BLE Spectrum Vs Bluetooth Classic V2.0

[Frederic]

I'm having trouble with certification in China. Here is what they are getting for spectrum using the nrf52832 with the nrf_radio_test_example. The lab is saying that this is Bluetooth Classic V2.0 spectrum:

Lab expect something like this but cannot specify me exactly what is wrong with mine:

I was wondering is this could be cause by using the Nordic proprietary radio mode in the Mode Register? The data that is sent?

I know I should test it but I don't have access to a spectrum analyzer right now.

[ketiljo]

Hi Frederic

This is how I measure it, 1 Mbps BLE modulation

As you see, it's not as "pointy" as yours. It might be due to the mode you're using, but it's definitively not Classic Bluetooth. If you can send me the code, I can check it.

best regards,

Ketil Aas-Johansen

[Frederic]

By changing Nrf_1Mbit to Ble_1Mbit I get this:

Instead of this:

So it look like the value of the Radio Mode register is changing the spectrum form. What bother me is that I have to set the RBW = 3KHz instead of 100KHz like the lab to get this. Otherwise I get this:

Could it be link to the spectrum analyzer and probe that I use?

[ketiljo]

Hi Frederic

3 kHz is too low to capture the modulation envelope. Use 100 kHz for these measurements. 

cheers,

Ketil

[Frederic]

I did and it look like this:

[ketiljo]

Hi Fredric

That looks very normal.

cheers,

Ketil