Acoustic radar imaging using parametric loudspeakers and coded ultrasonic emission

In recent years, acoustic sensing has emerged as a promising technique for detecting objects in invisible or occluded areas by leveraging the wave nature of sound. Unlike optical methods, which are limited in dusty, foggy, or visually obstructed environments, acoustic sensing can function reliably under such conditions. However, traditional acoustic systems often suffer from poor spatial resolution and low directivity. This study proposes a novel wide-range acoustic imaging method that combines parametric loudspeakers with coded ultrasonic emissions to overcome these limitations. An M-sequence signal was modulated onto an ultrasonic carrier and emitted using a parametric loudspeaker. The received reflections were processed using pulse compression techniques to improve temporal resolution and signal-to-noise ratio. Additionally, the acoustic beam was mechanically scanned across a wide angular range, enabling spatial mapping of objects based on the arrival time of reflected signals. Experimental results confirmed the ability to detect objects across a broad field, validating the feasibility of radar-style acoustic imaging. This method offers a high-directivity, non-contact sensing approach suitable for applications such as surveillance, search and rescue, and robotics, especially in visually restricted environments. The integration of acoustic beam steering and coded signal processing marks a new direction in long-range, high-resolution acoustic sensing.