The digital beam forming technique in AgileDARN high-frequency radar

• Published in: Polar Science
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Digital beam forming (DBF); Field-programmable gate array (FPGA); Dolph-Chebyshev window; Agile dual auroral radar network (AgileDARN); Super dual auroral radar network (SuperDARN); Polar Science
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=16469; http://id.nii.ac.jp/1291/00016345/

An all-digital agile dual auroral radar network (AgileDARN) was developed by the National Space Science Center, Chinese Academic of Sciences (NSSC, CAS). AgileDARN can achieve higher performance and greater flexibility based on highly digitized hardware and its distributed digital signal processing system. Multiple receiving beams can be created within the transmitting beam pattern better to determine the direction of arrival (DOA). In each beam, seven real-time azimuthal sub-beams are synthesized simultaneously with 16 main digital receiver channels. Each sub-beam detects the echo around the transmitting boresight with an angular separation of 0.46°. Comparing the echoes from different sub-beams, the azimuthal geolocation of the irregularities can be improved when their volume is smaller than the beamwidth. Furthermore, the Chebyshev window enables the control of the sidelobes and antenna pattern, effectively suppressing interference. To implement multi-beam forming, extra processing resources of the field-programmable gate array (FGPA) are required. This paper introduces the signal processing procedure and analyzes the requirements on the FPGA resources，and the technique is validated with meteor echoes received by the AgileDARN radar. The azimuthal geolocation of echoes increases by seven times compared with the single beamforming SuperDARN radar.