Ground Mobile Forces

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'Ground Mobile Forces (GMF) refers to the tactical satellite communications (SATCOM) component of the Tri-Service Tactical (TRI-TAC) program.[1] Developed by GTE-Sylvania in the mid-1970s, TRI-TAC was a joint-service military command, control, and communications initiative.[1] The program aimed to field advanced multichannel switched equipment, eliminate redundant acquisitions across military branches, and establish seamless interoperability between tactical and strategic communications systems.[1]

Architecture and technical specifications

GMF systems operate in a hub-and-spoke network topology.[1] In this configuration, a central hub terminal can simultaneously ingest up to four primary data feeds from outlying spoke terminals.[1]

Terminal classifications

The system utilizes four primary designated SATCOM terminals categorized by their operational role:

  • Hub Terminals (AN/TSC-85B and AN/TSC-100A): Equipped for point-to-point and hub operations.[1]
  • Spoke Terminals (AN/TSC-93B and AN/TSC-94A): Designated remote terminals that connect directly back to a hub.[1]

Data capacities and throughput

  • Hub Performance: Standard hub configurations ingest up to 48 multiplexed, encrypted channels from a maximum of four spoke terminals simultaneously.[1] Utilizing an external multiplexer doubles this capacity to 96 channels.[1]
  • Channel Configuration: Channels operate at 16 kbit/s or 32 kbit/s, translating to an effective true capacity of 48 kbit/s when accounting for protocol overhead.[1]
  • Spoke Performance: Outlying terminals support up to 24 multiplexed channels (16/32 kbit/s).[1]
Terminal Type Designation Primary Role Max Capacity (Channels) Antenna Type
Hub AN/TSC-85B / AN/TSC-100A Point-to-Point / Hub 48 (96 with external mux)[1] 20 ft (6.1 m) QRSAG dish[1]
Spoke AN/TSC-93B / AN/TSC-94A Remote Spoke 24[1] 8 ft (2.4 m) parabolic dish[1]

Radio frequency and environmental protection

GMF terminals communicate via Super High Frequency (SHF) X-band through the Defense Satellite Communications System (DSCS) satellite constellation.[1][2]

All GMF terminals feature external interfaces for field telephones, a 70 MHz Intermediate Frequency (IF) wideband input, and connection to an AN/TSQ-111 Tech Control Facility.[1] To support sustained tactical deployments, equipment shelters are sealed for operations in Chemical, Biological, Radiological, and Nuclear (CBRN) environments.[1]

Obsolescence and legacy

While legacy TRI-TAC and GMF hardware provided foundational field communications for decades, the bulky circuit-switched equipment has largely become obsolete.[1]

Over time, these systems were largely phased out in favor of modern, IP-based fly-away quad-band systems equipped with compact routers, switches, and advanced encryption hardware.[1] Despite their technical obsolescence, select GMF terminals remained active in field operations under severe conditions during military engagements in Iraq and Afghanistan.[1]

See also

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 Ground Mobile Forces, Wikipedia, The Free Encyclopedia.
  2. ↑ DSCS-3, GlobalSecurity.org.

Further reading




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