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Update packet-iq-self-loopback-test.md

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doc/app_notes/packet-iq-self-loopback-test.md
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@ -33,7 +33,10 @@ want to understand openwifi side channel (for IQ and CSI) deeper.
(Set 16 to register 8 -- set trigger condition to phy_tx_started signal from openofdm tx core)
./sdrctl dev sdr0 set reg xpu 1 1
(Unmute the baseband self-receiving to receive openwifi own TX signal/packet -- important for self loopback!)
./side_ch_ctl wh5h0
(Set the loopback mode to over-the-air)
./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:
```
@ -77,32 +80,30 @@ to do further offline analysis, or feed the IQ sample to the openwifi receiver s
```
tcpdump -i sdr0
```
After the packet injection, you should see the packet information printed by tcpdump from self over-the-air loopback.
Run the packet injection "./inject_80211 -m n -r 5 -n 1 sdr0" in another session, you should see the packet information printed by tcpdump from self over-the-air loopback.
- You can also see the openwifi printk message of Rx packet (self Tx looped back) while the packet comes to the openwifi Rx interrupt.
A new ssh session to the board should be opened to do this before running the packet injection:
```
cd openwifi
./sdrctl dev sdr0 set reg drv_rx 7 7
(Turn on the openwifi Rx printk logging)
./sdrctl dev sdr0 set reg drv_tx 7 7
(Turn on the openwifi Tx/Rx printk logging)
```
After the packet injection, in the same ssh session run:
Stop the "./side_ch_ctl g0" in the very first ssh session. Run the packet injection, then check the printk message:
```
./inject_80211/inject_80211 -m n -r 5 -n 1 sdr0
dmesg
```
You should see the printk message from openwifi_rx_interrupt() function in the openwifi driver (sdr.c).
You should see the printk message of packet Tx and Rx from the openwifi driver (sdr.c).
## Self loopback config
- By default, the loopback is via the air (from Tx antenna to Rx antenna). FPGA inernal loopback option is offered to have IQ sample and packet without
any interference. To have FPGA internal loopback, run before the packet injection:
any interference. To have FPGA internal loopback, replace the "./side_ch_ctl wh5h0" during setup (the very 1st ssh session) by:
```
./side_ch_ctl wh5h4
```
To change back to loopback over the air, run:
```
./side_ch_ctl wh5h0
```
- Lots of packet injection parameters can be set: number of packet, type (data/control/management), MCS/rate, size, interval, etc. Please run the packet injection
program without any arguments to see the help.