Abstract: A digital storage oscilloscope comprises an analog-to-digital converter for receiving an analog input signal and generating a succession of data words representative of the instantaneous magnitude of the input signal at a succession of equally-spaced sample times. A waveform memory has a plurality of separately addressable storage locations for storing the succession of data words at locations of which the addresses are related to the respective sample times. A trigger circuit compares the instantaneous magnitude of the analog input signal with a predetermined trigger level and generates a trigger pulse when the instantaneous magnitude of the input signal bears a predetermined relationship to the trigger level. The trigger circuit also causes an address word to be stored that defines the storage location for the first data word that occurs after the trigger pulse.

Abstract: A switch closure test method and apparatus is disclosed in which switch position information in the form of logic signals indicative of switch closure status of a plurality of switches is arranged in a predetermined waveform display format for simultaneous viewing.

Abstract: A trigger holdoff system for an oscilloscope is provided in which a desired trigger signal is taken out from a repetitive group of raw trigger signals with variable time therebetween. A trigger generator generates raw triggers which clock a divide by N counter programmable by a microprocessor. When the counter reaches its terminal count, a trigger is passed on to sweep or acquisition circuits from the trigger holdoff system and an enable signal is set so that the next raw trigger reloads the counter.

Abstract: A ski run snow preparation apparatus having a snow-contacting blade which flexes laterally to provide an arcuate snow-contacting surface. The blade is pivotally mounted to a frame which is adapted to be secured upon the towing mechanism of a suitable tracked vehicle. Also mounted upon the frame is a remotely controllable mechanism, including a pair of hydraulic motors, to adjust the tilt of the snow-contacting blade in relation to the snow surface. The blade may operate under its own weight and that of the towing mechanism, or may be forceably pressed into the snow, as by vehicle mounted hydraulic motors provided to raise and lower the towing mechanism.

Abstract: A trigger holdoff system particularly useful in digital oscilloscopes is provided in which a holdoff pulse is generated in response to a trigger pulse from a trigger generator and applied to the trigger generator to disable a time base control circuit.

Abstract: A signal-envelope display system for a digital oscilloscope includes a memory for storing minimum and maximum signal values in adjacent storage locations, an address counter for sequentially addressing the memory, and a control circuit for selectively inverting the least significant bit of the address count signal. The values retrieved from the memory are converted to analog values and a low-pass filter connects the analog values to provide a signal envelope display.

Abstract: A time interval meter for measuring extremely short time intervals includes a timing circuit operable at a fast predetermined rate over the time interval between first and second events, and operable at a slow predetermined rate which is precisely scaled to the first rate over a time interval between the occurrence of the second event and the upper limit of a predetermined timing window. During the slow ramp period, clock pulses are counted to provide a count which is proportional to that portion of the predetermined timing window occupied by the slow ramp interval. The fast ramp time interval may then be readily attained by subtracting the slow ramp interval from the total time of the timing window. The circuit includes a control circuit, a timing circuit including a capacitor and a pair of selectable constant current sources, and a counter.