BEAM CALIBRATION OF RADIO TELESCOPES WITH DRONES

Transcription

1 BEAM CALIBRATION OF RADIO TELESCOPES WITH DRONES Chihway Chang, Christian Monstein, Alexandre Refregier, Adam Amara astro-ph.im arxiv: v1 21 May

2 CONTENTS - Preliminary Remark - ABSTRACT -1. INTRODUCTION -2. EXPERIMENT DESIGN -3. BEAM CHARACTERISATION -4. ANALYSIS AND RESULTS -5. CONCLUSIONS 2

3 Preliminary Remark What is DRONES? Is it different from a radio-controlled helicopter? Drone: originally means unmanned robot (include radio- -controlled), and recently automatic(programed) aircraft. Radio-controlled helicopter: we know. (Multicopter: radio-controlled,and has over three rotors.) Some say there is no clear difference. Automatic or not is (weak) distinction. 3

4 ABSTRACT Using a commercially available drone, obtain a multi-frequency far-field beam map for the single dish telescope at Bleien Observatory (Switzerland). And compering other methods, discuss the advantage of this calibration method. 4

5 1. INTRODUCTION Mapping HⅠ intensity in the Universe probe of the Baryon Acoustic Oscillation 5m dish telescope is advantageous configuration Obtaining the beam map is needed. 5

6 1. INTRODUCTION Traditional calibration source bright, well-known stars(sun, Moon, TaurusA, etc ) few, relatively dark, fluctuate satellites or other artificial sources spectrum is limited 6

7 1. INTRODUCTION A flexible and controllable source is wanted. Using drone is the resolution. This method is available in other science areas. 7

8 2. EXPERIMENT DESIGN 2.1 The Bleien 5m dish f/d = { longitude: latitude : ~1300MHz horn feed 8

9 2. EXPERIMENT DESIGN 2.2 CALLISTO spectrometer is a programmable heterodyne receiver. built in the framework of IHY2007 and ISWI by former Radio and Plasma Physics Group (PI Christian Monstein) at ETH Zurich, Switzerland. 9

10 2. EXPERIMENT DESIGN 2.3 Drone Requirement: carry the weight hold the source stable fly long enough location is known 10

11 2. EXPERIMENT DESIGN 2.3 Drone Resolution commercially available using the gimbal GPS positioning and a barometric altimeter 11

12 2. EXPERIMENT DESIGN 2.4 Noise transmitter Composed of semiconductor noise source (980~1250MHz) attenuator amplifier band-pass filter transmission antenna power supply 12

13 2. EXPERIMENT DESIGN 2.5 Design of the flight pattern 13

14 3. BEAM CHARACTERIZATION FWHM( )=1.028 Z Z D A ( )= M ( )= Z Z 4 P ( ; ~ )d 2 main lobe P ( ~ ; )d 2 A e ( )= 2 A A g = (D/2) 2 A ( )= A e A g = 4 2 A D 2 M ( )= M ( ) A ( ) 14

15 4. ANALYSIS AND RESULTS 4.1 Data processing convert the unit match the position remove the standing-wave fill the gaps (2 patterns) remove the background remove the interference from the drone rescale 15

16 4. ANALYSIS AND RESULTS 16

17 4. ANALYSIS AND RESULTS 4.1 Data processing check the error from height from tangent plane Both are negligibly small. The grid-formed beam map was made. 17

18 4. ANALYSIS AND RESULTS 4.2 1D beam pattern 18

19 4. ANALYSIS AND RESULTS 4.3 2D beam pattern Each pattern has a main beam circle side lobe rings asymmetry grid-structure 19

20 4. ANALYSIS AND RESULTS 4.3 Other uncertainties Gimbal position /angle Radio Frequency Interference Polarisation Beam shape of transmitter horn 20

21 4. ANALYSIS AND RESULTS 4.5 Wavelength dependence 21

22 4. ANALYSIS AND RESULTS 4.6 Comparison with other measurements Beam measurement with the sun 22

23 4. ANALYSIS AND RESULTS 4.6 Comparison with other measurements Comparison of different measurement methods 23

24 5. CONCLUSIONS Described the calibration method with a drone. Obtained high quality data. The advantage is controllable and flexible. Discussed the measurement errors. 24

25 5. CONCLUSIONS Future improvement Drone flight pattern design Drone positioning system Characterization of telescope Characterization of horn feed Modelling 25