DEFT WIRE-LINE STUDY.

The program had to two-fold purpose considera tion of methods for adapting DEFT, a high-capa city communications system for use on the telephone network, and determination of the per formance of an experimental DEFT modem over a leased long-distance telephone circuit. A study of the characteristics of the telephone network as they affect data transmission was made. Based on this information, design criteria for a high capacity system 7000 bits per second, or more were established. Performance data was accumulat ed for 125 hours of testing of a single channel capable of handling 50 bitssecond in a 20 cps band. A K-carrier loop was used as the trans mission medium. Testing was done at five widely separated locations in the audio channel. The unused portion of the channel was filled with noise to simulate a complete system. The average bit error rate BER was found to be about 3 in 10 to the 6th power. Author