Telescopes using an UAV-based device

(1)

Antenna Pattern Calibration of Radio Telescopes using an UAV-based device

A. Martínez Picar, C. Marqué,

M. Anciaux, H. Lamy, and S. Ranvier

International Conference on Electromagnetics in Advanced Applications

September 7-11, 2015 Torino – Italy

Solar-Terrestrial Centre of Excellence

Royal Observatory of Belgium Belgian Institute for

Space Aeronomy

(2)

The Humain Radio-Astronomy Station

(3)

The Humain Radio-Astronomy Station

6m Parabolic Reflector 300 – 800 MHz LPDA (e-Callisto)

45 – 400 MHz

BRAMS Yagi Array

~ 50 MHz

(4)

Antenna Pattern Characterization

 LPDA

 6m-dish

 BRAMS Array

Humain Antenna Systems

Proper Gain

Characterization

Real

Flux Density

(5)

Antenna Pattern Characterization

 LPDA

 6m-dish

 BRAMS Array

Humain Antenna Systems

Proper Gain

Characterization

Real

Flux Density Measurements

using

Well-Known Test Signal (source) located at

𝐷

_𝑓𝑓

≥ 2𝐿

²

𝜆

(6)

Antenna Pattern Characterization

 LPDA

 6m-dish

 BRAMS Array

Humain Antenna Systems

Proper Gain

Characterization

Real

Flux Density Measurements

using

Well-Known Test Signal (source) located at

𝐷

_𝑓𝑓

≥ 2𝐿

²

𝜆

3 ~ 27 m

~ 3 m

75 ~ 195 m

(7)

Measurements using a test signal

H

AUT

Spectrum Analyzer

RF Unit

(8)

Measurements using an UAV

H

UAV Flight Path

AUT

RF Unit

(9)

RAMON System

H

UAV Flight Path

AUT

φ θ

Avionics &

Flight Log PC Sync

Clock

RF Unit

Radio Antenna

Measurement

ONsite

(10)

Unmanned Aerial Vehicle (UAV)

OktoXL – Mikrokopter

• Payload: 2.6 kg (max)

• Range: 500 m

• GPS-aided navigation

• Barometric altimeter

• ~ 15 min autonomy

(11)

Unmanned Aerial Vehicle (UAV)

OktoXL – Mikrokopter

• Payload: 2.6 kg (max)

• Range: 500 m

• GPS-aided navigation

• Barometric altimeter

• ~ 15 min autonomy

• Predefined waypoints-based autonomous flight path

• Position and hold mode with heading control (3º)

• 5 satellites (min): ~3 m accuracy

(12)

Unmanned Aerial Vehicle (UAV)

OktoXL – Mikrokopter

• Payload: 2.6 kg (max)

• Range: 500 m

• GPS-aided navigation

• Barometric altimeter

• ~ 15 min autonomy

• Predefined waypoints-based autonomous flight path

• Position and hold mode with heading control (3º)

• 5 satellites (min): ~3 m accuracy

(13)

RF Unit

Short Monopole Antenna

RF signal generator Battery Bank

SBC

(Raspberry Pi)

Metallic Mesh

(14)

RF Unit

Short Monopole Antenna

RF signal generator Battery Bank

SBC

(Raspberry Pi)

Metallic Mesh

-6 dBm (max) EM isolation

Freq Control Z = 50 Ω

+6h autonomy

(15)

Receiver / Data Logger

Spectrum Analyzer AUT

Ethernet

• Python script (GUI)

• SCPI commands over FTP

• Max Hold mode

• Output: received power &

timestamps

(16)

Measurement Strategy

Avionics &

Flight

Logging PC Spectrum

Analyzer

Received Signal

Circular paths around AUT, separated 10º in elevation

“Static”

Waypoints every 10º in

azimuth

+

(17)

Measurement Strategy

Avionics &

Flight

Analyzer

Received Signal Ethernet

“Static”

azimuth

+

(18)

Measurement Strategy

Avionics &

Flight

Analyzer

Received Signal Ethernet

“Static”

azimuth

+

(19)

Data Processing

Flight Track Received Power Log

t₁ : p₁[f₁], p₁[f₂], p₁[f₃], …, p₁[f_m] t₂ : p₂[f₁], p₂[f₂], p₂[f₃], …, p₂[f_m] t₃ : p₃[f₁], p₃[f₂], p₃[f₃], …, p₃[f_m]

t_x : p_x[f₁], p_x[f₂], p_x[f₃], …, p_x[f_m]

t_y : p_y[f₁], p_y[f₂], p_y[f₃], …, p_y[f_m]

t_n-1 : p_n-1[f₁], p_n-1[f₂], …, p_n-1[f_m] t_n : p_n[f₁], p_n[f₂], p_n[f₃], …, p_n[f_m]

… … …

(20)

Data Processing

Flight Track Received Power Log

t_A : lon_A, lat_A, alt_A, speed_A

… … …

(21)

Data Processing

Flight Track Received Power Log

t_A : lon_A, lat_A, alt_A, speed_A Quasi-Static

Waypoints

… … …

Group I

Group II

Group III

(22)

Data Processing

Flight Track Received Power Log

Waypoints

… … …

Group I

Group II

Group III

(23)

Data Processing

Flight Track Received Power Log

Waypoints

… … …

Group I

Group III Group II

(24)

Data Processing

Flight Track Received Power Log

t_A : lon_A, lat_A, alt_A, speed_A

… … …

Group I

Group III Group II

(25)

Data Processing

Flight Track Received Power Log

… … …

median(p₁; p₂) for each f

median(p_x; p_x+1; …) for each f

median(…; p_n-1; p_n) for each f median(lon_I; lat_I; alt_I)

median(lon_II; lat_II; alt_II)

median(lon_III; lat_III; alt_III)

median(lon_N; lat_N; alt_N)

(26)

First Task

Pattern of the Test Signal Source

• The UAV will be always oriented towards the AUT

• Measured with a calibrated antenna

𝑃

_𝑅

= 𝑃

_𝑇

− 𝐿 + 𝐺

_𝑇

+ 𝐺

_𝑅

(27)

First Task

Pattern of the Test Signal Source

• The UAV will be always oriented towards the AUT

• Measured with a calibrated antenna

𝑃

_𝑅

= 𝑃

_𝑇

− 𝐿 + 𝐺

_𝑇

+ 𝐺

_𝑅

(28)

Proof of Concept

𝑃

_𝑅

= 𝑃

_𝑇

− 𝐿 + 𝐺

_𝑇

+ 𝐺

_𝑅

• AUT: 6m-dish antenna

• f = 328.5 MHz

• Flights @ different distances

• 1 day mission

(29)

Numerical Simulation

(30)

Measurements

(31)

Discussion

• Statistical approach (more points are needed)

• Differentiate measurements under dry and humid conditions

• Variability of points location is less sensitive flying far away

• Authorization (BELGOCONTROL) – permission

for flying up to 120 m agl

(32)

Thank you!

Antonio Martínez Picar

antonio.martinez@observatory.be

International Conference on Electromagnetics in Advanced Applications

September 7-11, 2015 Torino – Italy

Solar-Terrestrial Centre of Excellence

Royal Observatory of Belgium Belgian Institute for

Space Aeronomy