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HABLANv2-users-manual

HABLAN - Multispectral and Multiangular Remote Sensing of the Light at Night from High Altitude Balloon

User's Manual

HABLAN v2

Martin Aubé^{1, 2}, Ph.D. (PI)

¹ Cégep de Sherbrooke, Sherbrooke, Québec, Canada

² Université de Sherbrooke, Sherbrooke, Québec, Canada

Jan 18, 2022

Creative Commons Attribution-ShareAlike 4.0 International License

Abstract

In collaboration with the Canadian Space Agency (CSA) and the European Space Agency (ESA) and in the framework of the STRATOS project, we will launch, in August 2022, a dual DSLR system to observe the multiangular and spectral properties of the installed light fixtures from an altitude of about 36 km. STRATOS project consists of high altitude balloon flights to perform a variety of near space experiments. The balloon will take off at Timmins (ON, Canada). In the HABLANv2 system, two Sony A7S DSLR cameras are attached to a gimbal in order to assure a nadir pointing stability. The two cameras are equipped with 24mm lenses, assuring the collection of high-resolution images (12 m per pixel at nadir). One camera point toward nadir while the second is tilted 60 degree. The camera assembly is attached to a step motor. With help of the compass sensor, the full downward half sphere can be sampled after 5 shots (5 azimuth angles). Data, such as multispectral radiance of light points, multiangular emission functions, spectral type recognition, ground cover, and obstacles properties will be derived from the images. Close to the flight path, ground-based data validation is acquired. For instance, we use the LANcubev2 multiangular and multispectral sensor in a roadrunner mode to map the light at night all over the overflown region. We also sample the sky brightness with a third A7S camera equipped with the same lens.

Hardware

Components

The system consists of the following items:

Component name	Number	Picture
Raspberry pi model 4 B	1
SanDisk Ultra 512GB micro SDHC Card	1
SanDisk 512GB Ultra Fit	1
U-blox based USB GPS dongle	1
Raspberry pi UPS hat	1
Sony A7S DSLR	2
24 mm Samyang manual focus lens -T1.5 VDSLR AS UMC Lens for Sony E Mount (model )	2
AC-PW20 Fully Decoded DC Coupler dummy battery	2
USB-C 3 Amp min cable to power the raspbery pi	1
DC-DC 5V PYB30-Q48-S5-U	1
DC-DC 12V PYB15-Q48-S12-T	1
DC-DC 5V PYBE30-Q48-S5-DIN	1
Speedbag swivel	1
12mm/0.47" Dia Shaft Coupling Motor Connector Steel Universal Joint	1
5/16in 1 1/2in hex bolt	2
Mat black spray paint - to apply inside the camera assembly enclosure	-
1/4-20 1/2in screws	2
XXXX in aluminium plates	1
makerbeam profiles
makerbeam XL profiles
Longruner NEMA17 Stepper motor	1
L298N stepper motor driver Board	1
stepper gears and strap
Optoswitch LM393	1
Motherboard switch	1
DHT22 temperature and humidity sensors	2
Triple Axis Magnetometer HMC5883L	1
5V heating pads	1
5V 4 relays module	1
A7S camera cage Nicerig a7rii cage-139	2
Aluminium foil heat resistant bounded insulation blanket

Mechanical components

Aluminium structure

Mass:

Insolated box and back face

Mass:

Optical components

Computer

Wiring

Pinout informations and GPIO pinout map

RPI GPIO pinout map

• GPIO 22 connects to IN4 on the relay module (reset camera 1)
• GPIO 04 connects to IN3 on the relay module (reset camera 2)
• GPIO 24 connects to IN2 on the relay module (reset DHT temperature and humidity sensors)
• GPIO 23 connects to IN1 on the relay module (heating pad control)
• GPIO 27 is used to determine if the UPS Hat is online (no wire required)
• GPIO 17 is used by the Raspberry Pi to determine if a power failure has occurred (no wire required)
• GPIO 18 is used by the UPS Hat to determine if the Raspberry Pi has shut down (no wire required)
• GPIO 16 is connected to IN1 of the stepper controller
• GPIO 12 is connected to IN2 of the stepper controller
• GPIO 20 is connected to IN3 of the stepper controller
• GPIO 21 is connected to IN4 of the stepper controller
• GPIO 2 is connected to SDA of the compass board
• GPIO 3 is connected to SCL of the compass board

Shutdown button

The shutdown button should follow the following configuration

The pin numbers below refers to figure "RPI GPIO pinout map".

• 1 wire connects to Pin 29 (GPIO 05)
• the other wire connects to Pin 30 (GND)

The RPI will reboot if the button is held for more than two seconds but fewer than five seconds and it will shut down if the button is held for more than five seconds.

Assembly

Setting up the HABLAN for measurements

Access to the data

Data format

The data is structured in the following way.

Shutdown of the HABLAN

Press the shutdown button at least 5 seconds.

Reboot of the HABLAN

Press the shutdown button 3 seconds.