Testing Mixed-Signal Devices

Testing ISDN devices, which mix analog voice information and digital data, puts special demands on the test system. The ISDN has multiple interfaces with devices that perform a variety of functions. What was usually performed by many individual ICs is now performed by a single ISDN device. Particularly challenging are network interface and device feature tests because the test system must generate and detect the specialized frame structures in the network communication links-structures that change not only between transmit and receive but also between interfaces. Techniques to conduct these tests are described in detail. The benefits of these techniques can be increased with the use of the proper hardware and interactive, graphics-based software tools.