Square law demodulator. How can we eliminate the term containing $m^2(t)$?
$|m(t)| \leq 1.0$, so for analog signals, ${m^2(t)}$ is going to be small most of the time.  Also $k_a &lt; 1.0$, so ${k_a}^2 \ll 1.0$.  You can ignore the term usually.  If you can't, then use something other than a square law demodulator.