a. Arrange the frequencies in a numerical sequence.

Divide the

frequencies available for use into two blocks that contain equal

numbers of frequencies, and arrange them so that each frequency in

the lower frequency block may be paired with a frequency in the

higher block, that is, separated from the lower frequencies by at

least 16.5 megahertz (figure 19).

Figure 19.

Frequencies divided into two blocks.

b. Assign transmitting frequencies beginning at terminal A. Then

alternately, select a frequency from Block I and then Block II

(figure 20).

Assign all transmitting frequencies in A to B

direction, when this is completed, assign frequencies in the same

manner from B to A direction (figure 20).