in a method of allocating carrier frequencies for simultaneous transmission of a plurality of modulated signals the carrier frequencies are chosen to satisfy the equation : f = n ± k where &# 34 ; p &# 34 ; is an integer number specific to each carrier frequency , &# 34 ; n &# 34 ; represents a given frequency bandwidth and &# 34 ; k &# 34 ; represents a given frequency bandwidth less than &# 34 ; n &# 34 ; and possibly a null bandwidth . the value of n is chosen to be sufficiently large relative to the width of the frequency channels occupied by the modulated signals that if k ≠ 0 second order composite distortion occurs outside the channels . alternatively , if n is insufficiently large relative to the width of the channels the capacity of the transmission system is such that second order composite distortion occurring inside the channels is offset sufficiently relatively to the carrier frequency not to disrupt the transmission of the respective signals .