An Experimental Pulse Code Modulation System for Short-Haul Trunks

The Boll System has a wealth of experience in frequency division systems. Through the years, as new systems have been developed, our knowledge of the factors affecting the performance of these systems has steadily increased. There has been no comparable experience with time division systems. Therefore, when the decision was made to develop a pulse code modulation system for commercial use, it was felt advisable to build an early experimental model to prove the feasibility of the general system arrangement and the circuit approaches adopted. The experimental system also established the over-all level of transmission performance that could be expected. This and companion articles in this issue describe the experimental system, analyze the results of measurements on the actual system, and compare performance with objectives.