Duration: 12 months
Beamforming architectures with multiple digital channels offer major advantages for Synthetic Aperture Radar (SAR) systems by enabling parallel signal acquisition through multiple subarrays. This enhances system performance in terms of swath width and resolution—often by an order of magnitude compared to conventional phased arrays. Distributing digital beamforming functionality across the antenna using Digital Beamforming Units (DBFUs) provides further benefits, including reduced thermal hotspots, lower per-unit processing load, and overall cost savings.
A key challenge in such distributed architectures is the precise generation, distribution, and synchronization of clock signals across the antenna. Accurate timing is essential for maintaining antenna pointing accuracy, signal-to-noise ratio (SNR), and Noise Equivalent Sigma Zero (NESZ). In advanced imaging modes such as High Resolution Wide Swath (HRWS), it also affects azimuth ambiguity suppression.
To address this, we propose LightSync, a novel optical clock distribution system using advanced opto-electronic RF synthesizer technology developed by QuSinus GmbH. Based on a mode-locked laser as a reference oscillator, it enables sub-picosecond synchronization of distributed DBFUs (ADCs and DACs) via ultra-low-jitter optical signals, achieving ~4–5 fs rms jitter.
The system distributes a 12 GHz sampling clock, a 10 MHz synchronization signal, and non-periodic trigger pulses to three DBFUs via optical fibers, all driven by a central optical source located at the antenna panel or in the instrument backend.
LightSync paves the way for scalable, lightweight, and high-performance distributed digital beamforming in future Earth observation radars. If successful, it will mark a breakthrough in onboard synchronization, offering unprecedented signal integrity, reduced system mass, and improved architectural flexibility. (Image Copyright Airbus Defence and Space GmbH)
