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I am creating a project on esp32, currently I need to gather information for esp about the distance of the device with wifi from the esp32 modules. I used the project from github to gather information,

https://github.com/StevenMHernandez/ESP32-CSI-Tool.

From this project I uploaded a program for passive listening on the channel.

The collected information shows information such as:

type,role,mac,rssi,rate,sig_mode,mcs,bandwidth,smoothing,not_sounding,aggregation,stbc,fec_coding,sgi,noise_floor,ampdu_cnt,channel,secondary_channel,local_timestamp,ant,sig_len,rx_state,real_time_set,real_timestamp,len,CSI_DATA

This is the data collected by the esp32 which was listening on my wifi channel and which was sent over my phone.

CSI_DATA,PASSIVE,54:72:4F:09:7B:7B,-57,11,1,7,0,1,1,1,0,0,1,-94,1,11,0,2970769,0,82,0,0,3.234535,256,[82 32 5 0 -9 -21 -10 -21 -9 -20 -10 -20 -10 -20 -10 -20 -11 -19 -11 -18 -12 -18 -12 -18 -12 -17 -13 -17 -13 -17 -13 -17 -14 -17 -14 -16 -14 -17 -15 -18 -14 -18 -14 -18 -14 -19 -14 -20 -13 -21 -12 -22 -10 -24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -4 -31 -2 -31 0 -30 1 -29 1 -28 2 -27 2 -26 2 -25 2 -25 1 -24 1 -24 1 -24 0 -23 -1 -23 -2 -23 -2 -22 -3 -22 -4 -22 -5 -22 -6 -22 -6 -22 -7 -22 -7 -22 -8 -22 -8 -21 -8 -22 ]
CSI_DATA,PASSIVE,54:72:4F:09:7B:7B,-61,9,0,0,0,0,0,0,0,0,0,-94,0,11,0,3340468,0,28,0,0,3.622702,128,[28 -64 1 0 -2 17 -1 17 0 16 0 17 1 16 1 16 2 15 2 16 3 15 3 15 4 15 4 15 5 15 4 15 5 15 6 15 6 15 6 15 6 16 6 16 7 16 6 17 5 17 4 19 2 19 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -17 32 -18 30 -20 27 -21 25 -20 23 -19 22 -18 21 -17 20 -17 19 -15 18 -15 17 -14 17 -13 17 -12 17 -11 17 -10 17 -10 17 -8 17 -7 17 -6 18 -6 18 -5 18 -4 18 -4 17 -4 18 -4 18 ]
CSI_DATA,PASSIVE,54:72:4F:09:7B:7B,-68,9,0,0,0,0,0,0,0,0,0,-92,0,11,0,66470508,0,28,0,0,66.710994,128,[28 -64 1 0 -12 -7 -12 -6 -12 -5 -12 -5 -12 -4 -12 -3 -12 -3 -12 -2 -12 -1 -11 0 -12 0 -11 0 -11 1 -11 1 -11 3 -11 3 -11 3 -10 4 -10 5 -10 4 -11 5 -11 4 -12 4 -11 4 -11 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -19 -38 -15 -38 -12 -38 -10 -36 -8 -34 -7 -32 -7 -31 -6 -29 -6 -27 -6 -26 -6 -24 -6 -23 -6 -22 -7 -21 -8 -19 -8 -18 -9 -17 -9 -16 -10 -15 -11 -14 -11 -14 -11 -12 -11 -11 -12 -11 -12 -10 -12 -9 ]
CSI_DATA,PASSIVE,54:72:4F:09:7B:7B,-58,9,0,0,0,0,0,0,0,0,0,-92,0,11,0,93555394,0,28,0,0,93.845638,128,[28 -64 1 0 -13 -19 -13 -19 -13 -18 -14 -18 -14 -17 -14 -17 -14 -17 -14 -16 -14 -15 -14 -15 -15 -14 -15 -14 -15 -14 -15 -14 -15 -14 -16 -13 -16 -14 -16 -14 -15 -14 -15 -15 -16 -15 -15 -16 -14 -17 -13 -18 -12 -19 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -11 -37 -8 -37 -6 -35 -4 -35 -4 -33 -3 -32 -2 -31 -2 -30 -2 -29 -3 -28 -3 -27 -3 -26 -4 -26 -5 -25 -5 -25 -6 -24 -7 -24 -8 -22 -9 -22 -10 -22 -10 -22 -10 -22 -10 -21 -11 -21 -12 -21 -12 -21 ]
CSI_DATA,PASSIVE,54:72:4F:09:7B:7B,-58,9,0,0,0,0,0,0,0,0,0,-92,0,11,0,93571320,0,28,0,0,93.868210,128,[28 -64 1 0 15 14 16 14 16 13 16 12 16 12 16 12 16 11 16 10 16 9 16 9 17 9 17 8 17 8 17 7 17 8 17 8 17 7 17 7 17 8 18 9 17 9 17 10 17 10 16 12 15 13 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18 31 15 31 13 31 11 31 9 29 9 28 7 27 8 26 7 25 8 24 8 24 8 23 8 22 9 21 11 20 10 19 11 19 11 18 13 18 13 18 14 17 14 17 15 16 15 16 15 16 15 15 ]

I can collect distance information from esp32 using RSSI, the smaller the distance the greater the value. But the RSSI is not very accurate, so the question is, can I read the distance to the device from the CSI_DATA?

somedisplayname21
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    You're not collecting distance information with RSSI. You're collecting signal strength. There are things other than distance that affect signal strength - if I put a wall with metal in it between two devices, the RSSI will drop, even if the two devices are quite near one another. You can try to infer distance with RSSI but you'll never have anything more than a very coarse approximation that doesn't reflect real world conditions around the devices. – romkey Apr 16 '21 at 16:57
  • @romkey CSI data does not solve this problem? – somedisplayname21 Apr 16 '21 at 17:58

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You can take a look at this project from Espressif.

CSI-Tools: https://github.com/espressif/esp-csi/blob/master/examples/console_test/tools/README.md

and

CSI-Example: https://github.com/espressif/esp-csi/tree/master/examples/console_test

For the distance in meter/feet you'll need to calibrate due the different aspects of the antenna.

For the ESP32-S2 and ESP32-C3 you have the ToF (Time of Flight) to calculate the round trip from the device and the router. You can try that if you have those boards.

https://github.com/espressif/esp-idf/tree/master/examples/wifi/ftm (only for S2/C3)

ESP_Minatel
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