ESP32 Receive RSSI Issue

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Joined: Tue Oct 13, 2020 5:32 am

ESP32 Receive RSSI Issue

Postby rushabh » Tue Oct 13, 2020 5:59 am

We are using ESP32 WROOM32 Devkit as shown in images. We are testing WiFi mesh using esp-mdf. Following is the github link from where we are using router example. ... ifi/router

As per documentation, ESP32 root Module once connected to router, will start a softAP for childs to connect. It works fine, the first module connects to router and starts softAP for childs to connect.

We then used another ESP32 Module in WiFi scan mode, which scans all softAP around it and gives RSSI of those APs.

We observed that when we placed the softAP Module and Scanning Module next to each other, it was giving a RSSI of -44dbm. When I moved these devices apart from each other at a distance of 50 cm (there antennas are facing each other), we measured RSSI of -70dbm.

The module is set to a max power of 20dbm in menuconfig.

When modules were placed next to each other, we expect a RSSI of less than -20dbm but it gives -44dbm. Just moving them 50cm apart gives -70dbm. The RSSI values are very bad. Since WiFi mesh works on RSSI values and does not connect to parent if its RSSI values are below -84dbm. In my case, at approximately 8 meters, RSSI worsens to -80 to -90 dbm. So I am not able to achieve hop distance of greater than 8 meters.

From website, we could see that distances of 30 meters were achieved with a wall in between (Reference from esp-mdf github: The transmission distance between two devices is 30 m through walls, and 200 m without any obstacles in between (relevant to ESP32-DevKitC)). So Are we making a mistake. What should we do to achieve the distances of 20m to 30m?

Also if there is need for any information please reply, I will post the information.
Module Used Front
IMG_20201013_111216.jpg (2.71 MiB) Viewed 319 times
IMG_20201013_111446.jpg (2.1 MiB) Viewed 319 times

Posts: 61
Joined: Thu Dec 10, 2015 1:11 pm

Re: ESP32 Receive RSSI Issue

Postby Franco » Tue Oct 13, 2020 9:19 pm

One quick check you could do is to use Espressif devkitC with an ESP32-WROOM-32D or 32E instead of the early version you are using. I know cases where this simple way increased the transmission range.

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Joined: Tue Dec 01, 2015 7:35 am

Re: ESP32 Receive RSSI Issue

Postby WiFive » Thu Oct 15, 2020 10:18 pm

Notice on real devkitc there is clear space around antenna

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