Anyone having problems with CBS Action?

[DishDick]

No to most things, but as there are many valleys here I am betweem 3 terrestrial transmitters and many mobile phone masts.

The closest transmitters are completely shut out by buildings, there is a possibility of one distant one having sight of dish, but only from behind it.

 

[hexah]

That is good to know.

So my theory...

That said it probably is a dect phone or router in a nearby house, the dish is so large it will amplify enough weak signal to put a spike on one frequency but not give the usual splatter.

...may be the right one.

Assuming you have checked the skew, as Huevos suggested.

 

[Huevos]

DD, the suggestion of DECT interference confuses me. DECT runs from 1.882 GHz to 1.897 GHz so if we add on local oscillator frequency (10600) we get interference between 12482 GHz and 12497 GHz. I'm just a layman though so I may be overlooking something here. Also in my experience DECT only causes problems when the phone is in use. For example I can just about receive the north beam here (12480V) and it works fine but it's only when I receive a call that I lose lock on the transponder. I can't say this is universal behaviour, just my finding.

Also don't forget interference can get in anywhere. Don't assume anything. In my case the DECT phone interference was happening in the living room and just moving the DECT phone a few meters from the satellite receiver cured the problem.

You didn't answer my question about skew. I seem to remember you have a proper meter. Try skewing the LNB for one of the stronger transponders on EB1, at least temporarily until you narrow this down.

 

[DishDick]

Skew was adjusted as was dish alignment as a comprimise between Astra (esp 2D) and Eurobird. Only two EB channels having any probs. Don´t think it is a DECT phone, unless they cause problems from long distances. I had two of my neighbours turn off their electric supplies and no one I know around here has a DECT phone. Still watching the film on 5 at mo. After that I will be on the roof, so hopefully will have some positive feedback very late tonight.

 

[DishDick]

No. Turns out its not interference. It is alignment issue. Lifting the arm slightly gives a perfectly good signal on 12560, but I loose BBC CH4 etc. Pressing slightly on the arm increases BBC etc.

Only thought is that packer round CM feedhorn has a grove for the CM bracket that is thinner than my bracket, hence the LNB is about 2mm higher in the LNB holder. Wonder if I file the whole packer to the depth of the grove whether that would make a difference.

I am sure CBS Action isn´t really worth this effort, but now its personal!

 

[DishDick]

Had a look at a friends big dish today, he doesn´t get CBS Action at all. Wonder why this is a tricky one.

 

[Huevos]

Wonder why this is a tricky one.

I don't know, but I'll tell you something strange. As expected I get mamimum signal from that transponder with the dish pointed at 28.5ºE, but, I get the lowest BER/MER with the dish pointed at 29.1ºE. It won't even lock if I'm pointed at 28.5ºE. I've tried this with 3 meters and 2 receivers so I know it's not an equipment thing. Also, there is nothing strong on that frequency on any of the adjacent satellites.

 

[DishDick]

Huevos, that is strange so you have to turn dish further away? Strange as obviously it is ok in the UK, but they mostly use the Sky mini dish which does receive a wide beam. Not good that, I cannot jepodise my main channels for this station.

Trying to find how to calculate the area of the top of a circle to see how much difference a too large 23mm to 40mm packer on my feedhorn will make to my potential performance.

At the moment my dish has a potential reception area of 5,7255526958 meters square and this is being focused on to a feedhorn with a receiving area of 0,004417865 meters square, so if I can work out the effect of the feedhorn being 2 or 3mm too high in the LNB holder, ie the loss of reception area, I can see the theoretical lost reception area, I can then calculate the theoretical % inprovement I could make, to see if it is worth machining the packer. Gee I really must get out more!

 

[DishDick]

Huevos, I forgot to mention, my local stockist has ordered a Black Ultra Quattro for me, so I will be able to see if it is as good as you and a few others say it is.

