T1 Carrier Characterization - Field-Measurement Results

965 the route between these terminals. Each span line is a series connection of T1 repeater sections between two central offices. Those sections adjacent to the offices are termed end sections; all others are referred to as intermediate sections. The T1 error-rate objective specifies that at least 95 percent of 50section systems shall have average transmission error rates less than 10" errors per bit. Since the digital signal is regenerated at each repeater location, the error performance of a T1 system is approximately equal to the accumulated performances of the individual repeater sections. Therefore, an understanding of T1 carrier repeater section performance and the elements that control that performance is needed to establish a model for system behavior. Measurements were conducted in the trunk plants of three Bell System OTCS during 1977 and 1978 using the automated equipment described in Ref. 3. In all, approximately 2000 repeater section lines were examined in 30 different repeater sections. Most of the measurements were performed on nearly full-length repeater sections (measured section lengths were about 6,100 feet for intermediate sections and about 4,000 feet for end sections), on 22gauge pulp-paired cable, terminated with apparatus cases, each of which holds 25 discrete-component T1 repeaters. Other situations examined included sections terminated with repeater cases that hold 25 smaller-size integrated-circuit versions of the T1 repeater. These two measurement situations are identified in this paper as 466/201 and 475/208, respectively.