Section 4.3 of document AN122 reads as follows:
(using the FB2PLL feature greatly reduces the required crystal accuracy compared to many competing solutions.)
However, in section 5 of the document Feedback to the PLL, we can see that FB2PLL requires "leading codes" and "synchronization words".
(The receiver consists of dedicated DSP hardware capable of finding the frequency of the signal in the preamble and synchronisation word.)
That's fine with the FSK protocol,
From the FSK protocol document, each frame of message contains 12Bytes of leading code and 4Bytes of synchronization word,
However, PWM, another protocol that needs to be compatible, does not contain leading codes and synchronization words, so FB2PLL cannot be utilized.
Therefore, for the PWM protocol, the precision of crystal oscillator 10ppm is not to meet the work requirements of CC1125?
In PWM, there is no leading code for data transmission, so a high-precision clock is needed.
I need to confirm whether this is the mechanism. If it works like this, it needs the clock accuracy of 2ppm.