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

Software package

<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/"><img alt="Creative Commons License" style="border-width:0" src="license" href="http://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International License</a>.

Introduction

The aim of this project is to develop a system capable of remotely sense multispectral and multiangular properties of light fixtures from above ground. The system is initially designed to fly on High Altitude Balloon but an application to commercial drones is also evaluated.

The linux distribution used for this system is raspbian Jessie.

We chose a development philosophy based on a complete control from the Linux command line. The system can be controlled simply with a low speed remote connection provided by a SSH client installed on the user workstation. The RPI connected to the system act as a server.

From a private network

Installing and configuring subsystems

Basic system installations and dependancies

If necessary, refer to this guide for the setting up of your Raspberry Pi.

• Install raspbian Stretch image on the microSD card link. We sugggest to use the NOOBS based installation.
• Put the microSD card on the RPI and power it on.
• Set time, time zone and date
  • time zone have to be GMT
   

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  • Select None of the above
  • Select GMT
  • Set time and date
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  • Adapt the date and time to your situation.
• Create the sand account

• Use the raspberry configuration tool to desactivate the Auto login

• Login as sand
• Edit the file /etc/passwd

• Install the following packages

SSH

SSH server allows any remote SSH client to connect to the server to remotely control system programs from the command line or to download (upstream / downstream) data.

• We must first be sure that the SSH server start automatically when you start the computer.

• Set up your personal firewall to allow the SSH and http connections to pass through the firewall.

Installing HABLAN applications

Latest available package release on bitbucket mercurial repository

• To download HABLAN apps:

• Copy apps to system directory:

Automatic startup of hablan.bash code

Edit /etc/rc.local

Enter the input mode by typing < i > and add the following line before the exit 0 (N.B. < i > is the keyboard key i)

Then save the file by typing: <escape> :wq (N.B. <escape> is the keyboard key esc)

Apache server

We are using the Apache2 web server. This server allow the remote control from a web interface. It allow also browsing the database.

To activate the web server, we must:

• activate userdir module

• Create the data directory and modify the permissions by doing:

• Edit the apache2 configuration file

Then type < i > to enter insert mode and add the following lines to the file

Then exit and save by typing: <escape> :wq

• Restart the webserver

USB GPS Stratux Vk-162 Remote Mount USB GPS (U-blox)

The GPS is controlled by the gpsd server. The GPS startup may easily take 45 seconds (time to connect to available satellites). Sometime, the GPS do not succeed to connect to satellites. Most of the time this occur when satellites are masked by obstacles like mountains or buildings. The observe-hablan.py is able to extract latitude and longitude from the GPS. To be sure that the gpsd server will work properly, do the following steps.

Edit the gpsd configuration

type < i > and set the following parameters

Save and quit by typing: <escape> :wq

Shutdown button

Enter the following commands in the terminal

Real time clock

We are using the DS3231 RTC module to keep the date and time after powering off the system.

Update the RPI

Configure the I2C interface

This command will bring up the configuration tool; this tool is an easy way to make a variety of changes to your Raspberry Pi’s configuration. Today, however, we will only by exploring how to enable the I2C interface.

Use the arrow keys to go down and select “5 Interfacing Options“. Once this option has been selected, you can press Enter.

1. On the next screen, you will want to use the arrow keys to select “P5 I2C“, press Enter once highlighted to choose this option.
2. You will now be asked if you want to enable the “ARM I2C Interface“, select Yes with your arrow keys and press Enter to proceed.
3. Once the raspi-config tool makes the needed changes, the following text should appear on the screen: “The ARM I2C interface is enabled“.

We must restart the Raspberry Pi. To do this first get back to the terminal by pressing Enter and then <escape>.

Type the following command into the terminal on your Raspberry Pi to restart it.

Run the following command on your Raspberry Pi to install python-smbus and i2c-tools:

With those tools now installed run the following command on your Raspberry Pi to detect that you have correctly wired up your RTC device.

If you have successfully wired up your RTC circuit, you should see the ID #68 appear. This id is the address of the DS3231 RTC Chips.

