Decomposing Wavelet Transform for PV Variability Studies

I need a code to decompose an irradiance time-series into its components at various timescales by using a wavelet transform. I already have the normalized irradiance time-series. The generated have 6000 points with 1 second resolution. I want to implement the wavelet transform given in a work called "A Wavelet-Based Variability Model (WVM) for Solar PV Power Plants" of Sandia National Laboratories. The equation is:

where \bar{t} is the wavelet timescale, t_{start} and t_{end} designate the start and end of the GHI timeseries and t' is a variable of integration. For the discret wavelet transform, \bar{t} is increased by factors of 2, such that values of \bar{t} are defined by \bar{t}=2^j.

This approach uses the top hat wavelet defined by:

I do not understand how to calculate the mother function .

I appreciate any help!