PSP FIELDS Digital Fields Board, DFB, Differential Voltage data:\n\nThe DFB is the low frequency, less than 75 kHz, component of the FIELDS experiment on the Parker Solar Probe spacecraft, see reference [1] below. For a full description of the FIELDS experiment, see reference [2]. For a description of the DFB, see reference [3].\n\nThe DFB continuous waveform data consist of time series data from various FIELDS sensors. These data have been filtered by both analog and digital filters [3].\n\nThe Level 2 data products contained in this data file have been calibrated for:\n\n 1) DFB in-band gain\n 2) DFB analog filter gain and phase response\n 3) DFB digital filter phase response\n 4) The search coil preamplifier gain and phase response, when applicable\n\nCalibrations for the DFB digital filter gain response have not been implemented, but the required convolution kernel is provided in this file. It was decided not to apply the digital filter gain response calibration to these Level 2 data because the application of the calibrations can introduce non-physical power at high frequencies when the non-corrected signal is dominated by noise. This effect should be examined carefully when determining spectral slopes and features at the highest frequencies. Calibrations for the FIELDS voltage sensor preamplifiers have not been implemented as the preamplifier response is flat and equal to one throughout the DFB frequency range. Corrections for plasma sheath impedance gain and antenna effective length have not been applied to the voltage sensor data. These corrections will be applied in the Level 3 DFB data products. Therefore, all voltage sensor quantities when present in these Level 2 data products are expressed by using units of Volts. Likewise, all magnetic field quantities when present in these Level 2 data products are expressed by using units of nanoTelsas.\n\nThe Level 2 data products contained in this data file are in spacecraft coordinates (e.g. x,y,z) or in sensor coordinates (e.g. dV12, dV34 for voltage measurements and [u,v,w] for the searchcoil magnetometer.\n\nThe time resolution of the DFB continuous waveform data can vary by multiples of 2^N. During encounter when PSP is within 0.25 AU of the Sun, the DFB continuous waveform data cadence is typically 256 samples/NYsecond [2].\n\nReferences:\n\n 1) Fox, N.J., Velli, M.C., Bale, S.D. et al., Space Sci Rev (2016) 204:7. https://doi.org/10.1007/s1121401502116\n 2) Bale, S.D., Goetz, K., Harvey, P.R. et al., Space Sci Rev (2016) 204:49. https://doi.org/10.1007/s1121401602445\n* 3) Malaspina, D.M., Ergun, R.E., Bolton, M. et al., JGR Space Physics (2016), 121, 5088-5096. https://doi.org/10.1002/2016JA022344