Tektronix, Inc.

Clark P Foley

Michael A Gauland

Donald L Taylor

Stanley K Sasaki

A dual-ranked time-interval conversion circuit. Two time trap circuits are employed to convert the time interval between a logic level transition of a first signal and a logic level transition of a second signal to an analog or digital signal representative of that time interval. Each time trap circuit employs a delay line for receiving and propagating the first signal and a series of taps and respective storage elements along the delay line for detecting and storing the logic level of the delay line at each tap at the time of receipt of a second signal. A first time trap circuit is employed to measure the time interval in course quanta of time and a second time trap circuit is employed to measure in fine quanta of time the time difference between the actual first signal-to-second signal time interval and the coarse measurement of that interval. A nulling circuit is provided for applying a delayed strobe signal to the second time trap circuit within a predetermined period of time following receipt of the first signal. This time is preferably equal to two coarse time quanta to allow for quantizing error. Delay circuits are provided to compensate for signal propagation delay through circuit devices. The outputs of the first and second time trap circuits are applied to a digital-to-analog conversion circuit or to a digital decoding circuit for producing an analog or digital output, respectively.

Dual-ranked time-interval conversion circuit

A method and apparatus performs time-interval to voltage conversion immediately and continuously allowing timing variations to be viewed and correlated with other voltage signals displayed on an oscilloscope. A calibration output assists in calibrating the vertical gain and offset of the oscilloscope. An automatic setup software routine finds suitable resolution and offset settings. The method includes the steps of selecting the type of time-interval to be measured, scaling the counting of a clock signal appropriately, offsetting the counting means as desired, counting the number of clock signals that occur during every selected time-interval, limiting the counted results to a preselected range, and converting the counted results to an analog voltage for display by an oscilloscope. And, in a preferred version of the method, when counted results are limited the operator is notified, and there is an additional step of detecting when time-intervals are occurring faster than they can be counted and notifying the operator of that too. A corresponding apparatus for performing the method is disclosed.

Real-time, uninterrupted time-interval to voltage converter

A method for producing a statistical profile of a repetitive electrical signal entails selecting a window pulse width that is preferably a large multiple of the period of the signal, setting a comparison threshold, and counting the time that the signal is above (or below) the comparison threshold during the window pulse. The comparison threshold is then repeatedly incremented (or decremented) over the amplitude range of the signal, while this procedure is repeated at each level. The difference is then taken between the times measured at adjacent amplitude increments and the absolute value of these differences is displayed as the waveform profile. An apparatus for implementing this method includes a counter/timer, a gate, a comparator, a pulse generation circuit, a comparison threshold generation circuit, and a microprocessor for controlling the other circuit elements and performing calculations. The incoming repetitive signal is coupled to one input of the comparator and the output of the comparison threshold generation circuit is coupled to the other input. The output of the comparator is applied to the gate input along with the output of the pulse generation circuit. The output of the gate enables the counter/timer. The microprocessor controls the comparison threshold generation circuit and the pulse generation circuit, reads back the output of the counter/timer, and calculates the absolute value of the differences between times counted at adjacent amplitude thresholds.

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Portland, OR, United States of America

Clark P Foley