1<!-- 2Author: Xianjun jiao 3SPDX-FileCopyrightText: 2019 UGent 4SPDX-License-Identifier: AGPL-3.0-or-later 5--> 6 7One 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. 8  9 10## Quick start 11- Power on the SDR board. 12- 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: 13 ``` 14 ssh [email protected] 15 (password: openwifi) 16 cd openwifi 17 ./wgd.sh 18 ./fosdem.sh 19 (After the AP started by above command, you can connect a WiFi client to this openwifi AP) 20 (Or setup other scenario according to your requirement) 21 ifconfig 22 (Write down the openwifi AP MAC address. For example 66:55:44:33:22:5a) 23 insmod side_ch.ko num_eq_init=0 24 ./side_ch_ctl wh1h4001 25 ./side_ch_ctl wh7h4433225a 26 (Above two commands ensure receiving CSI only from XX:XX:44:33:22:5a. In this case, it is the openwifi self-TX) 27 ./sdrctl dev sdr0 set reg xpu 1 1 28 (Above unmute the baseband self-receiving to receive openwifi own TX signal/packet) 29 ./side_ch_ctl g0 30 ``` 31 You should see on board outputs like: 32 ``` 33 loop 64 side info count 4 34 loop 128 side info count 5 35 ... 36 ``` 37 If the second number (4, 5, ...) keeps increasing, that means the CSI is going to the computer smoothly. 38 39- On your computer (NOT ssh onboard!), run: 40 ``` 41 cd openwifi/user_space/side_ch_ctl_src 42 python3 side_info_display.py 0 43 ``` 44 The python script needs "matplotlib.pyplot" and "numpy" packages installed. Now you should see figures showing run-time **CSI** and **frequency offset**. Meanwhile the python script prints the **timestamp**. 45  46 47 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(0)** in Matlab. 48  49 50 The following picture is generated by data processing on the captured openwifi CSI while people move in front of two directional antennas (Tx/Rx antenna). 51  52 53Please learn the python and Matlab script for CSI data structure per packet according to your requirement. 54 55Do read the [normal CSI app note](csi.md) to understand the basic implementation architecture. 56
