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I wonder if there is a way to detect if there is any RF/WiFi radio ON nearby?

I'm configuring an ESP8266 12E module in STATION MODE (not Access Point) to connect to a Wifi network (any Wifi network). So, no problem. However, there is a situation which I'll have to turn off the ESP8266 module's radio (turn it off the radio only ... I'm not talking about disconnecting from the Wi-Fi network).

I already have the code that supposedly turns off the Wifi module ESP8266, which is the one that follows below and seems to work fine:

WiFi.mode (WIFI_OFF);
delay (1);

I just need to know if the radio really turned off, because I have a system in which there are 40 ESP8266 modules operating side by side, connected to the WiFi network and all these radios together are generating so strong interference to each other. When executing the Wifi shutdown code of the module(s), I just want to know whether there was none left without executing the shutdown.

Does anyone know how to detect a simple RF device?

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  • \$\begingroup\$ Look to see if you something with RSSI which translates to dBm or use any laptop on software for Windows on WiFi SSID , I forget the title at present \$\endgroup\$
    – Tony Stewart EE75
    Sep 8, 2018 at 23:47
  • \$\begingroup\$ I think I did not write correctly what I need, so I've edited the text a bit. I need to know if there is a radio transmitting signal (not connected to a network, nor operating as an access point). Just broadcasting a signal nearby. If I make sure that none are connected (not transmitting anything), then I can delete that part of my debug. Thanks. \$\endgroup\$
    – wBB
    Sep 9, 2018 at 0:10
  • \$\begingroup\$ All you need is a good RF diode and DVM with any wire antenna \$\endgroup\$
    – Tony Stewart EE75
    Sep 9, 2018 at 1:34
  • \$\begingroup\$ Good idea! I'll try and let you know results. Thanks. \$\endgroup\$
    – wBB
    Sep 9, 2018 at 1:48
  • \$\begingroup\$ I don't think there is any place on the planet without some kind of RF radiation. You need to be more specific. \$\endgroup\$
    – Maple
    Sep 9, 2018 at 6:52

2 Answers 2

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An RF Spectrum analyzer will help show you that there is no signals being broadcast

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  • \$\begingroup\$ You could do with saying WHY this is the case and how to use it to do so. \$\endgroup\$
    – Puffafish
    Jan 27, 2020 at 16:06
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A good WiFi detector would be an laptop computer with its WiFi network adaptor on. If your unit is activated it will be displayed on the screen. When deactivated it will disappear from the screen.

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  • \$\begingroup\$ I think I did not write correctly what I need, so I've edited the text a bit. I need to know if there is a radio transmitting signal (not connected to a network, nor operating as an access point). Just broadcasting a signal nearby. If I make sure that none are connected (not transmitting anything), then I can delete that part of my debug. Thanks \$\endgroup\$
    – wBB
    Sep 9, 2018 at 0:10
  • \$\begingroup\$ A wifi adapter in promiscuous mode can see packets for both a client and AP, doesn't need to be joined. \$\endgroup\$
    – Passerby
    Sep 9, 2018 at 0:55
  • \$\begingroup\$ It will also any wifi transmission whether connected or not. It will also show the signal strength as well. \$\endgroup\$
    – Old_Fossil
    Sep 9, 2018 at 3:14

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