Here is another gem I found (edited)...
Following from:
www.10kb.com/fta/howto%5CHOWTO.htm
How the different types of switches work.
First there is a switch inside (almost) every LNBF, it is a Voltage Controlled Switch, this causes the LNBF to send out V polarity transponders or H polarity transponders, the voltage in the coax cable coming from the receiver is what switches this switch, 13volts = V/R transponders, 18volts = H/L transponders.
This is why you can NOT simply add a splitter to run 2 receivers from 1 LNB port, only 1/2 the channels are ever on the cable at one time. There is one Voltage Controlled switch on a single output LNBF, there are two Voltage Controlled switches on a Dual LNBF.
External switches:
There are only 2 main switches that work with most if not all FTA receivers and regular(legacy) LNBs they are:
22khz switch, connects 2 LNBs to one receiver
DiSEqC 4x1 switch, connects up to 4 LNBs to one receiver.
22khz switches, these are really simple, they look like a splitter but are a simple ON or OFF switch, 0khz and 22khz are the 2 input ports then one out to receiver port, when you have 22khz OFF in your receiver the 0khz port is connected, when you have 22khz ON in your receiver the 22khz port is connected. This switch is for hooking up 2 LNBs to one receiver.
The 22khz switch has big brother it is a
DTV or 22khz 4x4 switch, this switch has 4 inputs to hook up 2 DUAL LNBs and can be hook to as many as 4 receivers. 2 inputs are labeled 13v,0khz & 18v,0khz (remember the LNBFs internal switch), and the other 2 inputs are 13v,22khz & 18v,22khz. This allows both polarities from each LNB to be inside the switch at all times, so any of the 4 receiver can access any polarity on either of the 2 LNBs.
These switches also come in a 4x8 for up to 8 receiver hook ups to 2 satellites.
DiSEqC is a pulse switch, it also uses a 22khz signal but it uses a one time pulse to set the DiSEq switch to 1 of 4 ports, these switches come in 2x1 and 4x1 models, for 2 LNBs to ONE receiver or 4 LNBs to ONE receiver, respectively, these can NOT be used for more than one receiver, you must use another DiSEq switch for second receiver.
DiSEqC-1 or 2 or 3 or 4 in your menu will cause the
DiSEqC switch to switch to that numbered port, some receivers use A, B, C, D instead of 1, 2, 3, 4. This "pulse" is only sent once, if the DiSEq switch is to far away from the receiver it can miss it and not change ports, some times toggling back and forth between channels can make the change happen, the pulse is repeated each time you change channels, but moving the switch closer to the receiver can improve its performance.
DiSEqC = Digital Satellite Equipment Control, this was designed for FTA receivers.
DiSEqC switches come in 2 main flavors, Committed(1.0) and Uncommitted(1.1), but also Committed 2-way(2.0) and UnCommitted 2-way(2.1).
Committed(1.0) switches are the most common and are what come with the receivers.
These switches require FACTORY software in your FTA to operate properly,
1.0 means your receiver can operate Committed switches ONLY,
1.1 means it can operate Committed AND UnCommitted switches,
1.2 means it can operate Committed and UnCommitted plus DiSEqC motor controls.
2.0 is the same as above,
2.0, 2.1, 2.2 but the receiver can also receive information back from the switch,
2.0 switches receive the pulse command from the receiver, then change ports, they then send back a confirmation to the receiver, if a 2.0 receiver doesn't receive the confirmation it will send the DiSEqC pulse again and again until the switch confirms it is on the right port.
Putting 2 DiSEqC Committed switches on one cable is a no-no, which is why there are Committed and UnCommitted types of switches, a Committed switch is placed first in line (DiSEqC pulse comes from the receiver so first would be closest to the receiver), then you can hookup an UnCommitted switch to the Committed switch, the Committed switch
will ignore the UnCommitted switches commands. Committed 4x1 switches are about $20, UnCommitted 4x1 switches are about $80, so unless you have to have 16 LNBs hooked up to one receiver stick with Committed switches.
22khz switches and DiSEq switches can work well together, with one restriction, the 22khz switch must come AFTER the DiSEq switch.
So you can hook one 22khz switch to two LNBs then hook the output of the 22khz switch to port 1 on the DiSEq switch. So instead of 4 LNBs you could have 5 LNBs hooked up, you can add a 22khz switch to each DiSEqC port for a total of 8 LNBs hooked up to one receiver.
Linear Mode
