New Astra 2F satellite

russell · Post by **russell** » Fri 08 Feb 2013 21:10

I now have efficiency figures for a few dishes (calculated from their quoted gain figures):

Triax 110: 67%
Raven 1 m: 71%
Raven 1.2 m: 70%

Note that the triax dish, although marketed as 1.1 m is actually a 1 m x 1.05 m elipse so is equivalent to a 1.02 m round dish.

Hope this helps someone.

Russell.

Satbloke66 · Post by **Satbloke66** » Sat 09 Feb 2013 09:44

what can I say except.....

"In theory there is very little difference between theory and practice; in practice there’s a hell of a lot of difference"

russell · Post by **russell** » Sat 09 Feb 2013 11:42

Satbloke66 wrote:what can I say except.....

"In theory there is very little difference between theory and practice; in practice there’s a hell of a lot of difference"

Hi Satbloke,

Sorry if my reply has offended you. On reflection it was a bit brusque.

I have worked for many years in research and development of television and communications and I have always found that, provided you don't make any errors (and I have in my time), theory and practise always agree. Don't confuse theory (proven) with hypothesis (yet to be proven).

There is a lot of information on other fora of the nature "it works here with a 1 m dish", "it has stopped working here with my 1.5 m dish", etc. Unfortunately this is hearsay and not proper measurement. It is not known what equipment was being used, how well it was installed, what the weather conditions were, etc.

What is really needed is for someone to do a proper field survey with a dish of known performance and an accurate signal strength meter. Unfortunately it is unlikely to happen. I can remember traveling round the UK in the early days with a large van full of equipment and a 1.8 m motorised dish on the roof, an expensive exercise.

Just to explain my comment on the effect of errors in the transmitting dish profile: The errors reduce the gain in the desired direction but all the power coming out of the transmitter must go somewhere so if it is not going in the desired direction it must go somewhere else and thus it increases the signal on the fringes rather than reduce it. The effect though is very small. This gain reduction was first analysed mathematically in the 1950s and the same equations are still used today having been proved to be correct.
The gain reduction in dB is given by:

Where epsilon is the rms surface error and lambda is the wavelength.

Russell

montgolfiere · Post by **montgolfiere** » Thu 21 Feb 2013 12:18

Signal down today... hopefully something temporary.

Allan · Post by **Allan** » Thu 21 Feb 2013 12:34

montgolfiere wrote:Signal down today... hopefully something temporary.

Just here? Or UK as well?

montgolfiere · Post by **montgolfiere** » Thu 21 Feb 2013 14:45

here.

montgolfiere · Post by **montgolfiere** » Thu 21 Feb 2013 14:51

we have been doing the suggested tests above and that is how we are coming to our coinclusions for the whole region, not just the PO

montgolfiere · Post by **montgolfiere** » Sat 23 Feb 2013 19:40

Signal seems to have recovered somewhat this evening....

russell · Post by **russell** » Sun 24 Feb 2013 09:01

montgolfiere wrote:Signal seems to have recovered somewhat this evening....

Hope your dish is sheltered from the wind.

We've been having gusts (at only 2 m above ground) of 80 to 90 km/h). Bet it's windier on the coast! The best dishes seem to be specified to 80 km/h working and 200km/h surviival.

Russell.

montgolfiere · Post by **montgolfiere** » Sun 24 Feb 2013 19:06

Installing Dishes in the shelter of the wind is my main concern as we have to install the larger Dishes. This is the reason why i am spending so much time trying to find the 'smallest' Dish for any given area and not rushing to just install a 130 for the whole region.

montgolfiere · Post by **montgolfiere** » Mon 25 Feb 2013 16:21

The signal is down around 15% again which is not good news....
Hoping this is not for too long...

montgolfiere · Post by **montgolfiere** » Wed 27 Feb 2013 09:34

Signal up this morning by 5% on yesterday...that is a relief. Hopefully it will return to its previous level shortly.

