1. User Constructed Sonar Equipment
Presented to
PSUBS Convention 2004

2. Sonar Principles Basic Concepts Transducers Ping generation
Ping reception
Post-ping processing
Construction and testing

3. Sonar Principles Basic Concepts Transducers Ping generation
Ping reception
Post-ping processing
Construction and testing

4. 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

6. Speeds of Sound vm 0 Degrees Celsius [1]
Air m/s ,090 f/s
Fresh water 1,404 m/s ,610 f/s
Sea water 1,440 m/s ,730 f/s
Copper 3,560 m/s ,680 f/s
Iron 5,130 m/s ,830 f/s

7. Attenuation of signal by water
Sonar Considerations
Attenuation of signal by water
Spherical radiators
Sonar patterns
Choice of frequency
Sensitivity of receiver
Types of transducers

8. Attenuation of Sound Through Water [2]
Absorption
Roughly Related to frequency squared
Scattering
Signal scatters use to foreign materials in the water

9. Sonar Considerations Spherical radiators
Attenuation of signal by water
Spherical radiators
Sonar patterns
Choice of frequency
Sensitivity of receiver
Types of transducers

10. 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

11. Sonar patterns Sonar Considerations Attenuation of signal by water
Spherical radiators
Sonar patterns
Choice of frequency
Sensitivity of receiver
Types of transducers

12. Sonar Considerations Choice of frequency
Attenuation of signal by water
Spherical radiators
Sonar patterns
Choice of frequency
Sensitivity of receiver
Types of transducers

13. Sensitivity of receiver
Sonar Considerations
Attenuation of signal by water
Spherical radiators
Sonar patterns
Choice of frequency
Sensitivity of receiver
Types of transducers

14. Sonar Considerations Types of transducers
Attenuation of signal by water
Spherical radiators
Sonar patterns
Choice of frequency
Sensitivity of receiver
Types of transducers

15. Sonar Principles Transducers Basic Concepts Ping generation
Ping reception
Post-ping processing
Construction and testing

16. 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

17. 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.

18. Beam Angle

19. Piezoelectric Principles [3]
Voltage Creates DW
DW Generates Voltage
DW = Change in Thickness

20. Piezoelectric Ceramics Manufactured in a Variety of Shapes [4]

21. Ring and Disk Transducer Elements
Rings
Helps Eliminate Lateral Resonance Modes
Thin Discs
Showing Conductive Coating

22. Piezoelectric Modes [5]

23. Piezoelectric Modes [5]

24. Piezoelectric Modes [5]

25. Piezoelectric Modes [5]

26. Typical Piezoelectric Ceramics [6]
Channel Industries, Inc.

27. Fish Finder Transducers
Advantages
Disadvantages
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

28. Fish Finder Transducers (Eagle [7])
Transom Mount
Cylinder Thru Hull

29. Available Specialty Transducers [7]
Thru Hull Bronze
Thru Hull Plastic
Trolling Motor Mount

30. Sonar Principles Ping generation Basic Concepts Transducers
Ping reception
Post-ping processing
Construction and testing

31. Ping Generator System

32. Ping Generator Module

33. 192-KHz Frequency Generator Section

35. Alternative Design

37. 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

38. Ping Driver Circuit

39. Ping Driver Module

41. Sonar Principles Ping reception Basic Concepts Transducers
Ping generation
Ping reception
Post-ping processing
Construction and testing

42. Ping Reception

43. Ping Receiver Module

45. Sonar Principles Post-ping processing Basic Concepts Transducers
Ping generation
Ping reception
Post-ping processing
Construction and testing

46. 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!

47. Construction and testing
Sonar Principles
Basic Concepts
Transducers
Ping generation
Ping reception
Post-ping processing
Construction and testing

48. Construction and Testing
Pressure Housing
Electronic assembly
Modules
Transducer array
Testing

49. Pressure Housing

50. Microcontroller Board
Electronics Assembly
Microcontroller Board

51. Stepper Motor Driver Board
Modules
Stepper Motor Driver Board

52. Modules
Ping Generator

53. Modules
192-KHz Receiver

54. Gray Cylinder Contains Stepping Motor Drive System
Transducer Array
Gray Cylinder Contains Stepping Motor Drive System

55. Louisiana State University – Shreveport Pool
Testing
Louisiana State University – Shreveport Pool

56. Testing
Yes it is a desktop!

57. Bibliography
[1] Sidney Borowitz and Arthur Beiser, “Essentials of Physics”, Addison Wesley Publishing, 1971.
[2]
[3]
[4] Keramos Advanced Piezoelectrics
[5] “Piezoelectric Ceramics”, EDO Corporation.
[6] “Piezoelectric Ceramics”, Channel Industries, Inc.
[7] Lowrance Electronics, Inc.