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

[Mike@PebbleStack]

Have you tried using the AI? If found it really good at finding similar questions and suggesting answers.

Based on the information provided in the knowledge sources, I can address your question about the nRF7002 monitor mode sending signals out when changing Wi-Fi channels.

The behavior you're observing is likely related to the way the nRF7002 performs channel scanning and configuration. According to the [Wi-Fi regulatory support documentation](docs.nordicsemi.com/.../regulatory_support.html), the nRF70 Series devices typically use a combination of active and passive scanning, depending on the regulatory rules in place.

However, for monitor mode operation, we want to ensure that the device is only passively listening and not transmitting. To achieve this, you can try the following:

1. Enable forced passive scanning: As mentioned in the [DevZone forum post about nRF7000](devzone.nordicsemi.com/.../486207), you can set passive scanning in your configuration by setting "CONFIG_WIFI_MGMT_FORCED_PASSIVE_SCAN=y". This should prevent the device from performing active probing (transmitting) during channel changes.

2. Configure packet filter settings: The [Monitor mode receive operation filter configuration documentation](docs.nordicsemi.com/.../sniffer_rx_operation.html suggests that you can configure the type of IEEE 802.11 receive packets that the application receives. You might want to ensure that your filter settings are configured to receive only, without any transmission.

3. Check TX injection mode: Make sure that TX injection mode is not enabled unintentionally. As per the [Monitor mode receive operation in conjunction with TX injection documentation](docs.nordicsemi.com/.../sniffer_rx_operation.html, TX injection mode allows the transmission of raw 802.11 packets. Ensure that the `CONFIG_NRF70_RAW_DATA_TX` Kconfig option is not enabled in your project configuration unless you specifically need it.

If after applying these suggestions you still observe unwanted transmissions, it might be worth reaching out to Nordic Semiconductor's technical support for further assistance, as this behavior seems to contradict the expected operation of monitor mode.

Remember that the nRF7002 is designed to comply with various regulatory requirements, which might influence its behavior during channel changes. Always ensure that your usage complies with local regulatory standards for Wi-Fi devices.

An since it's AI, remember to verify any info provided before making any decision!

[Elfving]

Hello,

Like Michael and the AI suggested, did you try CONFIG_WIFI_MGMT_FORCED_PASSIVE_SCAN?

Regards,

Elfving

[Nulla]

Hello,

Yes, I tried using CONFIG_WIFI_MGMT_FORCED_PASSIVE_SCAN. This signal still appears.

[Nulla]

Hello,

Can I get any update on that please?

[Mike@PebbleStack]

Hi Nulla,

It's way beyond my expertise, so I'll defer to someone from Nordic.

Happy New Year!

rgds...mike