PSP FIELDS Digital Fields Board (DFB) DC-coupled Searchcoil Magnetometer, SCM, Spectra, Low Frequency, High Gain, d-component, Sensor coordinates, Level 2 (L2), 6.99054 s Data

PSP FIELDS Digital Fields Board, DFB, SCMdlfhg data:

The 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].

DFB DC spectra data consist of power spectral densities as a function of frequency and time. These spectra are averaged over both frequency and time as described in [3]. The spectra have pseudo-logarithmically spaced frequency bins with the bin central frequencies reported in the metadata.

The Level 2 data products contained in this data file have been calibrated for:

* 1) The Hanning window used in the spectral calculation
* 2) DFB in-band gain
* 3) DFB analog filter gain response
* 4) DFB digital filter gain response
* 5) The search coil preamplifier response, when applicable
* 6) The bandwidth of each spectral bin

Note that compensation for the DFB digital filters will introduce a non-physical positively sloped power trend 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 preamplifiers have not been implemented as the preamplifier response is flat and equal to one through the DFB frequency range. Corrections for plasma sheath impedance gain and antenna effective length have not been applied to voltage sensor signals. 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 squared per Hertz. Likewise, all magnetic field quantities when present in these Level 2 data product are expressed by using units of nanoTesla squared per Hertz.

The Level 2 data products contained in this data file are expressed in sensor coordinates: e.g. dV12, dV34 for voltage measurements. For solar orbits 1 and 2, the search coil magnetometer spectral data are rotated into a non-intuitive coordinate system with components [d,e,f]. For solar orbits 3 and beyond, the magnetic field spectral data are in expressed in search coil magnetometer sensor coordinates with components [u,v,w].

To rotate from [d,e,f] coordinates into [u,v,w] search coil sensor coordinates, use the following matrix, written in IDL notation, and the following equation: spectra_uvw_vector = R ## spectra_def_vector.

R = [[ 0.46834856, -0.81336422 , 0.34509170]
[ -0.66921924, -0.071546954, 0.73961249]
[ -0.57688408, -0.57733845 , -0.57782790]]

The time resolution of the DFB DC spectral data can vary by multiples of 2^N. During encounter when PSP is within 0.25 AU of the Sun, the DFB DC spectra data cadence is typically 30 NYseconds NYsecond [2]. Timestamps correspond to the center time of each window.

References:

* 1) Fox, N.J., Velli, M.C., Bale, S.D. et al., Space Sci Rev (2016) 204:7. https://doi.org/10.1007/s1121401502116
* 2) Bale, S.D., Goetz, K., Harvey, P.R. et al., Space Sci Rev (2016) 204:49. https://doi.org/10.1007/s1121401602445
* 3) Malaspina, D.M., Ergun, R.E., Bolton, M. et al., JGR Space Physics (2016), 121, 5088-5096. https://doi.org/10.1002/2016JA022344

PSP FIELDS数字场板（Digital Fields Board, DFB）SCMdlfhg数据集：DFB为搭载于帕克太阳探测器（Parker Solar Probe）上的FIELDS实验的低频（低于75 kHz）分量。如需了解FIELDS实验的完整细节，请参阅相关资料。DFB直流频谱数据以功率谱密度随频率与时间的变化形式呈现，此类频谱已在频率域和时间域上完成平均处理。本数据文件所包含的二级（Level 2）数据产品已针对以下参数完成校准：频谱计算所用的汉宁窗（Hanning window）、DFB带内增益、DFB模拟滤波器增益响应、DFB数字滤波器增益响应、搜索线圈前置放大器响应，以及每个频谱分箱的带宽。