TGO Ramfjordmoen Ionosonde Data February 1987

About this dataset: This dataset contains ionograms in PNG format and covers data from February 01-28, 1987.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.

本数据集概况：本数据集包含PNG格式的电离层探测图（ionogram），涵盖1987年2月1日至28日的探测数据。
特罗姆瑟电离层探测仪（1984-1992年）：1984至1992年间，该探测仪部署于挪威特罗姆瑟附近的拉姆峡湾莫恩（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维。该仪器早在1984年之前便已在此处运行，且截至2018年仍在持续工作，详细信息可参阅相关学术出版物。
该仪器已实现全数字化，搭载惠普（Hewlett Packard）21MX计算机作为核心运算平台。其低功率发射机与互补码传输技术的结合，使得该探测仪的性能等效于当时采用20微秒脉冲、峰值功率16千瓦的传统电离层探测仪。
常规运行模式为每20分钟获取一幅电离层探测图，扫描频率范围为1兆赫至12兆赫，单次扫描耗时2至3分钟。针对100千米高度区域，偶发E层（sporadic E layer）高度的测定精度可达±3千米。
此前所有电离层探测图均存储于磁带之上，计算机程序内置的噪声判别程序可将存储数据压缩至原始数据的10%以内。以此方式，一盘长度为2400英尺的磁带可存储约1300幅电离层探测图，对应18天的探测数据量。这批磁带在被读取时已有4至11年的存放时长，因此在向其他存储介质迁移的过程中出现了约20%的数据丢失情况。如今，该数据集采用在线磁盘存储与离线多介质归档相结合的方式进行保存。