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Why did early listening devices have limited success in detecting aircraft?
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warning system
U.S. Air Force Boeing E-3 Sentry, an airborne warning and control system (AWACS) aircraft.
Prior to the widespread adoption of radar, many nations experimented with alternative methods to detect incoming aircraft, including listening for the acoustic noise generated by engines and attempting to detect electrical ignition interference. These early acoustic listening devices ultimately proved ineffective for reliable military warning systems, as they lacked the necessary range, precision, and consistency required to track hostile aircraft effectively before they reached their targets.1