Patent ID: 8259839

Claim:
A method for avoiding spurious emissions in an amplitude modulation (AM) transmitter for digital transmission, the method comprising: converting a digital modulation for controlling the AM transmitter into an amplitude signal for an amplitude branch and a phase-modulated radio frequency (RF) signal for an RF branch; compensating, at the AM transmitter, for non-linear distortions in an amplitude response and a delay-time characteristic of the RF branch using a pre-equalization with inverse shapes by: measuring and storing the amplitude response and the delay-time characteristic for different conditions for a reactive antenna matching so that the pre-equalization can be optimally adapted for weather related variations in impedance; determining an inverse transfer function using respective inverse shapes of the measured amplitude response and delay-time characteristic by an inverse Fourier transform; dimensioning, in an equalizing network, the determined inverse transfer function; connecting the equalizing network in a series connection, the series connection being upstream of the RF branch; and combining, at the AM transmitter, the amplitude branch and the RF branch downstream of the amplitude and RF branches.