Accurate Phase Calibration for Digital Beam-Forming in Multi-Transceiver HF Radar System

Abstract

Abstract-The TIGER-3 radar is being developed as an "all digital" radar with 20 integrated digital transceivers, each connected to a separate antenna. Using phased array antenna techniques, radiated power is steered towards a desired direction based on the relative phases within the array elements. This paper proposes an accurate phase measurement method to calibrate the phases of the radio output signals using Field Programmable Gate Array (FPGA) technology. The method sequentially measures the phase offset between the RF signal generated by each transceiver and a reference signal operated at the same frequency. Accordingly, the transceiver adjusts its phase in order to align to the reference phase. This results in accurately aligned phases of the RF output signals and with the further addition of appropriate phase offsets, digital beamforming (DBF) can be performed steering the beam in a desired direction. The proposed method is implemented on a Virtex-5 VFX70T device. Experimental results show that the calibration accuracy is of 0.153 degrees with 14 MHz operating frequency.

Wuhan Ionospheric Oblique Backscattering Sounding System and Its Applications—A Review

“…Digital array radar (DAR) is a fully-digitized phased array radar in which digital beam forming techniques are used both in reception and transmission [ 159 ], and this technology has been successfully applied in HF radar, such as the SuperDARN HF radars [ 160 ]. If DAR technology is used in WIOBSS, the two-dimensional angle-of-arrival of echoes can be accurately measured to study the ionospheric irregularities, the fine structure of the ionosphere, and so on.…”

Calibrating the Amplitude and Phase Imbalances in AgileDARN HF Radar

“…Only a few groups have adopted or attempted to calibrate the radar system. Nguyen et al (2013) utilized two additional 14-bit analog-to-digital converters (ADCs) alongside the main receiver 16-bit ADC in each transceiver to calibrate the multi-transceiver phase variability in TIGER-3 HF radar. This method does not rely on reference channels and has distinct phase calibration accuracy between transceivers, which is 0.153° at 14 MHz operating frequency.…”