self.gaussian_taps = filter.firdes.gaussian(
        1,             # gain
        samples_per_symbol,    # symbol_rate
        bt,            # bandwidth * symbol time
        ntaps                  # number of taps
        )
self.sqwave = (1,) * samples_per_symbol       # rectangular window
self.taps = numpy.convolve(numpy.array(self.gaussian_taps),numpy.array(self.sqwave))
self.gaussian_filter = filter.interp_fir_filter_fff(samples_per_symbol, self.taps)