Time Division Multiplex (TDM) over Poor Quality Circuits.

The objectives of this program were to study techniques, and implement hardware, which would permit the improvement of framing synchronization and maintenance of Bit Count Integrity between transmitter and receiver portions of asynchronous digital multiplexers operating in troposcatter transmission media. Existing literature was searched to obtain empirical data which was then used to calibrate a Burst Error Simulator which was designed to produce burst noise typical of existing troposcatter systems. A simplex Bit Count Integrity Frame Protection Device BCIFPD Transmitter and Receiver was built incorporating techniques for continuous flywheel of framing synchronization through total signal loss the addition of added redundancy coding to the command codes and the correction of command code errors to restore Bit Count Integrity after deep fading. Testing of an existing asychronous multiplexer system was performed to show how it performed when burst error conditions typical of existing troposcatter transmission systems was injected between multiplexer and demultiplexer. Then the BCIFPD equipment was inserted into the test setup to show the improvement offered by that equipment. The BCIFPD equipment proved to contain much more capability than was necessary to provide good performance over typical troposcatter transmission links as defined by existing data. Author