Cyprus: Signals getting poorer

[geoffreys]

Hi all,
After the well debated drop-off in Channel 4 signal I had my dish checked,
all OK.

Over the last 3 weeks (NOT including the period of stormy weather) signals
on both north beams of 2A and 2B have fallen by about 30%, resulting in no pictures most of the 24H period.

On the other hand signals on both south beams have increased by about 25%.

I might be wrong, but does this perhaps mean the attitude of these 2 satellites may have been altered for some reason?

A friend of mine in the Hebrides, who has to have a 1.2m dish to get 2A, 2B, and 2D, all the time (and so could nor use a SKY 'mini dish') reports a vast improvement in reception over the same period.

Any comments?
Geoff
Cyprus

 

[billnot]

I can't report any difference here in Spain. The north beam has actually improved slightly - C4 is back to 24x7 with a 2,4m dish, and the 2D horizontals (our particular bête noir) are no better or worse.

The south beam has always been strong, so I can't comment.

It couldn't be anything to do with your LNB could it? - favouring one polarity over another is often a sign of a sick LNB.

 

[geoffreys]

I can't report any difference here in Spain. The north beam has actually improved slightly - C4 is back to 24x7 with a 2,4m dish, and the 2D horizontals (our particular bête noir) are no better or worse.

The south beam has always been strong, so I can't comment.

It couldn't be anything to do with your LNB could it? - favouring one polarity over another is often a sign of a sick LNB.

Thanks for your reply. Well I could try another LNB, in fact I might do that just to make sure that is not the problem.

But if the position/attitude of the satellites has changed, such that signal into Cyprus/East Med. area has reduced - then one would expect an increase somewhere else, whether it be Spain or the Hebrides/N.Scotland.

For sure SOMETHING has changed this year to affect reception here.
We have had several suggestions - interference from Arabsat, reduced transponder power, re-positioning of satellites, etc.

Just seems strange that no one seems able to come up with a definitive answer as to exactly what has changed.

Even small changes can make a huge difference to reception in fringe areas like Cyprus, Turkey, Greece, etc.

Geoff.

 

[billnot]

I know that Astra 2A shifted enough for the north beam to become troublesome here earlier in the year. It caused a lot of head scratching, and complaints by the strong and vociferous Countfown Crowd, but it seems to have been moved back in the right spot and normal service (i.e. just about OK 24x7 on a 2,4m dish) resumed.

I promise you that the Costa Blanca is a fringe area for 2D - even with a 3,1m dish I can't get the horizontallly polarised channels after about 2200 local time (and nor can anybody else).

What I'm saying is that for us reception conditions for 2D haven't changed recently, apart from the usual slight summer deterioration.

 

[MikeO]

From my own experience in Limassol, CH4 has been fine, and noticed no change at all. Even during the stormy period last week, at times when I completely lost 2D, CH4, SKY3 were coming in loud and clear, most of the time without even any pixelation. Maybe I am just lucky and in a hotspot?
There does seem to be variable recption of CH4 across the Island.
Lets hope things get better for you!

 

[geoffreys]

From my own experience in Limassol, CH4 has been fine, and noticed no change at all. Even during the stormy period last week, at times when I completely lost 2D, CH4, SKY3 were coming in loud and clear, most of the time without even any pixelation. Maybe I am just lucky and in a hotspot?
There does seem to be variable recption of CH4 across the Island.
Lets hope things get better for you!

My friendly installer has now done a full check of my dish, LNB, feeder, and Pace 430N sky digibox. The LNB was found to have an intermittant fault, and has been replaced with a 0.2 dB version (old one was 0.3 dB, also Invacom single outlet), and the dish re-aligned as it was found to have moved very slightly in the winter storms.

Reception is thus back to normal, much improved, but Channel 4 weaker than it used to be.

He then checked Channel 4 specfically, which had improved by only 2% compared to a general improvement on all other 2A/2B channels of more than 10%. An extensive investigation with various test gear and satellite (incl non-SKY ones) revealed without a shadow of a doubt that Channel 4 reception was being interfered with by an ARABSAT transmission on the same freq.

Not much we can do about that, he advised. A bigger dish, or extensions, MIGHT improve things, but might not. I am still thinking about that possible additional expense!

He also commented on LNBs generally, Invacoms in particular. From his experience here in Cyprus it makes little difference if you use a single, twin, or quad output version for 2A/2B reception. BUT, for 2D reception the quad outperforms all the others by a big margin. Such that for big dish installations here in Cyprus for 2A/2B/2D he only uses quad output LNBs by Invacom.

I hope the above might be useful to others in Cyprus etc?

Regards,
Geoff
Cyprus

 

[billnot]

I can confirm that here on the Costa Blanca we also find the Invacom quad best for 2D, and that outputs 2 and 3 are marginally better than 1 and 4.

