personnel qualification standard (pqs) - I Marine Expeditionary ...

114 Communications
HF Radio
HF radio equipment is capable of both long- and short-range secure voice and
data communications. Data communications capability is typically limited to rates
of 2.4 kilobits per second (kbps). Data transmission requires modems specifically
designed for operation in this band of the radio spectrum. The AN/PRC-104 is
capable of remote operation by using the analog AN/GRA-39B radio remote
control. See fig. 2-1.
High frequency communications are capable of traveling around the world under
the right conditions. This accounts for the large number of signals and noise in the
receiver (e.g., thunderstorms). Conversely, the HF transmission may be
intercepted and traced by the enemy who is many hundreds of miles away. VHF
and UHF communications are normally limited to line of sight; therefore, their
range is restricted. UHF transmissions may also be used in satellite
communications, increasing ranges to thousands of miles.
High Frequency Radio Employment Considerations.
The primary advantage of using HF radio is its capability to provide longrange,
over the horizon (OTH) communication. Successful data
communications over the HF range depends on several factors: equipment
siting, proper equipment grounding, types of antennas used, and other
considerations such as tactical employment of radio equipment, path
assessment and analysis, and frequency planning and assignment. When
commercial data terminal equipment (DTE) is used, users employing HF
radio equipment need to be aware of radio interference and potential shock
hazards that can easily affect unprotected DTE. Whenever possible, HF
radio equipment should be remoted from DTE.
114-6