Improving TMC on c550

[badass101]

Hello all,

I've just recently purchased a c550, and I'm quite impressed with it so far. However, I've found the traffic reporting a little flaky and from reading a lot of other posts here there are people with similar problems (and different types of Garmin kit).

I've tried having the aerial stuck vertical on the windscreen, and also lying horizontally across the back of the dash (at the bottom of the windscreen).

The problem I have is that I seem to get the green traffic LED when I'm stopped at my house/destination, but as soon as I get moving it goes orange after around 15 seconds.
Occasionally it goes green while driving (drove to Bristol at the weekend and had about 15 seconds of green when passing Membury services).
Obviously this is not great as the whole idea of traffic reporting is to warn of jams on the motorways, etc.

I'm pretty stuck with diagnosing if the fault is with the TMC data itself (is it broadcast continously on all the 88 odd transmitters in the UK, or is it sent in bursts?), the aerial on the unit (a bit of wire was never great for FM reception on clock radios, etc) or is it the positioning of my aerial?

Can anyone provide me with any tips or techniques to improve or diagnose TMC reception?
The unit itself really doesn't tell you much in the way of what it's tuned into or how good the signal is!!!

Oh, last point - when you get and loose TMC signal, the traffic info seems to stay on the machine. However, as soon as you get a sniff of a TMC signal again the unit seems to wipe all the traffic info from before (and then usually looses signal before it's got any more traffic info) which leaves me with a blank list - is this normal?

Sorry for all the newbie questions, but I couldn't find any substancial answers anywhere!

Craig

[cantgetlost]

If you search just around here and slightly further back you will see my take on this very subject under " Kin useless bit of kit".
Problem solved to the best I can find with the connection parts used as described right near your post here under " Traffic Again !!! "
Both Garmin Aerials proved useless in my car ( it has heat reflective gass) so the why connector to the car aerial and the facra connector from it to the GTM aerial socket sorted to probs.

[badass101]

Thanks,

I saw that post but I figured people talking about aerial splitters were those with units that connect to the car radio aerial... or do I have to chop and splice the garmin wire to a splitter? I have a GTM-21, not a GTM-11 or 10

Sorry for sounding silly!

Craig

[cantgetlost]

GTM 11 comes with a long wire aerial or a short stub aerial that both fit FAKRA socket on the GTM.
I'm not familiar with the GTM 11, but as your problem sounds the same as mine and that the two detachable aerials from Garmin proved next to useless in my Merc and wrapping the wire version around the cars aerial lead as advised by Garmin tachies proved useless.
I guess if you can join the 21's aerial to your car aerial you may get the same results as me.
I tried the unit attached out side the car with the stub aerial and ran the wire aerial between my roof bars , tried the same on top of the Hogs back road and draped wire aerial up a tree in my garden all with no signal.
Within a minute or so of pulling my radio free outside the store I had the Y splitter fitted and a signal and Traffic info on my nuvi. It works outside my home and I have data before I leave my driveway now and no probs on the Hogs back road either or the M25. But there are spots where you can't get a signal, but not many now with using the car aerial.

[swing]

[swing]

[badass101]

Thanks for the comprehensive reply Swing (and the others)!

Maybe I can hold out some hope that Garmin may improve the tuning or the error reporting/feedback on TMC signal in later firmware revisions?!?!

Will try your debug suggestions tonight and let you know how I got on...

[cantgetlost]

I take it that the GTM wire aerial is much the same as the GTM 11 wire aerial that plugs in.
Garmin put me through to one of their techies who has one in his own car, he solved his problem by wrappping wire aerial around the car radio aerial cable.
In my case that did not work, but surely bearing the end of the wire aerial and connecting to the car radoi aerial would have the same effecr as my fakra connection. If you found that improved the reception the aerial could surely be cut down shorter and fed via Y connector to the cars aerial

[swing]

[badass101]

Just to update you all, I had a play last night...
I know that I can get traffic reception outside my house, so I turned the unit on and held the aerial in my hand. I moved it from position to position, watching the LED and waiting for traffic reports to appear on the screen.

I found that when I moved the aerial to a vertical position, poking out of my window, the reception dropped off to nothing.
I determined that the best aerial position was running the lead horizontally, but draping it across the 'hump' where the instrument panel is rather than tight at the base of the window.