Nigel · Post by **Nigel** » Wed 27 Feb 2013 11:27

Any thoughts why the signal varies so much?

montgolfiere · Post by **montgolfiere** » Wed 27 Feb 2013 16:39

All Satellites 'Drift' off station bit by bit snd then are shunted back into position by 'firing' little directional 'motors'. This effect is not noticed where the signal is 'normal and strong' but this movement is noticable on the fringes where the signal is weak. This use of motors is one of the reaasons why the satellites have to be replaced as in effect 'they run out of Fuel'.
My own feeling is that they seem to be doing this repositioning every 3 or 4 weeks.....and this is why we are having a notcable reduction in signal during this 'cycle'

russell · Post by **russell** » Wed 27 Feb 2013 18:30

montgolfiere wrote:The signal is down around 15% again which is not good news....
Hoping this is not for too long...

Any idea what your meter measures?

If it's signal power that represents 0.6 dB
If it's voltage that represents 1.2 dB

If it's power it would need an increase in dish diameter of 7.5% to take this variation into account.

Russell.

russell · Post by **russell** » Fri 01 Mar 2013 21:11

montgolfiere wrote:Installing Dishes in the shelter of the wind is my main concern as we have to install the larger Dishes. This is the reason why i am spending so much time trying to find the 'smallest' Dish for any given area and not rushing to just install a 130 for the whole region.

Yes, not so bad for those of us with a reasonable sized garden where it could be installed behind a hedge but for those in apartments it will be a real problem.

Russell.

russell · Post by **russell** » Fri 01 Mar 2013 21:20

montgolfiere wrote:All Satellites 'Drift' off station bit by bit snd then are shunted back into position by 'firing' little directional 'motors'. This effect is not noticed where the signal is 'normal and strong' but this movement is noticable on the fringes where the signal is weak. This use of motors is one of the reaasons why the satellites have to be replaced as in effect 'they run out of Fuel'.
My own feeling is that they seem to be doing this repositioning every 3 or 4 weeks.....and this is why we are having a notcable reduction in signal during this 'cycle'

I think there must be something else going on. Any ideas?

The maximum positional drift allowed by th International Telecommunications Union is 0.1 degree from the quoted position. This is necessary to avoid possible collision with other satellites at the same nominal position. In other words it must be kept within a 0.2 degree rectangle as seen from earth. Given the beamwidth of a 1 m dish a 0.1 degree pointing error gives less than 0.1 dB drop of signal so there must be something else varying as well.

Russell.

neil mitchell · Post by **neil mitchell** » Sun 03 Mar 2013 12:13

Hi all, new to the forum but I've been following it for a few years. Thank you guys very much for sharing your expertise, really helpful and much appreciated.

I have a question about this satellite move thing, I didn't know anything about it until last week when I was at my house in Vernet Les Bains and couldn't get channel 5.

I have a 75cm dish and use a skybox and viewing card for ftv and fta channels. Always get a good strong quality signal (unless the rain is really heavy over Canigou).

So been doing a bit of research and am I correct in thinking that post changeover my options are:

Stay as I am on the UK Spotbeam but just change the dish for a bigger one (say 100cm).

or

If Sky go onto the Pan European Beam I could leave the current 75 cm dish, buy a Sky Multiroom package registered at my UK home and bring the multiroom digibox to Vernet Les Bains and use it there to get the sky package which I subscribe to.

My preference is the first option because I'm not a huge TV watcher and I hate paying for it and, if the first option is ok, Montgolfiere, do you operate that far up the valley?

Thanks guys.

Neil.

russell · Post by **russell** » Sun 03 Mar 2013 12:34

neil mitchell wrote: Stay as I am on the UK Spotbeam but just change the dish for a bigger one (say 100cm).

Yes but nobody is sure yet what size will be needed.

If Sky go onto the Pan European Beam

I think this is unlikely as their current copyright purchases only permit reception in the UK.

