def write(self, psd_data_or_future, time_start, time_stop, samples):
        """Write PSD of one frequency hop"""
        try:
            # Wait for result of future
            f_array, pwr_array = psd_data_or_future.result()
        except AttributeError:
            f_array, pwr_array = psd_data_or_future

        self.output.write('# soapy_power output\n')
        self.output.write('# Acquisition start: {}\n'.format(time_start))
        self.output.write('# Acquisition end: {}\n'.format(time_stop))
        self.output.write('#\n')
        self.output.write('# frequency [Hz] power spectral density [dB/Hz]\n')

        for f, pwr in zip(f_array, pwr_array):
            self.output.write('{} {}\n'.format(f, pwr))

        self.output.write('\n')
        self.output.flush()
Write PSD of one frequency hop