Abstract: A portable general-purpose oscilloscope employs circuitry for receiving and converting serial digital video signals to composite and component analog signals via a digital to analog converter. The converted analog signals are applied to signal inputs of the oscilloscope for monitoring and display. Preferably, the oscilloscope is a digital phosphor oscilloscope. The oscilloscope control menus are arranged to control all of the usual functions of the oscilloscope and also to control the serial digital video circuitry. Apparatus is provided for storing data and waveforms. Circuitry is disclosed for deriving a trigger signal from a specific digital word of the serial digital bit stream. The trigger signal is applied to the trigger input terminal of the oscilloscope to allow the oscilloscope capture and display television waveform information around a unique occurrence of an event, as specified by the digital word.

Abstract: An apparatus and method for deriving a signal from the AC line and conveying it to processing circuitry employs two wires each of which is non-conductively attached and capacitively coupled to a respective one of a two-wire AC power line. Each of the capacitive pick-offs is coupled to a respective input of a differential amplifier for amplification. Advantageously, because the output signal is a replica of the AC power line signal, the detection threshold can be set at or near zero volts. This makes the detection point insensitive to the amplitude variations of the AC power line. In one embodiment, an output signal is developed at a single ended output of the differential amplifier, and applied to a low pass filter to remove undesired higher frequencies. A further amplifier provides greater amplification of the filtered representation of the AC power line signal, and includes an amplitude limiting circuit to accommodate the wide range of AC line voltages which may be applied to the instrument.

Abstract: An automatic skew calibration technique for a multi-channel signal source uses a cross-coupled flip-flop calibration circuit and a microprocessor to align the timing of a pair of signals from the multi-channel signal source. The flip-flop calibration circuit indicates which of the pair of signals is leading, and the microprocessor uses the output of the flip-flop calibration circuit to determine in which signal source to adjust the signal delay. The signal source is incrementally delayed by the microprocessor while the microprocessor also observes the output of the flip-flop calibration circuit. When the flip-flop calibration circuit indicates a time interval over which the relative time position of the input signals changes, then the microprocessor determines a calibrated value for the signal delay, completing skew calibration of the multi-channel signal source.

Abstract: An electrical connector apparatus is provided for connection of coaxial transmission lines to etched circuit boards. The apparatus comprises a back plane carrying one or more circuit board edge connectors, a ground plane for engaging a contact on a circuit board plugged into the edge connector, and an arrangement of connector pins which permits most of the edge connector pins to be used for signals while maintaining a high frequency response for subnanosecond pulses.