One super power of the openwifi platform is "**Full Duplex**" which means that openwifi baseband can receive its own TX signal. Just like a radar! This brings a unique capability of "**joint radar and communication**" to openwifi. For instance, put two directional antennas to openwifi TX and RX, and the **CSI** (Channel State Information) of the self-TX signal will refect the change of the target object.   ## Quick start - Power on the SDR board. - Connect a computer to the SDR board via Ethernet cable. The computer should have static IP 192.168.10.1. Open a terminal on the computer, and then in the terminal: ``` ssh root@192.168.10.122 (password: openwifi) ``` - On computer, build the latest driver and FPGA package after clone/update openwifi and openwifi-hw-img repository: ``` export XILINX_DIR=your_Xilinx_install_directory (Example: export XILINX_DIR=/opt/Xilinx. The Xilinx directory should include sth like: Downloads, Vitis, etc.) export OPENWIFI_HW_IMG_DIR=your_openwifi-hw-img_directory (The directory where you get the open-sdr/openwifi-hw-img repo via git clone) export BOARD_NAME=your_board_name (Check the BOARD_NAME definitions in README) cd openwifi/user_space ./drv_and_fpga_package_gen.sh $OPENWIFI_HW_IMG_DIR $XILINX_DIR $BOARD_NAME scp drv_and_fpga.tar.gz root@192.168.10.122:openwifi/ scp ./side_ch_ctl_src/side_ch_ctl.c root@192.168.10.122:openwifi/ scp ./inject_80211/* root@192.168.10.122:openwifi/inject_80211/ ``` - On SDR board (/root/openwifi directory): ``` cd /root/openwifi/ ./wgd.sh drv_and_fpga.tar.gz ./monitor_ch.sh sdr0 1 insmod ./drv_and_fpga/side_ch.ko gcc -o side_ch_ctl side_ch_ctl.c ./side_ch_ctl wh1h4001 ./side_ch_ctl wh7h4433225a (Above two commands ensure receiving CSI only from XX:XX:44:33:22:5a, which will be set by our own packet injector later) ./sdrctl dev sdr0 set reg xpu 1 1 (Above unmute the baseband self-receiving to receive openwifi own TX signal/packet) ./side_ch_ctl g0 ``` - Open another ssh session on SDR board: ``` cd /root/openwifi/inject_80211 make ./inject_80211 -m g -r 4 -t d -e 0 -b 5a -n 99999999 -s 20 -d 1000 sdr0 (Above command injects the 802.11a/g packet, for 802.11n packet please use: ./inject_80211 -m n -r 4 -t d -e 8 -b 5a -n 99999999 -s 20 -d 1000 sdr0) ``` - Now you should see the increasing numbers in the previous ssh terminal of the SDR board. - On your computer (NOT ssh session!), run: ``` cd openwifi/user_space/side_ch_ctl_src python3 side_info_display.py 8 waterfall ``` The python script needs "matplotlib.pyplot" and "numpy" packages installed. Now you should see figures showing run-time **CSI**, **CSI waterfall**, **Equalizer out** and **frequency offset**. The following photo shows the CSI change in the waterfall plot when I left my seat in front of two directional antennas (Tx/Rx antenna).  While running, all CSI data is also stored into a file **side_info.txt**. A matlab script **test_side_info_file_display.m** is offered to help you do CSI analysis offline. In this case, run **test_side_info_file_display** in Matlab.  Please learn the python and Matlab script for CSI data structure per packet according to your requirement. Do read the [normal CSI app note](csi.md) to understand the basic implementation architecture.