Abstract: Methods and systems are provided for an interactive electronic technical manual system. A system includes a user interface for receiving input from a user and providing output to the user. A database stores instructions associated with tasks. The system also includes a diagnostic reasoner for receiving commands, controlling an external device in response to the commands to implement a test of the external device, and sensing signals associated with the test of the external device. The system further includes an interface module in communication with the user interface, the database, and the diagnostic reasoner. The interface module sends instructions associated with tasks to the user interface from the database, conveys commands from the user interface to the diagnostic reasoner, receives data associated with the signals sensed by the diagnostic reasoner, and analyzes the data associated with the signals.

Abstract: A circuit for producing sinusoidal wave-forms representative of signals used in voiceband signaling for telephone dialing, frequently referred to as DTMF signaling. A sine wave is broken into a predetermined number of time increments. The amplitude changes for each increment may be indicated in the form of a binary digital word for a quadrant of the curve. The remaining quadrants will exhibit essentially the same change characteristics at like time increments with only the bit order reversed or the polarity changed thus, the basic binary word is unchanged for each quadrant. A programmable memory is set to produce the binary word at a selected clock rate. In this way, synthesis of a plurality of sine waves may be readily produced using delta modulation techniques. For all sine curves, the number of time increments remains the same, the rate of pulsing the increments is varied responsive to the keyboard signals generated. For telephone use, a high and a low signal are synthesized at essentially the same time.