UNDERWATER TEMPERATURE TELEMETRY SYSTEM

• US 3,611,332 A
• Filed: 07/23/1969
• Issued: 10/05/1971
• Est. Priority Date: 07/23/1969
• Status: Expired due to Term

• Current Assignee: Allan Slater
• Original Assignee: Allan Slater
• Inventors: Slater, Allan
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Mooney, Robert J.
• Application Number:
  US04/844,121
• Time in Patent Office: 804 Days
• Field of Search: 340/207,183,177,3,4,15.5,18FM,347AD 128/2.1A 325/39,40,141 323/22T
• US Class Current: 340/870.18
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G08C 23/02 using infrasonic, sonic or ultrasonic waves

Abstract

A self-contained underwater telemetry system is provided for transmitting biophysical data from a freeswimming diver through the water to a receiving station. The system includes a pulse amplitude modulated FM transmitter carried on the diver and an FM receiver with an FM-to-pulse amplitude demodulation section. Also included are a precision oscillator whose frequency is controlled by sensor resistance; multiplexing circuits for monitoring several channels of biophysical information; an octal encoding system which generates the above-mentioned pulse amplitude modulated signal; a low drain voltage regulator; a hydrophonetuned amplifier combination; and a zero crossover-multivibrator demodulation section for the FM receiver.

Claims

1. Apparatus for monitoring the body temperature of a freeswimming diver at a location remote from said diver comprising in combination:

means for sensing the temperature of said diver at a number of body locations, said means including a plurality of elements each having an electrical resistance the magnitude of which varies in response to changes in temperature;

means for producing a first signal having a frequency proportional to the resistance of any of said elements;

means for connecting each of said elements to said first signalproducing means during successive time intervals;

means for sampling said first signal during each of said time intervals and for generating a series of pulses corresponding to successive samplings, each of said pulses having one of a predetermined number of discrete amplitudes depending on the frequency of the sample;

a frequency-modulated transmitter normally producing an output signal at a center frequency which falls within a region between the upper audio and the lower radio frequency bands;

means for coupling said series of pulses to said transmitter so as to shift the frequency of its output signal from said center frequency by an amount and in a direction depending upon the relative amplitudes of the individual pulses in said series;

means for radiating said output signal into the water surrounding said diver in an omnidirectional radiation pattern;

means at said remote location for detecting the signal radiated from said diver and for producing a demodulated signal having an amplitude proportional to the frequency of said radiated signal; and

means for recording the amplitude of said demodulated signal so as to provide an indication of the body temperature of said diver at said number of body locations.

2. The apparatus as recited in claim 1 wherein said successive time intervals are equal in length;

wherein said first signal is sampled during a predetermined portion of each equal time interval; and

wherein each pulse in said series of pulses has one of a predetermined number of discrete amplitudes depending on the number of oscillations of said first signal occurring in said predetermined portion.

3. The apparatus as recited in claim 1 wherein said sampling and generating means includes:

means for producing a series of clock pulses;

a multiple level ring counter coupled at one end to said clock-pulse-producing means, said counter having a series of output terminals corresponding in number to the number of levels in said ring counter;

a plurality of binary counters cascaded in series, said plurality being one less than the number of levels in said ring counter;

switching means interposed between said first signal-producing means and the first binary counter of said series for permitting signals produced by said means to be coupled to said series of cascaded counters during the appearance of a clock pulse at the first of said series of output terminals;

a like plurality of binary-to-octal converters, different converters being coupled to different binary counters for producing pulses corresponding in amplitude to the number in the binary counter to which it is coupled at their respective outputs;

a like plurality of gates, the inputs to different gates being coupled to the outputs of different converters and the outputs of said gates being coupled together to form a single output terminal, the gate corresponding to the fiRst of said series of binary counters being actuated by the appearance of a clock pulse at the second of said series of output terminals;

the subsequent gates corresponding to the subsequent binary counters in said series of cascaded counters being actuated by the appearance of clock pulses at output terminals subsequent to said second output terminal such that said gates connect the outputs of said converters to said single output terminal in successive time intervals whereby a series of amplitude-modulated pulses are produced at said single output terminal; and

a reset pulse generator having an output coupled to each of said binary counters for resetting each binary counter after the appearance of a clock pulse at the last of said series of output terminals.

4. The apparatus as recited in claim 1 wherein said demodulating means includes:

means for sensing the zero crossovers of the oscillations in the signal radiated from said diver and detected at said remote location and for producing a pulse for every zero crossover sensed; and

means for generating an output pulse having an amplitude proportional to the number of pulses produced by said zero crossover sensing means in a predetermined time period, whereby a number of output pulses so generated constitutes said demodulated signal.

5. The apparatus as recited in claim 1 wherein said apparatus includes means for providing a regulated source of electrical power, said means including:

a voltage regulator having first and second input terminals and first and second output terminals in which said second output terminal is connected to said second input terminal;

a first transistor having its emitter coupled to said first input terminal and its collector coupled to said first output terminal;

a resistive element coupled at one side to the base of said first transistor;

a second transistor having its collector connected to the other side of said resistive element and having its emitter coupled to said second input terminal; and

means coupled to the base of said second transistor for permitting electric current to increase therethrough whenever the voltage appearing across said output terminals drops below a predetermined voltage such that said first transistor is made to pass more current to said first output terminal whenever its base is connected through said resistive element and said second transistor to said second input terminal.