Title :
The Nobeyama radioheliograph
Author :
Nakajima, Hiroshi ; Nishio, Mas Anori ; Enome, Shinzo ; Shibasaki, Kiyoto ; Takano, Toshiaki ; Hanaoka, Yoichiro ; Torii, Chikayoshi ; Sekiguchi, Hideaki ; Bushimata, Takeshi ; Kawashima, Susumu ; Shinohara, Noriyuki ; Irimajiri, Yoshihisa ; Koshiishi, Hi
Author_Institution :
Nobeyama Radio Obs., Nat. Astron. Obs., Nagano, Japan
fDate :
5/1/1994 12:00:00 AM
Abstract :
A new 17-GHz radio interferometer dedicated for solar observations was constructed in two years at Nobeyama, Nagano. It consists of eighty-four 80-cm-diameter antennas arranged in a tee-shaped array extending 490 m in east-west and 220 m in north-south directions. Since late June of 1992, radio full-disk images of the Sun have been observed for 8 h every day. The spatial resolution is 10" and the temporal resolution is 1 s and also 50 ms for selected events. Every 10 s correlator data are synthesized into images in real time and displayed on a monitor screen. The array configuration is optimized to observe the whole Sun with high spatial and temporal resolution and a high dynamic range of images. Image quality of better than 20 dB is realized by incorporation of technical advances in hardware and software, such as (1) low-loss phase-stable optical-fiber cables for local reference signal and IF signals, (2) newly developed phase-stable local oscillators, (3) custom CMOS gate-array LSTs of 1-b quadraphase correlators for 4×4 combinations, and (4) new image processing techniques to suppress large sidelobe effects due to the solar disk and extended sources
Keywords :
calibration; image reconstruction; microwave antenna arrays; radio receivers; radioastronomical techniques; radiotelescopes; radiowave interferometers; reflector antennas; 0.8 m; 17 GHz; 17-GHz radio interferometer; 1b quadraphase correlators; 4×4 combination; Nobeyama radioheliograph; SHF; Sun; array configuration; correlator data; custom CMOS gate-array LST; image processing techniques; image quality; low-loss phase-stable optical-fiber cables; phase-stable local oscillators; resolution; sidelobe effects; solar observations; tee-shaped array; Antenna arrays; Correlators; Directive antennas; Image resolution; Monitoring; Radio interferometry; Signal processing; Signal resolution; Spatial resolution; Sun;
Journal_Title :
Proceedings of the IEEE