I took a journey into and out of London today and had traffic reception for most of the way, with decent accurate reports prompting the unit to alert me to avoid jams.

I also took a short trip in the countryside near Reading last night and had TMC for most of the trip (certainly enough to get the alerts in)
SO, it seems that TMC can work well if you spend time fiddling with aerial positions.

As swing says, I expect that if they up the signal strength of the transmission then most of these issues would be resolved... here's hoping!

[LEIGHTON]

I took delivery today of GTM12 TMC, after reading some of the threads in this Forum regarding the reception etc I began to get a little apprehensive and worried in case I had bought a "Pig in Pork" however when I connected the device to my 2720 there was no signal so I drove a few miles and sure enough it started to pick up a signal and showing traffic details as far away as 120 miles. So I think the answer is it does not always show a signal because of location etc and when it does pick up a signal it will give plenty of notice where there are traffic problems. I live in Rural Wales and accept there are places where there is bad reception however just driving a few miles to the A roads I pick up signals showing M25 Traffic conditions so I see no problem with the device.
There is only a very short aerial wire about 1 ft and I have it lying at the bottom of the windscreen of my Merc
At the moment I am most happy with my purchase and will write more when I use on my trip to Plymouth this weekend. ,

[cantgetlost]

When I had the probs with my GTM 11 I found that when moving the aerial around I seemed to be a good aerial. Holding the aerila I would getr reception, and as soon as I let it go I lost reception!

I think with all the posts here that Garmin really has issues re these units being fit for purpose.
I can accept that in some places you get reception black spots, but can't beleive that I and others living and working around London area and the South east should have so many reception problems.
Living in hilly wales or the Yorkshire Dales you can understand the problems.
My experience is that you NEED EXTERNAL AERIAL to get the best out of the unit.
It would seem that there could be issues with how good the Garmin receivers receptor is or how good the TMC signal strength is.
I would assume that the Garmin units are very capable providing aerial can get reception, if that is the case it is about time TMC boosted the signals.
Traffic Master web site seems very basic, I would expect to see more info on such a site and a good feedback link to help them give a good service. There doesn't even seem to be any info re expansion or proposed expansion of the TMC network.

Travelling through France I've found very minimall hard shoulder side of motorway and main route road works coming up on my GTM feed. It makes me wonder if the French system feed has more manual input about where road works that could present problems are.

[LEIGHTON]

Hi,
I went to Plymouth last weekend which is about 3 hours from home and found no problems with the TMC 12. In fact I was pleased with the way it performed.
I agree though that Traffic Master need to improve the signal as I did experience some black spots but on the whole it performed very well, perhaps I am lucky. I think the price for such a small item is a bit extortionate I paid with shipping etc £160.
The warning for delays etc were given in plenty of time sometimes giving an all clear before nearing a displayed delay which saved time by not re-routing.
Another little quirk is the aerial wire seems very delicate and will not take a lot of moving around, I think they should have made some kind of connection to replace the wire if it does break or get damaged instead of the sealed unit .
Overall I am quite satisfied with the unit but its a bit pricey for what it is,and can understand any body's dismay when there are problems when entering cities such as London after all the system should work in all major areas that is the whole point of having the unit.
Best of luck and regards to all.
Leighton.

[RDS]

As I've said elsewhere I took my Nuvi 310D back for a refund yesterday precisely because of GM12 TMC reception problems. I regularly drive around M40, M4, M25 and M1 and found the performance to be quite erratic. On an average day I could be receiving a good signal one minute, then after just a brief stop for fuel or something would find I'd get nothing at all.
While I plan to get another Nuvi when the whole TMC issue has been properly sorted I also have concerns as to how the GM12 receiver and aerial will stand up to regular use over time. Certainly it doesn't look particularly robust for a piece of kit that costs around £140-£150, and as has been noted if the thin wire breaks there doesn't appear to be an easy way of repairing it.

GPS manufacturers must realise that due to the security risks we're being advised by the police to remove all sat navs and related accessories when leaving a vehicle.Consequently they really now ought to be designing equipment that can stand withstand the constant connecting and disconnecting that everyday use now requires.

[n4nick]

Hi RDS

I have been trying to return my 310D for the same reasons as you but Halfords are refusing to accept there is a problem. Did you receive confirmation from Garmin? I have also spoken to them but so far no email to help! Even worse, my 28 day period expires on Saturday :-(

Cheers - Nick

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