 

[Analoguesat]

He then checked Channel 4 specfically, which had improved by only 2% compared to a general improvement on all other 2A/2B channels of more than 10%. An extensive investigation with various test gear and satellite (incl non-SKY ones) revealed without a shadow of a doubt that Channel 4 reception was being interfered with by an ARABSAT transmission on the same freq.
Not much we can do about that, he advised. A bigger dish, or extensions, MIGHT improve things, but might not. I am still thinking about that possible additional expense!

That Arabsat interference is exactly what I predicted a couple of weeks ago. :-worship

Unfortunately unless you can lobby Arabsat to change polarities of the interfering transmission theres going to be very little you can do about it. You would probably need a much bigger dish to narrow the acceptance angles enough to avoid the 26E signal.

 

[Zorba]

Well,right now 9.30pm Cyprus time,on my 3m dish,ch4,sky two and sky three are not working.My bbc/itv are working fine(this is the weakest time for 2d).
I cant be bothered to go up onto my roof to try and fix it.
I have been in Larnaca all day reassembling a 3m Andersen four piece dish(moved house) and fitted a new invacom quad lnb.
I have my Horizon meter set on three settings,Astra vertcal high(where ch4 is)horizontal high and horizontal low(for 2D).
i was getting a reasonable reading for 2D for that area but the vertical high was very low,indicating no ch4.The house is still being built so I couldnt check on a tv.
I have always believed that there was interference from Arabsat/badr,but when I check on 12.168v on my spectrum the "spike" for that frequency is low and on a Satlook it cannot lock .
I have installed loads of 3m dh dishes and its strange how the signal for vertical high is so varied ,some are just on the fringe and some are double the signal strength.

 

[Analoguesat]

But if the position/attitude of the satellites has changed, such that signal into Cyprus/East Med. area has reduced - then one would expect an increase somewhere else, whether it be Spain or the Hebrides/N.Scotland.

You would need to be a LOT further north than the Hebrides to see any appreciable drop off in signal - Astra 2D is available in Iceland on 80cm dishes (which is why it was chosen for the Icelandic tests a few years ago).
Unless there are any Eskimo forum members up in the far far north watching Astra 2D we will probably never know what reception problems there are up there.....

 

[deepbluesky]

You would need to be a LOT further north than the Hebrides to see any appreciable drop off in signal - Astra 2D is available in Iceland on 80cm dishes (which is why it was chosen for the Icelandic tests a few years ago).
Unless there are any Eskimo forum members up in the far far north watching Astra 2D we will probably never know what reception problems there are up there.....

Anybody interested in icelandic DX ? I recommend to visit http://skrifa.com/ .

 

[divibi]

Not much we can do about that, he advised. A bigger dish, or extensions, MIGHT improve things, but might not. I am still thinking about that possible additional expense!



Regards,
Geoff
Cyprus

Geoff,

I've just come back from reading your posts in the archives about phasing harnesses, phased arrays of lnbs. Did you do it? What is the latest concensus; can it be done? What did your friend in BBC enginneering advise you?

 

[geoffreys]

Geoff,

I've just come back from reading your posts in the archives about phasing harnesses, phased arrays of lnbs. Did you do it? What is the latest concensus; can it be done? What did your friend in BBC enginneering advise you?

It can be done, but would require specially modified LNBs, fed by an external local oscllator to ensure synchronisation of the received signal by each of the dishes. The outputs of the LNBs would then be combined by a suitable phasing harness/es. The dishes (say 2,could be any number) would each require accurate alignment in X, Y, and Z planes. Cost would exceed that of a single larger dish! Project therefore shelved,

Regards,
Geoff

 

[PaulR]

You want phased dishes?

http://www.berkeley.edu/news/media/releases/2004/03/22_ata32.shtml

Currently 32 dishes but plans for 350 in total. Featured on "The Cosmos: A Beginner's Guide" last Tuesday.

Mouth watering yet Geoff?

 

[geoffreys]

You want phased dishes?

http://www.berkeley.edu/news/media/releases/2004/03/22_ata32.shtml

Currently 32 dishes but plans for 350 in total. Featured on "The Cosmos: A Beginner's Guide" last Tuesday.

Mouth watering yet Geoff?

Hi Paul,
Yes! but I see Bill Gates is involved - hope no "blue screens". Such a set up would guarantee 24/7 reception of 2D I think; reminds me of a similar arrangement (albeit simpler perhaps) used at Jodrell Bank in the mid-1960s.

Geoff

 

[PaulR]

Not Bill Gates but the co-founder of Microsoft Paul Allen - hence the Allen Telescope Array or ATA. Paul Allen left a long time ago with more money than anyone could possibly need but with credibilty mostly intact.

Re Jodrell Bank. Yes I remember a group of smaller dishes scattered around the north west and north Midlands as well.

They weren't linked together to increase the amount of signal but to decrease the effective beamwidth so that smaller objects could be resolved.

Don't know if they're still active though.