The Sound of Bats. GEOINT Symposium. April Tom Ager. Geomatics Consulting and Teaching TomAgerLLC

Transcription

1 The Sound of Bats GEOINT Symposium April 2014 Tom Ager Geomatics Consulting and Teaching TomAgerLLC

2 Engineering Beauty

3 Bat Echo Location Bats Use Sonar Similar to Radar Geo-location Moving Target Indication Perhaps Mysterious Form of Sound Imaging

4 Bat Echo Location Bats Use Sonar Similar to Radar Geo-location Moving Target Indication Perhaps Mysterious Form of Sound Imaging Natural Selection No Design No Future View Produced Amazing Creature On-board Processing Outstrips Advanced Radars

5 Antenna Design

6 Bat Antennas High Frequency Sound Waves Much Higher Frequency Than Human Hearing Pulses are Powerful Cruise Mode PRF Targeting Mode PRF Antenna Gain

7 Antenna Protection Weak Return Waves Very Sensitive Ears Vulnerable to Damage from Loud Emitted Pulses Send-Receive Switching Mechanism Disengage Ear Bones During Transmission Engage During Reception

8 Chirped Pulses

9 Chirped Pulses Brute Force Sonar Narrow Pulses Needed for High Range Resolution Must be Very Powerful for Decent Echo

10 Chirped Pulses Brute Force Sonar Narrow Pulses Needed for High Range Resolution Must be Very Powerful for Decent Echo Sophisticated Bats Modulates Pulse Frequency Distinguishes Distances

11 Distance Estimation Consider Pulse Ramped Down Simultaneous Returns from Multiple Insects Return from More Distant Bugs Higher Frequency than Nearby Bug

12 Distance Estimation Consider Pulse Ramped Down Simultaneous Returns from Multiple Insects Return from More Distant Bugs Higher Frequency than Nearby Bug Higher Pitch Means Further Away

13 Adventures with Doppler

14 Tracking Moving Targets MTI Mode Emit Long Single-Frequency Hum Reflection is Shifted Bats Measures Doppler Determines Relative Velocity

15 Tracking Moving Targets MTI Mode Emit Long Single-Frequency Hum Reflection is Shifted Bats Measures Doppler Determines Relative Velocity Real-Time Targeting Long Single-Pitch Shriek with Short Chirp Simultaneous Velocity and Range Data

16 Tuning the Return Pulse Tracking Faint Echoes Bat Coordinates Pulses with Relative Motion Modulates Emitted Pulses Shifted Echoes Produce Constant Pitch Returns Tuned to Pitch that Bat Hears Best

17 Tuning the Return Pulse Tracking Faint Echoes Bat Coordinates Pulses with Relative Motion Modulates Emitted Pulses Shifted Echoes Produce Constant Pitch Returns Tuned to Pitch that Bat Hears Best Doppler Still Measured Bat Monitors How it Changes Pulse Frequency These Modulations Equivalent to Doppler Shift Great Work Little Bat!

18 Anti-Jamming

19 Bats Emerging from Cave Haphazard Choreography Millions of Bats All Emit Ultra-Sound Fly Within Inches of Each Other Each Can Distinguish its Own Echoes No Collisions

20

21 Bat Collision Avoidance No One Knows How Bats Manage No Personal Frequency Bands Perhaps Returns are Compared to Previous Returns World View Must Make Sense New Objects Cannot Pop Up in Empty Scene

22 Bat Collision Avoidance No One Knows How Bats Manage No Personal Frequency Bands Perhaps Returns are Compared to Previous Returns World View Must Make Sense New Objects Cannot Pop Up in Empty Scene Bats Maintain Signal Purity Vast Conglomeration of Echoes And Bats And More Echoes

23 Philosophical Considerations of Vision

24 Speculations of Sound Vision Imagine Darkened Dance Club Intermittently Illuminated by Strobe Light View Series of fixed Frames Motion Implied but No Continuous View Perhaps This is Bat View of World in Cruise Mode

25 Sound Vision Sound Waves are Not Light Waves Sound Waves not Source of Vision But Vision is Neurological Response to Energy Electrical Signals from Cones Sensed as Colors

26 Sound Vision Sound Waves are Not Light Waves Sound Waves not Source of Vision But Vision is Neurological Response to Energy Electrical Signals from Cones Sensed as Colors Sound Vision is Conceivable Bats Use Sound for Spatial Data and Signal Intensity Brains May Produce Sound-Based Images Hunt-Mode with High PRF Motion Image Sensation of Color May be Available Perhaps Female Sees Yellow Fur on Handsome Male

27 The Beautiful Bat

28 Detection and Ranging Creature Emits Pulses via Send-Receive Auditory System

29 Detection and Ranging Creature Emits Pulses via Send-Receive Auditory System Switches PRF for Cruise Mode and Hunt Mode

30 Detection and Ranging Creature Emits Pulses via Send-Receive Auditory System Switches PRF for Cruise Mode and Hunt Mode Increases Gain in Direction of Target

31 Detection and Ranging Creature Emits Pulses via Send-Receive Auditory System Switches PRF for Cruise Mode and Hunt Mode Increases Gain in Direction of Target Uses Chirped Pulses for High Range Resolution

32 Detection and Ranging Creature Emits Pulses via Send-Receive Auditory System Switches PRF for Cruise Mode and Hunt Mode Increases Gain in Direction of Target Uses Chirped Pulses for High Range Resolution Modulates Pulse Frequency to Set Return Pitch

33 Detection and Ranging Creature Emits Pulses via Send-Receive Auditory System Switches PRF for Cruise Mode and Hunt Mode Increases Gain in Direction of Target Uses Chirped Pulses for High Range Resolution Modulates Pulse Frequency to Set Return Pitch Performs In-Flight Precision Targeting

34 Detection and Ranging Creature Emits Pulses via Send-Receive Auditory System Switches PRF for Cruise Mode and Hunt Mode Increases Gain in Direction of Target Uses Chirped Pulses for High Range Resolution Modulates Pulse Frequency to Set Return Pitch Performs In-Flight Precision Targeting Flies From Cave with Millions of Mates

35 Detection and Ranging Creature Emits Pulses via Send-Receive Auditory System Switches PRF for Cruise Mode and Hunt Mode Increases Gain in Direction of Target Uses Chirped Pulses for High Range Resolution Modulates Pulse Frequency to Set Return Pitch Performs In-Flight Precision Targeting Flies From Cave with Millions of Mates May Even View Sound-based Images

36