lightly now sorry for that but it was a mistake . In light rain the signal level is 80% signal and 95% quality no break up as yet

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Den's 5 posts GB flag
Thursday, 2 June 2016

7:02 PM


A Zone 1 dish is borderline in central England and poor further north. A Zone 2 would be far better. In Trowbridge I use a 65 cm dish and have no issues. I would advise at least that size for you location. Remember that for satellite reception, you very rarely get too much signal but it is not uncommon for people to have too little.

When I wrote the initial dish installation manuals for installers, when the first Astra satellite was due for launch, we had to calculate some complex mathematics to determine dish positioning and size for may different parts of the UK. The fact that Sky and Freesat now use digital encoding does not alter the need for sufficient signal to give reliable reception. In the analigue days you would get 'sparklies' which showed you had reception problems due to insufficient signal to noise ratio. Nowadays you get break up and drop out telling you the same.

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MikeP's 3,056 posts GB flag
Thursday, 16 June 2016
7:25 PM

Hi im thinking of getting a signal booster becuase my freesat box losses all signal in heavy rain and some signal loss in light rain . Dry weahter signal on my manhattan plaza hd-s2 freesat box is 74% signal and 99% quality. On most channels some are 76% signal strength and 99% quality. I'm wondering if I should get a satellite signal booster or is my signal level perfectly good for a mindish or should I get a booster to see if it'll raise my strength.

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Ron's 2 posts GB flag
Friday, 17 June 2016

12:59 AM

Ron: These indications are perfectly in line from what would be expected on a Manhattan Plaza Freesat HD-S2 / minidish combination, and slight variations in strength between channels is quite normal as you are receiving signals from different transponders, i.e: Sat equivalent of a Mux transmitter.

As far as the variation in levels during certain weather conditions are concerned, you should consider scrapping the minidish in favour of purchasing a Zone 2 Sky dish such as used in most areas North of the border, (even larger in some Highland areas) as these types capture a higher percentage of the signal, likewise will perform better under adverse weather conditions over what you are presently using.

Of course, it has to be appreciated that signal breakup usually occurs in most satellite systems during really heavy thundery type downpours.

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jb38's 7,179 posts GB flag
9:08 AM

I am in Peterborough im glad to know I'm receiving a good signal I had another freesat box but had a freezing fault and that box showed a signal strength of 84% and on some 90% where's this one 74% on most and 76% on the most powerful just strange how it's lower but I guess as it's still a good signal level it's perfectly fine .

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Ron's 2 posts GB flag
Richard Cooper

10:19 AM

Ron: Hi, Ron. As far as satellite tv reception is concerned, I would concur with jb38 and recommend that you change your Zone 1 dish for a Zone 2, which works a lot better for people who are in the Midlands because Zone 1 dishes are only really any good for people who live South of Peterborough. It is always best to tackle the problem at source as they say. In the case of Freesat, it is the dish and its LNB that picks up the signal, so improving that by changing to a Zone 2 dish will do you a lot better than buying a booster which would amplify noise too, and in the end could actually give you worse results than you have at the moment. Whilst I remain an advocate of boosters for Freeview tv and for radio receivers, I don't advocate boosters for Freesat. Richard, Norwich.

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Richard Cooper's 466 posts GB flag
Richard's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage

1:46 PM


Having written the original satellite dish installation manual for fixed dishes before the Astra satellites were originally launched, in 1988/9, I concur with Richard and jb38 that a Zone 1 dish is just not good enough for anywhere north of a line roughly between Ipswich and Taunton, north and west of that line you need at least a Zone 2 dish. In northern Scotland they need to use even larger dishes, often resorting to 90 cm ones!

With satellite reception you should never use an amplifier as they also amplify unwanted noise, as Richard stated, and that makes it more difficult for the error correction system to resolve errors. As long as there is sufficient signal to resolve the data, any stronger is merely 'good insurance' against signal reduction due to weather, such as rain and especially snow. It is highly unlikely that using a larger dish would be any detriment unless you try using a massive one over 90 cm in your garden (but that needs planning permission!).

It is always better to use the appropriate dish/aerial for the location, aiming to not need any amplification at all. Only in known weak signal areas could signal amplifiers be any benefit.

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MikeP's 3,056 posts GB flag
Saturday, 25 June 2016
12:25 PM

Hi I also have problems with signal in rain the thing I find odd is in light rain my hd channels freeze in heavy rain or thunderstorms I lose all channels but why are hd channels affected in light rain when sd signal copes well until dropping to 50% quality where's hd channels freeze with the slightest drop of signal

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Leonardo's 1 post GB flag

1:19 PM


I assume you are discussing problems with satellite reception? If so, it would seem that your dish may not be of sufficient size to gather enough signal to cope with natural variations due to weather. An idea of your location would help (a post code will suffice) and an idea of the dish size installed.

If, on the other hand, you are referring to Freeview reception, then a full post code is essential to determine your local recption conditions. Objects, such as trees, in line between your aerial and the transmitter can cause signal reduction when the leaves get wet. There are other possible causes to so the full post code would be useful to help resolve the issues.

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MikeP's 3,056 posts GB flag
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