Abstract: An analyser and associated method for analysing a multi-channel radio frequency (RF) signal comprising, a down-converter for deriving an intermediate frequency (IF) signal corresponding to an RF signal to be measured; a measurement filter for filtering out all but a portion of the IF signal which includes signals from a desired channel to be measured and some of a neighbouring channel; a trigger filter responsive to the same IF signal and having a pass band narrower than and inside the pass band of said measurement filter and processing means for measuring and indicating parameters of the signal filtered by the measurement filter in response to a trigger signal filtered by the trigger filter.