SWEDISH STARTS USING THIRD GENERATION MARITIME SURVEILLANCE SYSTEM

Olov Fast Swedish Space Corporation Downloaded from http://meridian.allenpress.com/iosc/article-pdf/1987/1/137/2349501/2169-3358-1987-1-137.pdf by guest on 28 September 2021 Box 4207 S-17104 Solna,

ABSTRACT: Since 1981, the has been con- integrated in a Cessna 402C2 (Figure 1). After some further years of ducting daily oil spill surveillance patrols using small aircraft equipped development this aircraft was also slowly becoming too small for the with a remote sensing system. During this time, the use of the aircraft system. The third generation system is still compact enough to fit into has widened to include a number of Coast Guard tasks such as fishery a relatively small aircraft, but long daily patrols require greater endur- protection and sea traffic surveillance. This has necessitated the acqui- ance both of the crew and of the aircraft. sition of aircraft with greater endurance and more loading capability. To accomplish this and to leave room for additional sensors and Two CASA 212 aircraft were delivered in 1986. In response to re- other equipment, it was decided to procure two new CASA 212 quests from Coast Guard operators, the remote sensing system has at aircraft from Construcciones Aeronatiucas SA in Spain (Figure 2). the same time gone through a major revision. One of the main ideas in They were delivered in August 1986 and were equipped with the the third generation system is to give the operator computer aid in remote sensing system during the winter of 1986/87. producing charts and reports for documenting routine missions, viola- tions, and accidents. When necessary, as in the case of an accident, the charts can be immediately telecopied from the computer in the aircraft to a Coast Guard Command Center to ensure a quick and proper CASA 212—Some technical data response. Maximum take off weight 7,700 kg Maximum payload incl. crew 2,770 kg Cabin volume 22 m3 Length 16.2 m Wing span 20.4 m Take off distance 649 m The Swedish Coast Guard is responsible for all regular non-military Landing distance 615 m supervision of Swedish Coastal waters. To fulfill this task, a natural Maximum cruising speed 198 kn approach has been to develop technical means for detection, identifi- Endurance 6h cation, and documentation of all kinds of relevant incidents. When oil Fuel consumption 500 L/hr pollution became a threat to the environment, the technical develop- ment work was focused on airborne remote sensing devices for de- tection and monitoring of oil spills. The first field experiments in Sweden with remote sensing instru- Sensors. The sensor images given as examples are all from an ex- ments for oil spill detection were carried out in 1972. During the perimental oil spill in June 1985, as part of a field trial organised by following years several field tests have been performed and evaluated. IKU (Continental Shelf Institute) in Trondheim, Norway. The follow- In 1973, the Swedish Coast Guard started a close cooperation with ing discussion of sub-systems is in the order in which they are pre- the Swedish Space Corporation, established one year earlier. The sented, counterclockwise from the upper left corner of Figure 3. Space Corporation is a state-owned, limited corporation under the The camera system. The cameras are used for photographic evi- Ministry of Industry with responsibility for technical execution of the dence. They are Nikon professional cameras, modified for printing national space and remote sensing programs in Sweden. The Space date, time, position (lat. and long.), heading, altitude, and other Corporation had the technical expertise that was necessary in nego- mission data on each photo (Figure 4). The camera computer collects tiations with suppliers of equipment, and for development of hard- these data from the aircraft navigation system, compass, and altimeter ware and software. The cooperation between the Space Corporation and feeds them on to annotate all sensor recordings made in the and the Coast Guard gradually grew into a companionship. The aircraft. Coast Guard formulated the operational requirements and the The SLAR (side-looking airborne radar). This is the main sensor, Space Corporation conducted the technical development and system giving a large area coverage for oil spills and ships (Figure 5). Oil integration. shows up as dark areas against the sea clutter background, and ships The Swedish development has been continually reported to the Oil and boats as brighter spots. The position of a target is automatically Spill Conference.1'2'3 For reference, a brief review of the system and calculated when the operator marks it on the screen with a cursor. of the latest field trials is given below. One of the improvements in the third generation system is the pos- sibility to keep a record, with time and position, of several targets at the same time. The record of targets and observations can be auto- matically printed out, plotted on a chart, or fed as waypoints into the System overview navigation system. The IR/UV scanner system. This subsystem displays thermal infrared Aircraft. In the early stages of development the Swedish Coast (8-14 microns) in one channel and ultraviolet (0.3-0.4 microns) in the Guard used small Cessna 337s.1 The second generation system was other. Either or both images are presented in real time as a rolling

137 138 1987 OIL SPILL CONFERENCE Downloaded from http://meridian.allenpress.com/iosc/article-pdf/1987/1/137/2349501/2169-3358-1987-1-137.pdf by guest on 28 September 2021

Aircraft with complete Maritime Surveillance System Figure 1. The second generation system has been operated for five including Microwave Radiometer. years in this Cessna 402C. The image also shows (left) the antenna configuration of the scanning microwave radiometer, mounted in a The rotating platform with four antennas. pod under the aircraft fuselage.

