Beamforming using chip-scale atomic clocks in a controlled environment.

Area of Science:

• Oceanography
• Acoustics
• Atomic Physics

Background:

• Underwater acoustic arrays require precise timing for signal processing.
• Chip-Scale Atomic Clocks (CSACs) offer a portable solution for time synchronization.
• Lack of shared timing references limits current underwater acoustic array capabilities.

Purpose of the Study:

• To evaluate the effectiveness of Chip-Scale Atomic Clocks (CSACs) in underwater acoustic applications.
• To determine the importance of optimal clock disciplining for maintaining array coherence.
• To assess the performance of CSAC-equipped arrays in various acoustic oceanography scenarios.

Main Methods:

• Controlled laboratory experiments were conducted using a small acoustic array (N=4) equipped with CSACs.
• The study analyzed clock drift and its impact on array coherence at different frequencies.
• Experiments focused on time-coherent processing for directionality estimation.

Main Results:

• CSACs enable time-coherent processing essential for directionality estimation in underwater acoustics.
• Optimal disciplining of CSACs was found to be critical for sustained array coherence.
• Clock drift reached a 10% wavelength error at 0.3, 1, and 10 kHz within 25, 10, and 3 days, respectively.

Conclusions:

• CSAC technology enhances capabilities in acoustic thermometry, geoacoustic, biological, and under-ice oceanography.
• The findings highlight the potential of CSACs for advancing underwater acoustic research and applications.
• Careful clock disciplining strategies are necessary to maximize the benefits of CSACs in oceanographic studies.