Which splitter should I use?

Retty · Frequent Visitor Joined: Sep 07, 2006 Posts: 336

I've read posts describing the GNS Y aerial splitters and most reports seem to say that the GNS splitter (or equivalent) is the way to go.

Has anyone had success with an ordinary y splitter which is specifically designed for TMC?

Btw, does anyone know where it's possible to buy a GNS splitter or equivalent in the UK?

mikealder · Posted: Mon Apr 30, 2007 5:33 pm Post subject:

I would make up a cable from bits if I were you, get the connectors you require to match your vehicle/ equipment and layout from either Maplins or have a look at CPC, there are too many connector variables to make it viable to market the leads needed to split the aerial feed.
What equipment are you trying to interconnect, then I can suggest a few components that can be put together - Mike

diabeticpaul · Occasional Visitor Joined: Aug 21, 2005 Posts: 40

I bought mine from lowestontheweb (Evesham Computers). It was £29.95 incl P&P. I just looked and the item wasn't listed. May be worth 'phoning or emailing them.

Hope this helps

Retty · Frequent Visitor Joined: Sep 07, 2006 Posts: 336

mikealder · Posted: Mon Apr 30, 2007 5:58 pm Post subject:

I don't see any advantage with a boughtout lead over and above a home made one, the home made item is certainly cheaper and the cable lengths cut to length to match the install, 30 quid seems costly, I would expect change from a tenner building a lead from components - Mike

Retty · Frequent Visitor Joined: Sep 07, 2006 Posts: 336

mikealder · Posted: Mon Apr 30, 2007 7:21 pm Post subject:

swing · Posted: Tue May 01, 2007 6:55 am Post subject:

GPS_fan · Posted: Tue May 01, 2007 10:56 am Post subject:

The whole thing is a minefield and whilst most manufacturers go to the trouble of providing an optional aeriel to boost satellite reception, nobody seems to have thought much about FM/RDS reception required for TMC.

swing · Posted: Tue May 01, 2007 11:08 am Post subject:

Indeed - part of the "bigger" problem is that the single wire aerials are often "just" good enough in most (*) countries, allowing the SatNav manufacturer to produce a single solution worldwide.

(*) although not in the UK, where they really can't cope.

The cost of producing a "better" solution for the odd parts of some countries, and to improve the UK TMC situation may not be economical for all SatNav manufacturers.
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GPS_fan · Posted: Tue May 01, 2007 11:20 am Post subject:

Yes and the UK is complicated further by having 2 TMC providers.

...but, surely a better aerial would benefit everybody, not just a few

swing · Posted: Tue May 01, 2007 11:43 am Post subject:

A few other European countries have 2 (or more), so that shouldn't be a major issue to the manufacturers (although few other countries have all providers being commercial operations, which does complicate some of the logic required).

Although a car aerial connection would benefit all, in most other european countries, the signal strength is so high, even the single wire can pick up a strong signal in 99% of the country, so a better aerial would only increase this marginally towards 99.6% (say). Whereas in the UK, the better car aerial connection moves you from something like 40% to 80%.
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GPS_fan · Posted: Tue May 01, 2007 1:13 pm Post subject:

OK, I'll have to take your word for that because I've only experienced TMC in the south of England.

I haven't used GPS on the continent since 1998, when it was still relatively new, and I was stuck in French customs for about half an hour whilst the customs officials called over their colleagues to have a look at this impressive gadget.

Anyway, back on to the topic...

...could there be other advantages in going for a GNS splitter - signal amplification, for example.

There's no mention of this, but could there be amplification circuitry in that 'box' on the splitter.

If you're crerating your own splitter, is there not a danger of reducing the signal strength to both the car radio and the TMC receiver - ie if the car aerial produces 1 unit of signal, half of this unit will go to the radio and the other half will go to the TMC receiver.

Or am I over-complicating matters?

Also, if Retty is paying somebody to custom-make a splitter, is he not likely to end up paying at least as much as buying from GNS by the time he's paid for components and then labour on top?

diabeticpaul · Occasional Visitor Joined: Aug 21, 2005 Posts: 40

The GNS splitter uses a balun (a form of capacitor) to pick up the feed for the TMC signal. The advantage of this is that the TMC/RDS feed is totally isolated from the aerial lead. It does not weaken the feed to the car radio as a direct connection would do and matches the lead impedence to the TMC receiver.

GPS_fan · Posted: Tue May 01, 2007 1:41 pm Post subject:

I've seen balun transformers being used with aerials, but I couldn't find anything anywhere online (well, within the first couple of pages on Google) what this balun transformer did.

So, in effect, I guess that the TMC feed is amplified by being 'filtered out' for the TMC feed.

I guess, therefore, that an amplified car aerial may not necessarily improve reception because the background will also be amplified without this balun - or is over-simplifying things?

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