Digiplexer 246 v2.5.x User Manual – 11/2010
Page 59
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RDS resource allocation
(1)
The transmission of data according to the group sequence and extended group sequence does not
offer the timing constraints necessary for certain Open Data Applications, so two additional
mechanisms have been included to increase the flexibility of the RDS resource allocation: "Burst
Mode" transmission and "Spinning wheel" mode transmission.
The following table lists RDS groups that can include ODA information. It is necessary to configure
several parameters to be able to use a group for an ODA.
AID
ODA identification number. Assigned by the RDS forum.
Each application supported on the RDS forum has a unique AID.
MSG Message.
MSG2
Some applications require sending 2 messages in sequence. When there is data in
MSG2, the RDS encoder sends it.
Timeout
Timeout duration on data at the input, in minutes. Data loss at the input for a longer
time will cause a 3A group containing this AID and a group equal to 0x1F to be sent.
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"Burst mode" transmission
(2)
This mode enables ODA free-format groups like 14B and 15B groups with a predetermined number of
repetitions and inter-group spacing.
Burst mode parameters:
Repetition
Number of ‘free-format’ groups to be sent.
Spacing
Number of other groups to be inserted between the free format groups.
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"Spinning wheel" mode transmission
(3)
The so called “Spinning wheel” technique is based on the following ideas:
•
Divide the minute evenly into a number of time slots.
•
Split each of these time slots into two parts: a first part (activity time, Ta), during which ODA
groups may be inserted into the data stream; and a second part (window time, Tw), during
which no ODA groups shall be inserted into the data stream.
•
Between the start of the minute (as indicated in the RDS-data stream by the presence of a type
4A group, which must be transmitted to use spinning wheel transmission) and the start of the
first time slot it is possible to configure a delay (delay time, Td).
•
The structure of the parameters Ta, Td and Tw is illustrated below:
