EISCAT 3D Preparatory Phase - Site survey

Transcription

1 EISCAT 3D Preparatory Phase - Site survey EISCAT_3D System Overview The EISCAT_3D facilities will comprise one transmit/receive core site and four distant, primarily receive sites equipped with antenna arrays, supporting instruments, platforms for movable equipment and high data-rate Internet connections. The receive sites will be arranged at a pair of closer locations to the core to provide high resolution E-region vector drift measurements and another pair of locations spaced further from the core for F-region vector coverage over a larger region. The two pairs of receive sites with will be located at baseline distances within roughly 90 km d 280 km of the core site. The core site with full transmitting and receiving capabilities will be located within roughly 100 km of a point at 69 degrees North and 20.5 degrees East. Figure 1: EISCAT_3D geometry. The core site in red color. Receiver sites in blue color. 1

2 The Central core To meet the performance requirements laid down in the Integrated Specification Document for EISCAT_3D, the antenna array of the transmitter/receiver (Tx/Rx) element will be designed as a circular aperture central core. The target is a element, 70-meter diameter array. The array will be physically subdivided into hexagonal groups of 91 elements. All electronics for the group will be housed in a common equipment container. The central core will be complemented with smaller outlying antenna arrays that will facilitate aperture synthesis imaging for probing within the transmitted beam. The total size of the central site will exceed 1 km, given that the dense inner core of antennas will be accompanied by a sparsely distributed array of outlying antennas. The dense inner core will require approximately 70x70 m of space, with an additional buffer for safety. At any point on the 70-meter diameter perimeter of the central core, the maximum horizon elevation angle should not exceed 30 degrees. The Receiver (Rx) sites The receiver arrays will be designed in the same way as the Tx/Rx array. One of the receiver arrays will have limited transmit capability, in the order of 1 MW. Supporting instruments The sites shall be equipped with facilities for Optical Cameras, Ionosondes and Data Storage. Sites should be prepared over a range larger than what is needed for initial instrumentation in order to have the space for further instruments and in order for further construction works not disturbing measurements. Infrastructure To keep the construction costs down, it is important to have a good infrastructure in place in the area of a construction site. Access to a backbone fiber link and a power line, not too far away from the site is an advantage. Data communications: Very high speed data communication links are essential to the operation of the new radar, a minimum of 10 Gbit/s bandwidth will be required. 2

3 Power supply: The electrical power consumption of the transmitter site is estimated to be 12 to 13 MW. Access to a power line close to the site is an obvious advantage, but we must accept that a branch line may have to be constructed. RF environment It is essential that the RF (Radio Frequency) environments at the potential construction sites are free from interference. The radar receivers are extremely sensitive to interference from external sources. The external sources that can interfere with Incoherent Scatter Radar measurements are numerous and include: TV/Radio broadcast. GSM/UMTS base stations. Aeronautical and satellite communication. Radio equipment. Consumer electronics: computers, wireless systems, telephone equipment, etc. Besides these main concerns, secondary concerns as sources of RFI (Radio Frequency Interference) can be high-voltage power lines and motor traffic: cars, snowmobiles, four wheelers, etc. The site instrumentation will be housed in shielded equipment containers to prevent radio interference to the receivers. Leasing time Arrangements must be made to secure land, and to get the necessary permits to build and operate the EISCAT_3D facilities without restriction for a period of at least 30 years. Summary of the Site survey Site survey: The objective of the Site survey is to find potential construction sites for the EISCAT_3D radar system, on the basis the Integrated Specification Document for EISCAT_3D: A central transmitting/receiving core, located in Norway, within roughly 100 km of a point at at 69 degrees North and 20.5 degrees East. Two receiving facilities, located at ground distances of km roughly south and west of the transmitting facility, respectively. Two receiving facilities, located at ground distances of km roughly south and east of the transmitting facility, respectively. At each location, the search criteria for a potential construction site are: 3

4 A 100 by 100 meter area, relatively flat and dry. With possibilities to place smaller interferometry antenna arrays extending out to a distance of about 1 km from the system midpoint. The area should be large enough to accommodate supporting instruments. The absence of TV/radio transmitters and cell phone base stations in the neighborhood. Infrastructure data communications, power supply, road. RFI measurements: In parallel to this, the field team made RFI (Radio Frequency Interference) measurements at the potential EISCAT_3D sites, and collected basic data for the E3D receiver design engineers. This included measurements of the field strength and in-band interference. The in-band interference measurements aim at locating weaker signals, inside the frequency band of interest ( ,5 MHz). The field strength measurements aim at locating the strong signals that could potentially cause saturation and distortion in the receivers. The measurements were done using EISCAT-owned equipment: Spectrum analyzer: Rohde & Schwarz FSP7. Log-Periodic antenna: Create N, Mhz. Antenna gain dbi. Discone Diamond D-130J, MHz, Omnidirectional. Low Noise Amplifier: Angle Linear 224GNT, gain = 18 db, NF = 0,4 db Locations surveyed: The locations that have been surveyed during the Preparatory Phase Project are, Ramfjordmoen, Norway Skibotn, Norway Kautokeino, Norway Karasjokk, Norway Bergfors, Sweden Järämä, Sweden Karesuando, Sweden On page 5-10 follows a presentation on two of the potential EISCAT_3D sites that have been investigated by the site survey team, Skibotn and Bergfors. References Deliverable 6.4. Integrated Performance Specification for EISCAT_3D, 7 Nov 2013 Investigation related to location of EISCAT_3D core station, Arvid Övergård Consultancy. 17 Oct

