Wireless Picosecond Time Synchronization for Distributed Antenna Arrays

TL;DR

This paper presents a wireless method for picosecond-level time synchronization in distributed antenna arrays using a spectrally sparse two-tone waveform, achieving high precision over a short wireless link.

Contribution

It introduces a novel two-tone waveform and technique for high-precision wireless time synchronization, addressing oscillator drift and improving accuracy over traditional methods.

Findings

Achieved 2.26 ps synchronization precision in laboratory experiments.

Demonstrated effectiveness of two-tone waveform over LFM waveform.

Validated method over a 90 cm wireless link at 5.8 GHz.

Abstract

Distributed antenna arrays have been proposed for many applications ranging from space-based observatories to automated vehicles. Achieving good performance in distributed antenna systems requires stringent synchronization at the wavelength and information level to ensure that the transmitted signals arrive coherently at the target, or that scattered and received signals can be appropriately processed via distributed algorithms. In this paper we address the challenge of high precision time synchronization to align the operations of elements in a distributed antenna array and to overcome time-varying bias between platforms due to oscillator drift. We use a spectrally sparse two-tone waveform, which obtains approximately optimal time estimation accuracy, in a two-way time transfer process. We also describe a technique for determining the true time delay using the ambiguous two-tone matched filter output, and we compare the time synchronization precision of the two-tone waveform with the more common linear frequency modulation (LFM) waveform. We experimentally demonstrate wireless time synchronization using a single pulse 40$\,$MHz two-tone waveform over a 90$\,$cm 5.8$\,$GHz wireless link in a laboratory setting, obtaining a timing precision of 2.26$\,$ps.