Spread spectrum bandwidth
The first equation is simply the well known relationship for channel capacity derived by Claude Shannon.  The second equation is an approximation for cases when the SNR is much less than 1.  It relies on another approximation:  ln(1+x)=x when x is much less than one. The factor 1.44 is equal to 1/ln(2) which is needed because the Shannnon equation uses log2 rather than ln.