User Constructed Sonar Equipment Presented to PSUBS Convention 2004.
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Transcript of User Constructed Sonar Equipment Presented to PSUBS Convention 2004.
User Constructed Sonar User Constructed Sonar EquipmentEquipment
Presented to
PSUBS Convention 2004
Sonar PrinciplesSonar Principles
Basic ConceptsTransducersPing generationPing receptionPost-ping processingConstruction and testing
Sonar PrinciplesSonar Principles
Basic ConceptsTransducersPing generationPing receptionPost-ping processingConstruction and testing
Basic Sonar ConceptsBasic 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 Speeds of Sound vvmm
00 Degrees Celsius Degrees Celsius [1][1]
Air 332 m/s 1,090 f/sFresh water 1,404 m/s 4,610 f/sSea water 1,440 m/s 4,730 f/sCopper 3,560 m/s 11,680 f/s
Iron 5,130 m/s 16,830 f/s
Sonar ConsiderationsSonar Considerations
Attenuation of signal by waterSpherical radiatorsSonar patternsChoice of frequencySensitivity of receiverTypes of transducers
Attenuation of Sound Through Attenuation of Sound Through Water Water [2][2]
Absorption Roughly Related to frequency squared
Scattering Signal scatters use to foreign materials in the
water
Sonar ConsiderationsSonar Considerations
Attenuation of signal by water
Spherical radiatorsSonar patternsChoice of frequencySensitivity of receiverTypes of transducers
Spherical Sound RadiationSpherical Sound RadiationSound intensity: I = Power / Area (W/m2) Where area of a sphere = 4r2
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 / 4r12 and I2 = PT / 4r2
2
Combining we have: I1 / r12 = I2 / r2
2
We have: I2 = (r12 / r2
2) I1 or I2 = (r1 / r2) 2 I1
Conclusion: Intensity of sound drops off with the square of the distance (r) from the source
Sonar ConsiderationsSonar Considerations
Attenuation of signal by waterSpherical radiators
Sonar patternsChoice of frequencySensitivity of receiverTypes of transducers
Sonar ConsiderationsSonar Considerations
Attenuation of signal by waterSpherical radiatorsSonar patterns
Choice of frequencySensitivity of receiverTypes of transducers
Sonar ConsiderationsSonar Considerations
Attenuation of signal by waterSpherical radiatorsSonar patternsChoice of frequency
Sensitivity of receiverTypes of transducers
Sonar ConsiderationsSonar Considerations
Attenuation of signal by waterSpherical radiatorsSonar patternsChoice of frequencySensitivity of receiver
Types of transducers
Sonar PrinciplesSonar Principles
Basic Concepts
TransducersPing generationPing receptionPost-ping processingConstruction and testing
TransducersTransducers
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 FactsSonar 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.
Beam AngleBeam Angle
Piezoelectric Principles Piezoelectric Principles [3][3]
Voltage Creates W
W Generates Voltage
W = Change in Thickness
Piezoelectric CeramicsPiezoelectric CeramicsMManufactured in a Variety of Shapes anufactured in a Variety of Shapes [4][4]
Ring Ring andand Disk Transducer Elements Disk Transducer Elements
Rings
Helps Eliminate Lateral Resonance Modes
Thin Discs
Showing Conductive Coating
Piezoelectric Modes Piezoelectric Modes [5][5]
Piezoelectric Modes Piezoelectric Modes [5][5]
Piezoelectric Modes Piezoelectric Modes [5][5]
Piezoelectric Modes Piezoelectric Modes [5][5]
Typical Piezoelectric Ceramics Typical Piezoelectric Ceramics [6][6]
Channel Industries, Inc.
Fish Finder TransducersFish 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
Advantages Disadvantages
Fish Finder TransducersFish Finder Transducers((Eagle Eagle [7][7]))
Transom Mount
Cylinder Thru Hull
Available Specialty Transducers Available Specialty Transducers [7][7]
Thru Hull Bronze
Thru Hull Plastic
Trolling Motor Mount
Sonar PrinciplesSonar Principles
Basic ConceptsTransducers
Ping generationPing receptionPost-ping processingConstruction and testing
Ping Generator SystemPing Generator System
Ping Generator ModulePing Generator Module
192-KHz Frequency 192-KHz Frequency Generator SectionGenerator Section
Alternative DesignAlternative Design
Ping Driver CircuitPing 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
Ping Driver CircuitPing Driver Circuit
Ping Driver ModulePing Driver Module
Sonar PrinciplesSonar Principles
Basic ConceptsTransducersPing generation
Ping receptionPost-ping processingConstruction and testing
Ping ReceptionPing Reception
Ping Receiver ModulePing Receiver Module
Sonar PrinciplesSonar Principles
Basic ConceptsTransducersPing generationPing receptionPost-ping processingConstruction and testing
Post-ping Processing OptionsPost-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 PrinciplesSonar PrinciplesBasic ConceptsTransducersPing generationPing receptionPost-ping processing
Construction and testing
Construction and TestingConstruction and Testing
Pressure HousingElectronic assembly ModulesTransducer arrayTesting
Pressure HousingPressure Housing
Electronics AssemblyElectronics Assembly
Microcontroller Board
ModulesModules
Stepper Motor Driver Board
ModulesModules
Ping Generator
ModulesModules
192-KHz Receiver
Transducer ArrayTransducer Array
Gray Cylinder Contains Stepping Motor Drive System
TestingTesting
Louisiana State University – Shreveport Pool
TestingTesting
Yes it is a desktop!
BibliographyBibliography
[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.