Small extension node
Prior to the advent of the satellite based Joint Network Node (JNN), the United States Army used a system known as Mobile Subscriber Equipment (MSE) in order to provide tactical battlefield communications. MSE is a Line-Of-Site (LOS) terrestrial based communications system limited by terrain and distance. MSE is still in use in limited quantities.
The small extension node (SEN) is part of a US military communication system known as mobile subscriber equipment (MSE). A SEN is composed of two shelters, a switching shelter and a Line of sight radio terminal shelter(LOS)
A SEN switching shelter contains switching, multiplexing, and communications security (COMSEC) equipment for secure digital voice and data communications. A single switching shelter is mounted on the back of a HMMWV, powered is provided by a 10 kW diesel generator, and the SEN is operated by up to a six soldier team. To provide communications for a Corps area the Signal Battalion would deploy forty SEN's, amongst Node Centers, Large Extension Nodes, and Radio Access Units.
The current switch is designated AN/TTC-48, with a suffix to identify each of the ten versions in operation - (V)1, V(2), A(V)1, A(V)2, B(V)1, B(V)2, C(V)1, C(V)2, C(V)3, and C(V)4. The (V)1 provides 26 digital lines and 10-digital trunks and the (V)2 provides 41 digital lines and 13-digital trunks. Both versions interface at various levels with the MSE Area Communication Systems through cable, via line of sight or via tactical satellite terminal.