Calculation of Intermodulation Due to Amplitude Limiting of Multiple Carriers

A method of computation is presented enabling the estimation of suppression and intermodulation with multiple carriers as the input to a soft- or hard-limiting channel (without memory except for filtering to the first zone). The approach utilizes a direct representation in the time domain and a Monte Carlo simulation to gather statistics over the ensemble of the phase angles of the input carriers. For a small number of carriers the computer time involved is modest; hence the approach is computationally useful. The results display the hitherto unobserved behavior that, with respect to any selected carrier, the quadrature intermodulation has greater power than the inphase intermodulation. The impact of this behavior with a small number of phasemodulated carriers in multiple access to a limiting satellite repeater channel may be noted.