GTM12 Detail Strangeness

[tkerby]

I purchased a GTM12 which arrived on 24/01/07 at my work address in Corstorphine, Edinburgh. I plugged it in using my laptop to power the device over USB (through the mount plate on the back) and stuck the aerial to my office window.

The station picked up was listed as 101.7 in the setup pages - Classic FM. I received huge amounts of detail on the Edinburgh traffic including many Information messages on contraflows, all thr roadworks I knew about and traffic details including the bypass, Forth Bridge and even Seafield Rd near Portobello. The traffic all seemed genuine as I know the area and the roadworks were all correct. The furthest traffic info came from around 100 miles away

I then went to my car and plugged the GTM12 in using the new power supply I preemptively ordered from Garmin. 101.7 was removed from the setup menu presenting me with TMC_INFO and TM_TMC. I believe (from looking at the FM table in the hidden menus) that TM_TMC is the trafficmaster subscription and TMC_INFO is perhaps the ITIS info through Classic FM

Since these options appeared, I've had traffic info from all over the UK up to 350 miles away but very little local detail. I have no reception problems and hundreds of messages flood in but the closest info to Edinburgh has been 40 miles away. I've tried clearing the FM table, and manually selecting one of the two providers but have never got the detailed info back.

I can only presume the following

- Both TM and ITIS broadcast basic traffic info from the same source
- ITIS (Classic FM) also broadcast encrypted subscription data of a higher detail level than TM
- On that particular day, ITIS turned off the encryption by mistake

Did anyone else get the same blip or does anyone in the Edinburgh area get better traffic info than me?

[swing]

[tkerby]

I've diagnosed this a little futher - thanks for the info. I assumed an encryption of sorts as a key was involved but see now it's a location table difference that will lock you out of some services.

That aside, I've connected my GTM12 back in the office on USB power from my laptop and start getting the good data back again. It's very up to date, focuses on 1 mile to 60 miles away and includes info on roadworks, weather warnings, information on contraflows in place etc - e.g. a mix of green, amber and red severity alerts for the local area.

The strange thing is - im tuned into TMC_INFO on 101.7FM - Classic FM

I thought CLassic FM was only an itis service and see its causing some people problems in another thread.

I get

Tuned Channel: 142
CC: 12
SID: 10
LTN:10
Level 36
Error 91
Mode 5
N-Sync 0 Message Count:2370

Normally, I'm on TM_TMC broadcast by XFM scotland on channel 182 or 186. This gives me around 300 - 600 messages within half an hour or so, the closest being 30 miles away and covering the whole of the UK. Signal level is around 44 usually

So this is a bit weird.

When I've tried selecting TMC_INFO in the car, I dont get as many messages and the signal is much poorer.

So, I wonder if the filtered USB power is helping lock onto Classic FM in the office, where perhaps I dont get as good an XFM Scotland signal.....

I'm surprised to get data over Classic FM as I didn't think it was possible

My next experiment is going to be to leave the unit locked to TMC_INFO in the car instead of on auto and see what I get. I'm keeping my fingers crossed. I've also added some decoupling capacitors to my car cigarette lighter socket to smooth the power a little more (as I know it sometimes causes hum on powered audio devices) to see if my signal quality gets better

[swing]

One thought - which car charging cable do you have? If you have a car charger ending in 6017 then ring Garmin and ask for the new car charging cable which helps make traffic work better (ends in 6025).

Indeed you are correct that iTIS is Classic FM, whereas TM is the majority of other TMC signals in the UK.

[tkerby]

It's the new charger with the red light - I got one ordered a while back knowing I was buying a gtm12. I've not checked the product code but I presume there is only one kind of new charger with the single red led.

I've not fitted the ferrite they sent but I dont think that'll make much difference

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