1. An apparatus comprising at least one processor configured to cause the apparatus: obtain as an input a sampled signal; determine the 8 th order moment for a group of samples of the input signal corresponding to the length of one or two frames of a Global System for Mobile communication (GSM) signal; determine peak to average power and peak to average power variance for the group of samples of the input signal corresponding to the length of one or two frames of a GSM signal; compare the obtained 8 th order moment to predetermined thresholds and the obtained peak to average power and peak to average power variance to predetermined thresholds; determine whether the input signal is a GSM-type signal on the basis of the comparisons.