RDS and TMC

BeamRider · 06-14-2004, 02:05 PM

looking on the web I noticed that many PC FM tuners (both USB and PCI) are not RDS enabled so, after some search I started building a very small and inexpensive demodulator and level converter for the serial port and a software decoder library in C++. This version of the library is not very clean nor readable but it's working. Major features are:

- Basic RDS decoding: AF, TP, TA, PTY, ecc (AF can't use grouping by now)
- Pluggable interface "streams" (COM and Logfile implemented)
- Pluggable ODA classes
- TMC decoder(ODA plugin): not completed, but able to decode single mesages, locations and events and much more ...

I've built two simple MFC application (console and windowed/MDI) to test my library and I'd like to hack a D-Link radio instead of the Clarion HU that I'm using now.
My wish is to obtain an RDS capable tuner GUI (guys, I don't like GUI programming) and to be able to have TMC messages in Destinator via its SDK but I'm not sure if it'll be possible, maybe with V3.....
Someone wants to add RDS/TMC in its project?

stevieg · 06-15-2004, 02:29 AM

What's involved in making such a demodulator? Does it take the line-in and work with that? Also what location data does the TMC hold - lat/lon? I have been using UK TPEG messages via the internet to display traffic data in MapPoint successfully so far but this would negate the need for an internet connection for traffic data.

Is it possible that you could make available the schematics as I would be interested in making a module that works with the D-Link to test

felix99 · 06-15-2004, 07:59 AM

cool

i would also be interested in the shematics

chunkymonkey909 · 06-15-2004, 09:23 AM

Excellent!
This sounds very interesting. Traffic reports would be very useful and even better would be TMC data.

Jamez_Warner · 06-15-2004, 09:26 AM

be very interested to see more of this...
James

BeamRider · 06-15-2004, 11:23 AM

I'm very happy to hear some interest on this.....
To sort things TMC has no lat/lon in the messages but uses a 16bit code to identify a specific location (I hope that official country locations databases has geo. position fields in clear) and an extension value to specify how many nodes are involved in the message. This is the easy single message event, multiple messages events are more complex but still based on this logic.
I don't know if TPEG has lat/lon in clear or it's converted by the server. I'll study more TPEG but as for TMC multiple messages events, I don't have TPEG sources for my country.
Coming back to TMC, commercial navigators (from Alturion to VDO/PHILIPS) have TMC locations in their maps so the can convert TMC locations on the fly.
The decoder is quiet simple but it's not possible to use the line out because no RDS signal passes there, instead it must be connecte to MF section (it's easy to identify). On PCI TV/FM cards it can be found directly on the radio module, my plan is to use D-Link USB

The interface is composed from an RDS demodulator IC (TDA7330), a RS232 signal level converter (MAX232) and some passive components...
I've built mine from this schematcs:

http://users.pandora.be/hollie/picmi...ds_dec_pic.gif

Just remove the PIC, connect MAX232 to CLK and DATA and connect MAX232 output to RI and DCD of the serial port. I'm looking for some help on drawing schematics and hopefully to sort a printed circuit.
This small circuit can be placed just over an EPIA using COM2 connector leaving COM1 port available for other uses (OBDII I hope).
Cheers

Ricky327 · 06-15-2004, 12:03 PM

Nice work there BeamRider

Look easy enough to build the hardware. Ill be interested to build one myself

Got to read more when I get back.

felix99 · 06-15-2004, 01:10 PM

me too

will surely ( when i got time

) build one.

But there is one little thing interesting me which is a bit OT.
in europe we have NAvigon notebook a very popular software from ppcs which exists aussi in notebook version and wich supports TMC viua TMC gps's
Any idea if or how i could send the tmc data from this circuit to the nav soft i supporse the data from gps tmc receivers are speacial mixery of gps and tmc in dataflow ? if someone has infos i would be happy by receiving mail or PM . Tnx alot

SilentAdmirer · 06-15-2004, 01:24 PM

I think D-link USB FM uses philips TEA5757. Here is the datasheet of the TEA5757
http://www.engr.uconn.edu/ece/Senior...ps-tea5757.pdf

Hope this helps
Satish

Jeep · 06-15-2004, 03:41 PM

I use Terratech Cinergy 600 TV, a PCI card for TV/Radio and the radio has RDS. I have simple C++ example fore controling the radio ink reading RDS

http://productsen.terratec.net/modul...d=142&menu=401

BeamRider · 06-15-2004, 05:31 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, 10:53 AM

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

Satish

Jeep · 06-16-2004, 11:31 AM

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, 05:02 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, 05:02 PM

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

T