Once we have the Kernel driver up and running the tool will start to display UU instead, this is an indication that it is working as intended.

Setting up the Raspberry Pi RTC Time

With I2C successfully setup and verified that we could see our RTC circuit then we can begin the process of configuring the Raspberry Pi to use our RTC Chip for its time.

1. To do this, we will first have to modify the Raspberry Pi’s boot configuration file so that the correct Kernel driver for our RTC circuit will be successfully loaded in.

Run the following command on your Raspberry PI to begin editing the /boot/config.txt file.

Within this file, you will want to add the following line to the bottom of the file. DS1307

Once you have added the correct line for your device to the bottom of the file you can save and quit out of it by pressing <escape>, then :wq and then Enter.

With that change made we need to restart the Raspberry Pi, so it loads in the latest configuration changes.

Run the following command on your Raspberry Pi to restart it.

Once your Raspberry Pi has finished restarting we can now run the following command, this is so we can make sure that the kernel drivers for the RTC Chip are loaded in.

You should see a wall of text appear, if UU appears instead of 68 then we have successfully loaded in the Kernel driver for our RTC circuit.

Now that we have successfully got the kernel driver activated for the RTC Chip and we know it’s communicating with the Raspberry Pi, we need to remove the fake hwclock package. This package acts as a placeholder for the real hardware clock when you don’t have one.

Type the following two commands into the terminal on your Raspberry Pi to remove the fake-hwclock package. We also remove hwclock from any startup scripts as we will no longer need this.

Now that we have disabled the fake-hwclock package we can proceed with getting the original hardware clock script that is included in Raspbian up and running again by commenting out a section of code.

Run the following command to begin editing the original RTC script.

Find and comment out the following three lines by placing # in front of it as we have done below.

Find

Replace With

Once you have made the change, save the file by pressing <escape> then :wq then Enter.

Syncing time from the Pi to the RTC module

Now that we have our RTC module all hooked up and Raspbian and the Raspberry Pi configured correctly we need to synchronize the time with our RTC Module. The reason for this is that the time provided by a new RTC module will be incorrect.

1. You can read the time directly from the RTC module by running the following command if you try it now you will notice it is currently way off our current real-time.

1. Now before we go ahead and sync the correct time from our Raspberry Pi to our RTC module, we need to run the following command to make sure the time on the Raspberry Pi is in fact correct. If the time is not right, make sure that you are connected to a Wi-Fi or Ethernet connection.

1. If the time displayed by the date command is correct, we can go ahead and run the following command on your Raspberry Pi. This command will write the time from the Raspberry Pi to the RTC Module.

4. Now if you read the time directly from the RTC module again, you will notice that it has been changed to the same time as what your Raspberry Pi was set at. You should never have to rerun the previous command if you keep a battery in your RTC module.

You should hopefully now have a fully operational RTC module that is actively keeping your Raspberry Pi’s time correct even when it loses power or loses an internet connection.

Configure the network parameters of the raspberry pi

Edit the file /etc/dhcpcd.conf

Uncomment the section related to the static ip configurations but set ip address to 192.168.0.100

USB stick backup unit

Plug the usb stick in one of the RPI usb port. Type the following command:

You should see the usb drive on the sda1 drive

then do the following

Enter the insert mode by typing letter i and add the following line to the file

Save an quit by typing <escape> :wq

crontab

The crond daemon is scheduling repetitive task on lilux system. Users who have the right to use crond can schedule their own tasks to crond. We are using crond to schedule a webcam acquisition every 15 min.

Add program Camera.bash to the root crond schedule

Edit crontab

chose editor 3. /usr/bin/vim.basic

type < i > and add the following content:

Save and quit by typing: <escape> :wq

Desactivate wifi and bluetooth

In order to avoid interference with the space agency communication systems, it is required to turn off the wifi and bluetooth services.

Edit the file /boot/config.txt

and add the following lines at the end of the file

Save an quit by typing <escape> :wq

System reboot

Now all the relevant software are installed, in order to activate all newly added functionalities, restart the computer.

Optional stuff