CN1344044A

CN1344044A - Mobile submillimeter-wave telescope

Info

Publication number: CN1344044A
Application number: CN 01127067
Authority: CN
Inventors: 杨戟; 黄树频; 孙成华; 大石雅寿; 稻谷顺司; 宫泽敬辅; 野田一房
Original assignee: Purple Mountain Observatory of CAS
Current assignee: Purple Mountain Observatory of CAS
Priority date: 2001-08-07
Filing date: 2001-08-07
Publication date: 2002-04-10
Anticipated expiration: 2021-08-07
Also published as: CN1156057C

Abstract

A mobile submillimeter-wave telescope is composed of antenna, signal receiving system, control system and signal processing system. It features its off-axis Cassegrin antenna, small GPS receiver and modular design.

Description

Mobile submillimeter-wave telescope

The present invention relates to a kind of radio astronomical telescope, particularly a kind of mobile submillimeter-wave telescope.

Radio astronomical telescope is the main research tool of radio astronomy, mainly is made up of antenna, receiving system, control system and signal processing system.The frequency range of its work is generally in millimere-wave band or submillimeter region.The submillimeter-wave telescope that covers the 492GHz frequency range in the world uses generally, has considerable document that this is reported.But the radio telescope of so high frequency is still untapped at home.The radio telescope of home and abroad all is the three unities work that is fixed on, and can't do frequent moving.And a lot of work, the for example addressing work of observatory, need the submillimeter-wave telescope that configuration is transportable, be operated in 492GHz, this need reduce the volume and the weight of original radio telescope significantly, guarantee simultaneously the stability of its work again, the reliability of signal transmission, sometimes, its working power also needs to properly settle.Also there is not this telescope in the prior art.

Task of the present invention provides a kind of submillimeter-wave telescope of movable type, and this design should be convenient to move, so volume is little, it is light that weight is wanted, and it is compact, firm that structure is wanted, and need of work is very reliable.

In order to finish above-mentioned task, we are compact as far as possible in design, alleviate the weight that all may alleviate.Its scheme is: mobile submillimeter-wave telescope, form by antenna, receiving system, control system and signal processing system.It is characterized in that: antenna adopts the design from the axle Cassegrain, is equipped with small-sized GPS receiver simultaneously.Further the scheme of optimizing have following some: 1, telescopical critical piece adopts modularized design, is integrated into respectively in the different modules: receiver is arranged in the chest below the antenna, and the power supply of receiver and rear end are in a chest on antenna next door.2, the orientation of antenna and pitching adopt AC servo to add harmonic gear variable speed electric motors, particularly and PDM keyer, and azimuth axis adopts the scroll bar transmission, and pitch axis directly drives.3, the point and track towards of control system adopts the position feedback close-loop control mode, and feedback signal is produced by the output of increment code wheel, and computer provides the instantaneous coordinate of celestial body and the position by gpib interface control diaxon, and provides coordinate zero point by optical pickocff.4, in the approach of radio wave propagation, be provided with a clear films that sees through electromagnetic wave only and can effectively completely cut off thermal radiation, dust etc.Place at the circle that it is 6-7cm that this film is of a size of a diameter and the path of optic path angle at 45.5, be provided with environmental monitoring system: the basic meteorologic parameter of environmental monitoring system collection comprises temperature, humidity, air pressure etc. and record in addition.These parameters are important references of telescope operation, carry out submillimeter astronomy platform location measure in also as basic parameter.Here said antenna from axle Cassegrain design, effective aperture is 30cm, adopt bireflectance from shaft type Cassegrain antenna structure, no secondary mirror blocks and is optimized to circular beam, reaches maximum aperture efficiency and suppresses common owing to block the antenna pattern secondary lobe composition that causes.

