The A6 Channel Bank

The A6 channel bank is the latest of a series of Bell System frequency division multiplex terminal equipments used to provide the first step of modulation and the final step of demodulation in carrier telephony. Cost and size reduction are the primary objectives of the development and are realized through the use of monolithic quartz crystal filters and hybrid monolithic silicontantalum thin film integrated circuits. This paper includes a general description of system organization, a discussion of system features, and gives objective performance values of the significant transmission parameters. Of special interest are the channel filter discrimination characteristic and the hybrid integrated circuit functions. Designed to meet stringent inter-toll performance criteria, the A6 channel bank is intended to become the standard for new installations in the Bell System.