NRF7002 monitor mode sends signal out

[Nulla]

Hello,

NRF SDK version 2.6.2, tested on 2.8.0 as well

Hardware: NRF7002DK

Sample: Wi-Fi Monitor

When changing Wi-Fi channel using following function

ret = net_mgmt(NET_REQUEST_WIFI_CHANNEL, iface,

&channel_info, sizeof(channel_info));

nrf7002 generates some signal (for some reason can not upload image to devzone). https://imgur.com/a/rJSEvy4.

How to reproduce issue?

Flash Wi-Fi monitor sample, connect Wi-Fi antenna RF output to signal analyzer. Signal is shown once board is reset. Signal is moved when Wi-Fi channel is changed and is shown on the same frequency as the changed Wi-Fi channel (If Wi-Fi channel is 5GHz it is moved to 5GHz).

Problem

We do not want anything to be sent, we only want to monitor traffic. Is it possible to change Wi-Fi channel without this signal appearing in spectrum?

Best regards

[Nulla]

Hello Elfving,

Would it be possible to investigate why this signal occurs? 

Best regards

[Elfving]

Sorry about the wait Nulla,

You might have to set the regulatory region, as whether or not active or passive scan being allowed varies between them. 

I've asked about this internally, but in the meantime could you try setting CONFIG_NRF70_REG_DOMAIN?

Regards,

Elfving

[Elfving]

I've gotten a reply back from the relevant team now.

The Wi-Fi device has to do some channel calibrations every time a channel change is done to ensure best performance. Some short transmissions are required to accomplish these calibrations and you are seeing these in the spectrum analyzer when changing channels. This is expected. Note that when the Wi-Fi device is in the monitor mode, it will not do any SCAN, so CONFIG_WIFI_MGMT_FORCED_PASSIVE_SCAN does not affect operation in this mode.

So the current functionality available unfortunately doesn't allow you to ensure absolutely no TX during calibrations. If this is an important feature for you, please contact your local Regional Sales Manager about it (or ask me if you need info on who that would be for you).

Regards,

Elfving