This project provides wireless communication between ground and board systems. ------------------------------------------------------------------------------- git clone --recurse-submodules http://github.com/enacuavlab/vto-wifiraw.git (git clone --recurse-submodules git@github.com:enacuavlab/vto-wifiraw.git) Installation need internet connection and sudo cd vto-wifiraw ./install.sh or ./uninstall.sh ------------------------------------------------------------------------------- Before first run, compile the suitable executable file on BOARD and on GROUND src/Makefile ROLE := BOARD #ROLE := GROUND commented ! make src/Makefile ROLE := GROUND #ROLE := BOARD commented ! make ------------------------------------------------------------------------------- Usages: ------ 0) sudo apt install openssh-server sudo systemctl enable ssh 1) Remote shell ssh $USER@10.0.1.2 2) Wfb logs socat udp-listen:5000,reuseaddr,fork - 3) File transfert (tunnel mtu range 700,1400) rsync -vP --bwlimit=5000 $USER@10.0.1.2:/tmp/100M.log . (openssl rand 102400000 > /tmp/100M.log) 4) Video streaming (h264 parsing mtu range 400,1400) gst-launch-1.0 udpsrc port=5600 ! application/x-rtp, encoding-name=H264, payload=96 ! \ rtph264depay ! h264parse ! queue ! avdec_h264 ! videoconvert ! autovideosink sync=false 5) Telemetry-datalink link_py.py -d /dev/ttyUSB0 -t xbee -s 57600 -ac 122:127.0.0.1:4244:4245 6) Payload-datalink socat udp-listen:5800,reuseaddr,fork - socat - udp-sendto:5900 etc ... --------------------------------------------------------------------------------- 0) How does it works Using a specific wireless adapter with injection and monitor capabilities, to build a bidirectionnal link. An additional wifi adapter on both ends, enable channel hopping, to avoid occupied frequencies. Moreover, the wifi driver can be patched to increase transmission power. 1) Behaviour - On board: Todo - On ground: Todo 2) Software development : - Used - netlink : to retreive available wifi channels and switch among them - raw socket : to retrieve full traffic and detect occupied channels - Not used - fec : only recover partial information - pcap : not needed with raw socket 3) Context - Wifi traffic => delays CSMA-CA (Collision Avoidance) - Carrier Sending - Carrier signal detected => wait Backoff period (Backoff: random delay from previous trials) - Carrier signal not detected => wait for free carrier during duration DIFS (Distributed Inter Frame Space) - Carrier signal not detected during DIFS => transmit data 4) Todo - Available and used bandwitdh ? - Latency ? --------------------------------------------------------------------------------- Tested on Raspbian, Ubuntu/Debian and Nvidia Jetpack. 2023-02-21-raspios-bullseye-arm64-lite, Raspberry PI3: Ground Debian 11.3 (bulleyes) arm64 on Raspberry PI4,3,0V2: Board and Ground Ubuntu 20.04 (server+desktop) arm64 on Raspberry PI4 : Ground with Paparazzi Ubuntu 22.04 (desktop) Jetpack 4.6 (arm64) on Nvidia Nano and XavierNX: Board and Ground