Large Signal Strength variation when raining

[blackburnman04]

Hello,

I am currently having a problem with my motorized satellite dish. The problem is that when even light - medium rain occurs there is a large dip in signal strength. I checked on a number of satellites, and below are the numbers that I have been given.

28.2e - 100% goes down to around 87%, 90% channels go down to around 78-81%.
23.5e, 100% goes down to around 81-87%
19.2e, 93%, goes down to around 81%
16.0e, 71% goes down to around 59%
13.0e 100% goes down to around 81%
9.0e 87% goes down to around 68-71%
7.0e, 55-59%, goes down to around 28-31%
0.8w 90% goes down to around 69%
5.0w 100%, to around 89%.

The highest figures stated above are when there is no rain, and during the daytime. The lower figures are when there is light-medium rain. I know that signal seems to degrade slightly in adverse weather conditions, but for some satellites such as 7.0e, this makes the channels unwatchable.

Out of curiosity, I looked out at my LNB, and noticed that it was saturated with rain, Just to see what the effect would be on signal strength, I went out to clear the rain from the LNB eye, and when I did this the signal strength for every satellite went from the lower values stated above, back up to the higher values. But the problem is that when the LNB eye gets covered with rain drops, the signal drops to the low values again.

I have tried covering the LNB eye, working out ways to prevent rain from hitting the LNB eye (none of which have worked, as it seems like quite an impossible task, lol, but there is still the same signal deterioration.

My question is would anyone know what could be causing this problem?, I understand that rain can have an effect on the signal, but it seems as more rain drops appear on the LNB eye, the further the deterioration of signal.

I am looking for a solution, as it becomes quite annoying if I would have to keep going out to wipe the LNB eye when it is raining, as of course more rain drops will replace what I will wipe off.

When I was aligning my dish, as it is motorized to true south, I received 100% from my true south satellites (5W here in Northern Ireland), and after tightening the bolts, I was able to achieve high signal strength for 28.2e, 23.5e, 19.2e, 16.0e, 13.0e, 9.0e, 0.8w, 5.0w, and 30.0w and so on, and these signal strengths are maintained until the rain starts, and then the problems start.

Thank you for reading, and to anyone who tries to help.

 

[Captain Jack]

To be honest, it's fairly normal. I don't think your readings are anything out of the ordinary.

For example, today I was watching 9E - a nice strong satellite. On Platforma DV channels, I get between 96 and 99% SNR (daily variation) but today with persistent rain, they went down to 83%.

Likewise, on 53E, I get 60% SNR on 11043V transponder on a dry day, but today it was hovering just above 40%. Another transponder with GTRK Samara on it, which is normally around 51% SNR was unwatchable today as it hovered around 31-35%.

5E is more sensitive - on 12054V, I get around 50% SNR on a dry day - with rain it goes down to 40% and below.

Wiping the LNB does help, but also wiping the dish will bring results. Try spraying some water repellent on the LNB and the dish - the water should drip off more easy and not stick like it does normally. Helps that both components are vertical.

This is the reason many people get larger dishes than is required - to compensate for "rain fade".

 

[Costactc]

Rain fade can also be a symptom of a dish that is out of alignment or an lnb that needs to be skewed,I have to agree that size makes the difference in this biz.

 

[blackburnman04]

To be honest, it's fairly normal. I don't think your readings are anything out of the ordinary.

For example, today I was watching 9E - a nice strong satellite. On Platforma DV channels, I get between 96 and 99% SNR (daily variation) but today with persistent rain, they went down to 83%.

Likewise, on 53E, I get 60% SNR on 11043V transponder on a dry day, but today it was hovering just above 40%. Another transponder with GTRK Samara on it, which is normallyi around 51% SNR was unwatchable today as it hovered around 31-35%.

5E is more sensitive - on 12054V, I get around 50% SNR on a dry day - with rain it goes down to 40% and below.

Wiping the LNB does help, but also wiping the dish will bring results. Try spraying some water repellent on the LNB and the dish - the water should drip off more easy and not stick like it does normally. Helps that both components are vertical.

This is the reason many people get larger dishes than is required - to compensate for "rain fade".

Thanks for the quick response, I will try to get some water repellent tomorrow and post the results tomorrow. The most problematic satellite is 9E an below 35 percent causes pixelation.

I really appreciate the response. Thank you

 

[Robbo]

When on your worst satellite, check that the dish is optimally aligned and the lnb is at focus, if it is but you get problems with rain, then the dish needs to be larger. I sometimes have to go and wipe my lnb when on 7w if raining, as basically the dish is insufficient to give adequate rain margin.

 

[blackburnman04]

Thanks for the information everyone, I will try somethings tomorrow and see what happens.

 

[ralphmagno]

hello,
rain fade is normal.
also day and night will give you different levels and summer and winter.
the larger the dish the less the fade. how big is your dish?
and when the signal goes down a little does it affect your picture?
100% going down to 80% usualy will not affect the picture.
all receivers have AGC control and will increase gain when the signal drops.
Ralph

 

[blackburnman04]

hello,
rain fade is normal.
also day and night will give you different levels and summer and winter.
the larger the dish the less the fade. how big is your dish?
and when the signal goes down a little does it affect your picture?
100% going down to 80% usualy will not affect the picture.
all receivers have AGC control and will increase gain when the signal drops.
Ralph

Hello,
my dish is a 1.1m Triax dish, and you are correct when the signal drops the only real problem is on 7.0e, and some channels on 0.8w (especially the HD channels, in which the picture is affected when the signal strength is at around 56%, the signal drop on the other satellites has never got to an extent that the picture has been affected.

Thanks for the info,

I used the water repellent, as suggested above, and also cut a plastic bottle to offer some covering to the LNB eye, and the signal I achieved today on all satellites was greater, the greatest difference being 7.0e, which was coming in at 50-53%, and there was very heavy rain in Northern Ireland today, and the signal was able to maintain the strength that is usually only possible during a nice summers day.

I will keep monitoring the signal strength, as there is a wide variation in the weather over the next few days here in Northern Ireland.

Thanks for all the help everyone, I really appreciate it.

 

[Analoguesat]

7EW has two different European beams beams, and the B-beam is quite a bit weaker in the UK than the A-beam. There are also power fluctuations between transponders. 10721H is fine most of the time but 10722V is a fair bit weaker.

(Offset lnb on my Fraccaro Penta-not very well optimised and held in place with zip ties!)

 

[Robbo]

Whereabouts in the holder have you got the black ultra? That can make a difference on the Td110.