A method of detecting extra-system signals in a multi-node RLAN (radio local area network) involves: at each of a plurality of nodes in the RLAN, processing at least one respective received signal to produce detection results and deciding whether an extra-system signal has or has not been detected based on detection results of at least two of the plurality of nodes. The extra-system signal is for example a signal from a RADAR system. The detection results are produced using pulse pattern matching for example. Furthermore, in some implementations a decision as to whether an extra-system signal has or has not been detected is based on a comparison of a detection signature for at least two of the nodes to see if there is a substantial match. In some implementations the decision is further based on information representative of a direction of arrival of respective received signals.