The Sound of Bats
GEOINT Symposium
April 2014
Tom Ager
Geomatics Consulting and Teaching
TomAgerLLC
Engineering Beauty
Bat Echo Location
Bats Use Sonar Similar to Radar
Geo-location
Moving Target Indication
Perhaps Mysterious Form of Sound Imaging
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
Antenna Design
Bat Antennas
High Frequency Sound Waves
Much Higher Frequency Than Human Hearing
Pulses are Powerful
Cruise Mode PRF
Targeting Mode PRF
Antenna Gain
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
Chirped Pulses
Chirped Pulses
Brute Force Sonar
Narrow Pulses Needed for High Range Resolution
Must be Very Powerful for Decent Echo
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
Distance Estimation
Consider Pulse Ramped Down
Simultaneous Returns from Multiple Insects
Return from More Distant Bugs
Higher Frequency than Nearby Bug
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
Adventures with Doppler
Tracking Moving Targets
MTI Mode
Emit Long Single-Frequency Hum
Reflection is Shifted
Bats Measures Doppler
Determines Relative Velocity
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
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
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 !
Anti-Jamming
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
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
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
Philosophical Considerations
of Vision
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
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
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
The Beautiful Bat
Detection and Ranging Creature
Emits Pulses via Send-Receive Auditory System
Detection and Ranging Creature
Emits Pulses via Send-Receive Auditory System
Switches PRF for Cruise Mode and Hunt Mode
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
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
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
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
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
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