If you change the oversampling, the chip will decimate the data on RX by that amount - so if you set the chip to deliver 100kSample/sec to you, and you set oversampling to 16, the chip will internally sample at 1.6MSample/sec, then use a digital filter to reduce the data by 16. On transmit, if you set the chip to take 100kSample/sec and you set 16x oversampling, the chip will take the 100kSample/sec from you, use a digital filter to increase the number of samples by 16, and run internally at 1.6MSample/sec.
This is done for a few cases:
- you want to frequency hop very quickly in a limited bandwidth - you can set the chip to run 65MSample/sec, and then digitally tune +/- 16MHz within that pretty much instantly, and by using the oversampling you can reduce the amount of data you get to something manageable.
- You want to operate below 30MHz, which is the lowest the analog section can tune. So you tune to 30MHz, run the internal sampling at 60Msample/sec, and then tune the digital NCO to the desired frequency and decimate.