Using the RDS SECTION (FM version ONLY)
ENG
Page 89
23.9 AF METHODS A AND B
There are two ways to transmit lists of alternative frequencies: Method A and Method B.
In both cases the lists should include only those frequencies for the nearest transmitters and repeaters (with
overlapping coverage areas).
Generally speaking, Method A is used when the list contains no more than 25 frequencies, and Method B
when the list is longer (for a maximum of 24 lists).
Method B is recommended when splitting areas or when different programs are broadcast.
NOTE: use of encoding method A or B is not explicitly assigned by a dedicated signal to the receiver, as the
latter is capable of identifying which method is used by analyzing the transmitted data structure (whether or
not they are organized in pairs).
METHOD A
Compile the AF1 list assigning the tuning frequency (i.e. the frequency carrying the list of alternative
frequencies) in the first position, and then continue in strictly increasing order with the alternative frequencies
transmitting exactly the same program.
We recommend recording the alternative frequencies (those of adjacent transmitters and repeaters with
overlapping coverage areas) on each transmitter, being careful that the first position indicates the frequency
carrying the list of alternative frequencies.
For example, in the situation shown in the figure three transmitters (B, D, E) intersect only in two coverage
areas: between B and D, and between D and E. The following lists should be loaded in each transmitter:
AF1 AF2
f Tx B
f Tx D
Tx B lists
(tuning frequency: f Tx B)
f Tx D
f Tx B
Note that the frequency of transmitter C is not included
in the list, since the latter’s coverage area does not
overlap with that of transmitter A
AF1
AF2
AF3
f Tx D
f Tx B
f Tx E
f Tx B
f Tx D
f Tx D
Tx D lists
(tuning frequency: f Tx D)
f Tx E
Coverage area D partially overlaps that of both
transmitters B and E, and thus it is recommended to
load the lists for both adjacent transmitters. Be careful
to list all frequencies above the tuning frequency in
ascending order.
AF1
AF2
f Tx E
f Tx D
Tx E lists
(tuning frequency: f Tx E)
f Tx D
f Tx E
Note that the frequency of transmitter B has not been
included in the list, since its coverage area does not
overlap with that of transmitter E.
Summary of Contents for Falcon 35
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