Hope its ok I open a new thread on this topic. I've learnt a bit more about TMC, and discovered that an encrypted signal may be locking people out not only in Australia, but other countries also.

My situation is I own a 2013 Mazda CX5 that has a TomTom NB1 built into the dash. The NB1 includes a RDS/TMC receiver and the TomTom navcore (10.854) is able to use the traffic data received.

So I was scratching my head as to why I had a car with TMC hardware and software, in a city that has a TMC broadcast service - why it was not working. People in other countries like the UK and US were driving the exact same car and using TMC traffic! Well with some digging, and help from a few people, it has become clear that many TMC signals are in fact encrypted, and the car or GPS manufactures are required to purchase a license in order to incorporate the decryption key into the navcore in order to use the traffic data.

This is the case in Australia with SUNA, and most other countries. Unfortunately for me, either Mazda or TomTom have not paid for the license, and therefore my TMC capable GPS, whilst able to tune into the SUNA traffic channel, does not have the appropriate decryption key to use the SUNA traffic data.

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So, the question becomes - where exactly is the decryption key implemented into the navcore - and can perhaps the decryption key be extracted from another navcore that includes the necessary code.

Whilst no current TomToms seem to have valid licenses with SUNA, there were a number of old devices that did have lifetime subscription (and therefore the suna decryption key included in the navcore.

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Those devices are:
XXL 540, XL 340, One 140, 730 Traffic, XL Traffic and Go 720 Traffic

Perhaps if I can work out where the decryption key is, i can extract it from the old navcore - add it to mine and unlock TMC traffic!

In navcore 9, allot of things point to the mctx.dat file. But there is also the GNS folder, and the files in the maps folder - tmccodes.dat and traffic.dat. Issue I'm facing is mctx.dat and GNS folder are not part of navcore 10.854.

Its so frustrating. I actually quite like the TomTom - but end up using Google Maps on my phone most the time - as a GPS that routes you straight into traffic is useless! Interestingly, google maps uses that same traffic data SUNA broadcasts (Intelematics) I could make a request to MAZDA - but its unlikely they will add SUNA support as they have already moved away from TomTom and are using Navteq maps in the 2015 CX5 model.

Here is another article I stumbled across related to TMC decryption.

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poshea Reviewed by poshea on 15th December 2015. Decryption key for encrypted RDS-TMC Hope its ok I open a new thread on this topic. I've learnt a bit more about TMC, and discovered that an encrypted signal may be locking people out not only in Australia, but other countries also. My situation is I own a 2013 Mazda CX5 that has a TomTom NB1 built into the dash. The NB1 includes a RDS/TMC receiver and the TomTom navcore (10.854) is able to use the traffic data received. So I was scratching my head as to why I had a car with TMC hardware and software, in a city that has a Rating: 5