SBS and sky incompatible?

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al27

7 posts

Wannabe Geek

#85954 28-Jun-2011 19:06

Hello all,

I have sky hdi decoder and a Superview 380 freeview decoder which I bought especially to view SBS.
I have screwed the satellite cable into a 4 way splitter. The problem being although sky and the nz freeview channels work fine, I do not have a signal for SBS. If I disconnect the cable to sky, or if I unplug the power for the sky box I do have a picture on SBS. If I just turn the sky box off I do not get a sbs signal.
I understand that sky and sbs both use the horizontal polarisation from trolling through the forums.
Is there a solution out there? If it is impossible to have this set up on the same tv can the freeview box be connected to another tv which would then allow me to to view SBS and where would the splitter be positioned?
Thanks for any help.
Al

rscole86

4973 posts

Uber Geek

Moderator

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Lifetime subscriber

#487067 28-Jun-2011 19:10

What kind of splitter are you using? What are both boxes providing power to the lnb? (They should not be)

dolsen

1476 posts

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Lifetime subscriber

#487073 28-Jun-2011 19:21

The SBS channels we can pick up are vertical, so, you can't have Sky and SBS running at the same time normally without seperate coax lines and a dual output lnb I thought.

al27

7 posts

Wannabe Geek

#487076 28-Jun-2011 19:26

Antsig 4 way F-connector splitter AP144 bought at Mitre10.
I didn't understand the question regarding the lnb. I'm using the splitter inside if that helps.

michaelt

425 posts

Ultimate Geek

#487080 28-Jun-2011 19:31

al27: I understand that sky and sbs both use the horizontal polarisation from trolling through the forums.

That's incorrect.

Sky and Freeview use horizontal polarisation, SBS uses vertical.

Your Sky box is sending your LNB an 18V signal for horizontal, and your Superview is sending a 13V signal for vertical for SBS. The 18V signal overrides the 13V signal.

If you want them both to work independently, you'll need to install a dual-output LNB.

nickb800

2715 posts

Uber Geek

Trusted

#487083 28-Jun-2011 19:38

michaelt:
al27: I understand that sky and sbs both use the horizontal polarisation from trolling through the forums.

That's incorrect.

Sky and Freeview use horizontal polarisation, SBS uses vertical.

Your Sky box is sending your LNB an 18V signal for horizontal, and your Superview is sending a 13V signal for vertical for SBS. The 18V signal overrides the 13V signal.

If you want them both to work independently, you'll need to install a dual-output LNB.

al27

7 posts

Wannabe Geek

#487085 28-Jun-2011 19:41

Does anyone know if sky can provide the dual lnb? I ask as they've changed mine a couple of times over the years, and do you still use just the 1 coaxial cable or required to run an extra cable?
Thanks

Spyware

3761 posts

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Lifetime subscriber

#487089 28-Jun-2011 19:49

Dual output implies two cable runs, one to each decoder. Can't work without two cable runs if you bother to think about it.

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al27

7 posts

Wannabe Geek

#487093 28-Jun-2011 19:56

Spyware: Dual output implies two cable runs, one to each decoder. Can't work without two cable runs if you bother to think about it.

It's all foreign to me how it works which is why I'm asking the experts. Thanks for your reply.

al27

7 posts

Wannabe Geek

#487094 28-Jun-2011 19:58

Thanks everyone for all your input. It has been most appreciated.

Regards, Al

kiwisat

147 posts

Master Geek

#487132 28-Jun-2011 20:48

Hi Al

In a nutshell, there are two probes inside the LNB (dual polarity) on your dish, a horizontal and a vertical. The signal for Sky and Freeview is transmitted on the horizontal axis, whereas the SBS signal is on a vertical beam. The receiver accesses either probe by sending power up the coax cable; 18 volts for the horizontal, 13 volts for the vertical. As long as 18 volts is present from the Sky box, 13 volts for SBS from the freeview box just doesn't get a look in.

The simple solution is to utilize a dual polarity, twin output LNB, such as this (http://www.trademe.co.nz/Browse/Listing.aspx?id=387908969) one.

You will need two cables to the dish and you can then supply your receivers fully independently with one cable to each.

al27

7 posts

Wannabe Geek

#487140 28-Jun-2011 21:03

Thanks Paul, I did spy that one.
Cheers

al27

7 posts

Wannabe Geek

#489536 5-Jul-2011 09:54

An update to all that replied or have a similar query.
I checked and found I have a quad output LNB on my dish already. (Sky have changed the LNB a couple of times over the years.) After running the second cable I now have both sky and freeview sbs channels.