|
|
From Ship to Shore to Satellites
By Mary Jo Wagner
It used to be that the Marine Communications & Traffic Services (MCTS) branch of the
Canadian Coast Guard was primarily interested in any target less than 50 miles from
Canada’s shores. But then September 11th came, and as it’s happened to so many
government agencies, the MCTS’ service responsibility changed. Now the MCTS needs
to receive advance reports from vessels over a thousand miles off the coasts of Canada.
This increase in the branch’s “line of sight” requirements has prompted the MCTS to
augment its existing conventional vessel-monitoring methods including shore-based radar
and vessel call-ins with new technological approaches such as automatic identification
systems (AIS) and, most recently, it began to experiment with RADARSAT-1 satellite
information. Both technologies could help the MCTS personnel, along with government
colleagues in other agencies such as the Department of National Defence, to keep an eye
on what’s beyond the horizon.
Safety first
The MCTS branch operates five centres that control a total of 32 remote radio and eight
radar sites along the West Coast of Canada. It is one of the seven marine programs within
the Canadian Coast Guard. Its primary mission is to save lives at sea and to provide
accurate vessel traffic and safety information to transiting vessels. With a distributed
network of stations, radar receivers and radio frequencies, MCTS personnel continuously
monitor international distress and calling frequencies, coordinate rescue efforts,
disseminate weather and safety information and track the movements of commercial,
government, fishing and other types of vessels navigating within traffic sector
boundaries.
Tracking targets
Any vessel planning to enter Canadian or US waters must send a 24-hour-advance report
and a 96-hour-advance report, which includes its position, course and speed. Although
the 24-hour report has been in effect for a number of years, the 96-hour-report came into
effect as a result of Sept. 11th.
To monitor this vessel traffic, the MCTS uses a host of surveillance methods. Inmarsat-C
satellite communication is used to send and receive the ship reports, which are
transmitted to the MCTS’s marine information center located in Vancouver, BC. Shore-
based radar picks up shipboard radar signals within 50 miles of shore and tracks their
location, course and speed to the marine information center. In areas where no radar is
available the MCTS uses “dead reckoning” - the ship’s captain calls in his position,
course and speed. And recently, the MCTS began test trials of AIS, a mandatory initiative
that requires all newly built vessels over 300 tons to have a shipboard transponder, which
will use internationally designated VHF frequencies to transmit their positions. AIS is
being phased in over the next five years, starting with all cruise ships and tankers, which
must be fitted with AIS in 2003. There is a very good chance that this phase-in period
will be fast tracked as a result of Sept. 11th.
Tracking all the ship traffic is MCTS’s proprietary vessel monitoring system called
VTOSS (Vessel Traffic Operations Support System). A computer system similar to an air
traffic control system, VTOSS plots and continuously tracks all reported vessels within
800 miles of Canadian territory. Each time a vessel’s location, course and speed are
reported in, a color-coded icon resembling a tiny lollipop appears on the VTOSS screen.
The color indicates the information source (Radar, Inmarsat, AIS, etc) and the “lollipop
stick” indicates the course the vessel is heading. Clicking on any icon will provide
personnel with the ship’s attributes such as its name, its course and its speed. The icons
then move across the display as VTOSS continues to track the vessel.
Although the MCTS’s surveillance methods and tools provide staff with an effective
system to monitor vessels, the system is vulnerable to two overriding issues. One is that
to some extent vessel monitoring is based on an honor system - MCTS staff trusts that
ship captains will report in and provide accurate information. And second, legislation
dictates that vessels less than 20 meters are not required to report in.
It is in this arena where information derived from RADARSAT-1 satellite imagery could
be of benefit.
From shore-based to satellite-based radar
To try to safeguard against unknown vessels, the MCTS began a two-week trial in April
in conjunction with RADARSAT International (RSI) to test the strength of RADARSAT
as an operational surveillance tool.
At the beginning of the project, ScanSAR Narrow imagery over the West Coast EEZ was
acquired twice daily - once in the morning and once in the evening - and downlinked to
the Gatineau, Canada ground station for processing and interpretation. After the initial
results were in, the decision was made to switch to Single Beam, W2 and W3 because
critical information such as speed and heading information were more easily derived
from this beam mode than from ScanSar Narrow. RSI personnel process the imagery to
identify possible targets and then compile text-based ship reports complete with the date
and time each image was acquired, the latitude and longitude of the scene, the wind speed
and sea state, the presence of any environmental risks such as oil slicks and the location,
course direction and speed of each target identified. The report is sent to an FTP site for
VTOSS to automatically access and to download.
Once MCTS personnel retrieve the RADARSAT-derived ship report, they ingest that
data directly into VTOSS and all vessel positions are automatically plotted on the
VTOSS display, complete with a color-code to indicate its RADARSAT-derived
information. MCTS staff can then view the newly plotted vessels and verify who they are
and their positions through other information sources such as call-ins or shore-based
radar. If any vessel doesn’t correspond to any reported data or any other vessel location,
then it is coded as suspect. As the DND has a direct link to MCTS’s VTOSS, personnel
can then note the number of suspect vessels and dispatch aircraft to possibly investigate.
Vtoss4- April 11: RADARSAT-derived ship reports are ingested directly into
VTOSS and all vessel positions and they’re course heading are automatically plotted on
the VTOSS display. Those icons in red indicate they’re RADARSAT-derived
information
Vtoss6-April 11: VTOSS plots and continuously tracks all reported vessels
within 800 miles of Canadian territory. MCTS personnel can then use the information to
verify and to monitor vessel activity to promote efficient movement of marine traffic. The
trajectory lines shown here, for example, project where vessels could collide if they
continue on their same course. Staff could suggest routes to avoid any accidents.
Imagery is also being acquired over eastern Canada to provide ship reports via the
Internet to the MCTS’s colleagues on the East Coast.
To date, the RADARSAT-derived ship reports have proven useful to the MCTS,
broadening the agency’s view of ship traffic and detecting vessels that might have
otherwise gone undetected. By integrating RADARSAT data automatically into VTOSS,
and ultimately into the DND’s operational system, MCTS personnel have a layer of
information previously unavailable, providing a valuable complement to their existing
surveillance tools. In particular, RADARSAT-1 data will supplement AIS data to identify
vessels not equipped with AIS or those that are not reporting because AIS is inoperative
or deliberately shutdown to elude detection.
Provided the MCTS can receive ship reports on a consistent basis and the accuracy of the
target’s speed and direction can improve, RADARSAT-1 could be another valuable
monitoring tool to help the MCTS fulfill its mission.
This article was first published in RADARSAT International’s e-Reflections Newsletter Issue 4/Vol 2
and has been reprinted with the permission of RADARSAT International - Copyright (c) 2002, RADARSAT International.
Related Weblinks:
Submit a technical paper or comments to
imaging@geocomm.com
More GeoImaging Features
|
|
Sponsored by:
For information
regarding
advertising rates
Click Here!
|
