fcd-2 provides high-speed data channel connection over public e1 network(see figure 1-1 ).

   

    fcd-2 with ltu can be used as short-range modem with operating range up to 1.65 km (1 mile) as shown in figure 1-2.

   

    the user data rate is a fraction of the available e1 bandwidth. therefore, to reduce service costs, the e1 signal arriving from the user premises is processed at the central office that provides the fractional e1 service so as to make the unused timeslots available for other users. this reduces the cost of the service because each user needs only pay for the fraction of e1 bandwidth it actually uses (at least with respect to the long-distance link section starting from the serving central).