# US 5,703,594 A · Method for remotely detecting tides and the height of other surfaces > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,594 A - Document ID: US5703594A - Status: Granted - Kind: A - Application number: 08/668,874 - Filed: 1996-06-24 - Granted: 1997-12-30 - Earliest claimed: 1996-06-24 - Assignees: The United States of America as represented by the Secretary of the Navy - Inventors: Kenneth D. Anderson - Web page: https://patentgrep.com/patent/US5703594A ## CPC - G01C 13/004: {vertical movement} - G01S 11/02: using radio waves (G01S19/00 takes precedence) - G01S 11/04: using angle measurements - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## Abstract Transmitted signals are used to accurately and remotely determine the veral distance of an earth-based receiving antenna above a surface, and hence can be used to determine the tide condition of a water surface. A signal is transmitted from a signal source as it moves either through air or space. An antenna whose height is to be determined with respect to a reflecting surface, such as water, receives the signal directly from the signal source and indirectly from the signal source by reflection of the signal from the reflecting surface. The sum of the directly and indirectly received signals form an interference pattern as the signal source is moved. Points on the interference pattern are selected at identical phase angle for each cycle of the pattern. The points are assigned reference numbers and the numbers are plotted with respect to a measurement indicative of the distance between the signal source and the antenna whose height with respect to the reflecting surface is to be determined. The slope or gradient of the reference numbers with respect to this measurement is determined. Reference interference patterns are generated either through mathematical modelling and/or through direct physical measurement and these are used to establish an equation relating known antenna-to-surface distances to the slopes of the reference numbers verses measurement. The slope corresponding to the antenna of an unknown distance from a surface is inserted into this equation and the equation is solved for the unknown distance. ## Claims ### Claim 1 A method for determining the distance of a transducer from a surface comprising the steps of: (a) transmitting a signal from a source; (b) receiving on said transducer said signal directly from said signal source, said transducer being an unknown distance from said surface (c) receiving on said transducer said signal indirectly from said source by way of a reflection of said signal from said surface; (d) moving said source with respect to said transducer; (e) repeating steps a, b and c as said source moves; (f) generating an interference pattern from said directly and indirectly received signals, said interference pattern depicting a signal characteristic with respect to a measurement indicative of distance between said source and said transducer; (g) selecting points on said interference pattern at substantially the same phase angle of each cycle of said interference pattern; (h) assigning sequential reference numbers to said points; (i) creating a plot of said reference numbers with respect to said measurement; (j) determining the slope of said plot; (k) generating reference interference patterns for a plurality of known transducer-to-surface distances; (l) repeating steps g-j for said reference interference patterns; (m) creating a plot of said reference interference pattern slopes determined in step l with respect to said known transducer-to-surface distances; (n) describing said plot created in step m in terms of an equation relating said known transducer-to-surface distances with respect to said slopes created in step m; and (o) inserting said slope determined in step j into said equation and solving for said unknown distance. ### Claim 2 (depends on 1) The method of claim 1 in which at least one of the reference interference patterns generated in step k are mathematically modelled. ### Claim 3 (depends on 1) The method of claim 1 in which at least one of the reference interference patterns generated in step k are physically measured. ### Claim 4 (depends on 1) The method of claim 1 in which at least one of the reference interference patterns generated in step k is determined through ray-optics. ### Claim 5 (depends on 1) The method of claim 1 in which linear regression analysis is used in step n in describing said plot created in step m in terms of an equation relating said known transducer-to-surface distances with respect to said slopes created in step m. ### Claim 6 (depends on 1) A method according to claim 1 in which said reflecting surface is water. ### Claim 7 (depends on 6) A method according to claim 6 in which said step of moving said source includes moving said source through the air. ### Claim 8 (depends on 6) A method according to claim 6 in which said step of moving said source includes moving said source through the space. ### Claim 9 (depends on 1) A method according to claim 1 in which said transducer is an antenna. ### Claim 10 (depends on 1) A method according to claim 1 in which said transducer is an optical receptor. ### Claim 11 (depends on 1) A method according to claim 1 in which said transducer is an acoustic receptor. ### Claim 12 (depends on 6) A method according to claim 6 in which said transducer is an antenna. ### Claim 13 (depends on 6) A method according to claim 6 in which said transducer is an optical receptor. ### Claim 14 (depends on 6) A method according to claim 6 in which said transducer is an acoustic receptor.