Anyone having problems with CBS Action?

[DishDick]

Hi

Just curious if anyone else having problems with this channel (and the others at 12560). Last time it broke up like this I spent ages playing with the dish only to find out it was a problem at their end. I have perfect signal strenght but not much quality at mo. Noticed the quality on most Eurobird stations down, but only this transponder showing break up.

 

[Topper]

That frequency is suspiciously close to 12500, a frequency known to experience interference from DECT phone base stations
12480 to 12500 MHz (10600 MHz LO) IF is 1880 to 1900 MHz

 

[DishDick]

Yes,

I know that can cause probs, I don´t have a DECT phone and this problem only manifested itself tonight. Though thats not to say a neigbour hasn´t got one. WiFi wouldn´t be a problem would it?

 

[Analoguesat]

Anything that operates in L-band is possible to cause interference. Here in the UK BT Homehub wifi routers are known to be troublesome.

BTW - CBS Action is working fine here.

 

[DishDick]

Thanks Analoguesat. What sort of readings are you getting on your receiver for this channel. My Foxsat shows full signal strenght and about 20 quality. I spent hours adjusting the LNB after trying my new ones and the ss and sq that night were very good. Don´t want to mess with the dish tonight as I have a feeling its not the dish.

 

[Analoguesat]

Very good - see the screencap.

This is via an offset lnb on a 1m dish pointing at 16E

 

[DishDick]

Thanks. I think tomorrow I will disconnect things such as router and anything that may cause a spurious noise. If no luck will see if I can get my neigbour to switch off her main trip, to see if any interference is coming from there.

 

[Analoguesat]

Good plan. Unfortunately its often a case of trial and error to track down external interference. If you have a joint wall with the neighbour then see if they have a dect phone just the other side of the wall.

Are you having problems with the music channels on 11642V as well by any chance?

 

[DishDick]

No the music channels pictures are perfect. (SS about 90% SQ 50%). I think if I am getting interference it must be at the dish as all cables are good quality, the Humax is well made and my house has a metal frame which seems to absorb radio waves (hence I have problems with WiFi in the house)

 

[DishDick]

Looked at V TP below 12524 (Reality etc) and V TP above 12607 (Zing etc) both really good. And 12606H almost perfect SS and SQ. Very strange its only 12560. I am right in thinking its not an alignment issue as all my other channels are good.

 

[Topper]

No spiders nesting in the lnb?

 

[Huevos]

12560V, along with 11390V, 12524V, are all problematic on EB1. Even worse is 12643V. All the other transponders are a lot stronger.

 

[DishDick]

No, no spiders. All very new and well sealed. All joints sealed with self amalgamating tape.

Can´t remember if CBS Action ever suffered from poor reception when dish was in its old position.

 

[DishDick]

Hi Huevos,

11390 on mine good picture and good SS and SQ
12524 on mine good picture and good SS and SQ
12643 pic ok (even with a naked woman jumping about), full SS, low PQ but higher than 12560

 

[hexah]

It is possible that the source of interference is terrestrial.

Is there an airport nearby? Police, fire service, army or hospital nearby? Or any other transmitters? It is likely to be a harmonic of a lower frequency, but not necessarily (though could easily be a dect phone or router in a nearby house).

The source does not have to be line of sight, it may be a reflection. Although large dishes have narrower beamwidths, with this kind of interference it just has to cross the dish face to become a problem.

Without test equipment it is hard to track the down the source of the problem.

Perhaps the only way to find out the direction of the interference, if it is a terrestrial transmission, is to block off the sides and bottom of the dish face with metal sheets and see if the satellite signal swamps any residual interference. This is easier if you can actually see a transmitter or a possible source of reflection.

If this is the problem, the usual cure is to re-site the dish out of sight of the transmitter or the reflection, or if it cannot be moved, set up a second dish for that frequency in another nearby location which is better shielded. Or just put up with it. )(-red

In some cases potential interference can be prevented before it starts, e.g. if the site is close to an airport which is in the direction of the satellite, the dish could be installed low to the ground behind a wall which faces the airport. With modern high power satellites and smaller dishes this is less of a problem than it was.

 

[Huevos]

BTW DD, how much skew have you got set? Is the LNB skewed for A2D or EB1. There's almost 8º skew difference between the two and on a weak transponder that could be enough to lose lock.

 

[DishDick]

Hi Huevos,

Guess you went last night to watch the naked woman!

The dish is protected on two sides by two houses. I turned off my router and next door kindly turned off their electric, but still no joy.

I do remember when I set up the dish the other night the quality of Action was better than it had been, yet when I got inside that night and looked on my reciever it was low again. So maybe my large slightly porkie frame was absorbing some interference!

I will go up tonight and test, standing round different parts of the dish, holding a large wet towel.

 

[hexah]

When big dishes are installed on exposed roofs there are usually a few people involved as it takes some effort to haul them up say 5-12 storeys or more.

The lack of shelter and the size of the dish face means interference is much more likely than at ground level. So when interference is suspected it is easy to marshall them to stand in various places around the dish while someone watches the meter.

Perhaps it may be quicker if you could get a few volunteers, one to watch the signal on the TV and the others on the roof - as long as they are not clumsy or prone to vertigo!

 

[DishDick]

Its only a small roof. Volunteers are always good for heavy work, but as you warned can be clumsy. Will take meter up and play with towel tonight. Have visions of installing some huge mesh fence. Moaning neighbour will love that!

How do you stop the interference you find? I take it you don´t leave the people on the roof!

 

[hexah]

The best cure is to re-site the dish. On big buildings there is usually a small shed sized structure over the stair well or big cooling vents or similar which can get in the way of the interference.

Don't forget to look for any transmitters on roofs when you are at the dish. A pair of binoculars often helps as it could be a few miles away.

To quote myself from post #15:


Is there an airport nearby? Police, fire service, army or hospital nearby? Or any other transmitters? It is likely to be a harmonic of a lower frequency, but not necessarily (though could easily be a dect phone or router in a nearby house).

The source does not have to be line of sight, it may be a reflection. Although large dishes have narrower beamwidths, with this kind of interference it just has to cross the dish face to become a problem.

Without test equipment it is often hard to track the down the source of the problem.

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.

If the houses in front are lower than you, moving the dish back on the roof may help - but it may not, and may be more effort than one channel deserves.

Have visions of installing some huge mesh fence. Moaning neighbour will love that!

Put the huge mesh fence around him overnight and throw away the key...