Coupling device for allowing the connection to a public switched telephone network, and DCE or personal system using the same.

摘要

Coupling device or Direct Access Arrangement (DAA) for the connection of a system such as a Data Circuit Terminating equipment (DCE) or still a computer to a Public Switched Telephone network (PSTN) including a sigma-delta coder (103) for generating a train of sigma-delta pulses representative of the analog signal which is conveyed for the telephone line, and a first set of optical-couplers forming an optical barrier between the personal computer and the telephone line. Static relays such as optical couplers also used for introducing an additional optical barrier between the coupling device and the switching leads which are traditionaly used for controlling the switching functions such as seizing and decadic pulsing. Since all the signals exchanged between the system and couplers are in in digital and isolated from the personal system by means of an optical barrier, there no need for an additional transformer. Moreover, the amount of distorsion remains at a low level and the suppression of the line transformer saves physical surface of the Printed circuit board forming the coupler which facilitates its miniaturisation. At last, since all signals which are exchanged between the coupling interface of the invention and the system to which it is connected, are digital, the design of the personal system is also made easier. <IMAGE>