Mixed signal TV splitter

[asalcedo]

I have at home a satellite dish and an aerial for digital terrestrial TV (DTT).

After the aerial there is an amplifier for the DTT signal.

After the amplifier, there is a mixer that combines the satellite and DTT frequencies.

From the mixer I feed, with separate coaxial cables, three TVs.

I need now to feed four TVs from one of those three coaxial cables that come from the mixer.

What is the best way to do that?

Since the range of frequencies is wider, given the satellite and DTT signals in the cable, do I need a specific type of splitter or other device?

The satellite signal seems strong.

The DTT signal is not that strong, some of the channels are pixelated or lost often.

All equipment is very new and cabling is of good quality and condition.

I do have three cables coming straight from the satellite that would be idle if I use the signal from the mixer. These cables fed the TVs in those other three rooms just with satellite signal. I want now to add DTT signal to those TVs.

Thanks,

Antonio

[Graham.]

It's difficult to work out what this "mixer" box is. Two possibilities.

1) it's a Multiswitch. If that's the case you will have 4 cables that go from the satellite dish LNB direct to the Multiswitch. The TV aerial via an amp if needed will also connect to the Multiswich. A wallplate in each room will connect to a separate connectors on the multiswich. If any of the rooms have recording satellite boxes like Sky+ they need to use two feeds from the Multiswich

The other arrangement you might have for the "mixer" is that it's

2) a distribution amplifier of the "loftbox" type here the satellite signals from the LNB do not connect to the loftbox, they go direct to the satellite receiver(s) in the normal way A UHF analogue RF output from the satellite box goes up to the loft-box and is mixed with the aerial signals so the drop cables to the TVs will carry DTT signals + an analogue satellite picture that will be what ever the sat box is tuned to. Obviously a far more restrictive setup than "A"

Your description does not fully satisfy either if the above scenarios.

[Tabby]

. [e-mail]...

ey go direct to the

the satellite box

ll be what ever the sat box

I presume the mixer really is a combiner, but there must also be a 3 way splitter after that which isnt mentioned. It sounds like the op needs to replace the 3 way splitter with a 4 way. This will of course reduce signal strength, whether this will affect the dtt picture quality depends on the cause of the trouble. With no info on general signal strength, aerial type and location etc, its hard to comment further.

NT

[The Wanderer]

Doesn't help you over much, but I suspect you've gone for the wrong equipment.

's a labgear distribution amplifier that handles just about all variations of input and up to 8 outputs. I have one and it does just what it says on the box.....

[Andy Burns]

Except it *doesn't* send any satellite feeds to the secondary rooms, it sends the RF modulated output of the satellite decoder in the primary room to the secondary rooms, which is fine, so long as everyone wishes to watch the same thing from satellite at the same time, or arranges to watch something at a time when nobody else is watching or recording from satellite at the same time.

[asalcedo]

This is for my house in Spain.

The LNB has four cables.

One of them goes to the mixer or combiner. The other three go straight to different TVs (they would become idle if I do what I want to do).

One cable from the aerial goes to the combiner.

One cable comes out of the combiner and goes into a dumb or passive splitter (no electronics in this splitter, just a block of metal).

Three cables come out of this splitter.

I need to further split the signal of one of these three cables into 4 cables.

Since it seems too much splitting I think I may need a splitter that reduces the signal loss and that splits the wider range of frequencies required to view DTT and Satellite.

If the above is correct, which splitter is this?

[Alan]

In message , asalcedo wrote

Does each room have its own satellite receiver STB?

[Andy Burns]

You *can't* simply split a satellite signal, the receiver actively powers and controls the LNB on the dish, multiple receivers wouldn't work.

As suggested you need a multiswitch, which takes four inputs from the LNB and usually an input from the aerial, and delivers 4 our 8 or more outlets each of which can have a passive faceplate to separate the TV and SAT signals.

It's almost certain you will have a quad LNB, most multiswitches require a quattro LNB, though if you look around there are multiswitches which are compatible with quad LNBs, though most of them are more expensive than replacing the quad with a quattro and using a 'normal' multiswitch.

[Alan]

Or maybe something like Triax DDU112 Loft Box

[Andy Burns]

Yes, that's a potentially useful half-way house, providing you only want 'full' SAT reception in a limited number of the secondary locations (two locations for single tuners, one location for dual tuner) and RF viewing of the main SAT receiver in the rest of them.

Cuts down on the number of cable drops required and on having separate di/tri-plexers.

[John Rumm]

This sounds like it ought not work correctly anyway if you have more than one satellite box in use.