5 EISCAT_3D Site survey LGV, AT Skibotn, Storfjord municipality, Norway Three alternative areas. Location: Area 1: coordinates N E alt. 64 m Area 2: coordinates N E alt. 54 m Area 3: coordinates N E alt. 24 m 5 km southeast of Skibotn. Map and photo, see figure 2 and 3 Ground: Area 1: Grass field, 230 x 100 m. 3 m slope to the south. Max horizon profile angle: 20 deg to the southwest. Area 2: Clear-cut area, 330 x 70 m. 3 m slope to the south. Max horizon profile angle: 20 deg to the southwest. Area 3: Mountain birch forest. Flat area. Max horizon profile angle: 22 deg to the southwest. Infrastructure: Existing gravel road m to main road, E8. The distance to a high power transformer station is 5 km. The military have a fiber optic cable installed and it may be available for EISCAT use. Skibotn Field Station and Optical Observatory, operated by Tromsö University RF surrounding: See RF survey plot example: Figure 4 TV and radio transmitter, distance 7 km to the northwest. FM radio, 24 W. DVB-T (UHF), 100W. DAB radio broadcasts is planned to start in December Neighbours: Brennfjell guesthouse, distance 800 m(area 1) and 1700 m (area 3) Brennfjell camping area, distance 1,5 km. Skibotn recycling deposit, distance 400 m (area 3) and 1500 m (area 1) Others: Land owner: Statsskog SF (state-owned) Area 1 and 2 are leased to a local farmer. 5

6 Figur e 2: Skibotn map. Three alternative areas recorded with a GPS receiver. Skibotn Feild Station 1,5 km to the west Figure 3: Photo of area 1 6

7 Figure 4: Example of RF measurement from the Skibotn area. The allocated EISCAT_3D frequency band is 230, ,544 MHz 7

8 EISCAT_3D Site survey LGV, AT Bergfors, Kiruna municipality, Sweden Location: Coordinates: N E alt. 440 m 40 km northwest of Kiruna. 133 km south (189,4 deg.) of Skibotn (core site) Map and photo, see figure 5 and 6 Ground: The area is an old, abandoned gravel pit. Almost flat. Some correction work is needed. Max horizon angle: 11 deg. (to the northwest). Infrastructure: 500 meter to main road, E10. A 400 kv power line runs over the area. A 10 Gb/s fiber optic cable runs along the railway, distance 750 m. RF surrounding: See RF survey plot example: Figure 7 TV and radio transmitter, distance 8,5 km. FM radio, 30 W. DVB-T (UHF) GSM radio mast, distance 700 m. Neighbours: One private cottage nearby, distance 200 m. Others: Land owner: National Property Board (state-owned) Natura 2000 area. 8

9 Figure 5: Bergfors GPS map. Figure 6: Photo of Bergfors area. 9

10 Figure 7: Example of RF measurement from the Bergfors area. The allocated EISCAT_3D frequency band is 230, ,544 MHz 10

11 Procurement of construction sites Initial contacts with the authorities in Norway and Sweden have been taken in order to start the procedure to procure land for EISCAT_3D construction sites near Skibotn in Norway and Bergfors in Sweden. Skibotn: Tromsö University have contracted a consultant, Arvid Övergård Consultancy, with the objective to perform a preliminary investigation with respect to locating the EISCAT_3D core station in northern Norway. His work is summarized in the report, Investigations related to location of EISCAT_3D core station, October The landowner of the proposed areas is Statsskog SF (state owned). Statsskog is positive to assist in finding area for the core station. Skibotn is part of Storfjord municipality. Locating an EISCAT_3D station in Skibotnvalley will require exemptions from the existing approved County plans. The process to obtain such exemption may take from 9 to 12 months. Bergfors: Bergfors is part of Kiruna municipality. The landowner is National Property Board (state owned). The land is administered by the Couny Administrative Board (Länsstyrelsen). Initial contacts have been made with Kiruna municipality office and with Länsstyrelsen. The area in Bergfors is located inside a Natura 2000 area and is protected by law, (7 chapter 28a Miljöbalken). Our application will be subject to an Natura 2000 examination. This is handled by the Nature department at Länsstyrelsen. The procedure is as follows. 1. Consultations with local stakeholders: Sami community, property owners, etc. EISCAT takes initiative to these meetings. The meetings must be documented and the notes sent to Länsstyrelsen. 2. Environmental Impact Assessment (EIA). EISCAT takes initiative to this. 3. The EIA together with the application is sent to Länsstyrelsen. 4. Länsstyrelsen takes decision. The decision is only based on environmental impact. To possess land for a site we also need permission from Fjällförvaltningen (Mountain area administration)at Länstyrelsen. Fjällförvaltningen will investigate if the planned radar site has impact on other interests, for example reindeer herding. A building permit application is handled by the Kiruna municipality office. Locating an EISCAT_3D station in Bergfors will require exemptions from the existing approved County plans. Lars-Göran Vanhainen 11