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Taps & Splitters

2old4this

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#1
Anyone have a link to a site with a GOOD description of the usage and workings of taps, splitters, combiners, distributors and multiswitches? By "good", I mean: complete, technical and with diagrams.

It should cover nuances such as the nature & purpose of power pass-through, the differences in frequency ranges, signal attenuation, etc.

Site language should preferably be English, Dutch or German.

Thanks in advance.
 

Llew

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#2
Hi 2old4this

Good to hear from you again!

Spaun do a range of pdfs covering some technical aspects of multiswitches, taps etc. Obviously limited to that company's products, but maybe of some interest.

_www.spaun.com/tech_advice.php

Llew
 

2old4this

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#3
thanks Llew, some nice kit and docs. Not exactly what I'm looking for though. I was interested in the how more than the what.

My ideal resource would explain, for example, what the purpose of DC power pass-through is, what the consequences would be of connecting multiple receivers through various types of kit (splitter/tap/switch/...), up to various types of LNB(s) (universal/double/quad/...). EG voltage considerations at the LNB, 22khz control considerations.

Most resources online don't cover these details in any depth, or only cover those pertinant to the vendor's own product offerings.
 

rolfw

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#4
Hello 2old, long time no hear from. :)

If you haven't already seen it, there is this thread, I will have a dig around for any other literature.

I use them quite regularly, so if you need any help or specific information, PM me.:)
 

2old4this

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#5
yeah, haven't been involved in the scene for a goodly while now, but I'm keeping an occasional eye on you guys ;)

Spiney's FAQ (your link) is very nice. I'm still hoping for a complete technical and practical guide on the whole range of connection possiblities. Even a book suggestion do. As ever, the Devil's in the details, an it's all very much a black art.

I struggle, for example, to see the purpose of a single-input multiple-output sat-splitter (as opposed to a multiswitch), since multiple receivers connected to a single LNB through such a device would never gain simultaneous independent high/low/H/V switching control of the LNB. And yet the market is full of such devices. They appear to be intended for single-master/multiple-slave receiver set-ups, but how is such a set-up ever likely to be useful? I think I must need a more complete understanding of the potential uses of such devices.
 

rolfw

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#6
1 in, several out satellite/IF splitters, can be used to cascade multiswitches, so from one four way IF amp, you could say feed 4/6/8/12 or more separate 6/8/12/24 way multiswitches in remote locations from a single dish and Quattro LNB.

If the remote locations are all in one direction (linear), instead of splitters at the central location, one would more likely use taps, with descending attenuation values as the distance increases.
 

2old4this

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#7
That makes sense. And yet splitters are being sold as a cheap (albeit stupid) way of connecting multiple receivers to a single LNB. See for example Maplin UK: http://www.maplin.co.uk/module.aspx?detail=full&ModuleNo=9273&doy=24m2#more_info

Another question I had as I was thinking about al this stuff: some splitters have DC power pass-through on one line, others on all lines. There's a jolly good reason for this I'm sure, but I've no idea what. In fact, is it not the case that a splitter with a single power-pass-through is actually a tap, in which case Maplin's labelling its goods wrongly? Or should I have taken up a different hobby?
 

rolfw

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#8
If you were to use a single LNB to supply several receivers via a splitter, then you would need through power on every leg, as each receiver would need to control the LNB when the other/others were switched off. I also use these for sitting in front of a UHF masthead amplifier, then I can power it via any point in the house. The ones with line power on one leg are almost exclusively used for UHF systems, even though they are sold by people like Maplin for IF use. :)
 

2old4this

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#9
The MAPLIN one I linked to has a 2GHz range. I assumed the 1GHz versions were for UHF signals.

Here's another thought: If one were to connect, say, a single universal LNB and 4 receivers to a 4-way splitter with DC passthrough on all lines, what would happen if more than one receiver were on at once? Would the first one to power-up grab the LNB? What would happen when that receiver powered down while the others were still on? Or does each successive receiver grab it, and what about when the last one on powers down -which receiver then gets control?
And would there be any danger of damage to the LNB while having multiple receivers trying to power it?
Which high/low and H/V switching signals would get through?
 

rolfw

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#10
Not sure, have never tried it. :) I would imagine that the LNB would switch to the highest voltage, but as you say, it is pretty much unworkable.

Was thinking, also the trhough power can be used in a multiswitch scenario, to send line power to a four way IF amp.

I use full band splitters 5-2000 for most of my UHF work.
 