This project is a Purple Mountain Observatory and Japanese state-run observatory cooperates the project of carrying out, the application provide can satisfy at any time move, the convenient radio telescope design of using.Antenna has adopted two from the design of axle Jia Kude focus, and the wave beam that has following superior effect: a. can obtain the symmetry of a circle distributes; B. can eliminate the occlusion effect of secondary mirror, reduce minor level, make solid-beam efficiency improve; C. can drop to cross polarization level minimum; D. can make the antenna structure compactness, reduce weight.The clear films that can effectively completely cut off thermal radiation, dust etc. only through electromagnetic wave that designs in the approach of radio wave propagation can allow the electromagnetic wave that enters receiver system purer, helps constant receiver temperature inside simultaneously and keeps clean.The effect of this film is equivalent to a thermal insulation and dust-proof filter, and just the position of placing is in the approach that light path is propagated.This design and former design are not quite alike, and generally other telescope does not have such design.For movement requirement, telescope has been equipped with small-sized GPS receiver, and the geographical longitude and latitude of UTC and observation place is provided.The weight of antenna is less than 30 kilograms.Carry out the quantitative measurment of submillimeter astronomy platform location and carry out milky way galaxy large scale carbon neutral atom submillimeter wave spectral line and tour the heavens.Adopted GPS to add module (box) system configuration on the POST structure; GPS can measure local longitude and latitude and height above sea level, time exactly; Modularized design all has been integrated into telescopical main parts in the different modules, just can be carried to different places easily with several chests.Antenna and receiver are chests, and antenna is exposed, in the chest of receiver below antenna; The power supply of receiver and rear end are in a chest on antenna next door; Remaining frequency spectrograph, recorder, computer (comprising control board) have been instruments all, also are easy to carrying.Therefore can be transported to different places to POST easily, can gather the observation that data necessary is accurately carried out cosmic radio source soon.

Now be described further with embodiment in conjunction with the accompanying drawings.

Fig. 1 is embodiment 1 a mobile submillimeter-wave telescope system layout;

Fig. 2 is that antenna is two from the axle Ka Jiao Jia Kude of system focus design diagram among the embodiment;

Fig. 3 is an antenna structure view.

