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Merge pull request #183 from redfast00/iq-self-loopback-docs

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Fix instructions for self-loopback
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Jiao Xianjun 2022-06-29 08:23:26 +02:00 committed by GitHub
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doc/app_notes/packet-iq-self-loopback-test.md
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@ -19,24 +19,33 @@ want to understand openwifi side channel (for IQ and CSI) deeper.
- Put the Tx and Rx antenna as close as possible.
- 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 into the SDR board, password: openwifi
ssh root@192.168.10.122
(password: openwifi)
cd openwifi
# Bring up the openwifi NIC sdr0
./wgd.sh
(Bring up the openwifi NIC sdr0)
# Setup monitor mode in WiFi channel 44. You should find a channel as clean as possible in your location. Note that some channels don't work, so stick to 44 or 48 for now.
./monitor_ch.sh sdr0 44
(Setup monitor mode in WiFi channel 44. You should find a channel as clean as possible in your location)
# Turn off CCA by setting a very high threshold that make the CSMA engine always think the channel is idle (no incoming signal is higher than this threshold)
./sdrctl dev sdr0 set reg xpu 8 1000
# Put the receiver into reset state, so it won't affect our system in case it runs into dead state
./sdrctl dev sdr0 set reg rx 0 1
# Load side channel kernel module with buffer lenght of 8187 (replace this with 4095 when using low end FPGA board)
insmod side_ch.ko iq_len_init=8187
# Set 100 to register 11. It means the pre trigger length is 100, so we mainly capture IQ after trigger condition is met
./side_ch_ctl wh11d100
(Set 100 to register 11. It means the pre trigger length is 100, so we mainly capture IQ after trigger condition is met)
# Set 16 to register 8 -- set trigger condition to phy_tx_started signal from openofdm tx core
./side_ch_ctl wh8d16
(Set 16 to register 8 -- set trigger condition to phy_tx_started signal from openofdm tx core)
# Unmute the baseband self-receiving to receive openwifi own TX signal/packet -- important for self loopback!
./sdrctl dev sdr0 set reg xpu 1 1
(Unmute the baseband self-receiving to receive openwifi own TX signal/packet -- important for self loopback!)
# Set the loopback mode to over-the-air
./side_ch_ctl wh5h0
(Set the loopback mode to over-the-air)
# Relay the FPGA IQ capture to the host computer that will show the captured IQ later on)
./side_ch_ctl g0
(Relay the FPGA IQ capture to the host computer that will show the captured IQ later on)
```
You should see on outputs like:
```
@ -50,9 +59,9 @@ want to understand openwifi side channel (for IQ and CSI) deeper.
```
cd openwifi/inject_80211/
make
(Build our example packet injection program)
# Build our example packet injection program
./inject_80211 -m n -r 5 -n 1 sdr0
(Inject one packet to openwifi sdr0 NIC)
# Inject one packet to openwifi sdr0 NIC
```
Normally in the previous ssh session, the count becomes 1. It means one packet (of IQ sample) is sent and captured via loopback over the air.
@ -88,7 +97,7 @@ to do further offline analysis, or feed the IQ sample to the openwifi receiver s
cd openwifi
./sdrctl dev sdr0 set reg drv_rx 7 7
./sdrctl dev sdr0 set reg drv_tx 7 7
(Turn on the openwifi Tx/Rx printk logging)
# Turn on the openwifi Tx/Rx printk logging
```
Stop the "./side_ch_ctl g0" in the very first ssh session. Run the packet injection, then check the printk message:
```