Russell.

Allan · Post by **Allan** » Sun 03 Mar 2013 16:17

It is definite that the main UK channels, ITV,BBC,C4,C5 and their miscellaneous variants either have moved or will move to the new satellites on the UK spot beam, so whatever Sky box you have, you will not be able to receive these all the time without a bigger dish.

Sky's own channels are also moving to new satellites and nobody knows yet which spot beam they will use. If they choose the UK spot beam then again you will need a bigger dish.

Until all channels have moved, nobody really knows what size dish you need.

In the past, the size of dish required was known as lots of people had dishes and installers knew from experience what size to use. Unfortunately that experience is no longer valid and it will only be when enough people have had bigger dishes installed that the new size requirement will be known.

Because of the uncertainty, a lot of people are taking a wait and see attitude and it will only be when all signals disappear that there will be a mad panic and enough dishes will be installed that a pattern will emerge of what size is needed where?

In short, there is no easy answer

montgolfiere · Post by **montgolfiere** » Sun 03 Mar 2013 19:09

I estimate it will probably take me more than 2 or even 3 years to change all the Dishes from my previous Customers!!!! (and that does take into account maybe 50% who do not want to / cannot have such large Dishes installed)

I am also sure that it will only be Specialist UK Installers who will have the 'handle' on the new Signal and we are rather few and far between...

so....if you want your TV to carry on after the Summer it may be wise to 'take a chance' and get the work done BEFORE we lose all the Channels in the Summer,,,, as i for one will only be able to operate on a 'First Come First Served' basis!!!.

Installing these larger dishes is not 'straight forward' and does take much more time than installing the 80cm. Dishes we used in the past!!!

and yes i work all over the PO.

neil mitchell · Post by **neil mitchell** » Sun 03 Mar 2013 19:24

Hi. Thanks all for that. I think I thought that the BBC, ITV etc were sort of "re-bundled" into a SKY package which would be available if SKY used the Pan European Beam. Glad I asked, I've never subscribed and I don't reallt want to start.

Montgolfiere, thanks, I have no doubt that you're right and I hate being behind everyone else. If I was to "beat the rush" and get in with a bigger dish, what is your best guess for dish size in Vernet Les Bains (66820) and what sort of cost, you can do it for me, you really seem to know what you're talking about.

Thanks.

montgolfiere · Post by **montgolfiere** » Sun 03 Mar 2013 20:11

At the moment i am still in the testing Phase for the Southern Half of the P.O.
and cannot give a price. However it will be more than installing a 100/110 Dish !! (the prices for this are indicated on my website. www.british-tv-in-france.co.uk.)

Although we cannot be sure of the reception from Astra 2E (it is meant to be the same Specification as 2F) it is likely that once you have a Dish big enough to give relatively reliable reception of C5, 4Seven and the likes of Yorkshire ITV 1 + 1 this will work for the BBC, ITV, C4 etc when they are transferred in the Summer.

But unfortunately this is completely out of our hands and i for one cannot 'Guarantee' this.

We have been researching the solutions for 3 months already and due to the nature of the reception, it varies from day to day and week to week, it is only now that we have an idea of what is actually suitable for the region as a whole with the last area to resolve , the southern half of the PO.

neil mitchell · Post by **neil mitchell** » Sun 03 Mar 2013 22:17

Ok thank you, understood. Just one more question, you said that the cost is likely to be more than the 100/110 cm dish installation on your website. Is that because you anticipate needing a larger dish and when you do establish a dish size will you post it here so that we can book you early. Many Thanks.

montgolfiere · Post by **montgolfiere** » Tue 05 Mar 2013 07:29

Yes, larger dishes are both expensive to purchase and expensive/difficult to transport. ( we are in favour of collecting ourselves to avoid damage/costs but the nearest wholesaler is a 7 hour round trip from here!!! ).

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New Astra 2F satellite