A wireless communication apparatus is arranged to detect, among a plurality of modulated carrier signals of different frequencies, at least one of the modulated carrier signals modulated with a tone burst. A receiver provides a composite signal comprising the plurality of modulated carrier signals received simultaneously. An ADC generates samples of the composite signal, and the samples of the composite signal are divided into a plurality of blocks. The samples of each block are transformed into frequency domain components, and the frequency domain components of each block are divided into a plurality of groups, each group corresponding to a range of frequencies occupied by a different one of the modulated carrier signals. Tone burst detection is performed on each group, and it is determined which of the modulated carrier signals is modulated with the tone burst, according to which of the groups the tone burst is detected in.