Using 5 million samples per second and the device’s real mode, the tests look at a what comes out when the IC reads a noise source. There are two registers that set the IF parameters, but the tests show the effects these registers have in precise terms.
According to the post, there are three things you can set:
- Coarse IF filter bandwidth : narrow/mid/large
- Manual fine tuning IF filter bandwidth from 0 (large) to 15 (narrow)
- High pass filter frequency from 0 (high) to 15 (low)
Some of the settings don’t make sense — at least at the 5 MHz sample rate — because of aliasing. However, it is instructive to see what each setting does. [TLeconte] uses Octave to visualize the data.