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User Constructed Sonar Equipment. Presented to PSUBS Convention 2004. Sonar Principles. Basic Concepts Transducers Ping generation Ping reception Post-ping processing Construction and testing. Sonar Principles. Basic Concepts Transducers Ping generation Ping reception

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user constructed sonar equipment

User Constructed Sonar Equipment

Presented to

PSUBS Convention 2004

sonar principles
Sonar Principles
  • Basic Concepts
  • Transducers
  • Ping generation
  • Ping reception
  • Post-ping processing
  • Construction and testing
sonar principles3
Sonar Principles
  • Basic Concepts
  • Transducers
  • Ping generation
  • Ping reception
  • Post-ping processing
  • Construction and testing
basic sonar concepts
Basic Sonar Concepts
  • Generate a signal at some frequency f0
  • Drive an transducer at f0 for a short duration of time generating a “ping”
  • Allow the sound waves generated to propagate outward at the speed of the medium Vm
  • Receive the return echo signal measuring the time of flight from transmission to reception Tf
  • Calculate the distance to target, D = ( Tf · Vm ) / 2
speeds of sound v m 0 degrees celsius 1
Speeds of Sound vm0 Degrees Celsius [1]
  • Air 332 m/s 1,090 f/s
  • Fresh water 1,404 m/s 4,610 f/s
  • Sea water 1,440 m/s 4,730 f/s
  • Copper 3,560 m/s 11,680 f/s
  • Iron 5,130 m/s 16,830 f/s
sonar considerations
Sonar Considerations
  • Attenuation of signal by water
  • Spherical radiators
  • Sonar patterns
  • Choice of frequency
  • Sensitivity of receiver
  • Types of transducers
attenuation of sound through water 2
Attenuation of Sound Through Water [2]
  • Absorption

Roughly Related to frequency squared

  • Scattering

Signal scatters use to foreign materials in the water

sonar considerations9
Sonar Considerations
  • Attenuation of signal by water
  • Spherical radiators
  • Sonar patterns
  • Choice of frequency
  • Sensitivity of receiver
  • Types of transducers
spherical sound radiation
Spherical Sound Radiation
  • Sound intensity: I = Power / Area (W/m2)
  • Where area of a sphere = 4pr2
  • Same power through any radius (r) we can imagine, with the source in the center
  • Let PT = Total power through any radius (r)
  • Therefore: I1 = PT / 4pr12 and I2 = PT / 4pr22
  • Combining we have: I1 / r12 = I2 / r22
  • We have: I2 = (r12 / r22) I1 or I2 = (r1/ r2) 2 I1
  • Conclusion: Intensity of sound drops off with the square of the distance (r) from the source
sonar considerations11
Sonar Considerations
  • Attenuation of signal by water
  • Spherical radiators
  • Sonar patterns
  • Choice of frequency
  • Sensitivity of receiver
  • Types of transducers
sonar considerations12
Sonar Considerations
  • Attenuation of signal by water
  • Spherical radiators
  • Sonar patterns
  • Choice of frequency
  • Sensitivity of receiver
  • Types of transducers
sonar considerations13
Sonar Considerations
  • Attenuation of signal by water
  • Spherical radiators
  • Sonar patterns
  • Choice of frequency
  • Sensitivity of receiver
  • Types of transducers
sonar considerations14
Sonar Considerations
  • Attenuation of signal by water
  • Spherical radiators
  • Sonar patterns
  • Choice of frequency
  • Sensitivity of receiver
  • Types of transducers
sonar principles15
Sonar Principles
  • Basic Concepts
  • Transducers
  • Ping generation
  • Ping reception
  • Post-ping processing
  • Construction and testing
transducers
Transducers
  • Sonar transducer facts
  • Beam Angle
  • Piezoelectric principles
  • Piezoelectric ceramics
  • Ring and disk transducers elements
  • Piezoelectric modes
  • Typical piezoelectric ceramics
  • Fish finder transducers
  • Available specialty transducers
sonar transducer facts
Sonar Transducer Facts
  • Transducers convert electrical signals to sound.
  • Transducers convert sound into electrical signals.
  • Most transducers send and receive best at one characteristic frequency f0.
  • Most small sonar transducers are of a piezoelectric form.
  • Most piezoelectric materials for sonar application are ceramics.
piezoelectric principles 3
Piezoelectric Principles [3]

Voltage Creates DW

DW Generates Voltage

DW = Change in Thickness

ring and disk transducer elements
Ring and Disk Transducer Elements

Rings

Helps Eliminate Lateral Resonance Modes

Thin Discs

Showing Conductive Coating

typical piezoelectric ceramics 6
Typical Piezoelectric Ceramics [6]

Channel Industries, Inc.

fish finder transducers
Relatively Inexpensive

Encapsulated

Wiring Attached

Wide or Narrow Cone

Locally Available

Little Choice of Resonate Frequencies

Unknown Piezoelectric Material Used

Unknown Electrical Properties of Material

Fish Finder Transducers

Advantages

Disadvantages

fish finder transducers eagle 7
Fish Finder Transducers(Eagle [7])

Transom Mount

Cylinder Thru Hull

available specialty transducers 7
Available Specialty Transducers [7]

Thru Hull Bronze

Thru Hull Plastic

Trolling Motor Mount

sonar principles30
Sonar Principles
  • Basic Concepts
  • Transducers
  • Ping generation
  • Ping reception
  • Post-ping processing
  • Construction and testing
ping driver circuit
Ping Driver Circuit
  • Amplifies 192-KHz Signal from Generator and Drives Transducer
  • Generates Drive Only when Ping Enable is Active
  • Multiplexes Sonar Transducers if System Requires
sonar principles41
Sonar Principles
  • Basic Concepts
  • Transducers
  • Ping generation
  • Ping reception
  • Post-ping processing
  • Construction and testing
sonar principles45
Sonar Principles
  • Basic Concepts
  • Transducers
  • Ping generation
  • Ping reception
  • Post-ping processing
  • Construction and testing
post ping processing options
Post-ping Processing Options
  • Sample return analog for feed to computer or microcontroller.
  • Use analog means of measuring time between ping and the breaking of a return threshold level.
  • Be creative with your own methods of monitoring returned amplitude vs time!
sonar principles47
Sonar Principles
  • Basic Concepts
  • Transducers
  • Ping generation
  • Ping reception
  • Post-ping processing
  • Constructionand testing
construction and testing
Construction and Testing
  • Pressure Housing
  • Electronic assembly
  • Modules
  • Transducer array
  • Testing
electronics assembly
Electronics Assembly

Microcontroller Board

modules
Modules

Stepper Motor Driver Board

modules52
Modules

Ping Generator

modules53
Modules

192-KHz Receiver

transducer array
Transducer Array

Gray Cylinder Contains Stepping Motor Drive System

testing
Testing

Louisiana State University – Shreveport Pool

testing56
Testing

Yes it is a desktop!

bibliography
Bibliography

[1] Sidney Borowitz and Arthur Beiser, “Essentials of Physics”, Addison Wesley Publishing, 1971.

[2] http://www.fas.org/man/dod-101/navy/docs/fun/part08.htm

[3] http://www.Azom.com

[4] Keramos Advanced Piezoelectrics

http://www.piezotechnologies.com/keramos.htm

[5] “Piezoelectric Ceramics”, EDO Corporation.

[6] “Piezoelectric Ceramics”, Channel Industries, Inc.

[7] Lowrance Electronics, Inc.

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