Bigger Dish, Worse Signal Quality

[KuchKuch]

A few days ago I asked an engineer to replace my existing Zone 1 dish with a Zone 2 dish. Unfortunately this has now led to a dramatic decrease in signal quality, whereas previously my assumption was that it will either improve slightly or stay about the same. Is there any possible reason for this?

For comparison my Zone 1 dish would show SNR at approximately 82%, whereas my new Zone 2 dish is showing SNR at approximately 64%. These readings are about an hour apart where weather conditions don't seem to have changed.

My biggest concern is that this will now lead to a broken or distorted picture on a regular basis when it rains whereas previously I only use to get this when there was heavy rain and lightning

 

[Mickha]

A larger dish should increase your signal quality, slightly, if aligned correctly, and depending on the quality of the LNB.
Have you called the engineer and explained your problem?

 

[Lazarus]

A few days ago I asked an engineer to replace my existing Zone 1 dish with a Zone 2 dish. Unfortunately this has now led to a dramatic decrease in signal quality, whereas previously my assumption was that it will either improve slightly or stay about the same. Is there any possible reason for this?

For comparison my Zone 1 dish would show SNR at approximately 82%, whereas my new Zone 2 dish is showing SNR at approximately 64%. These readings are about an hour apart where weather conditions don't seem to have changed.

My biggest concern is that this will now lead to a broken or distorted picture on a regular basis when it rains whereas previously I only use to get this when there was heavy rain and lightning

The Quality reading is only a crude guide on most kit. Can be affected by many things and, at the end of the day, the proof of rain margin is in the pudding.

Did the Installer change the LNB, I wonder?

Is the LNB, whether original or replacement, skewed correctly?

Have Signal Strength readings altered? If so, which way? An unnecessarily bigger dish, properly aligned, may well cause the receiver's AGC to kick in full bore, which tends to manifest itself as a limited, lower SS. That's not a problem though, in practice.

 

[KuchKuch]

A larger dish should increase your signal quality, slightly, if aligned correctly, and depending on the quality of the LNB.
Have you called the engineer and explained your problem?

I haven't been able to get hold of him unfortunately. The LNB hasn't changed between the 2 setups - I was using a Sky Q Hybrid LNB and still am. I'm not entirely sure how well this is regarded within the community.

I take it then this decrease is probably due to the alignment of the dish?

 

[KuchKuch]

The Quality reading is only a crude guide on most kit. Can be affected by many things and, at the end of the day, the proof of rain margin is in the pudding.

Did the Installer change the LNB, I wonder?

Is the LNB, whether original or replacement, skewed correctly?

Have Signal Strength readings altered? If so, which way? An unnecessarily bigger dish, properly aligned, may well cause the receiver's AGC to kick in full bore, which tends to manifest itself as a limited, lower SS. That's not a problem though, in practice.

It's still the same original LNB that was used before, but I'm not sure how well it has been skewed.

Signal strength has also decreased from approximately 86% to approximately 82%

 

[Lazarus]

Ok. It's not easy to determine whether there actually is a problem here as the larger dish is probably overloading the receiver.

Why did you go for a bigger dish, as a matter of interest?

 

[KuchKuch]

Ok. It's not easy to determine whether there actually is a problem here as the larger dish is probably overloading the receiver.

Why did you go for a bigger dish, as a matter of interest?

Didn't need or want a bigger dish. I just wanted to extra feeds into my house for another TV on freesat and didn't wnat to increase my Sky subscription. The engineer said my old dish is quite old (approx 15-20 years according to him) and it'll be in my interest to replace it, but he said he only had a Zone 2 dish with him, instead of a Zone 1 that is mostly used in my area, and as there was no extra cost to me I told him he may as well replace it.

 

[Lazarus]

Ah, I see.

Did you notice if the Installer use a decent Meter to set up the replacement dish?

If he did, then all should be well.

For Sky/Freesat receivers, the S/Q metering is only of use for optimising a system as is. Because the system has changed, by virtue of the increased dish size, the new readings aren't realistically able to be compared with the old.

 

[KuchKuch]

Ah, I see.

Did you notice if the Installer use a decent Meter to set up the replacement dish?

If he did, then all should be well.

For Sky/Freesat receivers, the S/Q metering is only of use for optimising a system as is. Because the system has changed, by virtue of the increased dish size, the new readings aren't realistically able to be compared with the old.

I'm afraid I don't have a clue if he used a decent meter.

I take it then I'm probably reading too much into this and should trust the setup is OK?

 

[Lazarus]

Possibly.

It won't be long before we have heavy rainfall, so you'll know for sure, one way or the other, when that happens.