Image link. The original image link works on X-band for quick transmission of large amounts of data, as when cooperating with ships in a cleanup operation or sending ice information to icebreakers. This link is line-of-sight and designed to work at close distances only. For transmitting information over longer distances, it is necessary to reduce the information further, into reports and charts that only consist of black lines on white background. It is then possible to use a low data-rate link for telecopying the information. In the third generation system, computer aid is available to the operator for pro- ducing this kind of information from the sensor images. Data storage and TV monitors. All remote sensing data is presented as TV images in real time on the system operator's color monitor. A much-appreciated feature is a slave monitor for the pilots, so that they can also see the sensor information and get some immediate feedback on the results of the mission. All data can be stored on digital tape for later replay and analysis. Hard copies are also immediately available in the aircraft, to save for quick reference later or for stapling onto reports. In the third genera- tion system, the reports themselves are generated in the computer and can be printed in the aircraft or on the ground via radio. map on the operator's TV screen. It can be presented in color or black and white (Figure 6). These images can be combined with those from the microwave radiometer. Scanning microwave radiometer. This system gives a real-time thick- Field trials ness map of an oil spill. The image is geometrically corrected and presented in equal scale beside the IR (or UV) image on the TV The Swedish Coast Guard has taken part in a number of oil spill screen (Figure 7). When the rolling image is stopped and the scene trials for verification of the system. The latest international ones were frozen on the display, the computer also produces a volume estimate the IKU one in June 85, from which the illustrations are taken, and of the oil spill. This can be done both in replay and in live mode, due Archimedes II, organized by the Joint Research Centre of the Com- to the digital recording of sensor data. mission of European Communities. The latter trial took place off Television system. TV cameras and video tape recorders can be Helgoland in the North Sea. A number of national field trials have connected to the system for documentation purposes. Photographic also been organized by users of the Swedish system, a list that now material is generally preferred, since the video images are of limited includes the Federal Republic of Germany, Great Britain, the Nether- quality. lands, Norway, and the People's Republic of China. CLEANUP OPERATIONS 139 Downloaded from http://meridian.allenpress.com/iosc/article-pdf/1987/1/137/2349501/2169-3358-1987-1-137.pdf by guest on 28 September 2021

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Figure 2. Two new CASA 212 aircraft have been procured by the Swedish Coast Guard to operate with the third generation maritime surveillance system.

Nav Data from A/C

Scanning Signal C0—© Handheld Camera Camera Computer Processor SSP-1000 Monitor Operator Monitor Pilots

IR/UV Scanning Head Micro Wave Radiometer TV Camera Pod

Ground Ground Station for Data Evaluation Terminal (DET) Image Link

Figure 3. Block diagram of the 2nd generation Maritime Surveillance System—In the third generation, the SSP-1000, DSU-1200, FLI-1300 and SLAR Control Panel are integrated into a new presentation system. 140 1987 OIL SPILL CONFERENCE

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Figure 4. Photo of the command ship taken from the Swedish Coast Guard aircraft during the IKU oil spill trial in June 1985—annotation with date, time, position, aircraft heading, altitude, etc. at top of picture

Figure 6. IR/UV image of the same oil spill, IR to the left, UV to the right, 200 m between crossmarks—thicker parts of the oil in top of image, ship at bottom, annotation below the image

on his judgment of the texture and edge quality of patches in the radar image. Figure 5. SLAR image of oil slick (dark spot upper left) with ship As another example, the activity of fishing fleets can be judged appearing as a white spot in the oil—10 km between crossmarks, from the SLAR image, based on experience in seeing the ships several annotation at bottom of image times in different situations both with the eyes and with the radar. A further testimony to the importance of experience in using re- mote sensing images was given in the winters of 1985 and '86, when receiving stations for SLAR images were placed on a couple of Swedish icebreakers. The crew on the icebreaker bridge was immedi- Operational experience ately able to draw a lot of conclusions from the SLAR images, due to the fact that they were already quite experienced in watching their Through the continuous joint development effort of the Swedish ice environment with radar, both from the icebreaker and from a Coast Guard and the Swedish Space Corporation, the airborne re- helicopter. mote sensing system has now become a fairly complete tool for oil Knowing the need for experience in interpreting the images, the spill surveillance. The aircraft carries sensors for detecting, mapping, approach when designing the image links was to let the operator in the quantifying, and documenting an oil spill incident. aircraft select a few good images for sending to the ground. The integrated system has been in operational use for the past In the field trials, when the image link ground station has been five years, while bits and pieces of it have been under constant placed on the ship leading the trial, an experienced operator has also development. been present on the ship to interpret the images. This way, the useful- During this time of operational use of the system, a lot of experi- ness has been convincingly demonstrated every time. The on-scene- ence has been gained on how to design it to fit the users. Several ideas commander gets a lot of information both on the extent of the oil spill and suggestions for improvement have come from the system oper- and on the progress of the cleanup operation. ators and from the Coast Guard headquarters. In operational Coast Guard use, however, it turns out that major oil A leading principle in the development work has been that all spills are not frequent enough to give surface personnel regular train- information should be processed and interpreted in the aircraft. This ing in interpreting the remote sensing images. has been considered necessary because even though the remote sens- The effort of giving regular training to all personnel that may be ing images are computer enhanced and presented in a maximum involved in interpreting remote sensing images is very costly. Also, as easy-to-read way on the TV-monitor, the experienced operator still stated above, the eye of the experienced operator adds quite a lot to finds much more information than the inexperienced. For instance, a the image. It was therefore decided that the way to go is to have the skilled operator can tell an oil spill from other phenomena in the system operator refine the information even further in the aircraft. SLAR image with an accuracy hardly believed by the designers, based This has been the major requirement for the new presentation system CLEANUP OPERATIONS 141