 

[Huevos]

Huevos, that is strange so you have to turn dish further away? Strange as obviously it is ok in the UK, but they mostly use the Sky mini dish which does receive a wide beam.

I've seen this with tv aerials before, i.e. max strength and max quality are not quite the same direction. Maybe turning the aerial away is filtering out some interference. Main difference between here and the UK is that 12560 is very weak compared to the rest. Signal to noise is only 6.5dB and MER 7.2dB. If FEC were 5/6 like A2D there would be no chance of receiving it at all.

 

[DishDick]

Ok, the mystery deepens. Went for a quick walk, walked out of my gate and spotted this (see pics).

Must have gone up in last few days, very new and in line of my dish (just top part of aerial).

Any ideas what it is, and could this be my problem?

 

[Analoguesat]

Its quite possible its causing your problems. All sorts of of things can happen when transmitters appear near dish installations.

Can you shield the dish from that direction with some sort of wire grid, or relocate the dish to behind a wall?

 

[Huevos]

Must have gone up in last few days, very new and in line of my dish (just top part of aerial).

Nice! Looks very Spanish. Love the jubilee clips. Maybe it will come down in a few days.

 

[DishDick]

Analogesat, no chance of relocating a 3m dish with a 2.5 tonne base! Going to have to look at some sort of screen.

Know a guy who works at the hotel, so will try and find some info about it.

 

[tonemorgan]

Hi

I recently turned my dish back to 28 deg for the World Cup on ITV /BBC. I had previously had no problem picking up all the transponders (except 2D ) I am getting great signal on all except for anything above 12441, where there is nothing.

 

[Analoguesat]

Analogesat, no chance of relocating a 3m dish with a 2.5 tonne base! Going to have to look at some sort of screen.

Know a guy who works at the hotel, so will try and find some info about it.

Ah I see - no chance of moving it in that case!!

 

[DishDick]

Well just seen on another forum (non-analogue spy) that a couple of people in the UK have reported problems in UK.

"Lately I've noticed some of the channels from Eurobird seem to be running at very low power (I don't think it's a dish alignment issue as my Freesat box reports other channels on the same sat are coming in at 100% quality & strength).

In particular, 12560 V & 12643 V seem to be significantly affected (around 30-40% quality), affecting things like the CBS channels, Teachers TV and Horse&Country. Has anyone else noticed this? "

"Yes I too have noticed this, including a drop for S4C, its not a dish problem or the lnb, I use a motorised system. The loss on my system, is over half the power for the bird "

So maybe its not me.

 

[DishDick]

Well I have now found out what that aerial is. Its a transmitter for a local radio station! Its FM 102.5. Does anyone know if that would that cause me problems? And if so on what fequencies.

Thanks in advance.

 

[Huevos]

Well I have now found out what that aerial is. Its a transmitter for a local radio station! Its FM 102.5. Does anyone know if that would that cause me problems? And if so on what fequencies.

Thanks in advance.

Well first of all it depends on the power output and linearity of the transmitter. Most obvious frequencies for interference would be anything that is a multiple of 102.5 (i.e. 1.025GHz, 1.1127GHz, 1.230, keep adding 102.5 here until you get to 2GHz). Then get each of those frequencies and add the local oscillator frequency. For 1.025 that would give: 1.025 + 9.750 and 1.025 + 10.600. So for that harmonic any problems would appear on 10.775GHz and 11.625GHz. You'd need to do that for every harmonic between 1GHz and 2GHz. And that still doesn't cover non-linearity of the transmitter or mixer products within your receiver but does give the most likely frequencies where there will be problems. If you had a spectrum analyser the easiest thing would be take off the LNB and point it towards and away from the aerial and see what the trace looks like. This would give you an idea if anything nasty is being produced by that aerial.

 

[Turok]

this transponder here much weakger then bbc,only around 6,5 db with gregory 1,25m,contains also travel channel,but picture okay,withouth artefacts hard on the signal limit!