problem with CTE packets on nrf5340

[Mohammad Ranjbar]

I want to use nrf5340  on DTM mode (installed through nrf connect) to test Carrier frequency offset for CTE packets using CMW500. However, CMW uses power trigger to find the packets and based on my investigation, in nrf5340 CTE packets, TX power is always enabled even in between packets (We always have power). So CMW can not find packets. I'd appreciate any help.

[Simonr]

Hi Mohammad

This doesn't make much sense to me, can you try to explain this in a bit more detail? An unmodulated carrier isn't a packet, and won't contain any information. The direct test mode has specified when the packets will be sent, so you shouldn't have to trig this on your end. 

If you only want to use unmodulated carrier to verify if the DUT is transmitting or not, you should be only to just turn the spectrum on without a trig on the CMW500 (I think).

Best regards,

Simon

[Mohammad Ranjbar]

Hi Simon,

sorry for the confusion; maybe I did not explain the problem clearly. I am using Direct Test Mode (DTM) for BLE tests. For BLE tests under DTM mode, the tester (in my case CMW500) sends command through UART to the DUT (nrf5340) on what kind of packet it should send. Then the DUT responds to the command  (sent by tester) and transmits the requested BLE packet to the tester. For example for Frequency Offset and Drift test for CTE packets, the requested packet has PDU length of 37 bytes with pattern 11110000, CTE length of 20 bytes (customizable). The tester receives this packet, detects it and does some calculation on it and gives us the test result. The tester that I use (CMW 500) uses power trigger to detect the start of the received packets. But the DTM firmware that I downloaded using nrf connect transmits packets with CTE in a way that we have always transmit power even in between packets, so CMW500 can not detect the packets.

[Simonr]

Hi Mohammad

Okay, that makes more sense, thank you for explaining. But can you explain what DTM firmware you are referring to? 

Best regards,

Simon

[Mohammad Ranjbar]

Hi Simon,

The description of the DTM project is in the following link:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/bluetooth/direct_test_mode/README.html

This project is included in nrf connect SDK v1.4.0

[Simonr]

Hi Mohammad

I have contacted the developers of this project with a request asking how we can make the CMW detect these packets (either by making some changes to the project or by some other clever solution). Thank you for your patience and explanations thus far. I will get back to you as soon as I hear from the devs.

Best regards,

Simon