History of EISCAT – Part 5: Operation and development of the system during the first 2 decades

This paper gives an inside view of the first 20 years of operation of the Kiruna–Sodankylä–Tromsø (KST) part of EISCAT as experienced and remembered by myself. The paper is subdivided into an Introduction and 14 additional sections. Sections 2 to 7 describe the organisation, staffing and responsibilities of the sites, with particular emphasis on the transmitter-related work at Tromsø and the commuting of staff and equipment between the sites. The headquarters operation is treated in Sect. 8. The UHF radar system is treated in Sect. 9. Section 10 is a review of the VHF system, including a summary of transmitter and antenna problems not available elsewhere in easily accessed media. Section 11 treats the computer system and the proprietary control languages EROS, TARLAN and CORLAN. Section 12 describes the signal processing hardware, with special emphasis on the Alker correlator, its idiosyncrasies and the gradual unlocking of its capabilities through UNIPROG, the GEN system and the G2 system, culminating in the ability to run alternating code experiments routinely. Section 13 presents the time and frequency keeping, a non-trivial task in the early 1980s. Finally, Sect. 14 discusses the UHF spectrum problem and relates how the UHF system had to be constantly upgraded in order to be able to co-exist with the emerging mobile phone networks until the final closure of UHF reception at Kiruna and Sodankylä in 2012. The paper ends with some personal reflections (Sect. 15).