Optically-coupled data access arrangement and transhybrid

Claim 1

A data access arrangement for interconnecting a telephone network of tip and ring lines and a subscriber digital data bus, comprising: a modem for bidirectionally converting analog signals to digital signals, having a bidirectional digital bus port for connection to the subscriber digital data bus, an analog transmit port, and an analog receive port; and means for connecting the modem to the telephone network and isolating the modem from the telephone network, the means for connecting and isolating having first means for transferring signals received on the tip and ring lines of the telephone network to the analog receive port of the modem and suppressing signals originating at the analog transmit port of the modem, the first means having an output provided to the analog receive port of the modem; second means for isolating the tip and ring lines of the telephone network from the modem and transferring signals originating at the analog transmit port of the modem to the tip and ring lines of the telephone network, the second means being connected between the analog transmit port of the modem and the tip and ring lines of the telephone network; and third means for isolating the tip and ring lines of the telephone network from the modem and transferring signals received on the tip and ring lines of the telephone network, the third means being connected between the tip and ring lines of the telephone network and the first means.