M.Eng., Harbin Engineering University · Underwater Acoustic Engineering

Wireless Communication for Underwater Acoustic Engineering

Before Advanced Air Mobility, my graduate research at Harbin Engineering University was underwater acoustics: characterizing the transducers and hydrophones that generate and receive acoustic signals, reconstructing a real OFDM/QPSK communication link from an unlabeled lake-trial recording, building the detection-theory and array-processing foundations that both depend on, and using BELLHOP ray-tracing simulation to connect a canonical deep-ocean sound channel to real, measured shallow-water channel behavior. Four technical reports, each independently verified against real measured data, cited literature, and original from-scratch algorithm implementations, not reproductions of any textbook or paper.

OFDM / QPSK Matched-Filter Detection MUSIC DOA Estimation Hydrophone & Transducer Calibration Channel Estimation BELLHOP Ray Tracing

Reports

Tank Measurement

Underwater Acoustic Transducer & Hydrophone Systems

Tank characterization of a piezoelectric transducer and hydrophone: electrical impedance in air vs. water, free-field voltage sensitivity calibration, transmitting voltage response, and a measured directivity pattern, each cross-validated against a computational model.

Real Lake Trial

Underwater Acoustic OFDM/QPSK Communication

Engineered the exact modulation scheme of a real, undocumented 2018 underwater OFDM/QPSK recording from first principles, then used that model to measure real channel signal-to-noise ratio, coherence time, and a repeating synchronization pulse in the field data.

Theory & Foundations

Digital Signal Processing for Underwater Acoustic Channels

Connects DSP processor architecture, detection theory, and array signal processing to the measured results in the other two reports, with two original from-scratch demonstrations: a matched-filter detector and a MUSIC direction-of-arrival estimator.

Ray-Tracing Simulation

Ray-Tracing Simulation of Underwater Acoustic Channels

BELLHOP ray-tracing simulation connecting the canonical deep-ocean Munk sound channel to a communication-relevant frequency case and a custom shallow-water channel, validated against independent physical and geometric expectations, then used for matched-filter signal detection over the resulting channel impulse response.

Key Results

Every number below is measured or independently reproduced, not simulated for illustration alone. See each report for full methodology.

Tank Measurement
Directivity Index
9.06 dB
at 39.8 kHz · TVR peak 225.7 dB

Measured beam width of 42.99° with an effective transducer diameter of 52.2 mm, matched against a computational model.

Lake Trial
Demodulation Accuracy
0.001%
Error Vector Magnitude, all 6 bursts

Real signal-to-noise ratio measured falling from 7.9 dB to 3.3 dB across the recording's 3-15 kHz band, consistent with underwater acoustic absorption.

Theory & Foundations
Detection & DOA
0° error
Matched filter + MUSIC, both exact

Matched filtering later found a real synchronization pulse at correlation scores above 0.99 in the lake trial's own recording.

Ray-Tracing Simulation
Deep Sound Channel Loss
79.2 dB
at 100 km, vs. 100.0 dB spherical spreading

BELLHOP-computed transmission loss reproduces the Munk deep-ocean channel's real loss reduction, with every eigenray at 48 kHz terminating within 2 km and 50 m of the target receiver.