Relying on TMC? Better be careful!

mikealder · Posted: Tue Apr 24, 2007 5:37 pm Post subject:

I have been trying out a Navman T1 RDS-TMC unit in the North West of the UK which is renowned for poor coverage (NW that is not the T1).

Guess what - it works, this uses iTIS data supplied via Classic FM it uses an external (to the device) the aerial stays in the car though. I was going to make up a lead to couple the mMCX connector on the T1 to the cars aerials but found this wasn't necessary - but at least I have this as an option available to me.

Just goes to prove RDS-TMC can work, this wasn't an issolated freak occurance either, so far it has received data on 7 separate power ups (nothing else I have tried local to home works this well).

The supplied aerial is considerably better than a "shoe string" but the really important part is the availability of the connector which provides the upgrade path for a top quality feed aerial to be connected should you need it. I will try it connected to the Hirshmann amplified feed once I get a connector from CPC later in the week (cheaper then the addaptor leads some are using, I think I can make a lead to length for under a tenner with top quality cable and gold plated connectors if anyone wants one) - will post the results of the external feed once I try it - Mike

jonandmarkuk · Posted: Tue Apr 24, 2007 5:52 pm Post subject:

Rumour has it there is two different versions of the T1, the latter being released in responce to customer complaints about receiption.
Could be wrong though as Navman would never confirm or deny this rumour

GPS_fan · Posted: Wed Apr 25, 2007 8:11 am Post subject:

GPS_fan · Posted: Wed Apr 25, 2007 8:33 am Post subject:

Hamie · Regular Visitor Joined: Dec 30, 2003 Posts: 177

I'll worry about fake messages when I start to get some real ones... Maybe we could all build one and finally get some bloody traffic on these pathetic examples of engineering that the vendors are pushing off on us.

jesus, there are better things to worry about that the ability to fake radio messages (Which people have been able to do for about 70 years now, ever since WWII).

Hamish.

idiot · Regular Visitor Joined: Aug 22, 2005 Posts: 72

GTM 12...GTM 21 Garmin this Garmin that-I give up, back to TomTom One v2 and a bluetooth phone.

Hamie · Regular Visitor Joined: Dec 30, 2003 Posts: 177

Kar98 · Posted: Fri Apr 27, 2007 1:49 am Post subject:

swing · Posted: Fri Apr 27, 2007 7:35 am Post subject:

Yup, they only managed 3 main connectors Smile

However, one would have thought the car manufacturers could provide 1 connector, and then, if needed, the SatNav vendors could provide an adaptor cable to their chosen connector type.

However, look at how long it's taken the car manufacturers to offer Bluetooth Handsfree, or ipod / mp3 connectors - why should they provide an aerial connection for a third party SatNav unit when they will want to sell their £800-3000 fully fitted SatNav unit (which might also do traffic, when the can be bothered to provide TMC disks).
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thezerocool · Occasional Visitor Joined: Jul 23, 2005 Posts: 24

mikealder · Posted: Sun Apr 29, 2007 12:06 pm Post subject:

I can assure you I have tried this all over the country with very little reception at all, this being in various cars - as an example only last week, Blackpool to London aprox 250 miles, RDS-TMC for 25 miles, the remaining time it sat there "tuning".

Get an external aerial I hear you say Laughing

, I have one of the best external aerials you can buy 8) , I have also tried the device coupled to other aerials as a test, this improves matters but not to the point where I would consider it acceptable. Where I live is a poor reception area, but from experience even when close to a transmitter reception is at best patchy.

I guess you have hit lucky and got a device off the production line that exceeds normal reception, best of luck with it for the future, the fact it works for you as an isolated individual gives hope to the others that are still awaiting a hardware fix to actually solve the problem. - Mike

GPS_fan · Posted: Tue May 01, 2007 1:32 pm Post subject:

Also, it depends upon how your GPS indicates the presence (or otherwise) of TMC and what prompts this to change.

For example, on my Mio, TMC is indicated by an icon (the satellite reception icon, which shows 2 small cars when a TMC signal is present). However, simply loosing a TMC signal is not alsways sufficient to change the icon - often the screen has to be changed (eg to a menu screen and back) before the icon changes.

I can illustrate this example further by using my journey to work:

I have a full strength TMC signal at home, but NO TMC in the car park outside work.

If I drive to work without changing the screen displayed, my GPS indicates the presence of TMC throughout my journey and until I turn the GPS off upon arrival at work.

However, if I have to TMC control screen showing as I drive to work, it shows 'TMC present' for less than 50% of the journey.

If, I leave work and drive home, then the GPS indicates an absence of TMC for pretty much the whole journey.

Is it possible, therefore that thezerocool is not actually receiving TMC as well as it appears on face value and they are, in fact, in the same situation as the rest of us?

When the TMC data is viewed and TMC is present, there appears to be a constant stream of updates rather than udates at 15minute intervals as indicated by thezerocool

jonandmarkuk · Posted: Tue May 01, 2007 1:46 pm Post subject:

My Viamichelin icon goes red when the TMC has been lost, but this is a delay as I have seen it be green when first switching on with the aerial unplugged.
Driving down the motorway I have seen it change without changing screens, it is useful to know the signal has been lost.

The Navman 530 I had didn't have anything on screen to let you know it was receiving TMC or not, although the manual suggested it should.... another bug Navman refused to fix maybe?

jimbo_hippo · Frequent Visitor Joined: May 18, 2005 Posts: 444

I agree with those who argue that bad data is no better than no data. I use TT Traffic over GPRS and it's hardly faultless although this idea of monitoring mobile phone movements for quick reliable info is interesting and I hope we might see something that works on the summer (dream on). But as for the TMC issue, with the speed we seem to change our devices and the tumbling cost of GPRS access I opted not to get a TMC reciever as I already have a collection of devices which were state of the art for 5minutes and I don't want another. Even if TMC worked, I'm not gonna shell out £xx on something to clutter up my dash if I can use that money to pay for GPRS costs which are minimal anyway.

The only time a TMC stick might be useful is when I'm abroad in a hire car as GPRS roaming ain't cheap. But a quick single connection before departure gives general info on big problems then switch it off. This usually works well enough and I really don't want another bit of kit to drag around in my hand-luggage then shoehorn into a hire car.

For all it's faults GPRS Traffic seems to be occasionally useful with little pain or cost.

And whichever way you go that vision of sailing past motorway traffic on a little B road grinning and waving as you arrive home early is still a long way away anyways. So if you get a signal will you trust what you recieve or just use it as a guide and cross chech with RDS. THat's what Traffic has become for me.
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inspiredron · Posted: Wed May 02, 2007 5:49 pm Post subject:

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