RDS / RBDS SETTINGS (FM Version only) ENG
Page 65
18.8 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:
