TMC help/info please

iuw · Occasional Visitor Joined: Jun 09, 2005 Posts: 19

I recently aquired a Navman F30 which has the T1 TMC receiver.

My questions are:-

Does this service cover the whole country?

Does it transmit data all the time or intermittantly?

Here in this area (mid Gloucestershire) absolutely nothing seems to haapen with this setup.

Am I using it wrongly? or is there no service? the info in the paperwork is sparse to say the least.

Thanks

Roger

mikealder · Posted: Thu Jul 19, 2007 5:55 pm Post subject:

The Navman RDS-TMC system uses information supplied by iiTIS who transmit the data using Classic FM radio stations.
The data supplied is regional but will cover a fairly large area as you move around the country the device will re-tune to a different transmitter thus receiving data more pertinant to your position.
The problem with Classic FM is one of coverage the signals are often too weak to be picked up, this is further compounded if your vehicle has athermic glass as this further attenuates the allready weak signal. The answer it to connect the T1 receiver to an external aerial or even the existing car aerial is known to provide dramatic improvement in terms of reception.
On the device you should see a TMC box this is the indication the receiver is functional:
Grey/ Blue means the unit is scanning for a signal
Green means signal acquired with no problems on route
Red means expect a hold up on route
To get the most from the device you need to configure the TMC options with the device connected and powered up in the car, the options allow auto reroute to avoid hold up and such like - Mike

iuw · Occasional Visitor Joined: Jun 09, 2005 Posts: 19

Thank you, Mike,

Funnily enough, Classic FM is fine on the car radio (Golf which uses the rear window heater as an antenna).

I get the blue box on-screen, but it never seems to change and there never seems to be any data in the list, likewise, no preferred stations listed.

Thanks
Roger

mikealder · Posted: Thu Jul 19, 2007 6:43 pm Post subject:

Audio reception of Classic is one thing the digital RDS data requires a much stronger signal to work effectivley.
As you have a VW you can connect the T1 to the rear screen aerial but you will need a special addaptor in order to do this safely (VW card use an amplifier to boost the signal which requires a 12V feed that is supplied via the radio - connection to the T1 will damage the unit unless you use the correct kit, it is much easier to connect a Maplin mini scan aerial to the device which is a mag mount unit, this will work better than coupling to the heated rear window - Mike

keithjeffrey · Posted: Thu Jul 19, 2007 6:48 pm Post subject:

I've got an F20 and I purchased the T1 Traffic Unit seperately.
What I did to get it to work was to buy an external magmount aerial with a Garmin lead to connect aerial to T1 and now my T1 works perfectly.
You have to lay out about another £ 30 to £ 35 but as least it will work after that.
I must just add that I live and work in the South of England ( I could'nt tell you whether it will / won't work any differently in Mid-Gloucestershire )
No doubt people on this forum will be able to help you with that.
_________________
Keith
TomTom GO 730T App 8.392 (1909/091109) , W and CE 2GB v835.2419

iuw · Occasional Visitor Joined: Jun 09, 2005 Posts: 19

Thanks Mike,

Interesting info...I will give it a little longer before taking more action. I am by profession a radio systems engineer, but not entertainment radio!

Thanks again
Roger

iuw · Occasional Visitor Joined: Jun 09, 2005 Posts: 19

Update

Just to satisfy my curiosity, I just made up a couple of adaptors and connected the T1 to our domestic VHF antenna (in the loft space) the T1 straight away jumped into life a gave quite a list of data....

I think a mimi-scam mag-mount may be the way to go.

Thanks all for the info

Roger

mikealder · Posted: Sat Jul 21, 2007 11:32 am Post subject:

Roger, The Sky Scan is a better bet as the frequency range extends down to 25MHz, the Mini-Scan base frequency starts at 100MHz which is right where you need it to work (Classic FM uses 99,9 to 101,9)

The mini scan is great for its size and doesn't attract attention, since fitting the Sky Scan I have been asked quite a number of times by people wanting to know what it is for!! - Both work, but the larger aerial does work better when in a marginal area for coverage (like where I live) - Mike

iuw · Occasional Visitor Joined: Jun 09, 2005 Posts: 19

Thanks for that Mike,

They appear to be vertical co-linears so at, say 80mHz, the performance on recieve, will only be marginally down on its designed range....on transmit, howver, the VSWR is likely to be well outside the acceptable.

I now wish that I had hung-on to some of my amateur mobile kit!!!

Regards
iuw (Roger)

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