Underwater computer

Apparatus for carrying by a diver while under water (and at the surface between dives) and for providing information useful for enabling the diver to ascend therefrom both expeditiously and safely in order to avoid decompression sickness, comprising

• transducer means for providing an electrical capacitance responsive to the pressure of the water thereon,
• electronic circuit means comprising a resistance means in circuit with the transducer capacitance means for providing a signal responsive to the time constant therein and substantially unaffected by normally encountered variations in supply voltage, such that the signal varies in duration proportionally to the capacitance of the transducer means and comprises an oscillating voltage whose period is proportional to the said time constant, the said circuit means comprising operational amplifier means, means for providing a first potential as a first input to the amplifier means, and means for providing a second potential as a second input to the amplifier means, the said resistance means being connected between the first potential and a first input terminal of the amplifier means, and the second potential being connected to a second input terminal of the amplifier means, a voltage comparator means, means for connecting the output of the amplifier means to a first input terminal of the voltage comparator means, and means for connecting a third potential to a second input terminal of the voltage comparator means;
• electronic data processing means, responsive to the signal from the resistance-capacitance circuit means, for computing the water pressure, the depth of the transducer capacitance means in the water, the minimum depth to which the diver can from there ascend safely, and the minimum time within which the diver then can ascend safely to the surface of the water, and
• means for providing indications perceptible to the diver of the computed values.

Apparatus for carrying by a diver while under water (and at the surface between dives) and for providing information useful for enabling the diver to ascend therefrom both expeditiously and safely in order to avoid decompression sickness, comprising

• transducer means for providing an electrical capacitance responsive to the pressure of the water thereon,
• electronic circuit means comprising a resistance means in circuit with the transducer capacitance means for providing a signal responsive to the time constant therein and substantially unaffected by normally encountered variations in supply voltage,
• electronic data processing means, responsive to the signal from the resistance-capacitance circuit means, for computing the water pressure, the depth of the transducer capacitance means in the water, the minimum depth to which the diver can from there ascend safely, and the minimum time within which the diver then can ascend safely to the surface of the water, and
• means for providing indications perceptible to the diver of the computed values,
• the said data processing means comprising means for carrying out the operations listed in the Data Processing Software Summary in the foregoing specification.

Apparatus for providing an electrical signal that varies in duration proportionally to the product of a resistance therein multiplied by a capacitance therein, comprising

• operational amplifier means;
• capacitance means connected between the output terminal and a first-input terminal of the operational amplifier means;
• resistance means connected, at one end, to the first input terminal of the operational amplifier means and, at the opposite end, to means for providing a first potential;
• means for providing a second potential to a second input terminal of the operational amplifier means;
• means for connecting the output of the operational amplifier means to a first input terminal of voltage comparator means;
• means for providing a third potential to a second input terminal of the voltage comparator means;
• and
• means for periodically interchanging the value of the first potential with the value of the third potential.