Thread: Using TMC in Garmin nuvi for free

Originally Posted by Giomen

Is Bulgaria only for 2xxx, 3xxx unit? Which GTM models is supported?
My ID for GTM20 do not give me a result! Then I see info in "Compatible products" folder for product...

No, many other GPS models are on the list of compatibility of Garmin page, just take in the acquisition sequence to check the signature. Will be asked for ID of the GTMxx and the code signature is given automatically. From what I could check in this list, some GPS models are compatible with the GTM20, but there is the possibility of it not working if you use it in another model off the list, because some GPS firmwares can not handle some parameters (as ecc) of some types of signatures. If your intention was just to get the parameters of the official Garmin to study it, I can save work for you: 30721,1,1. I find very curious that in Portugal, with Garmin Traffic Free service, no signature is required and no configuration, tuning is automatic (no providers and parameters in trafficproviders.xml). In the case of Bulgaria, even with free Garmin Traffic, is required signature. I've also found that even in countries where the service is paid, you can use it without any signature, just knowing the frequency of radio transmitting TMC and manually setting it (Developer Info/GTMStatus/Test, in Nuvs 13/14xx US fw, easier in Asians fw), attending to that the automatic scanning are in the same parameters that appear in the FM Table of tuning (cc/ecc/pid/ltn). I understand then that the parameters (cc/ecc/pid/ltn) are broadcast on radio and tuned automatically by the receiver GTMxx and the signature is only one element that can facilitate (or complicate) automatic tuning correct, especially when more than one radio with RDS (Traffic ) in the region, but even in these cases of multiple transmitters Traffic, we can manually set the tune and use the service without problems .. So, from what I could see the signature looks more like a smart way of Garmin to make more money than an absolute necessity for using the service. It remains to check if is a rule or are isolated cases ..