ISIS-2 Topside Sounder Average Ionogram over Resolute Bay, NU, Canada: RES, Latitude 75, Longitude 265

These Ionograms were digitized from the original ISIS-2 7-Track Analog Telemetry Tapes using the Facilities of the former Data Evaluation Laboratory at the NASA/GSFC. This Data Restoration Project is headed by Dr. R.F. Benson (NASA/GSFC). Ionograms were digitized at the Rate of 40,000 16-bit samples/s. This Sample Rate is higher than the Nyquist Frequency of 30 kHz. The Sample Frequency of 40 kHz provides a Measurement every 25 µs corresponding to an Apparent Range Interval equal to 3.75 km from c*t/2, where c is the Speed of Light. Ionograms with this Sample Rate are designated as 'Full' Ionograms because they have the full 3.75 km Apparent-Range Resolution. The Ionograms used for most Analyses, and those available from CDAWeb, were produced by averaging every four Samples of the Sounder-Receiver Video Amplitude Output to yield an average Value every 100 µs corresponding to an Apparent-Range Resolution of 15 km. These Ionogram Files are referred to as 'Average' Files with Standard Resolution. Each Ionogram consists of a Fixed-Frequency Portion and a Swept-Frequency Portion. The Time Resolution between Ionograms is typically 14 or 22 s depending on the Frequency Sweep Range.

本数据集由原始的 ISIS-2 七轨模拟遥测磁带在 NASA/GSFC 的前数据评估实验室进行数字化处理而成。此数据恢复项目由 NASA/GSFC 的 R.F. Benson 博士领导。离子图以每秒 40,000 个 16 位样本的速率进行数字化。此采样率高于 30 kHz 的奈奎斯特频率。40 kHz 的采样频率提供了每 25 微秒的测量，对应于从 c*t/2 计算出的 3.75 公里的视在距离间隔，其中 c 为光速。具有此采样率的离子图被指定为‘完整’离子图，因为它们具有完整的 3.75 公里视在距离分辨率。用于大多数分析以及从 CDAWeb 可获取的离子图是通过平均声纳接收器视频幅度输出的每四个样本来生成的，每 100 微秒产生一个平均值，对应于 15 公里的视在距离分辨率。这些离子图文件被称为具有标准分辨率的‘平均’文件。每个离子图由一个固定频率部分和一个扫描频率部分组成。离子图之间的时间分辨率通常为 14 或 22 秒，具体取决于频率扫描范围。