Abstract: An up/down tracking counter stores a digital count signal equal to the time interval to be converted and provides this signal as the parallel digital output of the converter. Prior to the interval to be converted the count from the up/down counter is loaded into a down counter. At the leading edge of the interval to be converted the down counter is counted down, from the count loaded therein, by a clock signal until the occurrence of the trailing edge of the interval. A decision PROM responsive to the output of the down counter provides a message signal in accordance with the residual error count remaining in the down counter. The message signal commands a bit pattern generator that applies pulse burst controllably to the count up input or count down input of the up/down counter in accordance with the error count in the down counter so as to tend to reduce the error count in the down counter to zero.

Abstract: A digital hysteresis circuit which generates a stable signal for driving a digital readout indicator from an analog signal indicative of the position of a mechanical driving device having noise signal components leading to erratic indications superposed thereon.A reference signal generated by an up-down counter is compared with the digitized input signal in a memory store. Only when the difference in the compared digital values exceeds a predetermined digital hysteresis value in the memory store corresponding to the allowable noise signals is a command signal generated to increment or decrement the counter so as to reduce the difference in digital value. The reference signal is applied to drive the digital readout indicator, thereby precluding unstable indications due to noise, jitter, and system threshold uncertainty.