Channel Hopper

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#11
Hi there

I really thought the mechanics / usage of couplers and splitters was somewhat below you, but just to get you up to speed

Short on maths, but nicely scripted

http://marine-electronics.net/techarticle/sp_taps/sp_taps.htm

Bit more mathy, and some scribbles

http://www.hometech.com/learn/video1.html

somewhat more brain juice with introduction of the dB in the calculations

http://www.sencore.com/newsletter/May04/signallevel.htm

and the full English

http://www.bicma.gov.bt/paper/catvdesign.doc

Hope you are well and prospering
Regards
CH
 

2old4this

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#12
Wotcha CH. Yes, doing just fine out here in cloud-cuckoo land. If there's one thing people will always need, it's clouds. And cuckoos. Two things.

Nice info at those links, thanks.
All of it refers to CATV & similar, not (as far as I could see) to sat. The principles are undoubtedly the same, it's just that the control signals travelling from receivers to LNB complicate matters so much. I'm still left wondering exactly how (badly) a multi-receiver/one-LNB setup would operate if connected only via splitters (or taps). It'd be so much cheaper than using quad LNBs and multiswitches, and while it would never be acceptable if wiring separate appartments from a single feed, it might be adequate for separate rooms in one house.

Maybe I'll just try it and see...
2old
 

rolfw

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#13
You might also want to look at the new single cable solution 2old, the equipment is starting to appear with some of the mainstream companies, June will probably be the time when it becomes properly available. Unicable LNBs are already on the market and I believe that the Triple Dragon has Unicable support.

What are you actually trying to achieve?
 

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#14
2old4this said:
Nice info at those links, thanks.
All of it refers to CATV & similar, not (as far as I could see) to sat. The principles are undoubtedly the same, it's just that the control signals travelling from receivers to LNB complicate matters so much. I'm still left wondering exactly how (badly) a multi-receiver/one-LNB setup would operate if connected only via splitters (or taps).
Ah, LNB control is almost always outside the scope of distribution of signals because of the DC passing and the filters required each side of the bypass. Notches invariably get into the system, which lead to dips in signal at particular frequencies.

I recall many years ago that Philips brought out a five cable solution in a tap design (Switchline ?) , and whilst very neat, did have issues that limited its functionality.

As long as you remember that one LNB output can switch with one receiver only, up to 8 receivers (or four dual input units) can run on a single octo LNB. Beyond that you need to double the dish farm, or use the range of IF distribution boxes (Sedna/Delta etc) then you can't really go wrong.
 

2old4this

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#15
Yes, the Unicable solution is attractive, but there are two problems:

(a) anyone with older receivers no longer actively supported via software upgrades will have to replace not only the LNB but the receiver too, and

(:cool: since the technology is not controlled by Murdoch, he's highly unlikely to embrace it for his digiboxes. And since there's STILL no sign of an official Videoguard CI CAM for the consumer, most Sky viewers will not be able to make use of this facility (unless they too change their receivers and invest in one of the "unofficial" CAMs (Dragon, Matrix, TRex etc.).

2old
 

rolfw

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#16
Point :cool: is incorrect, I believe that Sky are actively looking at Unicable to solve many of their users' problems, particularly where they live in apartments with only single cable feeds.

Also I believe that there are going to be breakout units available, so a Unicable receiver won't be necessary. ;)

Unfortunately there isn't much to see at the moment, I'm hoping to look at some working models at the big CAI show in June/July.
 

2old4this

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#17
A stand-alone device that sits between the receivers and the Unicable LNB, performing the necessary translation of control signal protocols would be great, assuming that's what you mean by a "breakout" unit. Any hard info on that?

Ideally Sky would offer Unicable support via an OTA software upgrade for all digiboxes. But I just can't see it happening. Call me a cynic, but I think they're more likely to build it into a new product for new installations only. I can't see any business case for them to engage on a programme of swapping out existing LNBs for Unicable versions, and I can't see them wanting to make it possible for their existing customers to do it themselves either - half would probably screw it up and over-burden their support desks.

Hope I'm wrong though... I've got several digiboxes scattered about the house, and they're not so easy to come by in my part of the world.
2old
 

rolfw

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#18
It'll be for the new boxes, as not needed for current Sky+ and HD installations.

No hard info on any of this, as the manufacturers are keeping their cards close to their chests and I didn't go to the local show this month, was too busy.
 

tesla

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#19
2old4this said:
Anyone have a link to a site with a GOOD description of the usage and workings of taps, splitters, combiners, distributors and multiswitches? By "good", I mean: complete, technical and with diagrams.
I 've been far away from the forum for a long time.
I saw the posts, i have to admitt that i did not spend the appropriate time to read every post carefully.

If you are still looking for info, send a pm to me.
 

rolfw

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#20
I've found out a little more on the sky system, they are not as I'd thought going with Unicable, but with another system, Single Cable Router, which will require a new digibox, so you were right, they've gone their own way.

The system will consist of a module which fits on four multiswitch outlets, with loopthrough for existing outlets and a single cable feed to the user. There is then apparently a breakout box, but it willrequire the new type of receivers.

Will update this when I see something a little less vague. :)