Multiswiching

MultiSwitch ABC's !
ZZZSPARKS

Multiswitches----- just another boat anchor (paper weight) if you don’t understand their limits, their operational characteristics, and the variations. All mutiswitches share one common characteristic; they work in pairs, singles have no place in this Legacy world unless tweaked, massaged, and exceptionalized (sat C LNB for Direct TV). The purpose of this discussion is to explain the ABC’s of multiswitches with just a hint of information about specialized versions.

Rule number one: Specialty, increases the cost and lightens your wallet exponentially. The lower the insertion loss, the higher the price.

We will pick a more complicated example (5x4 or 5x8) rather than the 3x4 for the purpose of this discussion. A general rule is the number of inputs includes one input for terrestrial (TV through the air, or cable), thus limiting usage to two pair of inputs. The word pair should tell you that single output LNBs are useless here; we are only using dual LNBs. There are manufacturers who make 4x4 switches (22KHz controlled) that do not have the terrestrial input. We will look at some of them too, and yes, DP LNBs can be used in specific set-ups.
Exception one: DP duals and DP Quads can make things simpler or more complex, depending on your personal viewpoint and needs. I have no use for them, but others would be lost without them and their special applications. These special needs also need a special channel list due to the difference in operating frequencies as compared to Legacys. That being said, the uniqueness of the DP opens possibilities that would take a multitude of hardware to duplicate……especially when talking great numbers of receivers, 6 or more. The special feature of a DP LNB is that all incoming signals are made vertical polarity (stacked). In a multiswitch, the low side voltage is the vertical side and one could use one output of a DP LNB to receive all the transponders. Nothing gets connected to the high side of a pair of inputs (Horizontal, 18volts)..
There are considerations that have to be accounted for regarding built in switches, internal switch, DP34 switches which I’m not going to go into at this time. We will concentrate on Dual Legacy standard and dual Linear LNBs for our example drawings. Satellite 121 is linear and is in my area, but you can feel free to substitute that sat for any linear sat in your viewing area. I will leave that up to you to determine whether you want it in your system or not.

We will be using two, standard, dual, Legacy type LNBs for this explanation of multiswitches (110 & 119).
This dual device (LNB) is capable of tuning to a satellite transponder that is broadcasting in either vertical or horizontal polarity (left-hand or right-hand polarity). The reason for two polarities is to increase the channels per transponder for the same amount of bandwidth. The switching information from your receiver (13 volts [V] or 18 volts [H]) selects the polarity of the transponder that is broadcasting the channel you wish to see (Home and Garden [vertical] verses Playboy [horizontal] …play on words). When the number of receivers increases to three or more, or the number of sats you view increases to 4 or more, a multiswitch may be used.

You can think of a multiswitch as the only correct DSS signal splitter combined with built-in A/B switches (simplified) that translate the information from your receiver to get you the right polarity and the right satellite with every channel change you make. One side of a dual LNB is set to always look for vertical transponders, the other side is set to always look for horizontal transponders, and the two series A/B switches decode the information sent by the receiver. You have to program the receiver properly to make all of this work for all 4 or 8 locations. This means the 13-18 volt signal from the receiver no longer picks the LNB switching, since each side is constantly turned “on” by the multiswitch. The 13 or 18 volts is now used to toggle the A/B switch (choose between the V or H outputs of the dual LNB by the high DC voltage or the low DC voltage). This multiswitch provides 4 or 8 outputs for distribution to receivers, to Tivos, or to PVRs (more if you own an oil company and have a need for 17 inputs and 16 receivers ---approximately $2000 for the Gigant switch). That is just one LNB. The other LNB tied to a 5x4 or 5x8 switch goes through the same process of providing continuous vertical transponder choices on one side of the dual LNB and continuous horizontal transponder choices on the remaining half. The split outputs of the LNBs are paired and connected to a series of A/B switches, such that one side of the of the switch sees input Vertical and the other side sees input horizontal for both LNB’s sets of switches.

How do we choose which satellite we want to see (119 or 110---just an example of two satellites)? Just when you think you’re done we add another choice to confuse you.
There is another set of A/B switches that are in series with the previous discussion of A/B switches that actually choose which of the two satellites we want to view. This set of A/B switches is toggled (moved from the Normal closed to the normally open set of contacts) by the 22KHz burst signal from your receiver. There is a steady state condition (let’s say 119 normally selected) that gets switched to position B of the A/B switch when the receiver says we want to view the 110 satellite. The action of the two sets of A/B switches picks the polarity (V or H) by voltage and 110 LNB or 119 LNB by frequency tone (22KHz). All of these choices are available at every output of the multiswitch, whether we are talking 4 outputs, 8 outputs, 12 outputs, or 16 outputs. Neat huh?
Right now with one 5x4 (8) multiswitch, we can choose between two satellites, independent of whatever the other 3 or 7 receivers are doing, by using one DiSEqC switch, a 2 x1 (if more than two satellites we use a 4 x 1) at each receiver….. Woo Hoo! Below is a functional sketch showing the decision-making that takes place if you program your receiver correctly. In this drawing 119 is the normally selected satellite with the 22KHz switches off. The 110 satellite would then be software controlled with the 22KHz switch on. The normally closed contact of switch 119 says the steady state for this switch is the vertical transponder. If the voltage should be 18 volts that switch would toggle to the horizontal transponders.

