In DTM test ,nrf21540 out power is difference on Different frequencies

[david@2024]

Hi,

During the testing of nrf21540DK conduction power, a strange phenomenon was encountered: in DTM testing, when the transmission power was set to 0dB, there was a significant difference in conduction power between channels 37 and 39. The conduction power of channel 37 is 4dB, and channel 39 is 8dB. Why is that?
The DTM example I am using is nRF5_SDK_17.1.0_de560 \ examples \ dtm \ direct_test_made \ pca10112

The test results are as follows：

[Bendik Heiskel]

Hi,

The nRF21540 does not have linear TX gain over the 2.4GHz frequency band:

 

These plots are for the default 20 and 10dB gain settings using the MODE pin.

What does tx_power 0 and 2 refer to? output power from the SoC?

 

The DTM example I am using is nRF5_SDK_17.1.0_de560 \ examples \ dtm \ direct_test_made \ pca10112

The nRF21540 has very limited support in the old nRF5 SDK, I highly recommend you switch to the nRF Connect SDK. For RF testing it is best to use the radio test sample instead of DTM, as it is easier to use for this type of testing.
Can you redo the measurements using this sample instead?

 

Best regards,

Bendik

[david@2024]

1.These plots are for the default 20 and 10dB gain settings using the MODE pin.

the MODE pin is setting to 1,use default  10dB gain.

2.What does tx_power 0 and 2 refer to? output power from the SoC?

yes,it from soc output power