Embodiment 1: with reference to Fig. 1, Fig. 2, Fig. 3: the POST antenna has adopted and has twoly designed from the axle Ka Jiao Jia Kude of system focus.Antenna structure is as follows, antenna is made up of two mirrors, the primary mirror parabolic shape, secondary mirror hyperboloid type, these two mirrors are confocal, and common focus is as origin, and so-called " two from axle " are meant: a. two mirrors on the x direction of principal axis interlock, do not have overlappingly, this is the most frequently used from axis structure; B. the axis of two mirrors staggers on the z direction of principal axis, and an angle β is arranged; This pattern be exclusive among the design from axle; So-called " Ku Deshi focus " generally adopts in the optical telescope system, is meant a kind of technology of folding light.Because electric wave is propagated when frequency is very high and has been had the character of light ray propagation, therefore in this telescopical design, when secondary mirror reflects, use two level crossings when electric wave and come reflection wave, so just changed the propagation path of electric wave, made telescopical antenna part compact conformation.α among the figure is the angle that the mid point of secondary mirror is become with the Z-Y plane; θ m is the mid point of primary mirror--the angle that the initial point line is become with the Z-Y plane; φ is the mid point of primary mirror--edge of initial point line and the primary mirror--angle that the initial point line is become; All angles are through computer fitting optimization, to determine the shape of two mirrors.The telescope planning work is to 809 GHz, and in view of the above, the antenna surface precision requires to reach below 15 microns in theory.The surface accuracy of actual measurement is 7 microns (rms values).Antenna adopts altitude azimuth form device and built-in coiling, has both guaranteed the precision of point and track towards and has made the system configuration compactness, also can make receiver be maintained fixed the position to guarantee that running steadily.AC servo adds the harmonic gear variable speed electric motors, particularly and PDM keyer can guarantee that antenna can the whole day point and track towards.On antenna,, calibrate pointing of the telescope with optical means with the small ccd camera.Control system: the hardware of control system is based on the S-Bus bus.Different needs according to hardware each several part transfer of data adopts industry standard interfaces such as GPIB, RS-422, RS-232 respectively.For satisfying the requirement that telescope moves, control system has been selected for use based on the centralized control model of the real-time multi-task of single computer.Software is workbench with UNIX class real-time multi-task (process) operating system Solaris 1.3, and ANSI C is a programming language.According to the difference of mode of operation, process can be divided into forward and backward process; Can be divided into permanent process and temporary process according to mode resident in internal memory.Shared drive and signal and communication mode swap data and control information between process, have been used.Software provides the repertoire of submillimeter wave spectral line observation station need and the various measuring abilities of system maintenance.Receiver system: the operation of receiver frequency is 492GHz, adopts normal temperature work Schottky frequency mixer and double-side band pattern.What frequency mixer adopted is the normal temperature barrier diode structure, and intermediate-freuqncy signal is 1.4GHz, and bandwidth is 600MHz.Receiver signal is lower sideband work, and the operating frequency of Gunn oscillator is 493.6GHz, and local oscillator is issued to 10 in the phase-locked control of closed loop ^-6Frequency stability and can carry out frequency-tracking.Adopted the low-loss collimator optical system with aerial signal and receiver coupling mutually.The rear end possesses gross power and two kinds of patterns of spectral line observation.The noise temperature experimental determination of receiver system is 1400K (DSB), and the whole system noise temperature that comprises the noise contribution of antenna and collimator optical system during actual observation is 2000-3000K (DSB).Environmental monitoring system: the basic meteorologic parameter of environmental monitoring system collection comprises temperature, humidity, air pressure etc. and record in addition.These parameters are important references of telescope operation, carry out submillimeter astronomy platform location measure in also as basic parameter.

Claims

1, a kind of mobile submillimeter-wave telescope is made up of antenna, receiving system, control system and signal processing system, it is characterized in that: antenna adopts the design from the axle Cassegrain, is equipped with small-sized GPS receiver simultaneously.

2, according to the described mobile submillimeter-wave telescope of claim 1, it is characterized in that: telescopical critical piece adopts modularized design, be integrated into respectively in the different modules: receiver is arranged in the chest below the antenna, and the power supply of receiver and rear end are in a chest on antenna next door.

3, according to claim 1 or 2 described mobile submillimeter-wave telescopes, it is characterized in that: the orientation of antenna and pitching have adopted AC servo to add harmonic gear variable speed electric motors, particularly and PDM keyer, and azimuth axis adopts the scroll bar transmission, and pitch axis directly drives.

4, according to the described mobile submillimeter-wave telescope of claim 3, it is characterized in that: the point and track towards of control system adopts the position feedback close-loop control mode, feedback signal is produced by the output of increment code wheel, computer provides the instantaneous coordinate of celestial body and the position by gpib interface control diaxon, and provides coordinate zero point by optical pickocff.

5, according to claim 1 or 2 described mobile submillimeter-wave telescopes, it is characterized in that: in the approach of radio wave propagation, be provided with one only transparent and can effectively completely cut off the clear films of thermal radiation, dust etc. to electromagnetic wave, film is the angle at 45 placement of the path of a circle and optic path.

6, according to the described mobile submillimeter-wave telescope of claim 4, it is characterized in that: in the approach of radio wave propagation, be provided with one only transparent and can effectively completely cut off the clear films of thermal radiation, dust etc. to electromagnetic wave, film is the angle at 45 placement of the path of a circle and optic path.

7, according to the described mobile submillimeter-wave telescope of claim 5, it is characterized in that: also be provided with environmental monitoring system.

8, according to the described mobile submillimeter-wave telescope of claim 6, it is characterized in that: also be provided with environmental monitoring system.