A radio transmitter for transmitting signals in a predetermined frequency
band has a transmit filter and a compensating filter. The transmit filter
filters a signal to be transmitted from the transmitter to suppress the
transmission of parts of the signal outside the band. The compensating
filter, e.g., operating in the digital domain, filters the signal
upstream from the transmit filter, wherein the compensating filter is
arranged to alter the signal to counteract at least one of a phase
ripple, an amplitude ripple, and a group delay variation of the transmit
filter within the band.