It is computationally impossible to analyze a signal using all wavelet coefficients, so one may wonder if it is sufficient to pick a discrete subset of the upper halfplane to be able to reconstruct a signal from the corresponding wavelet coefficients. One such system is the system for some real parameters "a" > 1, "b" > 0. The corresponding discrete subset of the halfplane consists of all the points ("am", "namb") with "m", "n" in Z. The corresponding "child wavelets" are now given as