L5 System : Physical Design

The L5 repeatered line is presented from the viewpoint of a distributed equalization process. Reliable transmission of 10,800 circuits over 4000 miles of coaxial cable with minimum noise is the sole objective of this process. The strategy is to provide equalization in cause‐associated increments that place specific bounds on signal‐level excursions, thereby insuring an ultralinear, low‐noise predictable transmission medium. The individual causes of signal misalignment, both static and dynamic, are examined and the realization of the strategy, which forms a hierarchy of equalizers, is described.

L5 System: Repeatered Line

Angell¹,

Cho²,

Kretsch³

et al. 1974

L5 System: Jumbogroup Multiplex Terminal

Maurer¹

1974

The jumbogroup multiplex (JMX) translates basic jumbogroup signals to and from the L5 line spectrum. Each of three jumbogroups provides 3600 4-kHz voice circuits. In addition to frequency translation, the JMX provides regulation and equalization on a jumbogroup basis and auto matic one-for-one protection.Performance objectives are discussed and interpreted from the perspec tive of their influence on the design philosophy and approach used and the resultant physical realization. All subsystems are presented in detail. Particular mention is made of the double-balanced diode-ring modulator developed for JMX application.

L5 System: Signal Administration and Interconnection

Bates¹,

Zorn²

1974

Each L5 coaxial line is capable of carrying three 3600‐channel basic jumbogroup signals that are translated to and from the L5 line spectrum (3.124 to 60.556 MHz) through jumbogroup multiplex equipment. The L5 line signal also includes several line pilots and switching, maintenance, and reference signals. Administration of all these signals is performed by the L5 line connecting circuits, which vary in complexity with the type of main station they serve. In addition to the circuits required to handle the various components of the L5 line spectrum, signal administration is also required at basic jumbogroup frequencies, before the jumbogroup multiplexing step, to allow interconnection to lower‐order multiplex or other systems using the basic jumbogroup frequency format of 0.564 to 17.548 MHz. To perform this function, the basic jumbogroup trunk bay was developed and provides interconnection flexibility hitherto unavailable for direct connections to other long‐haul systems, such as L4, lmd, td, or th radio, or L5 systems of another route.