WASEM has two period constraints:

(i) Firstly, the smallest detectable period P1 is a constraint since one quarter of a pulse needs this minimal number of (e.g., temporal) samples for its definition. The rest of the pulse is reconstructed with knowledge of the first quarter (Torrence & Compo 1998). It can be used at least twice the data time cadence for the smallest possible period P during the separation process. Therefore, the periods < P1 cannot be contained in the diagram.

(ii) Secondly, the highest detectable period P2 is the second constraint and it equals four times the total (time) interval (Torrence & Compo 1998). For example, if we used the two-hour time interval under study. Its quadruple is eight hours = 288 000 s. With the data cadence of 12 s, the highest detectable period P2 is 24 000 s (=288 000/12). These types of periods are always non-real since they are derived from the whole (time) series length. Thus, the lowest period P1 and highest possible periods P2 that can be detected depend on the data (temporal) cadence and the (time) series length, respectively.

Then the wavelet analysis can estimate the most likely period in the range of P1–P2, that is to say, these periods have a probabilistic character, which depends on the selected wavelet parameters (e.g. red noise, selected significance). WASEM separates individual physical phenomena according to their different periodicities found in the data set. In such a case, when two physical phenomena have the close periodicity features, WASEM cannot recognise them from one another successfully. There is no universal rule regarding how to determine convenient AGWS limits L because of the different physical properties of individual subjects under separation.

Different period ranges PR between the limits L should be tried to reveal reasonable hidden structures. Knowledge of the physical phenomenon under study can help do this. For example, the characteristic wavelet pattern of the tadpole wave is well-known. Then, we need to check the smallest tadpole period (P_minimal) carefully to see the whole tadpole head with its possible fins as well as the highest tadpole period (P_max), which might reveal the entire bottom part of the tadpole body. This is important for the characteristic and maximal (P_max) period determination.