🔊 Sonar & Echolocation
Active sonar rotating sweep — detect submarines and fish schools by echo travel time t = 2R/c
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About Sonar & Echolocation
What It Demonstrates
Active sonar emits a high-frequency sound pulse that reflects off objects. The two-way travel time t = 2R/c (c = 1,500 m/s in seawater) gives range R = ct/2. Higher frequencies (20 kHz+) give better angular resolution but absorb faster — limiting detection to short ranges. The detection range formula is Rmax = R0 / √(f/f0) where R0=500 m, f0=5 kHz. Passive sonar listens without transmitting — stealthy, but range-limited by ambient noise floor.
How to Use
Watch the green sweep rotate and trigger bright blips when passing over objects. Slide frequency up to see detection range shrink — high-frequency sonar trades range for resolution. Slide sweep rate to change how quickly the screen refreshes. Switch object presets to compare fish schools (many small targets) vs. submarine (single large low-RCS target) vs. seamounts (fixed seafloor terrain). Objects beyond the max detection range are invisible.
Did You Know?
The word SONAR stands for Sound Navigation And Ranging. It was developed during World War I to detect German U-boats after the sinking of the Lusitania (1915). Modern military towed-array sonars stretch 2–3 km behind a submarine and can detect another sub at 100+ km range. Dolphins use biological sonar (echolocation) at 40–150 kHz — far beyond human hearing — and can distinguish objects as small as a golf ball from 100 m away.