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1068 posts

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Topic # 50803 25-Nov-2009 23:22
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Don't know why I can't read the first topic... thought I'd better repost.

Hi all

For some time now I've been wondering how difficult/expensive it would be to get a really tidy and reliable multi-Satellite TV setup up and running.
I have limited knowledge in the satellite TV department so I thought I'd ask for some advice...

My current setup is a 90cm (I think) fixed position dish with a single 11300 ku band LNB focussed for Optus D2. The cable is connected to a Phoenix FTA decoder in the lounge (~5-10m length), and then daisy chained a PC with a dual hybrid and dual DVB-S PCI-e tuner in an adjoining room (~10m length).

I'm not exactly certain of what is possible/available, but I think I'd like to add Optus D1 (for Freeview) and (if possible) Optus C1/D3 (recommendations for other satellites with FTA channels are welcome!). I know there are probably a number of ways to do this, but I want to keep cable clutter and expenses to a minimum. I have also heard the following things through the grapevine:
1. Multiple LNBs can be mounted on a single dish, either by bracket or by using dual LNB hardware.
2. Dish size is a factor when considering point 1.
3. Aerial/dish signals can sometimes be multiplexed onto a single cable.

Now I don't know if this would be possible, but here is what I was thinking about doing:
1. Mount 3 independent LNBs on the existing dish using a bracket.
2. Select the LNBs in such a way that the 3 satellite signals could be multiplexed onto a single cable.
3. Multiplex the signals at the dish.

This approach would mean no need for extra dishes, no need for extra cabling, and no need for extra decoders. The ultimate question is really whether that setup is feasible...

I have concerns:
1. Multiplexing, cable length and signal quality: currently the Phoenix decoder shows 100% signal level and quality and picture is great (or as good as highly compressed MPEG2 ever gets!), however I get the occasional glitch on the PC. MediaPortal signal level is ~75% and quality ~60%, however I do wonder whether it is related to signal issues.
The question: is the multiplexing of 3 LNB signals possible, and how would signal quality be affected?

2. Tuning/focussing with LNB brackets: I have no experience with Satellite tuning and no equipment to do it with; I also don't know anyone that does. I have heard that a multi LNB setup on a single dish can be finicky for tuning.
The question: how hard is it to hire/contract someone to focus LNBs, and how reliable would a bracketed 3 LNB setup be?

I am an engineering student but I don't have a lot of experience with satellite related issues so I'm probably either pushing my luck way too far or overlooking some issues. Any advice would be most welcome!

Thanks in advance...

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1677 posts

Uber Geek
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  Reply # 276701 26-Nov-2009 23:36
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yes, you can do it. I have a 90cm and point it at D2, C1 and D1.

Go and buy one of these and one of these and that should set you right.  You point the centre LNB onto C1, fit the bracket on and adjust the skew of it.  Piece of pie.  This should be no real drama, the bracket is set up quite well, once you're locked onto C1, it's pretty straight forward.  You'll need to move your dish a tiny bit if you're currently pointing at D2 (152E to 156E). 

Only confusing factor may be that the only C1 transponder in NZ is also on D2 (12407).  So be aware of this, but don't stress yourself about it.  Lock can be tested by looking for the Aurora tuning channel.

If you go and get more LNB's, get 10750 ones, they have a better reception range.

You'll have to make sure your dish is well aligned, as if you don't there is more scope to not get good quality.  With my setup, I get good signal on all channels.  With digital, it's either on or off.  You just need to minimise the drop outs.

Those cable runs sound fine.

The only difficulty with this setup is that you can only watch one satellite at once.  You could rig it up so you could run more than one, but I guess it's how often you use it.  D1 has most of the stuff on it.  C1 has Aurora and nothing else (for now, maybe they'll use D3 at some stage in NZ).  D2 has foreign, and religious stuff, but the main thing for this is uplinks.

Think that's all for now.

1068 posts

Uber Geek
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  Reply # 276729 27-Nov-2009 05:00
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Thanks for the reply allstarnz. The first link doesn't work - was it meant to point at this?

I'm not sure that the solution you have proposed is going to be a viable option for me because I want the computer and the STB to be able to operate independently (with access to any of the satellites at any time). My understanding of DiSEqC is that it switches rather than multiplexes (meaning you can only access one satellite at a time like you said). This is why I asked about multiplexing and why I thought LNB selection was going to be very important...

To expand further on my original post:
My understanding is that it is possible to select LNBs in such a way that cables can be multiplexed. For example:

Satellite   | Transponder Frequency Range (MHz)  | Intermediate Frequency (MHz)
Optus D2 | 12394-12734                                   | 1094-1434 (11300 LNB)
Optus D1 | 12331-12734                                   | 1581-1984 (10750 LNB)

In the above example the cables should be able to be multiplexed because the intermediate frequencies don't overlap. However it would not be possible if both the LNBs used a more similar frequency because then the intermediate frequency bands would overlap. Am I on the right track or am I completely misunderstanding?

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