I would go with Alan's suggestion. Change the LNB for a quattro, stick in a multiswitch with enough outputs to take two to every TV position. Take five cables into the switch (four from each of the LNB outlets and one from the amplified TV aerial). Run a pair of coax to each TV from the multiswitch, and then fit a faceplate at the end that will also undiplex the DTT from the Sat feed.

[David Robinson]

I wonder if the OP has tried it in each room one-at-a-time and concluded that it does work?

Or tried two or more STBs tuned to the same channel (that can sometimes work, though it can potentially kill the STBs and/or LNB!).

asalcedo - if you want satellite in multiple rooms, the cheapest option for a small number of rooms is what you have now (separate feed from LNB to each room) - the _only_ way of "splitting" a satellite feed so that it works in more than one room at once is to take four feeds from the dish to a multiswitch, and then the multiswitch provides multiple outputs, each of which can be connected to exactly one STB. (PVRs require two feeds).

Cheers, David.

[asalcedo]

I left the installation to a local specialist without me getting too involved.

Perhaps he did go for the wrong kind of equipment.

Is it then a multiswitch the one to go for? Since I am reading conflicting inputs, which one in particular?

I will nevertheless try first a simple four way splitter and see if it works. It is a much simpler solution for my present arrangement.

[Andy Burns]

A multiswitch will let you view from satellite and aerial in all locations, the various "loftboxes" that have been shown as alternatives will work, but only allow viewing of satellite in a one or two extra rooms (depending on whether single or twin tuners required).

Don't forget the quad versus quattro LNB too.

It won't (unless you disconnect or turn off all but one satallite receiver at a time).

[Andy Burns]

Not to specifically recommend this make, or this supplier, but you will see the "5 in" (4 in from quattro LNB plus 1 in from aerial) and "8/12/16 etc out" multiswitches.

supplier *does* sell quad LNB switches, but they are "prefessional" range and so more expensive

are cheaper quad compatible ones, e.g.

but you may find it even cheaper to replace the quad LNB with a quattro LNB provided access to the dish is not an issue ...

[John Rumm]

Just in case any readers wonder why this is the case, a brief explanation may help.

With Sat systems the "aerial" (i.e. dish/lnb) is not passive in the way a TV aerial is. The LNB actually does the first stages of tuning the signal. Hence LNBs not only shift the frequency of the incoming signal down into a range which can be usefully sent down co-ax cabling, they also tune to either high or low band operation, and select horizontal or vertical polarisation. So when STB is tuning in any one channel, it also commands the LNB to adopt one of 4 unique combinations of band / polarisation. If two or more STBs are involved they could obviously end up with conflicting LNB settings depending on which channel the user wants to view. You can circumvent this issue by either giveing each STB its "own" LNB (or more commonly its own switchable output on a multi output device), or using a multiswitch.

The multiswitch solves this by having all four LNB settings made available to it concurrently, and then connecting the appropriate one to the STB based on which combination of LNB settings it is asking for. So as you flip channels you are also potentially swapping between different LNB outputs rather than changing the settings of "your" LNB output as you would with a dedicated LNB output to play with.

[asalcedo]

Hi Andy, thank you very much for your helpful comments.

I understand that the satellite receiver (what in the UK I call the Sky box) powers on the LNB, but why exactly will only one satellite receiver work if using a simple splitter?

[Andy Burns]

Because the receiver sends 22kHz pulses and/or different voltages to the LNB to select a combination of high/low frequency band and horizontal/vertical polarisation signal from the satellite(s).

If you use a passive splitter and more than one receiver is connected it's likely they will each want to tune to different frequency bands and polarisations, at best it won't work, at worst it could damage receiver or LNB.

[Dave Liquorice]

The reciver does more than just power the LNB it also tells it which polarisation and which band to send back to the reveier. Polarisation is selected by the voltage sent up the cable and band by the precense or not of a 22kHz tone.

Which band and which polarisation that the LNB needs to convert for the receiver depends on the channel you want to watch. There may or may not be a conflict but if there is things will get "messy".

[asalcedo]

David,

Thank you for your simple explanation that clarifies it all.

I understand now that what the professional did was close to optimal given his understanding, at the time, that the satellite feed would mostly always provide all DTT channels.

That is not the case now, quite a few DTT channels are not available in the local satellite feed. Thus, I want to provide DTT signal to the rooms that at the moment have only satellite signal.

And yes, I have had simultaneous viewing of different satellite channels at the same time in at least two different rooms. Caveat, one room was fed directly from the satellite, the other one was via the combiner. Which may confirm that my understanding that it did work was incorrect.