PERFORMANCE OF TACTICAL PULSE-CODE MODULATION SYSTEMS UTILIZING MULTIPLEXER TD-352/U.
ARMY ELECTRONICS COMMAND FORT MONMOUTH N J
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A test program was undertaken to determine the performance of tactical PCM systems with respect to word intelligibility as a function of various system configurations, and to determine the characteristics which limit such performance. This report covers the detailed procedures and results of Phase II of this program. The Fairbanks Rhyme Test was employed to determine the word intelligibility of numerous laboratory and field-deployed PCM systems, using 2-wire and 4-wire audio interconnections, and varying the losses in the audio terminations. Electrical measurements of selected parameters were made on the systems tested to permit correlation of the percent word intelligibility with readily measured parameters. The results indicate that 4-wire systems provide better performance than 2-wire systems of equivalent length. The limitations of 2-wire PCM systems are due to the inherent losses in the audio interconnections. However, there is no practical limit on the length of 4-wire tactical systems, since the 4-wire systems are essentially loss-free. Also, the results disclose that PCM system performance can be readily predicted knowing the system configuration with audio interconnection losses, or knowing the overall system loss and the measured signal-to-quantized noise ratio of the system. Author
- Voice Communications