Travis AFB Sustainability Study Report Final Background Report | Page 165
Frequency Spectrum Impedance /
Interference (FSI)
military installations and operational areas, the potential for frequency
spectrum interference increases.
Frequency spectrum is the entire range of electromagnetic frequencies used
for communications and other transmissions, which includes communication
channels for radio, cellular phones, and television. In the performance of
typical operations, the military relies on a range of frequencies for
communications and support systems. Similarly, public and private users
rely on a range of frequencies in the use of cellular telephones and other
wireless devices on a daily basis.
VORTAC radio navigation beacon. A very high frequency (VHF)
omnidirectional range and tactical air navigation system (VORTAC) is a
navigational aid for aircraft pilots consisting of a VHF omnidirectional range
(VOR) beacon and a tactical air navigation system (TACAN) beacon. Both
beacons provide low‐level en‐route navigation, with the VOR system
typically used by civilian aircraft and the TACAN system used by military
aircraft, including Travis AFB aircraft. The beacons provide pilots with
location information to assist with navigation.
Key Terms
Technical Background
Doppler shift. The change in frequency of a wave (or other periodic event)
for an observer moving relative to its source, or the source moving relative
to the observer.
The DOD use of frequency spectrum allows for safe operations and the
effective delivery of weapons on target without interference. The DOD’s
frequency spectrum needs for testing, evaluation, and training is constantly
increasing, while the spectrum available for DOD use is decreasing. The
National Telecommunications Industry Association (NTIA) Office of Spectrum
Management (OSM) explains that:
Frequency Spectrum. The frequency spectrum is the entire range of
electromagnetic frequencies used for communications and other
transmissions, which includes communication channels used for radio,
cellular phones, and television. In the performance of typical operations,
the military relies on a range of frequencies for communications and support
systems. Similarly, public and private users rely on a range of frequencies in
the use of cellular telephones and other wireless devices used on a daily
basis.
…almost every agency of the Federal Government uses the spectrum
in performing mandated missions. The DOD uses the spectrum
extensively for tactical uses and non‐tactical uses. In the United
States tactical uses are generally limited to a number of specific
testing sites and training facilities, but DOD's non‐tactical
applications are extensive and include aircraft command and
control, mobile communication in and around military bases, and air
fields and long distance communications using satellites.
Impedance. Impedance is the interruption of electronic signals due to the
existence of a structure or object between the source of the signal and its
destination (receptor). Certain structures have the potential to block, or
impede, the transmission of signals from antennas, satellite dishes, or other
transmission / reception devices affected by line‐of‐sight requirements.
Interference. Interference is the inability to effectively distribute or receive
a particular frequency because of similar frequency competition. As the use
of the frequency spectrum increases (such as the rapid increase in cellular
phone technology over the last decade) and as development expands near
TSS Background Report
Page 5‐45