You may also use. the two-block method for simple parallel systems.
The two-block plan does not provide alternate routing or operating
between three different sites. To accomplish this, use the six-block
b. ABM Frequency Assignment Plan. You use the ABM plan for more
receivers are at the same location. To use the ABM plan, proceed as
(1) Designate each site with a letter A, B, or M as shown in
Do not designate interconnected sites with the same
letter (see figure 2-14B). In other words, location A can establish
a link with locations B or M, but not with another A.
(2) Draw a triangle such as in figure 2-15.
Radio sets used
with multichannel systems do not require transmitter-to-transmitter
frequencies from the same block.