Figure 3-4. Example of digital .signal with interference.

TM 11-490-5

Figure 3-4. Example of digital .signal with interference.

system the audio channels are assigned to discrete

d. Multiplexing Techniques. In order to transfer

frequency bands just wide enough for the audio signal

multiple audio channels over a single radio link, a

being transferred. The total frequency bandwidth is the

method of combining or multiplexing the individual

sum of the total number of frequency bands desired.

channels into one transmitted signal and separating or

This signal is then transferred over a single transmitter-

de-multiplexing the channels at the receiver must be

receiver link. At the receiver, the overall signal is

used. The two most common techniques employed in

detected and the discrete frequency bands are

military communications are frequency division

separated for transfer over individual audio channels.

multiplex (FDM) and time division multiplex (TDM) (fig

Depending

the

intensity

and

frequency

3-5). While FDM is currently the prime technique for

characteristics of the interfering signal, only a few

multiplexing, there is a trend toward increasing use of

channels may be affected or the whole system may be

TDM.

adversely affected.

(1) Frequency division multiplex. In an FDM

3-4