RDS and TMC

**BeamRider** · 06-15-2004, 06:31 PM

Feelix99: I think that TMC GPS is nothing more than a GPS with an FM receiver (without audio section) and RDS decoder builtin. Alturion has similar solution available for both PDA and Laptop (it souldn't be too custom solution)...edit... it's a GNS GPS/TMC it's standard and emulable with a virtual com port

SilentAdmirer: well if D-Link uses that IC seems pretty easy to get signal for the RDS demodulator from FM-IF out...I hope that the ebay seller that sold me the D-Link will ship the radio, then I'll let you know

Jeep: does your card gives you complete RDS control? Can you read block/groups or just specific data? If you're able to get groups watch for 8A groups presence that is TMC! If your card can give such data it'll be easy to use it for TMC decoding without any additional hardware

More to come.....
Cheers

**SilentAdmirer** · 06-16-2004, 11:53 AM

I have opend my d-link radio today , it does use TEA5757

Satish

**Jeep** · 06-16-2004, 12:31 PM

I think Terratec just give you simple RDs info. See the attached ZIP, code in C++ and documentation of the card.

What info is in the 8A groups? I have done some software for controling RDS encoders, but can't remember using 8A.

BTW, can anyone port the sourcecode to C# for me?

**BeamRider** · 06-17-2004, 06:02 AM

8A groups are defined as ODA (Open Data Application) and are assigned to TMC when specific flag is sent in group 3A (from EN50067:1998 for Europe or RBDS standard for US). In my screenshot you can see the presence of 8A and relative TMC messages in natural language (Italian).
Coming back to GPS/TMC I'm able to emulate it (the GNS 1.0 protocol is very simple, but I have no infos on 2.0). What I need is to create a virtual com port: let's see some more on MS DDK.
The GNS protocol is nothing more that RDS groups mixed with GPS messages. By a serial port log and some reverse engineering:

$GPGGA,104137?¢Jc 3?.149,0000.0000,N,00000.0000,E,0,00,50.?¢åEœL¤? 0,0.0,M,,,,0000*37

As you can see, there're two blocks of data mixed in the GPS message. Both are 10 bytes long and in this form:

?<B1><B2><B3><B4>?

Bn is 2 bytes = a block data
B1..B4 is a RDS group

Very simple!!

From the Terratec API you posted seems that the API exposes only high level data so no access to raw groups

This night I'm going to do some refactoring on my code to enable also group plugins so it can decode from GPS/TMC also

**ccsnet** · 06-18-2004, 06:02 PM

Any chance some one can build one for me - not very good with schematics... ?

T

**felix99** · 06-19-2004, 12:53 PM

i think ill try adding rds out to a low cost radio head unit just to test

**felix99** · 07-06-2004, 11:59 AM

Any news ??

due to exams i had to put my rds out project on standby .but in august i 'll surely build it

**BeamRider** · 07-06-2004, 07:55 PM

I hold the development because I ran out of TDA7330 ICs and I'm unable to find more.....I plan to be back on it as fast as I can build the interface for the D-LINK that I got (finally).
I've got a schematic also then I think we could post it, just a pair of modiciations needed on values and connector pinout.
I've a software issue with serial port programming and threads but I don't think that this will stop me.

I'll give out a naked library . I'm not skilled on GUI and I want to give all my time to the decoder part so tuner logic should be implemented in the tuner part (with logic I mean AF usage, EON usage, TMC notifications, ecc).
What we'll need are the locations and events databases for the various countries. Actually I'm compatible with the Tricksy files, but they're commercial (free download from their site) and I don't know if there'll be issues on using this format.
Cheers

**BeamRider** · 07-08-2004, 06:06 AM

Felix, to test the interface you can use this decoder:

http://www.esslinger.de/rds/rdsdec.htm

The company has a commercial RDS library and a freeware decoder application that's compatible with the hardware we were talking about.
I'm using this application to crosscheck my library.
Cheers

**felix99** · 07-08-2004, 06:15 AM

tanks

think i'll buy the components next week

and after my exams i'll build a RDS/TMC out and test.

I think even if we don't have success by merging the GPS/TMC Data it would still be nice to have TMC data displayed grafically with some nice icons

as a list consultable via the car-pc'ing appz.

mille grazie (hope i remember right

)

ciao

Félix

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