Satellite Distribution Systems

There are two kinds of Satellite Distribution

  1. Distribution of the Modulator signal in a Satellite TV Set-box. Every connected TV gets the same channel, which ever is on the set-box.
  2. Distribution of the LNB signals to several or many satellite receivers for each TV. Every TV can have different channels.

You can't use a TV distribution amplifier to "split" the LNB signal from the Dish. The LNB at dish either goes via a Multiswitch to the Sky box IF in (screw on connection) or direct to Sky Box IF in (screw on connection).

The F180 (or any other TV distribution amp, or any kind of splitter) can't be connected to LNBs or IF inputs on any Satellite Set-box.

TV RF = 175MHz to 862MHz

Satellite IF from LNB = 950MHz to 2100MHz with 13V or 18V feed to LNB and 22kHz signal on/off feed to LNB from Set-box.

There are four groups of channels on LNB from dish.

  • Horizontal 10.7GHz to 11.7GHz  (18V, 22kHz off)
  • Horizontal 11.7GHz to 12.6GHz (18V 22kHz on)
  • Vertical 10.7GHz to 11.7GHz  (13V, 22kHz off)
  • Vertical 11.7GHz to 12.6GHz  (13V, 22kHz on)

1. Modulator Distribution from a Sky set-box.

The TV Link F180 distribution amplifier (or other Sky eye compatible amplifier)  input is connected to Sky box RF 2 out (male push connection on sky box)
The TV aerial (if there is one) connects to the Sky Box RF in (Female push connection on sky box). Optionally a Sky Eye goes at remote TV set to change channel on the Sky Box. Generic adaptor for ANY set-box with a modulator is available from Triax. This solution is poorer than off air analogue due to the quality of modulator, which always uses up the next lower channel as well as the one it's set too.

The signal is only Composite PAL with mono sound and SD, never HD even from an HD channel on HD set-box.

2. LNB Distribution to Multiple Satellite Set-boxes.

A satellite Distribution system is best used where there may be more than four receivers (especially PVRs), or more than two satellite positions and more than two receivers or more than one PVR. For four ordinary receivers or two PVRs /HDRs (dual tuner recorders with Hard Disk Drive HDD) you can simply use a Quad LNB. Octo LNBs exist but they are heavy, expensive and less reliable. A Quad LNB can be expanded by a suitable Multiswitch system to give 16 to 2000 outlets.

The central aspect is a "Multiswitch" connected via up to 50m (or more with line amplifier) directly to LNB IF in of the receiver.

A distribution system needs better initial signal to noise, so if using separate dishes, use 70cm to 110cm, or if a single dish use 90cm to 1200cm (or larger for edge of footprint signals). Also since more receivers are using it, why scrimp on dish size especially on an Apartment, Hotel or other communal system?

Example Dish.

Since the dish is offest and circular focus ring LNBFs are used, the 90cm wide/95cm tall Triax is good choice. You can't sensibly use a Sky dish, even for a single satellite feed as it's poor quality and too small for most of Ireland to give a good rain margin.

Example 90cm/95cm approx Triax dish with Triax bar

multi4-quattro

Three different models of Quattro. Alps is the skinny one, Triax are fatter ones.

28E - - - - 19E - - 13E - 9E

Being able to use an existing Quad is handy for upgrades, you then can use Quattro on other positions, so the EMP centauri "profi" and some other multiswitches allow a Quad for first position. If a satellite only uses one band & polarisation, then that set of 4 ports only needs a single connection from a single output LNBF.

Similarly C Band only needs two connections, not four as there is only polarisation, not band. You need a Dual LNB, not a Twin.

LNB Types

  • "Twin-output"  Two separate outlets, two receivers or one PVR.
  • "Dual-output"  For distribution system only (obsolete on Ku, still OK on C-Band), outlets are the two polarisations. (can be LH & RH circular or H & V linear/orthogonal depending on satellite and model purchased) 
  • "Duo or MonoBloc" Dual feed horns and integral Diseqc or Multiswitch. Fixed offest and inflexible.
  • "Quad, Octo"  4 or 8 outlets for 4 or 8 receivers, or half as many PVRs, or mix. Only some distribution systems can use a Quad, or 4 ports of an Octo, and usually only on 1st set of inputs.
  • "Quattro"  4 outlets, one each of LV, LH, HV and HH possible combinations. Only for a distribution system.

Splitting LNBF feeds

LNB Outlets can be split only on a Distribution system and only between the LNBs and the Multiswitch(es)
OR
If the satellite position only uses one band and polarisation, then the LNB outlet(s) can be split. If it's a Quattro or Dual, then only one outlet in such a case actually has a signal.
See http://www.satcure.co.uk/tech/lnb.htm  (read carefully, twice!) 

Offset Bar

The Triax multi-LNBF bar is for Triax Dish. It can manage about 20 degrees to 25 degrees of spread, depending on your location and the strength of satellites. The reception is weaker the further from the centre of the dish is used.

Avoid Monobloc

"Dual LNB" or "Monobloc LNB" have two LNBs and horns in a fixed package. AVOID These.The spacing is for particular market and dish, these should never be used in Ireland. Common kind has built-in two way Diseqc switch and single outlet. There are Twin Outlet and Quad outlet versions. They can't easily be used with an external Diseqc or at all with a Distribution system (multiswitch). Do not purchase or Install outside France/Germany, or for any system that might be upgraded in anyway.

Sky vs regular LNBFs

Sky Dish LNBs have oval focus rings inside to suit Sky horizontal oval dish. Non-Sky LNBs have circular rings inside for a circular, or on large offset dish, oval vertically. Sub optimal performance results from using wrong LNB type.

Receiver Configuration

Switches usually have ports numbered 1 to 4. But some Receiver configurations has A, option A or B, and B option A or B

 LNB  Port  Option  Recommend  Slot
1 A A  Sky/Freesat 28.2E
2 A (or B) B (or A)  Astra 1 series 19.2E
3 B (or A) A (or B)  Hotbirds 13E
4 B B  Other*  any

* Other: If you can't get Terrestrial Irish TV then from April 2011 might be Ka-Sat (Saorsat) @ 9E (Saorsat is Island of Ireland only)