User:Darkroom/L System

Transcontinental Cable System - L System

System	Year	Frequency	Coax per cable	Distance between repeaters	Capacity
L-1	1941	3 mhz	4	8 miles	600 voice circuits
L-2	1942	840 khz	4	16 miles	360 voice circuits
L-3	1953	8 mhz	8	4 miles	5,580 voice circuits
L-4	1967	17 mhz	20	2 miles	32,400 voice circuits
L-5	1972	57 mhz	22	2 miles	132,000 voice circuits

The Transcontinental Cable System was developed by AT&T to create a hardened telecom network for defense related communications during the cold war. There were five phases of development of the system, designated L-1 through L-5.

The system was designed to provide for land line connections between key command and control facilities inside the United States. Starting with L-4 the system was upgraded to withstand a nuclear attack. The system consisted of over 100 "Main Stations" and 1000 individual repeater vaults. The "Main Stations" had generators, blast doors and accommodations for staff for a two-week post-attack period.

In the late 1970's and early 1980's the system was determined to be redundant with the advance of satellite based communications. Most stations were never ugraded past L-4 due to advancement of technology.