Numerous LNB's on one dish.

[pooksahib]

Hi. I'm not far away from installing a satellite system and I have loads of questions. This certainly looks like the best place to ask them. The amount of information here is almost overwhelming. Here's the source of my first query, an intriguing picture I found on the 'Pictures of member's setups....' thread:-
http://www.satellites.co.uk/satelli...12574d1189606874-my-3-dishes-5-sats-zone2-jpg

Is this one dish really receiving signals from five different satellites?
How is that possible if the dish itself is only pointing in one direction?
Where do the five co-ax cables end up? – a receiver can only accommodate two as far as I know...
How does the user choose which LNB to watch? A special remote?

If it IS possible to tune into more than one satellite with a single (fixed) dish, I'd be interested. Probably just two LNB's though, three tops. What would I need to specify when ordering the hardware so that the LNB's are properly atached to the dish?

Many thanks to anyone who responds. There's lots more I can ask but that'll do for now.

 

[Topper]

Welcome to the forum pooksahib

Well you are going to have to do a lot of reading then, this is a self help forum and question should really only be asked when no answer is currently posted but as it is your first post I will answer them as best I can

Is this one dish really receiving signals from five different satellites?

Yes

How is that possible if the dish itself is only pointing in one direction?

Signals are hitting the dish from many directions

Where do the five co-ax cables end up? – a receiver can only accommodate two as far as I know...

You need a diseqc switch

How does the user choose which LNB to watch? A special remote?

No the stb allows for different lnb's in the settings and chooses the appropriate path to the appropriate lnb 1, lnb2 etc

If it IS possible to tune into more than one satellite with a single (fixed) dish,

With a multi lnb setup or with a monobloc lnb
but it depends upon which satellites you require and the angles between them

 

[Robbo]

The zone 2 dish, is not really the best dish for such a setup, it's abit on the small size, but yes multi LNBs on a single dish is possible and if set up correctly with a large enough dish, it works very well.

Most of my experience with such setups is using the triax TD dishes with the Triax multiblock. With the TD78 and TD88 for example, satellites up to a total span of approx 20 degrees can be received.

The dish has a focal point, where the LNB normally goes, but if the satellite is in a different direction to where the dish is pointing, a blurred 'image' will be received away from the focal point, this is where you put the offset LNB.

A DiSEqC switch is used to switch between LNBs, almost every sat receiver has the capability to use a basic DiSEqC switch.

Here's an example of one I set up.


It depends on what sats you want? not all combinations are possible.

Some dishes (usually more expensive) are preset for certain sats, but others(like the TD dishes) you buy the dish and the bracket, and set it up yourself. It is actually, much easier to do than it looks.

 

[pooksahib]

Thanks, Topper and Robbo. Be assured, Topper, I do try to find answers for myself but it can be tricky when you know so little to begin with. Plus, I sometimes find myself asking questions that are so specific I'd be surprised to find them posted anywhere else. One thing I've found out since the advent of t'internet is that people with knowledge welcome the chance to share it with others and long may that continue.

Robbo mentions a blurred image being received from satellites other than the one being pointed at. Does that mean that the picture from such a satellite (via the offset LN is not as sharp as it could be?

Before thinking of extra satellites, my priority is a fully functioning PVR allowing one channel to be watched while recording another. As Sky doesn't 'do' Diseqc (I found that out for myself, Topper!) then I'll be going with a Freesat+ box. Now then – Freesat+ requires 2 cables coming from one LNB, is that right? If you fed those two cables into a Diseqc switch along with a third cable from an offset LNB, would that allow you to use Freesat+ as normal AND flick over to the other LNB? Somehow, I think not, something tells me you'd need to connect a coax to the two inputs of the Freesat+ box if it's to be used as designed.

I have an old Skybox. If I set up a bog standard Freesat+ system, could I then attach an extra LNB to the same dish and view the result through the Sky box?

Many thanks.

 

[Huevos]

A Freesat+ receiver has 2 LNB feeds because it contains 2 tuners. If you only want to record from 28 East then just add a dual LNB at this position and link the second port direct to the receiver. If you want full functionality for both tuners all LNB's will need to be dual port and each coax line would contain a switch which would link to one port on each LNB.

P.S. Does a Freesat box really have Diseqc?

Edit: I have just read on another forum that when this Freesat box is used in FTA mode (i.e. to receive channels that are not part of the Freesat group) it turns into a single tuner unit.

Also read this thread: _http://www.hummy.org.uk/forums/showthread.php?t=5016

 

[Robbo]

Robbo mentions a blurred image being received from satellites other than the one being pointed at. Does that mean that the picture from such a satellite (via the offset LN is not as sharp as it could be?

No,this is digital satellite, it will not cause a blurry picture, but instead reduce the signal level and quality. At the extreme, total picture loss occurrs, when marginal, pixelation is caused.

Sorry, maybe the wrong choice of words there. At the offset LNB you don't get all the reflections from a particular satellite landing at the same point, like you do when you are the dish focus, and the overall signal ends up being weaker.

P.S. Does a Freesat box really have Diseqc?

Yes, it does apparently.


Hmm, FTA mode, single tuner, doesn't sound too good.

 

[nusrath]

Hi,

I have a dish installed with multi lnbf 68.5, 83 and 100.5 degrees, i am getting good signal in 68.5 in the evening times (Singal Quality as 35%) but if i check in the morning, the signal quality goes to 4%.

Pls help, why this difference ?.