Abstract: An apparatus for sensing the location of user input is disclosed. The apparatus may include a display unit including a screen having a resistive coating disposed on its surface. The apparatus may utilize a sensing signal emanating from the screen through the resistive coating. A sensor array may be disposed about the screen, and sensing electronics are provided to determine the location of user input on the screen by sensing localized deviations in the amplitude of the sensing signal.

Abstract: An apparatus for sensing the location of user input is disclosed. The apparatus may include a display unit including a screen having a resistive coating disposed on its surface. The apparatus may utilize a sensing signal emanating from the screen through the resistive coating. A sensor array may be disposed about the screen, and sensing electronics are provided to determine the location of user input on the screen by sensing localized deviations in the amplitude of the sensing signal.

Abstract: A subscriber loop tester for testing local loops of telephone switching networks has a partitioned "U" interface and an internal bus architecture for converting various transceiver circuit output data formats to a common data format. The "U" interface has a high impedance transformer meeting bandwidth and line matching requirements for different line codes and protocols for ISDN telecommunication systems. The transformer is selectively coupled to option cards each containing circuitry having AC and DC terminations matching specific line codes and protocols for ISDN telecommunications systems and other types of telecommunications systems. The option cards further contain programmable attenuators for producing a proper nominal signal level as a function of the specific line code and protocol and providing variable insertion loss. A high speed bus is selectively coupled to the option cards for coupling the formatted transceiver circuit output data between the cards and a digital bus translator.

Abstract: A multifunction test apparatus which is capable of performing total communication network measurments and includes a primary processor linked to a number of dependent processors. The primary processor plays a number of different roles in the functioning of the test system, which roles require substantial interaction between the primary processor and dependent processors. In some test configurations, the primary processor becomes a dependent processor. In other configurations, the primary processor is timeplexed and interleaved with the operation of the dependent processors in performing subfunctions for the dependent processors. The architecture also provides for direct communication and resource sharing between the dependent processors. In another aspect of the subject invention, the primary processor performs overflow calculations for the dependent processors. Finally, the device is arranged such that all test functions are displayed with consistent screen formats.

Abstract: A digital signal processing apparatus for operating upon analog signals having wide dynamic and frequency ranges is described. The invention includes a digital section and an analog section, the digital section providing digital words representative of analog signals to be transmitted, and receiving digital representations of analog signal received from the test subject, and processing said digital representations. The analog section transforms the digital representations of the signals to be transmitted into analog form and applies them to the test subject by way of a balanced output driver. The analog section includes a receiving section which receives analog signals from the test subject and transforms the analog signals into digital representations thereof. The digital section also provides control information to the analog section. The data and control information being communicated between the analog and digital sections are transferred by way of optical isolators.

Abstract: A switching system for connecting any one of a plurality of electrical circuits to any one of a plurality of test positions, wherein a central controller including a microprocessor directs, in a pre-programmed manner, all necessary switching functions. In the preferred embodiment, the electrical circuits are telephone circuits and the test positions include test ports positioned in various locations around a central office so that any of the telephone circuits can be accessed for testing from any of the test ports. The controller communicates with each of the test ports and controls switching units one at a time over a common control bus.