PART A: SIMPLEX WORKING
1. There are two types of radio frequency usage. The terms used to describe frequency
usage are simplex working and complex working.
2. Simplex working is the term used to describe the method of frequency usage in which two
or more stations communicate on the same frequency, that is, they use the same frequency to
transmit and to receive. This means that on any given radio communication structure, a link,
group, or net, only one frequency is used for communications between the stations involved.
When a link, group, or net uses simplex working, we combine the term "simplex" with the
specific communication structure, for example, a simplex link or simplex group. Figure 2-1 is
Figure 2-1. Simplex Link.
3. The above link is called a Simplex link. The use of this term even without the figure, tells
you that only two stations are involved and they both use the same frequency to communicate.
4. We can also combine the term "simplex" with the type of directed operation. For example,
if it has been determined that a group is a "star" or a "star-lateral," the resulting combination
of terms would be a simplex star or a simplex star lateral.
5. There is an inherent limitation in simplex working, for only one station in the net can pass
traffic at any given time. If two or more stations try to pass traffic, they succeed only in
blocking one another out. For this reason, this type of frequency usage is normally used only
on low echelon nets.