How to simultaneously trigger LTF and corresponding mobile phone MAC for dual antenna IQ signal acquisition

[Onesirme]

0. Could you send email to xianjun.jiao@ugent.be to introduce your self?
   Yes, I have already sent it

1. Our image is used directly or you build your own image?
   Image version:openwifi-1.5.0-shahecheng.img.xz

2. What is your own modification?
   I just modified the IP address in side_ch_ctl. c

3. Versions: OS, Vivado, openwifi/openwifi-hw repo branch and commit revision
   Os:win10 and ubuntu 18.04 Vivado :18.03

4. Board/hardware type
   zedboard + ad9361

5. WiFi channel number
   44

6. Steps to reproduce the issue, and the related error message, screenshot, etc

   At first, I wanted to collect CSI from two antennas to obtain phase difference, and then I saw on GitHub that it was recommended to use dual IQ signals to obtain long training sequences and CSI data. When I was collecting IQ signals, I set the binding of my phone's MAC trigger, but I don't know which signal the long training sequence is, and when I set the long training sequence trigger, I don't know which signal is emitted by my phone.
   The instructions I entered are as follows:

./wgd.sh
./monitor_ch.sh sdr0 44
echo manual > in_voltage1_gain_control_mode
echo 25 > in_voltage1_hardwaregain
insmod side_ch.ko iq_len_init=4095
./side_ch_ctl wh1h4001
./side_ch_ctl wh7h89e06df8
./side_ch_ctl wh11d1000
./side_ch_ctl wh3h11
./side_ch_ctl wh8d8
./side_ch_ctl g1

7. Describe your debug efforts by Linux native tools, such as tcpdump and "cat /proc/interrupts"
   My question probably doesn't require these tools for modulation.
8. Describe your debug efforts by: https://github.com/open-sdr/openwifi/blob/master/doc/README.md#Debug-methods
   I have read iq.md, iq_2ant.md, and related issues but have not found a solution to my problem.
9. Any other thing we need to know for helping you better?
   Is there a method I overlooked to simultaneously obtain CSI from two antennas.

[Onesirme]

I extracted LTF using correlation method. Can this system trigger simultaneously from the hardware level？

[HavingaThijs]

I see that you configured the trigger condition already for "long preamble detected", and your pre-trigger length is set to 1000. Hence, the "long preamble detected" moment as determined by the hardware will be at sample 1001 (see also this for the explanation). This will only be determined by the signal captured at the "main antenna" referred to in the application note.

[Onesirme]

I see that you configured the trigger condition already for "long preamble detected", and your pre-trigger length is set to 1000. Hence, the "long preamble detected" moment as determined by the hardware will be at sample 1001 (see also this for the explanation). This will only be determined by the signal captured at the "main antenna" referred to in the application note.

But when I turn off my phone's WiFi, there is still an IQ signal output. How can I confirm that the IQ signal comes from my phone and also confirm the location of the LTF. I have set wh1h4001, but it doesn't seem to be working.
I have also used MAC triggering, and the IQ signal does indeed come from my phone. But this way, I cannot confirm the location of LTF.

[HavingaThijs]

The MAC filter using wh1h4001 only works when capturing CSI, which does not support two antennas currently.

If you only care about the phase difference between the two antennas, you can still use the MAC trigger when capturing IQ, and indeed correlate the location of the LTF yourself.

Otherwise, you could trigger on the LTF and map the timestamp to a packet in e.g. Wireshark, and filter the MAC address yourself: https://github.com/open-sdr/openwifi/blob/master/doc/app_notes/iq.md#map-the-iq-information-to-the-wifi-packet.

[Onesirme]

The MAC filter using wh1h4001 only works when capturing CSI, which does not support two antennas currently.

If you only care about the phase difference between the two antennas, you can still use the MAC trigger when capturing IQ, and indeed correlate the location of the LTF yourself.

Otherwise, you could trigger on the LTF and map the timestamp to a packet in e.g. Wireshark, and filter the MAC address yourself: https://github.com/open-sdr/openwifi/blob/master/doc/app_notes/iq.md#map-the-iq-information-to-the-wifi-packet.

Thanks for your answer. I will try.