 

[PaulR]

Ah, I see.

Did you notice if the Installer use a decent Meter to set up the replacement dish?

If he did, then all should be well.

For Sky/Freesat receivers, the S/Q metering is only of use for optimising a system as is. Because the system has changed, by virtue of the increased dish size, the new readings aren't realistically able to be compared with the old.

I disagree somewhat. As only the dish itself has changed then readings are surely comparable? Any change, positive or negative, are entirely down to the dish. As neither strength nor quality have gone up then it has to be down to an installation problem,

The setup is definitely not all OK although, as Lazarus says, you need a heavy rainstorm to be sure.

 

[Lazarus]

qv comment about AGC.

I've on many occasions seen box readings suppressed under overload conditions, whereas an independent meter told a different story.

Either way, the next rain will clarify ....

 

[KuchKuch]

Possibly.

It won't be long before we have heavy rainfall, so you'll know for sure, one way or the other, when that happens.

Hopefully it's in the summer some-point. As I have trees nearby i wanted to make sure the signal can't get through gaps in the branches past the leaves.

I disagree somewhat. As only the dish itself has changed then readings are surely comparable? Any change, positive or negative, are entirely down to the dish. As neither strength nor quality have gone up then it has to be down to an installation problem,

The setup is definitely not all OK although, as Lazarus says, you need a heavy rainstorm to be sure.

This was my initial assumptions as well. However, I have a very crude understanding of a satellite dish installation.

The installation was done by a local engineer. I did book a Sky engineer to come in tomorrow, in case there were problems from the installation by my local. I think I will tell him that ever since the Sky Q installation I've had problems with the picture and whether he could check the alignment. Unless someone has some other suggestion as to what I should tell him/her?

 

[Lazarus]

Well, as you've got a Sky Installer coming, he should consider all possibilities without prompting, but it won't hurt for you to over-egg the pudding, as it were.

Whether or not the foliage presents a problem, I can't really say. Has it done so in previous years? Have the trees grown taller/broader?

 

[Channel Hopper]

I disagree somewhat. As only the dish itself has changed then readings are surely comparable? Any change, positive or negative, are entirely down to the dish. As neither strength nor quality have gone up then it has to be down to an installation problem,

The setup is definitely not all OK although, as Lazarus says, you need a heavy rainstorm to be sure.

If you can reach the dish by hand then throwing a wet towel over about half the reflector will tell you if the accompanied loss will lead to breakup of signal, or if it is purely down to the receiver interface providing a visual signal guide.

Is this a Sky install or something providing signals for a different kettle of fish ?

 

[KuchKuch]

If you can reach the dish by hand then throwing a wet towel over about half the reflector will tell you if the accompanied loss will lead to breakup of signal, or if it is purely down to the receiver interface providing a visual signal guide.

Is this a Sky install or something providing signals for a different kettle of fish ?

I can't reach the dish easily unfortunately. I will need to go up the ladder as the dish is on my roof.

I'm using the dish at the moment for Sky Q and Freesat.

 

[KuchKuch]

Well, as you've got a Sky Installer coming, he should consider all possibilities without prompting, but it won't hurt for you to over-egg the pudding, as it were.

Whether or not the foliage presents a problem, I can't really say. Has it done so in previous years? Have the trees grown taller/broader?

Thanks for the advice.

In the past the trees have grown taller and broader, but this hasn't caused me a problem (as far as picture quality is concerned), but the Sky engineers seem to bring it up all the time.

 

[Channel Hopper]

Your confirmation of system came through as I was typing
Try a swop over of the two cables into the receiver (disconnect power first though)

 

[Lazarus]

As the dish is at roof level, the offending trees would need to be quite close to become an impediment: Even though the dish might appear to be pointing only the merest bit upwards, it's actually looking up at around 25 degrees, owing to the fact that the LNB is offset and simple optics come into play.

You might benefit from taking a look at Dishpointer.com, where you can find your precise location and then use the obstacle checker.

 

[KuchKuch]

Your confirmation of system came through as I was typing
Try a swop over of the two cables into the receiver (disconnect power first though)

Tried this and haven't seen any change in signal quality to strength

As the dish is at roof level, the offending trees would need to be quite close to become an impediment: Even though the dish might appear to be pointing only the merest bit upwards, it's actually looking up at around 25 degrees, owing to the fact that the LNB is offset and simple optics come into play.

You might benefit from taking a look at Dishpointer.com, where you can find your precise location and then use the obstacle checker.

Dishpointer tells me I do have an obstacle and it is one of the trees Sky engineers are always concerned about.