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

(1) The UHF follow-on satellite provides twenty-one 5-kHz channels and
seventeen 25-kHz channels. In addition to the tactical channels, the Navy uses super
high frequency (SHF)-uplink/UHF-downlink broadcast channels to disseminate data to
ships. Each footprint has two primary satellites. USSTRATCOM provides a current
reference for satellite channel availability at http://uhfweb2.usspace.spacecom.smil.mil.
(2) UHF TACSAT channels provide two types of satellite access, dedicated and
DAMA. Each type of access can support both voice and data communications.
(3) A combination of fleet satellite communications (FLTSATCOM) and UHF
follow-on satellites provides coverage. Each satellite coverage area terminates in at
least two adjacent NCTAMS/Naval computing and telecommunications station (NCTS).
This redundant coverage ensures global connectivity when using DAMA capabilities.
c. Dedicated TACSAT. All terminals in a net operate on one uplink radio frequency
paired with one downlink frequency and assigned exclusively to the net. A net’s
associated uplink frequency paired with its downlink frequency constitutes a single
channel dedicated for the net’s operational use during an assigned span of hours or
days. All stations in the net monitor its channel for calls. Each station has a unique
station identifier (or call sign) that is used to identify it to other station operators in the
net. Usually, one station in the net is designated as NCS to supervise and authenticate
the entry and exit of authorized stations.
d. DAMA. DAMA is a channel access scheme; a TACSAT channel can
accommodate multiple concurrent communications. Uuser terminals access is allocated
in accordance with demand. DAMA multiplexing channels allow dedicated access to
portions of the channel without interference and, through time division multiple access
(TDMA), enables more networks to access the channel. TDMA is accomplished when a
network controller station transmits control signals that establish precisely recurring
intervals of time (frames). A frame is typically one or more seconds in duration. Each
frame is subdivided (time-division) into precise time-slots. Certain slots in each frame
are reserved for the controller station to receive user station service requests, or to
transmit control signals via the satellite. These kinds of signals are called orderwires
(OW). Other time-slots are available for user stations to transmit signal bursts to each
other via the satellite. User nets are assigned slots within the frames on a given
channel. This allows multiple nets to access the same channel simultaneously.
e. Five-kHz DAMA. A 5-kHz DAMA channel supports one 2.4-kbps voice time-slot
(with current MIL-STD 188-182 terminals) and provides a dedicated point-to-point (or
point-to-network) connection between two outstations.
(1) Point-to-point or point-to-network private circuit is used primarily for data.
The time delays in the waveform cause extensive latency for voice and, therefore, limit
voice circuits.
(2) The users manually disconnect (teardown) from the time-slot on completion
of send/receive to make the time-slot available for other users.
f. Twenty-five-kHz DAMA voice/data. When a dedicated 25-kHz channel is
converted to DAMA, it supports up to five 2.4-kbps time-slots that support voice and
data communications. A 25-kHz DAMA channel can provide two types of service.
(1) TDMA DAMA (preassigned time-slots).
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