Methods and Apparatus for Cross-Medium Communication

Patent metadata

Field	Value
Publication number	US-2019342012-A1
Application number	US-201916396731-A
Country	US
Kind code	A1
Filing date	Apr 28, 2019
Priority date	May 4, 2018
Publication date	Nov 7, 2019
Grant date	—

Abstract

An underwater transmitter may generate underwater pressure waves that encode bits of data. The pressure waves may travel to, and created minute vibrations in, the water's surface. An airborne radar may detect radar signals that reflect from the water's surface. The surface vibrations may modulate the phase of the reflected radar signal. The radar receiver may, based on the variation in the phase of the reflected radar signal, decode the data that was initially encoded in the underwater pressure waves. The underwater pressure waves may be frequency modulated, such as by orthogonal frequency-division multiplexing. Alternatively, the surface vibrations may be detected by a camera, interferometer or other light sensor. Alternatively, the pressure waves may propagate through a media other than water. For instance, the pressure waves may propagate through bodily tissue, or may propagate through oil or a liquid fracking mixture in an oil or gas well.

First claim

What is claimed:

1 . A system comprising:
(a) an underwater acoustic transmitter configured to transmit an acoustic signal that (i) represents data, (ii) travels through water to the water's surface, and (iii) causes displacements in the surface; (b) a radar transceiver configured to take measurements of the displacements by (i) transmitting a wireless signal that propagates through air to the surface, and (ii) measuring a reflected wireless signal that reflects from the surface; and (c) one or more computers that are programmed to determine, based on the measurements of the displacements, at least some of the data that is represented by the acoustic signal.

2 . The system of claim 1 , wherein the radar transceiver is a millimeter-wave radar.

3 . The system of claim 1 , wherein the radar transceiver is a frequency modulated continuous wave radar.

4 . The system of claim 1 , wherein the one or more computers are programmed to determine displacement of the water's surface, based on phase of the reflected wireless signal.

5 . The system of claim 1 , wherein the one or more computers are programmed:
(a) to computationally separate the reflected wireless signal into range bins; and (b) to select a range bin that corresponds to height of the radar transceiver above the water's surface.

6 . The system of claim 1 , wherein the one or more computers are programmed:
(a) to computationally separate the reflected wireless signal into range bins; (b) to select a particular range bin that corresponds to height of the radar transceiver above the water's surface; and (c) to unwrap phase of the reflected wireless signal for the particular range bin.

7 . The system of claim 1 , wherein the one or more computers are programmed to filter the reflected wireless signal in such a way as to filter out frequencies that are due to wind waves on the water's surface.

8 . The system of claim 1 , wherein the acoustic transmitter is programmed to modulate the acoustic signal with orthogonal frequency division multiplexing.

9 . The system of claim 1 , wherein:
(a) the acoustic transmitter is programmed to frequency modulate the acoustic signal; and (b) the acoustic transmitter is programmed to optimize allocation of signal power among frequency channels.

10 . The system of claim 1 , wherein the acoustic transmitter is programmed to adjust a modulation scheme, bitrate, or coding rate for a particular frequency channel of communication, based on an estimate (i) of power, amplitude, attenuation or signal-to-noise ratio (SNR) of the particular channel, or (iii) of any parameter that is positively correlated with the power, the amplitude, the attenuation or the SNR.

11 . The system of claim 1 , wherein:
(a) the system further comprises a pressure sensor that is configured to measure water pressure and to determine, based on the pressure, depth of the pressure sensor below the water's surface; and (b) the acoustic transmitter is programmed (i) to estimate, based on the depth, a value that represents power, amplitude, attenuation or signal-to-noise ratio of a channel of communication.

12 . The system of claim 1 , wherein:
(a) the system includes one or more hydrophones that are configured to take measurements of sound signals that have reflected from the water's surface; and (b) the system includes one or more computers that are programmed to estimate, based on the measurements, a value that represents power, amplitude, attenuation or signal-to-noise ratio of a channel of communication.

13 . The system of claim 1 , wherein the one or more computers are programmed to estimate horizontal location of the acoustic transmitter, based on where amplitude of the displacements is greatest.

14 . A system comprising:
(a) an artificial acoustic transmitter configured to transmit an acoustic signal that (i) represents data, (ii) propagates through at least a first medium to a surface that is between the first medium and a second medium, and (iii) causes displacements of the surface; (b) a radar transceiver configured to take measurements of the displacements by (i) transmitting a wireless signal that propagates through the second medium to the surface, and (ii) measuring a reflected wireless signal that reflects from the surface; and (c) one or more computers that are programmed to determine, based on the measurements of the displacements, at least some of the data that is represented by the acoustic signal.

15 . The system of claim 14 , wherein:
(a) the first medium comprises bodily tissue; and (b) the surface comprises skin.

16 . The system of claim 14 , wherein the first medium comprises a liquid in a well.

17 . A system comprising:
(a) an artificial acoustic transmitter configured to transmit an acoustic signal that (i) represents data, (ii) propagates through at least a first medium to a surface a surface that is between the first medium and a second medium and (iii) causes displacements of the surface; (b) a sensor configured to take measurements of the displacements by measuring a reflected wireless electromagnetic signal that reflects from the surface and propagates through the second medium; and (c) one or more computers that are programmed to determine, based on the measurements of the displacements, at least some of the data that is represented by the acoustic signal.

18 . The system of claim 17 , wherein the electromagnetic signal is collimated.

19 . The system of claim 17 , wherein the electromagnetic signal comprises visible light.

20 . The system of claim 17 , wherein the electromagnetic signal comprises infrared light.

21 . The system of claim 17 , wherein the system further comprises a source of the electromagnetic radiation.

Assignees

• Massachusetts Inst Technology

Inventors

• Tonolini Francesco
• Adib Fadel

Classifications

• G01S13/86

  Combinations of radar systems with non-radar systems, e.g. sonar, direction finder · CPC title

• G01S7/415

  Identification of targets based on measurements of movement associated with the target · CPC title

• G01S13/583

  using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets · CPC title

• G01S7/003

  Transmission of data between radar, sonar or lidar systems and remote stations · CPC title

• H04B13/02 Primary

  Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy · CPC title