The images are stored on the two Raspberry Pi Zeros. The Image download station provides image download via two parallel Wifi links from the drone. The image download station is based on two GL-AR750 access points. The datatransfer itself is handled by rsync via its rsync protocoll which doesnt rely on SSH. SSH is not used as the pi zero is not fast enough to encrypt the huge data we want to transfer for each flight.

This is the main router which provides DHCP service.

Router IP: 192.168.8.1

Admin password: XXXXXXXXXXXXXXX

WAN Port is Lan Port

2.4 GHz SSID: SW-AP1 Channel 1 WIFI Password: XXXXXX TX Power: 10 dBm 300 MBit

5 GHz SSID: SW-AP1-5G Channel 36 WIFI Password: XXXXX TX Power: 20 dbm

This router is connected with the WAN port to a LAN port of AP1.

Router IP: 192.168.8.200

Admin Password: XXXXX

WAN Port is Lan Port

2.4 GHz SSID: SW-AP2 Channel 11 WIFI Password: XXXXX TX Power: 10 dBm

5 GHz SSID: SW-AP2-5G WIFI Password: XXXXX Channel: 44 433MBit TX Power: 20 dbm

The laptop is a ASUS TUF FX505DV 8/512 R5-3550H RXT2060 with

• AMD Ryzen 3550H CPU
• 8 GB DDR4-SDRAM
• 512 GB SSD
• 15.6“ Full HD 1920×1080 IPS screen
• AMD Radeon Vega 8 GPU
• NVIDIA GeForce RTX 2060 (6GB GDDR6) GPU
• LAN
• Dual-band WLAN
• Bluetooth

running Ubuntu 18.04 LTS (Bionic Beaver)

Configure datastorage with rsync in /etc/rsyncd.conf on ship laptop.

Each flight should have a unique name and needs two folders to be configured. e.g.

[ringo-05032020_0915h-cam-r]
path=/home/USER/flightdata/ringo-05032020_0915h-cam-r
hosts allow = *
list = true
uid = root
gid = root
read only = false

[ringo-05032020_0915h-cam-l]
path=/home/USER/flightdata/ringo-05032020_0915h-cam-l
hosts allow = *
list = true
uid = root
gid = root
read only = false

IMPORTANT Please add cam-r or cam-l at the end, as this encoding is needed for the searchwing-gui to work in correct manner IMPORTANT

start rsync daemon on ship laptop

sudo systemctl start rsync

run datatransfer task on each pi ( later triggered via script @ groundcontrol pc): e.g.

rsync -auv --progress /data/bilder/ rsync://GROUNDSTATIONIP/ringo-05032020_0915h-cam-r

Don't use the -z option which compresses the data. The images are already compressed and the CPU load will result in 1 MB/s transfer rate compared to 3-4 MB/s without the -z option. (Beck, 23.2.20) If you like to transfer and delete the images from the pi, use the –remove-source-files option.

rsync error: error starting client-server protocol (code 5) at main.c(1675) [sender=3.1.3]

Check if folder on receiverside exists.

To get an idea whats the cause of the error - checkout rsync service status on receiverside (laptop):

sudo systemctl status rsync

If Wifi isn't working, first check if the firmware file can be loaded!

dmesg | grep rtw_pci

In Ubuntu 18.04 the firmware for rtw8822 wifi adapter (ASUS TUF FX505DV Laptop) isn't included in linux-firmware ubuntu deb package! So after a Kernel update it can be necessary to fetch it again and copy it to the lib folder.

git clone git://git.kernel.org/pub/scm/linux/kernel/firmware/linux-firmware.git
cp ./linux-firmware/rtw88/rtw8822c_wow_fw.bin /lib/firmware/rtw88/

Eduroam does not work with the default wpasupplicant 2.6 version. I have made a backport of wpasupplicant 2.9 from Ubuntu 19.10.

wpasupplicant package 2.9

You need to install that package. Please download from this wiki and unzip it.

sudo apt install libnl-route-3-200
sudo dpkg -i wpasupplicant_2.9-1ubuntu2_amd64.deb

Check that the wpa supplicant service is running with

sudo systemctl status wpa_supplicant.service

In the Wifi Settings for eduroam choose in the “security” settings

• Security: WPA & WPA2 Enterprise
• Authentication: Tunneled TLS
• Anonymous identity: eduroam@hs-augsburg.de
• Check “No CA certificate is required”
• Inner Authentication: PAP
• Username: YOURUSERNAME@hs-augsburg.de
• Password: YOURPASSWORD