The system is also designed for integrating a FLIR (forward- looking infrared) and a laser fluorosensor to aid in identifying the polluter and the pollutant, especially at night or in bad weather. The FLIR will get its viewing direction from the computer, using coordi- nates from the target marked in the radar image. 2. Reduced operator load. Using the experience from several thou- sand hours of operational flights, it has been possible to reduce the number of sensor controls to a minimum. By careful grouping of the controls, the operator's workload can be kept down. Also, an oper- ator can start working after only a few days of training. This makes it possible to continue adding sensors while still needing only one per- son for system operation. The low workload is essential in order to give the operator time to work on producing information in the aircraft. 3. Improved reporting. To aid the operator in conveying informa- Downloaded from http://meridian.allenpress.com/iosc/article-pdf/1987/1/137/2349501/2169-3358-1987-1-137.pdf by guest on 28 September 2021 tion to Coast Guard ships and command posts, the new system con- tains a number of facilities for semi-automatic generation of reports. The basic report is presented as an electronically stored chart, which is completed partly automatically, by plotting all remote sens- ing recordings made during a mission, and partly semi-automatically by plotting and listing the observations made by the crew. Other types Figure 7. Image of the thicker part of the oil spill. IR to the left, 35 of report sheets are available in the computer, such as map overlays GHz Microwave radiometer image to the right—The latter is coded to made interactively from SLAR scenes and text pages made by typing give thickness, 0.2 mm per color, meaning that the thickness mea- in full or by completing electronically stored forms for describing sured in the middle of the slick is 0.6 mm. Volume discharged: 10 observations. tons, volume measured: 5 tons The charts and reports can then be telecopied to headquarters or to a local command to serve as a basis for decisions on when, where, and how to use ships and shipborne equipment for maximum effective- ness. It is, of course, also possible to print the reports in the aircraft and, in fact, the primary reason for going on to develop a third genera- to put in the mail or use as statistics. tion system. Conclusion Further development The airborne remote sensing system has on numerous occasions shown its usefulness to the Swedish Coast Guard, and it has become To meet the extended requirements and in order better to fit the an integrated part of the Coast Guard organization. airborne remote sensing package into the Coast Guard organization, The present work aims at making it a refined tool for headquarters the new presentation system was designed. It gives the operator in the in finding the optimum distribution of resources for every incident. aircraft a set of tools for enhancing and commenting on the remote sensing images before passing them on to other units. The front end of the third generation system basically consists of an image analysis workstation and a personal computer. References The new presentation system aims at three goals: 1. Open to integration of new sensors. In the first installation of the 1. Backlund, L., 1979. Airborne oil spill surveillance systems in third generation system, it is already more closely integrated with the Sweden. Proceedings of the 1979 Oil Spill Conference, American aircraft navigation system and forward-looking radar. This will both Petroleum Institute, Washington, D. C., pp305 -311 serve to document incidents better and to aid in feeding back informa- 2. Backlund, L. and L. Holmström, 1983. Second generation oil spill tion to the pilots. For example, the position of oil spills detected in the and maritime surveillance systems now operational in Sweden. SLAR image can be presented to the pilots as navigation waypoints Proceedings of the 1983 Oil Spill Conference, American Petroleum and as synthetic targets in the forward-looking radar. This will greatly Institute, Washington, D.C., pp349-353 facilitate the tracking of incidents, particularly when approaching in 3. Fast, O., 1985. Monitoring an oil spill experiment with the Swedish bad weather to make a detailed map. Maritime Surveillance System. Proceedings of the 1985 Oil Spill An integrated VHF direction finder facilitates the finding and iden- Conference, American Petroleum Institute, Washington, D.C., tification of ships. pp597-602 Downloaded from http://meridian.allenpress.com/iosc/article-pdf/1987/1/137/2349501/2169-3358-1987-1-137.pdf by guest on 28 September 2021