läbimõõt (aperture?) 500m, raadius 300m ja ümbermõõt 1.6km, Focal ratio 0.46-0.47, Opening angle 100-120, Sky coverage Zenith angle 40, tracking range 4-6h
*koosneb 4450paneelist.
*hind ca 160 milj.€.
(Yle)
http://yle.fi/uutiset/maailman_suurin_r ... eo/9000715
wiki
Location(s) Pingtang County, People's Republic of China
Coordinates 25.6525°N 106.8567°ECoordinates: 25.6525°N 106.8567°E
Wavelength electromagnetic spectrum: (10 cm to 4.3 m)[1]
Built under construction
Telescope style spherical reflector
Diameter 500 metre
Collecting area 196,000 square metre
Dome none
Website fast.bao.ac.cn/en/
pildid
https://www.google.ee/search?q=guizhou+ ... 80&bih=702
Feed Cabin suspension System
Feed cabin suspension system includes the following structure:
(1) The optical, mechanical and electronic integration first-order cable support system: 6 tower supports with height of about a hundred meter are built in the mountain around the depression. A kilometer-scale steel cable soft support system and the guide rope, cable reel are installed to realize the first-order spatial position adjustment of the feed cabin.
(2) The 10-meter-diameter feed cabin. A parallel robot is installed in the feed cabin for the second-order adjustment to realize a spatial position accuracy of 10 mm.
(3) The steering gear between first-order and second-order adjustment mechanisms to help adjust the attitude angle of the feed cabin.
(4) The power and signal channels between ground and the feed cabin.
(5) The safety and health monitor system: It includes lightning protection, cable stress force monitor, emergency prevention and dealing equipments.
Measurement and Control System
There is no rigid structure connecting the FAST reflector and focus. Therefore it requires high-accuracy measurements of their spatial coordinate in a common well-defined reference frame. Besides, all moving parts of the telescope require real-time measurement and reaction control during operations to meet the position accuracy requirement. Various modern measurement technology will be applied to the site exploration, earth work, reflector and feed cabin support, receiver and terminal systems, and the real-time detect and health monitor of the telescope during operation in future. Large dimension, high sampling rate, high accuracy measurement and control is the key points.
We plan to build a reference datum net comprised of 10 datum station with mm-accuracy. There are two most challenging tasks to be accomplished.
(1) Real-time reaction control of the feed cabin: to read the 3-D spatial positions of the feed cabin, four API laser trackers are used to measure 4 follow-up targets in the Stewart platform. Two API laser tracker systems are used to measure the position and attitude of the lower platform, and monitor the control results.
(2) Surface scanning of the reflector: There are more than 2000 nodes, the joining points of the element panels on the reflector, and the number of nodes being illuminated is ~1000. As a plan, nine close-range instrumentations with accurate rotating platforms and digital cameras will be built to scan 1000 control nodes in the illuminated portion of the reflector during observations.
We are also developing control technology to realize the spatial positioning of the receiver in the feed cabin.
Receiver System
The feeds and receivers are planned to be built through international cooperation, which cover a frequency range from 70 MHz to 3GHz. The present 9 feeds and receivers in plan are displayed in the table.
tabel: http://fast.bao.ac.cn/en/Receiver.html
The proposed construction mainly includes:
(1) Feeds and low-noise receivers: to develop feeds and polarizer at 9 bands, LNAs, band selection filters, radio frequency circuit, frequency mixers and IF circuits.
(2) Refrigeration machine: Helium GM refrigeration machines and vacuum Dewar are used to refrigerate the head amplifier and other key instruments, especially for receiver at bands higher than 560 MHz, which requires a temperature of 10-20 K to keep low noise.
(3) Optical fiber to transform IF data: to develop a wide-band optical fiber transformation. IF data is converted to light signal, and then transform in the optical fiber over a distance of about 3 km, and convert back to IF data to the digital terminals.
(4) Digital data-processing terminals: to construct multi-band terminals for cosmic neutral hydrogen, pulsar de-dispersion, molecular lines observations, VLBI data-record terminal, SETI terminal and digital record and process terminal based on computer clusters.
(5) Receiver monitor and diagnosis system: to monitor the receiver in real-time, and test the remote trouble diagnosis to shorten the feed cabin maintenance time in harbor.
(6) The time frequency standard: this will be provided by GPS and high stationary hydrogen clock to fulfill the requirements of pulsar, spectral lines and VLBI observations, etc.
