Abstract: A fast dosimeter for ion implantation and other systems that produce charges or current to be measured. When a charge accumulator reaches a predetermined charge, a fixed charge is removed to reduce the accumulated charge. A counter records each charge removal. Between removals, an analog-to-digital converter measures the accumulator charge. The outputs from the counter and the analog-to-digital converter provide a continually updated value for the total accumulated charge, and by differentiation, current with respect to time.

Abstract: A fast dosimeter for ion implantation and other systems that produce charges or current to be measured. When a charge accumulator reaches a predetermined charge, a fixed charge is removed to reduce the accumulated charge. A counter records each charge removal. Between removals, an analog-to-digital converter measures the accumulator charge. The outputs from the counter and the analog-to-digital converter provide a continually updated value for the total accumulated charge, and by differentiation, current with respect to time.

Abstract: The fiber optic receiver disclosed herein is adapted to receive optical signals which are digitally modulated between an "ON" state in which light is being transmitted and an "OFF" or dark state. The analog output signal of a photodetector is thresholded to obtain a binary electrical output signal and is also sampled during the binary state corresponding to the "ON" received signal. A liquid crystal element is energized as a function of the sampled amplitude thereby to establish a feedback loop driving the sampled amplitude toward a preselected level providing predictable skewing of transitions in the binary output signal.

Abstract: A transmitter is provided for transmitting an analog signal. The transmitter has an input receiving the analog signal within a range of values. The transmitter also includes a duty cycle modulator generating a modulated two state signal having a maximum frequency at an intermediate value of the range. The duty cycle of the modulated signal is monotonically related to the analog signal while the frequency of the signal decreases with increase and decrease of the value of the analog signal from the intermediate value. The transmitter further includes an output for transmitting the modulated signal on a communication channel. A receiver is also provided that includes an input receiving the modulated two state signal from the transmitter, and a circuit for translating the received signals to an output analog signal.

Abstract: The DC power supply disclosed herein is adapted to be energized from AC supply mains and incorporates a DC to DC switching inverter provided with an energy storage or filter capacitor for supplying an input voltage to the inverter. The capacitor is charged from the AC supply mains through a rectifier. A semiconductor switching device is interposed between the AC supply mains and the capacitor. A sensing circuit actuates the switching device to disconnect the capacitor from the supply mains when the voltage applied to the capacitor exceeds a pre-selected level.

Abstract: In the aircraft navigation computer disclosed herein, a first voltage is generated which is varied as function of the position of a map strip and this voltage is compared with a second voltage which varies in accordance with the passage of time. A signal is generated when these voltages cross each other, signifying satisfaction of the navigation equation: distance=time.times.speed.

Abstract: In the ion gauge system disclosed herein, the ion current obtained from an ion gauge tube is directly converted to a signal having a frequency proportional to the ion current so that a digital measurement of vacuum may be obtained. The ion current charges an integrating capacitor which is periodically discharged after reaching a preselected threshold. Preferably, the threshold is adjusted in proportion to the ion gauge emission current so that automatic compensation for variation in the emission current is obtained, the output frequency being proportional to the ratio of the ion current to the emission current. The variable frequency output signal generated by the integration and discharge process is counted by a scaling circuit which automatically changes the timing interval to provide the desired number of significant figures while incrementing the exponent value in a scientific notation display in keeping with the active time base.

Abstract: In the ion gauge system disclosed herein, the ion current obtained from an ion gauge tube is directly converted to a signal having a frequency proportional to the ion current so that a digital measurement of vacuum may be obtained. The ion current charges an integrating capacitor which is periodically discharged after reaching a preselected threshold. Preferably, the threshold is adjusted in proportion to the ion gauge emission current so that automatic compensation for variation in the emission current is obtained, the output frequency being proportional to the ratio of the ion current to the emission current. The variable frequency output signal generated by the integration and discharge process is counted by a scaling circuit which automatically changes the timing interval to provide the desired number of significant figures while incrementing the exponent value in a scientific notation display in keeping with the active time base.

Abstract: In the ion gauge system disclosed herein, the ion current obtained from an ion gauge tube is directly converted to a signal having a frequency proportional to the ion current so that a digital measurement of vacuum may be obtained. The ion current charges an integrating capacitor which is periodically discharged after reaching a preselected threshold. Preferably, the threshold is adjusted in proportion to the ion gauge emission current so that automatic compensation for variation in the emission current is obtained, the output frequency being proportional to the ratio of the ion current to the emission current. The variable frequency output signal generated by the integration and discharge process is counted by a scaling circuit which automatically changes the timing interval to provide the desired number of significant figures while incrementing the exponent value in a scientific notation display in keeping with the active time base.