While the MAX2982 does have "advanced narrow-band interference rejection circuitry" (as advertised by the data sheet), it isn't necessarily a "unit". This rejection circuitry is automatic and does not need to be setup. Very few details of the circuit exist in the MAX2982 data sheet.
The only information available is that the jamming cancelling circuit acts like an adaptive notch filter that attenuates in-band narrowband interference if it’s much higher than the HomePlug signal.
There is no further collateral available on this subject.