Abstract: A failsafe supervisor system for a processing module of a modular multi-parameter patient monitor which detects a module error or malfunction, places such module in a safe state, and alerts the operator to improper operation of the patient monitor module processor hardware or software. Upon detection of a hardware or software error, an inconsistent system/module time-base check, or other malfunctions during module operation, the impaired parameter module and its associated parameter data gathering apparatuses are powered down and the patient monitor system electrically isolates the impaired module in a failsafe manner to a safe state while permitting other parameter modules to continue with their normal operation. The failsafe supervisor system preferably includes a watchdog timer and discrete logic incorporated with the parameter module's microprocessor control system.

Abstract: A method for selecting fundamental clock frequencies in order to achieve electromagnetic compatibility in electronic products which employ a plurality of clocks. The method require first selecting an ideal frequency for each clock in the product. Then, and until the goal of avoiding coinciding harmonics is complete, the method includes the steps of computing all harmonics of all clock frequencies chosen, determining a minimum difference tolerable in the chosen frequencies and their harmonics for sufficient minimization of electromagnetic interference, and determining if the harmonics of the chosen frequencies coincide impermissibly within the frequency range. If there exists coincidence of harmonics within the predetermined minimum range, then the fundamental frequency of at least one of the clocks corresponding to an interfering harmonic must be adjusted to eliminate the interference.

Abstract: A pressure swing apparatus includes two sorption beds, one of which extracts a component from an inlet gas mixture while the other bed is regenerated. Valves are provided for controlling the flow of the inlet gas mixture to each of the sorption beds and for venting the beds during regeneration. Sensors are provided for repetitively sensing ambient pressure and the temperature and pressure of the inlet gas mixture. A microprocessor repeatedly samples the measured temperature and pressures and repetitively calculates adsorption and purging intervals, altering the adsorption and purging intervals by controlling the valve actuations to respond in real time to changes in the conditions of the ambient and the inlet gas and thereby to optimize the production of a product gas from an inlet gas of limited supply and widely varying in temperature and pressure. The invention may be applied in aircraft to produce a breathable gas mixture.

Abstract: A method and apparatus for fractionating a mixture of gasses, by using a bed of sorbent which is conditionally depressurized and purged after adsorption intervals of a predetermined time duration, varies the time duration in response to demand as indicated by the decisions of whether purging is required. Preferably a historical record is kept of the recent purge decisions, and based upon this historical record, the duration of the adsorption interval is increased at a limited rate up to a maximum duration when purging is infrequently required, and is decreased at a limited rate down to a minimum duration when purging is frequently required.