Not everyone plays by the same rules so we need to make provisions, as we impose different criteria to our system. There are two types of multiswitches to choose, active or passive. The active has amplification to make up for people who can’t stay within the 100-foot boundary of RG-6u cable, as well as those who have insertion losses and lack signal strength due to location, small dish sizes, or adverse climate conditions. In this case, size matters. I’m sure “Horsegirl” would agree.

Any and all connections represent a loss. The more devices, the more connections, the more signal loss in each leg of the system which drains the signal strength as well as the control voltages coming from the receiver.
As long as the losses don’t exceed a maximum amount, we still have enough signal strength for good viewing and control of the devices. When losses are too great we must make up the difference in signal strength to have a solid operational system and eliminate erratic behavior.

A powered multiswitch detects this drop in signal (voltage) and compensates for it by using an external power supply. A passive system requires no external power supply and can operate from the small voltage supplied to it from the 13-18 volts of the receiver. Guess which costs more? Some manufacturers state their device can operate with/without power. Some manufacturers lie.

When the number of added devices increases greatly for decoding and switching of multiple LNBs, receivers, or both, consider using powered (active) multiswitches. The losses can be staggering with all those connections.
A design to cover 5 LNBs and 8 receivers can be accomplished with the cheapest of parts, 3x4 multiswitches, 22KHz switches, and 4 x 1 DiSEqC switches. The problem is the number of connections and losses from insertion of that many devices render the signal to “almost enough” status. It takes eight 3x8s, thirty-two 2x1KHz switches, and eight 4x1 DiSEqC switches. Multiply every input and output terminal by the number of devices and that’s how many connections it will take….good connections.
A slightly more expensive, more reliable system would need three 5x8s, and eight DiSEqC switches (4x1). With the runs within 100 feet, one should be able to handle all of these additions with passive multiswitches. I chose active because of the radical temperature swings in Ohio, and because this time my distribution board will be inside (easy power availability), and the antennas are 25 feet in the air. The insertion losses per receiver are within reason and I’m still under the 100-foot rule, per unit. I purchased the powered units for near the same costs as the passive units, resulting in a no-brainer decision. Maybe you can be as lucky.

See Drawing two, 5 LNBs and 8 receivers



See Drawing three, 4 LNBs-one and two receivers.



Pass through types:

The voltage and 22KHz tone stop at the built-in A/B switches. They have done their job by picking the satellite and the polarity. When one limits the number of satellites to view and then decides that 4 outputs are not enough because he wants to recorder (Tivo) at the four locations, one needs to expand the system, and to accommodate this one can add a pass-through type multiswitch. The four outputs of the first 5x4 (pass-through) that device and become the inputs of the next 5x4 multiswitch. The pass-through multiswitch is the only one that will allow the receiver control voltages for the A/B switches (22KHz too) to operate the next series of multiswitches. These are sometimes referred to as cascadable multiswitch. These are more expensive and have limited use except for Dish Pro installations (the DP34 is a pass-through device).
Here are some names for multiswitches that are not prevalent in this country….yet.

9 x 4 Switch-X (Giga 9024)
13 x 4 Chess
17 x 4 Ankaro DK (limited to quad inputs or 4 satellites + 1 terrestrial)
17 x 8 Gigant
17 x 12 Gigant
17 x 16 Gigant

Prices vary from the hundreds of dollars to the thousands of dollars, for each system (layout).
Just when you think you know all you need to know we throw in the special DP34 switch. It operates on a pass through basis, works with DP LNBs, which comes in single, dual, or quad choices. If one wanted to hook up 2 sats to 4 receivers (119 & 110), or (82 &91) using a DP34 would be the simplest route. No other switches would be required. Once you surpass the two sats to something greater, or increase the number of receivers over 4, then things get a little more complicated, hence the many varieties of multiswitches, with multiple inputs and outputs. (See Goodq’s Pansat 2500A receiver Testing manual, rev. 6 for many diagrams using 22KHz switches. There are many contributors on various hardware problems, no matter what the receivers

Before tackling these more complicated set ups I suggest a trip to the local electrical supply house to purchase wire numbers/letters. Get a card for each satellite you have (87,97,101,110,119,121,123, 105, 148, etc). You can get some letters that work with lower digit numerals too. You will be so glad you marked your switches with corresponding marked wires going to your different receivers.
They are 1.25 inches of sticky white tape, marked with numbers, letters, and a combination of both. Mark your wires on both ends, designate a marking for each device (110/119 multiswitch) and be consistent in ports, numbers, and receiver locations. A little extra work on your part will save you a lot of headaches in the long run. One has to plan ahead for when things go to hell in a hand basket. A systematic arrangement of your system will allow you to troubleshoot the problem areas that pop up, rather than the areas that have nothing to do with the issue.