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45
13.2 Traffic Message Channel (TMC) Application Notes
13.2.1 Basic requirements
The TMC service can work only if there is an application that we can call 'TMC data provider'. The TMC data provider
collects all related information and translates it into RDS groups 8A type. The output of the TMC data provider must
be either by means of ASCII command
G=
or (more often) coded as UECP command with MEC 30. We will deal with
the second case in following text.
Nowadays the TMC service is coded as an ODA application. Thus there must be ODA AID groups 3A transmitted in
addition to the 8A groups. This can be done for example using the UECP MEC 24. The 3A groups typically carry fixed
content so in some cases they can be inserted into the RDS encoder also one-time using the command
UDG1=
or
UDG2=
.
The Address and Site fields are optional. When the TMC data provider drives one RDS encoder only, these fields are
usually set to zero. However there can be more RDS encoders connected with various Address and Site values. Each
encoder will accept only the UECP records that match the Address and Site criteria. This configuration has been tested
successfully simulating a network of more than 60 encoders (equivalent to full load of one 9600 bps channel).
13.2.2 Preparing for the TMC transmission
1. Configure all static parameters of the RDS encoder. Enable the UECP (
UECP=1
↵
*UECP
↵
).
2. Where required, store the fixed 3A groups using the commands
UDG1=
or
UDG2=
(for example:
UDG1=30100646CD46,30104080CD46
↵
*UDG1
↵
).
In this case make sure the UDG groups are included in the Group sequence (symbols X or Y).
3. Decide for the communication baudrate. Configure the RDS encoder and TMC data provider baudrate.
4. Configure the Site and Address values.
13.2.3 Application example
This application example shows TMC data and ODA AID information inserted by UECP commands 30 and 24.
Time
Group
UECP command
Comment
...
9:27:58
3A: 8A 0646 CD46
FE 00 00 D0 07 24 06 10 06 46 CD 46 B9 68 FF
ODA AID variant 0
9:27:58
8A: 07 C801 4689
FE 00 00 D1 08 30 06 06 07 C8 01 46 89 94 54 FF
TMC 8A, two repeats
9:27:59
8A: 07 4984 6000
FE 00 00 D2 08 30 06 06 07 49 84 60 00 F2 5C FF
TMC 8A, two repeats
9:27:59
3A: 8A 4080 CD46
FE 00 00 D3 07 24 06 10 40 80 CD 46 49 7E FF
ODA AID variant 1
9:28:00 -
FE 00 00 D4 09 0D 0A 0C 10 09 1C 00 00 02 60 F3 FF
Encoder time adjust
9:28:00
8A: 01 883D 1A74
FE 00 00 D5 08 30 06 06 01 88 3D 1A 74 5F DC FF
TMC 8A, two repeats
9:28:00
3A: 8A 0646 CD46
FE 00 00 D6 07 24 06 10 06 46 CD 46 E3 E0 FF
ODA AID variant 0
9:28:01
8A: 02 8F50 15DD
FE 00 00 D7 08 30 06 06 02 8F 50 15 DD D3 6E FF
TMC 8A, two repeats
9:28:01
8A: 02 5404 ABD4
FE 00 00 D8 08 30 06 06 02 54 04 AB D4 1D E6 FF
TMC 8A, two repeats
9:28:01
3A: 8A 4080 CD46
FE 00 00 D9 07 24 06 10 40 80 CD 46 A6 E6 FF
ODA AID variant 1
9:28:02
8A: 05 497C 8000
FE 00 00 DA 08 30 06 06 05 49 7C 80 00 A6 D5 FF
TMC 8A, two repeats
...
Notes:
1) Any group inserted using the UECP elements 24, 30, 40 or 42 is not affected by the Group sequence. Instead
of this the group is put in the UECP FIFO buffer and transmitted as soon as possible.