Cluster-Samba Wideband (WBD) High Time Resolution Dynamic Spectrogram Plot

This dataset contains 30 s duration survey spectrogram plots from the WBD instrument on the Cluster spacecraft. The spectrograms are created by 1024 point FFTs and plotted with frequency on the vertical axis, increasing time on the horizontal, and color indicating power spectral density, in relative dB. The AC electric field data are obtained by using one of the two 88m spin plane electric field antennas of the EFW instrument as a sensor. The AC magnetic field data are obtained by using one of the two search coil magnetometers (one in the spin plane, the other along the spin axis) of the STAFF instrument as a sensor. The WBD data are obtained in one of three filter bandwidth modes: (1) 9.5 kHz, (2) 19 kHz, or (3) 77 kHz. The minimum frequency of each of these three frequency bands can be shifted up (converted) from the default 0 kHz base frequency by 125.454, 250.908 or 501.816 kHz. The time resolution of the data shown in the plots is determined from the WBD instrument mode. The highest time resolution data are sampled at 4.6 microseconds in the time domain, 4.7 milliseconds in the frequency domain (generally the 77 kHz bandwidth mode). The lowest time resolution data are sampled at 36.5 microseconds in the time domain, 37.3 milliseconds in the frequency domain (generally the 9.5 kHz bandwidth mode). Above the spectrogram plot are a line plot panel, followed by four status lines. The line plot panel at the top provides the gain state (0 to 75 dB, in 5 dB steps) of the instrument. The four status lines provide the following information according to the color code in the upper right corner: Data mode - whether from DSN mode (real time telemetry), or from BM2 mode (recorded onboard in Burst Mode 2) as digitally filtered or duty cycled. Antenna - the electric field (Ey or Ez) or the magnetic field (Bx or By) antenna used. Resolution - the data digitization level, which can be 1 bit, 4 bit or 8 bit. Translation - the translation from base frequency of 0 kHz. In the lower right-hand corner are the ephemeris values applicable to the start time of the plot. At the middle right-hand side are given the date and start time of the plot as well as the spacecraft number. The University of Iowa repository maintains two types of high time resolution spectrogram plots in GIF format: a ten minute (PT10M Display Cadence) and a 30 second time span (PT30S Display Cadence). Both types of files provide information on WBD gain and operational mode, the spectral data from one spacecraft, the start date and time and ephemeris data. Overview spectrograms are also available. The availability of these files depends on times of DSN and Pansak Ves ground station telemetry downlinks. A list of the status of the WBD instrument on each spacecraft, the telemetry time spans, operating modes and other details are available under Science Data Availability on the University of Iowa Cluster WBD web site at http://www-pw.physics.uiowa.edu/cluster/ and through the documentation section of the Cluster Science Archive (https://www.cosmos.esa.int/web/csa/documentation). Details on Cluster WBD Interpretation Issues can be found at http://www-pw.physics.uiowa.edu/cluster/interpretation_issues/interpretation.html For further details on the Cluster WBD data products see Pickett, J.S., et al., "Cluster Wideband Data Products in the Cluster Active Archive" in The Cluster Active Archive, 2010, Springer-Verlag, pp 169-183.

本数据集包含来自星簇（Cluster）航天器上的宽频带数据（Wide Band Data, WBD）仪器的30秒时长巡天声谱图。该声谱图通过1024点快速傅里叶变换（Fast Fourier Transform, FFT）生成，纵轴为频率，横轴为随时间递增的序列，颜色编码表示相对分贝（dB）下的功率谱密度。交流电场数据通过采用电场与波（Electric Field and Waves, EFW）仪器的两根88米自旋平面电场天线中的一根作为传感器获取。交流磁场数据则通过采用场波动时空分析（Spatio-Temporal Analysis of Field Fluctuations, STAFF）仪器的两根搜索线圈磁强计（一根位于自旋平面内，另一根沿自旋轴方向）中的一根作为传感器获取。WBD数据采用三种滤波带宽模式之一获取：(1) 9.5 kHz，(2) 19 kHz，或(3) 77 kHz。上述三个频段的最低频率可相对于默认0 kHz基准频率向上偏移（转换），偏移量分别为125.454 kHz、250.908 kHz或501.816 kHz。

图中展示数据的时间分辨率由WBD仪器模式决定。最高时间分辨率的数据在时域采样率为4.6微秒，频域采样率为4.7毫秒，该模式通常对应77 kHz带宽模式。最低时间分辨率的数据在时域采样率为36.5微秒，频域采样率为37.3毫秒，该模式通常对应9.5 kHz带宽模式。

声谱图上方设有折线图面板，其后跟随四条状态线。顶部的折线图面板用于展示仪器的增益状态（0至75 dB，步长为5 dB）。四条状态线根据右上角的颜色编码提供以下信息：数据模式——为深空网络（Deep Space Network, DSN）模式（实时遥测），还是突发模式2（Burst Mode 2, BM2）（星上记录的经数字滤波或占空比处理的数据）；天线——所采用的电场（Ey或Ez）或磁场（Bx或By）天线；分辨率——数据数字化等级，可为1比特、4比特或8比特；偏移量——相对于0 kHz基准频率的偏移值。

右下角为适用于该图起始时间的星历数据；右侧中部则标注了该图的日期、起始时间以及航天器编号。艾奥瓦大学（University of Iowa）数据存储库存储了两种GIF格式的高时间分辨率声谱图：时长为10分钟（PT10M显示帧率）和30秒（PT30S显示帧率）。两类文件均包含WBD增益与工作模式信息、单航天器的声谱数据、起始日期与时间以及星历数据。此外还提供概览声谱图。此类文件的可用性取决于深空网络（DSN）与潘沙克韦斯（Pansak Ves）地面站的遥测下行链路时段。

各航天器上WBD仪器的状态、遥测时段、工作模式及其他详细信息，可通过艾奥瓦大学星簇WBD官网（http://www-pw.physics.uiowa.edu/cluster/）的"科学数据可用性"板块，以及星簇科学档案馆（Cluster Science Archive）的文档板块（https://www.cosmos.esa.int/web/csa/documentation）查阅。关于星簇WBD数据解译问题的详细说明，可访问http://www-pw.physics.uiowa.edu/cluster/interpretation_issues/interpretation.html查阅。如需了解星簇WBD数据产品的更多细节，请参阅Pickett, J.S.等人发表于《星簇主动档案馆》（The Cluster Active Archive）2010年卷的论文"Cluster Wideband Data Products in the Cluster Active Archive"，发表于施普林格出版社（Springer-Verlag），第169-183页。