uhf tacsat /dama multi-service tactics, techniques ... - UHF-Satcom.com

preamble Consists of a carrier segment modulated by a predetermined
signal used for acquisition. The preamble may also include
an unmodulated segment, immediately preceding the
modulated carrier segment, which is used by the receiver
during carrier acquisition. The carrier segment modulated
by a predetermined bit pattern is used by the demodulator
for bit synchronization. The preamble bit pattern
immediately precedes, and is phase-locked to, transmitted
baseband data
preassigned
service
Glossary-20
A type of service whose channel or time-slot allocation is
scheduled and set up well in advance of being used.
preempted service A service that has been interrupted to allow for higherprecedence
network activities.
primary channel
controller
quadrature phaseshift
keying
The control station function that actively controls the DAMA
channel.
A form of PSK in which the instantaneous phase of the
carrier can be either unchanged, shifted ±90 degrees, or
shifted 180 degrees. QPSK may be represented as two
independent binary bit streams modulated onto the in phase
(I) and quadrature phase components of the carrier. The
information content of a QPSK signal is 2 binary digits (bits)
per symbol; therefore, the symbol rate is one-half the
information rate.
queued service A service in the request queue at the PCC waiting to be
assigned communications resources. Queued services are
either blocked or pending.
range The round-trip distance between a satellite and a terminal
within the satellite footprint. (Because signal propagation
velocity is constant, terminals measure range in units of
time.)
range lock The status a terminal achieves when it has determined its
range time delay with an uncertainty of less than or equal to
875-microseconds (Fs). [Terminal transmissions are
inhibited (except for active ranging transmissions) until the
terminal achieves this status.]
range time-slot A shared slot used to measure two-way range to the
satellite.
ranging A process by which a terminal determines signal
propagation time to a satellite to establish uplink timing.
ranging epoch
interval
The interval between scheduled dedicated ranging attempts
by a terminal.
relay A method of communications in which data is passed from
one DAMA channel to another to achieve greater
connectivity than that which is provided by the one channel.
requested party The address to which a call is placed.