| 摘要 |
The proposal allows a switching center to be loaded with a combination of bothway circuit and unidirectional circuit-carrying systems with no increase in control complexity, no new switching stage(s), no frequency changing and no alteration to the super-highway format. The bothway serial highways are assembled in groups of four, as compared with the groups of eight employed in the original unidirectional-working scheme. Each bothway channel is associated with two time-slots on the parallel super-highway, one time-slot being inherently originating and the other terminating. In the receive direction the distribution of one serial channel on a highway to two parallel channels on the super-highway is accomplished at the serial-parallel converter stage. The length of each serial-parallel shift register is increased by one bit relative to the unidirectional scheme. Two sets of multiplexing gates are then associated with the output of each such shift-register, and this gating is such that if the two sets of gates are enabled in turn, at consecutive bit-times, then the complete channel contained in one shift-register appears at consecutive time-slots (one originating, one terminating) on the super-highway. In the transmit direction a complementary function is employed.
|
