of establishment of the systems (command links and area links).
Figure 25 shows all frequencies allocated for all systems with the
proper guard band.
49. Double ABM Plan.
If the traffic load on a particular system is so great that
additional multichannel radio systems and additional frequencies are
needed, and when the single ABM plan becomes too complicated for more
should be used.
a. The double ABM plan uses the same six frequency blocks as the
single ABM plan.
The double ABM plan uses symbols A, B, and M for
these blocks and also three more symbols: A1, B1, and M1. Figure 26
shows all six symbols in use. Also, this figure shows that station
labeled A can communicate with at station one hop away labeled A1.
between A and A1 (two blocks in each direction).
Thus, a heavy
traffic route could be made up of multichannel radio stations labeled
A, A1, etc., similarly B and B1,for M and M1, could be used.
Double ABM plan.