NRF7002 Radio test RX_CAP 2 trigger

RE: NRF7002 Radio test RX_CAP 2 trigger

Håkon Alseth — Mon, 12 Aug 2024 09:55:19 GMT

Hi,

My deepest apologies for the long waiting time.

The fix, highlighted in this PR https://github.com/nrfconnect/sdk-nrfxlib/pull/1399, is now merged to the main-branch.

There is unfortunately no tag release where this is currently present, meaning that you will have to use the main branch to test this specific fix.

Here's way to update your ncs installation to main:

* Open up a command line with the NCS environment set

* change to folder \path\to\ncs\nrf

* Issue these git commands:

git fetch origin
git checkout origin/main
west update

Kind regards,

Håkon

RE: NRF7002 Radio test RX_CAP 2 trigger

Julianstj — Tue, 28 May 2024 15:33:02 GMT

Hi Håkon, ok this is great, please let me know when a new version is ready to test. thank you!

RE: NRF7002 Radio test RX_CAP 2 trigger

Håkon Alseth — Wed, 22 May 2024 12:08:18 GMT

Hi,

My deepest apologies for the long wait.

I just got feedback from the developers that a fix is on-going, but unfortunately not released, as the fix has some negative side-effects:

Default thresholds in our detection logic are such that there is minor probability for false detection. These thresholds are chosen intentionally. This is leading to capture to happen when there is no WLAN signal present. For radio test application, we modified thresholds so that capture does not happen when no WLAN signal is not present. So, we have a solution for the problem reported by customer. However, this has shown up a limitation in handling of this command for negative test scenario (i.e., capture timing out).

I am unfortunately not able to provide a more detailed timeline of when this fix is ready, but if this is a high priority for your evaluation/development, you can send me a direct message with your location, and I will provide you information to your local RSM.

Kind regards,

Håkon

RE: NRF7002 Radio test RX_CAP 2 trigger

Julianstj — Tue, 21 May 2024 23:31:41 GMT

Hi Håkon, any update on this? Thank you!

RE: NRF7002 Radio test RX_CAP 2 trigger

Julianstj — Fri, 26 Apr 2024 15:03:52 GMT

Hi Håkon, that makes sense, thank you for the additional details and looking forward to hearing more details. I do actually need it to be triggered by packet detection, as I do not want to have IQ samples constantly, but only during packet times.

Please let me know if there is any experiment I can collect data from to help debug.

Thank you!

RE: NRF7002 Radio test RX_CAP 2 trigger

Håkon Alseth — Fri, 26 Apr 2024 13:30:34 GMT

Hi,

My apologies, I have misinformed you previously:

[quote user="hkn"]"rx_cap 2" will enable raw access to the radio, meaning no checksums or address matches etc. It dumps out raw data from the demodulator.[/quote]

"rx_cap 0": Unfiltered output, i.e., ADC output. Please note that analog filter in RF is applied on these samples. Digital filter in baseband is not applied. This is at 40MHz sampling rate (ADC sampling rate).

New
"rx_cap 1" : Filtered output, i.e., both analog filter in RF and Digital filter in baseband are applied. Output is at 20MHz sampling rate.

"rx_cap 2" : Filtered output. Output is at 20MHz sampling rate. Only difference compared to "rx_cap 1" is that capture should be triggered after packet detection.

When you have set "rx_cap 2" and placed the device in a shielded box, with no other traffic around, it should not output any data. I have reported this as a bug back to R&D for further investigation.

[quote user="Julianstj"]Raw data from the demodulator is perfect, that's what I want.[/quote]

It sounds like rx_cap 0 or 1 is the mode that you want, based on your preference wrt. digital filtering on or off.

Kind regards,

Håkon

RE: NRF7002 Radio test RX_CAP 2 trigger

Julianstj — Thu, 25 Apr 2024 15:33:17 GMT

Hi Håkon,

Here's the data I captured in the chamber, at channel 1 and channel 144, along with the script I used to parse the data.

Raw data from the demodulator is perfect, that's what I want. The statement about rx_cap 2 says "To capture AGC adjusted baseband samples after WLAN packet detection" , so AGC adjusted baseband samples is fine, but the WLAN packet detection part. Based on my measurement, it isn't WLAN packet detection but something else? If it's in an RF chamber I wouldn't expect it to trigger or give IQ samples at all. Or is that not how the code is operating?

My goal is to have IQ samples that correspond with a specific packet, so I'm very interested in the "after WLAN packet detection" component. I was surprised that I stuck the board in the chamber, see nothing on wifi scan, but still see IQ data come back when running rx_cap 2.

Thanks!

devzone.nordicsemi.com/.../EvalBoardLogs.zip

RE: NRF7002 Radio test RX_CAP 2 trigger

Håkon Alseth — Thu, 25 Apr 2024 08:23:25 GMT

Hi,

"rx_cap 2" will enable raw access to the radio, meaning no checksums or address matches etc. It dumps out raw data from the demodulator.

[quote user=""] If I look at the IQ dump frequency content, it does show an arc around the center, which seems to point towards it trying to detect something.[/quote]

Without seeing the shape/form/magnitude, it is hard to state exactly what it is, but given that this was measured in a shielded chamber, it has to be coming from the design itself. What you're describing sounds like a Receiver local oscillator leakage (RX-LO), meaning a small leakage from the receiver logic inside of the nRF7002.

Kind regards,

Håkon