Splitting Sat signal via MMDS system

Funky Phantom

Hi folks,

Just a query, I've just moved house and the original owners have their dish wired through the pre-wired MMDS system, so I connected my subbed box and hey presto SKY.

So I had a look around and in the MMDS service box theres a 4 way splitter but the other 3 connections have been removed, so my question if i reconnect these can i connect my other digiboxes to the prewired cables in the other rooms.

Do I need to change the "splitter" for a Sky digital type...? suggestions

I'm a bit cautious about just trying off the cuff in case I damage any equipment, SKY or MMDS


Thanks in advance

watty

1) MMDS quality of cable is OK for Digibox RF out, not for Dish in.

2) You can't split the dish to box signal at all (the box signals back to the receiver at the dish which has 4 modes).!

3) You can split the RF out of a Digibox.


The LNB (receiver on dish arm) to Digibox signal overlaps the UHF TV and some other Bands and is at a VERY high level. The signal leaks out on ordinary coax (causeing interference), which is why the satellite grade cable has very heavy briad and a foil screen.

Also the higher channels in each of the two bands the LNB uses on its output are nearly twice UHF TV Group A and FIVE times the MMDS downcable frequency, so the cheaper cable can cause trouble for some channels just below 11.7GHz and 12.6GHz (as the LNB splits the dish signal into two bands and ouputs at 750MHz to 2150MHz = 0.75GHz to 2.15GHz.


Although the MMDS dish works at 2.5 GHz (= 2500MHz), a MMDS version of LNB called MMDS downconvertor behind or built into the aerial converts the signal to 250MHz .. 420MHz approx for the cable.

It is a much skinnier cable and MMDS has only one "mode" on its downconvertor so the signal can be split.

Cable TV or MMDS gear should NEVER EVER be used for Dish to Digibox connection. It should be a dedicated CT100 grade or better coax with no sharp bends or joints. (Joints are possible but best avoided as are wall plates as often they are really Cable TV or MMDS parts).

watty

To drive multiple digiboxes you need either multiple dishes OR
a multiple output LNB (almost 4 LNBs with one horn). A Quad LNB is commonest solution to more than one digibox.

A few "more than 4" o/p LNBS exist, but not common. For Hotel, apartments etc a special Quattro LNB (or somtimes regular Quad) feeds a distribution system. It can feed remote distribution points with four cables.

The distribution box is NOT a splitter, each output simulates an LNB for the digibox and selects one of the four inputs.

In such a case each of the four LNB cables CAN feed a splitter or an 8 way distribution amp. Then you can feed 2, 4, 8 distribution boxs etc as desired.

Thus almost any number of rooms can be fed with just 4 connections on the LNB.

Advanced apartment/hotel distribution systems in Europe and USA even can accept multiple quad inputs from different satellites. Then the distribution box simulates a Disqec switch (2 or 4 way) for the satellite reciever. For marketing reasons the Digibox while capable of Disqec controlling does not have the built in software (or does but it is disabled).

Unlike MMDS which just has 12 or 14V up the cable to power the "Downconvertor" on the dish/aerial (really a simple LNB), Satellite uses:

14V = Vertical polarised channels
18V = Horizontal polarised channels
22KHz off = 10.750GHz to 11.700GHz band
22KHz on = 11.701Ghz to 12.600GHz band

The MMDS band, even for digital is at 2.5GHz and is about 180MHz wide, and an area is either Horizontal or Vertical polarised, never both.

The Satellite band is 10.750 to 12.6, nearly 3000MHz wide. Because no hills etc mess up the signal direct from space, Horizontal and Vertical can even be used on the same channel!.

This is why the Satellite LNB has 4 modes to "chop" almost 6000Mhz of channel space into FOUR 1500 chunks (each of which is nearly six times the amount of channels of MMDS.

Because a dish is 16 times more narrow in its beam at 11.7 GHz compared with 2.5GHz MMDS and the satellite dishes are bigger, while an MMDS dish can only have a choice of 2 transmitters, a Satellite dish if moved can have a fresh satellite every 3 degrees.

Plus and Minus 48 degrees is reasonable from due south on a 90cm dish. This 96/3 = 32 Satellites, EACH with TWENTY FOUR times the capacity of Digital MMDS.

Currently a motorised 1m dish can get over 1000 FREE TV, not counting almost as many or more radio channels and not counting Pay TV (i.e. Sky Italia, Sky UK, Canal+, Canaal Digitaal, etc etc).

Sky of course for marketing reasons:
1) Don't emphasise the number of free channels you still get even without moving dish

2) Make it hard to use Channels not listed on Sky EPG

3) Will never provide 4 Way Disqec or Motor control Disqec as this is only useful for non-Sky free channel

4) Will not let someone elses pay TV card work in their box.

5) Won't let Sky cards work in a non-Sky approved box that does work cards for other satellite providers.

6) Won't let you blank channels you don't want (even if you have no sub for them). Other non-Digiboxes let you delete unwanted channels.

In any other industry such limitations would be regarded as unfair and monopolistic.

All of the irratating "features" of Digibox are for Marketing reasons, not at all a techical issue.

If forced by UK gov, they can change all of these automatically over the air.

Mike 1972

$ky of course for marketing reasons

7) Limit the range of symbol rates the digibox can deal with to 22,000 and 27,500 wheras most FTA boxes can handle any symbol rate between 2000 and 45000 this limits the range of non $ky channels that can be recieved :mad:

OFCOM/The EU/Office of fair trading should intervene to stop these market abuses by $ky to protect their near-monopoly in the UK & Irish market. Sky will argue they subsidise their boxes but on the other hand the cost of a non-subsidised box (to watch FTV channels) is pretty steep

watty

The boxes arn't really subsidised, in that the minimum contract is one year and at Family Pack level Sky do break even on that. That is why a Premium Sky sub gives an ever cheaper installed.

Agreed ON SR. Forgot that.
Also missing (but in there) is arbitary audio channel PID selection. Only the audio languages defined in Sky menu can be used.

Tony

Breaking even after a year is still a subsidy

Originally posted by LurkingIcon
The boxes arn't really subsidised, in that the minimum contract is one year and at Family Pack level Sky do break even on that.

watty

Okk... it *is* subsidised, but not as free as people think, is I suppose what I'm trying to say.


They really are on the gravy after 1 year.

I have cancelled twice now. I got a letter offering some sort of deal if I would come back, or regular price 1 year min and a replacement box free if I wasn't subscribing simply because I had no box anymore...

I don't sub anymore because I have caught up on the repeats and would not watch the Import Junk, or Sky's idea of programming (Kirsty, Dream team, Ibiza etc etc..)
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:ninja: Your eyes go this shape with too much TV