Updated diver navigation device

• US 3,944,967 A
• Filed: 12/23/1974
• Issued: 03/16/1976
• Est. Priority Date: 12/23/1974
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Watson, Stanley J., Acks, Robert S., McCracken, Howard B.
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US05/535,542
• Time in Patent Office: 449 Days
• Field of Search: 340/6 R, 340/16 R
• US Class Current: 367/117
• CPC Class Codes: G01S 3/8083 determining direction of source
• CPC Class Codes: Y10S 367/91 Portable sonar devices

Abstract

In a diver'"'"'s navigation system employing a receiver having three equal, alarly disposed hydrophone locations, a digital signal processing circuit is employed which receives frequency shift keyed digital data from remote beacons. Circuitry is provided to process this data to derive a bearing indication to the beacon.

Claims

1. An underwater navigation system comprising:

a beacon transmitter structured for transmitting a series of frequency shift, FSK, keyed transmissions and including;

a source of electrical power, and

timer means connected between said source of electrical power of said beacon transmitter and the individual circuits thereof for energizing said circuits at predetermined intervals to produce a low, power-conserving duty cycle; and

a beason receiver configured for location at a station remote from said beacon transmitter for receiving the signals from said beacon transmitter and display of a bearing angle therebetween and including,

three spaced hydrophones located at points spaced as the verticies of an equilateral triangle,

a plurality of FSK signal processing means each of which is operatively connected to one of said hydrophones to be associated therewith for processing the electrical outputs therefrom to obtain an amplified and detected output signal corresponding to the signal transmitted by the aforesaid beacon transmitter,

digital phase comparator means connected to said FSK signal processing means for timely comparison of the output signals therefrom to obtain a signal corresponding to the sine and cosine of the bearing angle to be displayed,

digital error rejection circuitry operatively connected to said digital phase comparator means so as to receive the sine and cosine signals therefrom and sample said signals to distinguish real from spurious signals,

digital latch circuit means operatively connected to said digital error rejection circuitry for storing the distinguished real signals until updated by a subsequent reception of transmitted beacon information, and

display means operatively connected to said digital latch circuit means for converting said real signals to a visual signal indicating the bearing angle between the beacon receiver and the beacon signal source.

2. An underwater navigation system according to claim 1 in which each FSK signal processing means includes:

preamplifier means operatively connected to the associated hydrophone for voltage amplification of the output signals therefrom;

bandpass filter means operatively connected to said preamplifier means for limiting the frequencies of the voltage amplified output therefrom to a predetermined range of values;

amplifier means connected to said bandpass filter means for amplifying the output signals within said predetermined range of frequency values; and

Fsk detection means to detect the frequency shift keyed modulation envelope therefrom.

3. An underwater navigation system according to claim 1 in which said digital error rejection circuitry includes:

a first pair of sample circuits each operatively connected to said digital phase comparator means to receive a single sign value of the sine function output thereof;

a first function selection latch circuit operatively connected to said first pair of sample circuits and to their inputs to select and hold the particular sign value of the sine output from said digital phase comparator corresponding to the sample circuit of said first pair which first reaches a predetermined sample level;

a second pair of sample circuits each operatively connected to said digital phase comparator means to receive a single sign value of the cosine function output thereof; and

a second function selection latch circuit operatively connected to said second pair of sample circuits and to their inputs to select and hold the particular sign value of the cosine output from said digital phase comparator corresponding to the sample circuit of said second pair which first reaches a predetermined sample level.

4. An underwater navigation system according to claim 2 in which said digital error rejection circuitry includes:

a first pair of sample circuits each operatively connected to said digital phase comparator means to receive a single sign value of the sine function output thereof;

a first function selection latch circuit operatively connected to said first pair of sample circuits and to their inputs to select and hold the particular sign value of the sine output from digital phase comparator corresponding to the sample circuit of said first pair which first reaches a predetermined sample level;

a second pair of sample circuits each operatively connected to said digital phase comparator means to receive a single sign value of the cosine function output thereof; and

a second function selection latch circuit operatively connected to said second pair of sample circuits and to their inputs to select and hold the particular sign value of the cosine output from said digital phase comparator corresponding to the sample circuit of said second pair which first reaches a predetermined sample level.