I performed tests with a CC2400. I injected on its digital I/O a square signal which is half of the programmed bitrate. On the edges of the signal, I can identify a superposition of a sinusoid which frequency's is the double of the deviation. Here is a screenshot of the oscilloscope.
Is it normal ? Is there a problem with my design ?
If it's normal, why do we get this kind of signal ? Thank you for your answers.