hump in both modulation and CW mode when continuous transmit(bandedge test)

[Damian Gai]

When we check the bandedge, we find Hump at Fc±N*16MHz. the level is about -45dBm(while FCC limit -41.2dBm).

This happens at both CW mode and moduation mode.

I notice there is 16MHz PCLK in the chipset block diagram

Is this normal or Is there any way to reduce the hump level?

[ketiljo]

You probably don't have the cache enabled. Without this, there will be more flash activity and this will affect the carrier. 

Call this in your init routine: 

NRF_NVMC->ICACHECNF = (NVMC_ICACHECNF_CACHEEN_Enabled << NVMC_ICACHECNF_CACHEEN_Pos) & NVMC_ICACHECNF_CACHEEN_Msk;

[Damian Gai]

Really appreciate for you answer.

We check with our SW engineer. They already applied this.

So is there any other possible reason?

[ketiljo]

Hi Damian

Can you attach the code here please? 

Can you check how it looks like if you program it with this hex file? nrf52_unmod_ch40.hex

cheers,

Ketil