TGO Ramfjordmoen Ionosonde Data April 1985

<p>About this dataset: This dataset contains ionograms in PNG format and covers data from April 01-30, 1985.</p><p>About the Tromsø Ionosonde (1984-1992): During the period 1984-1992 the Ionosonde was situated at 69° 35' N, 19° 13' E at Ramfjordmoen near Tromsø, Norway and operated by the Auroral Observatory of the University of Tromsø. The instrument operated at this location prior to 1984, and still operates there (as of 2018); see the related publication for details. The instrument was fully digitized and based on a Hewlett Packard 21MX computer. The combination of a low power transmitter and complementary code transmission made the Tromsø ionosonde equivalent to a conventional ionosonde (at the time) with 20 µs pulses and 16 kW peak power. Routine operation was one ionogram every 20 min with a frequency sweep from 1 MHz to 12 MHz lasting between 2 and 3 min. For the 100 km altitude region the precision of determining the height of a sporadic E layer is ± 3 km. The ionograms were stored on magnetic tape. A noise discrimination routine in the computer program reduced the stored data to less than 10% of the raw data. In this way one 2400' tape held about 1300 ionograms, equivalent to 18 days' data. The tapes were 4-11 years old when they were read, resulting in around 20% data-loss during the process of transferring to other media. Today, storage is on online disk and with offline an archive on a variety of media.</p>本数据集说明：本数据集包含PNG格式的电离图，涵盖1985年4月1日至30日的观测数据。 关于特罗姆瑟电离测高仪（Ionosonde，1984-1992年）：1984年至1992年间，该电离测高仪部署于挪威特罗姆瑟附近拉姆峡湾莫恩（Ramfjordmoen），地理坐标为北纬69°35′、东经19°13′，由特罗姆瑟大学极光观测台负责运行。该仪器早在1984年之前便已在此处运行，且截至2018年仍持续运作；详细信息可参阅相关公开文献。本仪器实现全数字化，基于惠普（Hewlett Packard）21MX计算机搭建。其低功耗发射机与互补码传输技术的组合，使得该特罗姆瑟电离测高仪等效于当时采用20 μs脉冲、峰值功率16 kW的传统电离测高仪。常规观测模式为每20分钟获取一帧电离图，频率扫描范围为1 MHz至12 MHz，单次扫描耗时2至3分钟。针对100公里高度区间的偶发E层（sporadic E layer），其高度测定精度可达±3公里。早期电离图均存储于磁带上。计算机程序内置的噪声判别算法可将原始数据压缩至原规模的10%以下，以此方式，一盘2400英尺长的磁带可存储约1300帧电离图，对应约18天的观测数据。这批磁带在读取时已有4至11年的存储时长，因此在向其他介质迁移的过程中出现了约20%的数据丢失。如今，该数据集已存储于在线磁盘，并辅以多种介质的离线归档存储。