Section 5. Potential Applications (Test Beds)

Section 5.1. Real AIS AtoN

Some Real AIS AtoN units may be connected to buoy equipment (lantern, battery, RACON, etc.) and supply information about their status.

One of the main benefits of Real AIS AtoN is the broadcast of the floating aid’s position in real time. Depending on the length of the chain used to anchor it, the magnitude of the tides and the water levels, a floating aid to navigation can move several metres from its charted position, leading mariners to assume it is off position. However, and as illustrated by the black circle in Figure 5-2, the position assigned to a floating aid to navigation may cover a large area. The aid is considered within its assigned tolerance radius as long as it remains within a certain distance of its charted position. If this tolerance is exceeded over a certain period of time, the Real AIS AtoN will broadcast an “Off Position” message (see Figure 5-3). The “Off Position” message will stop if the aid returns to its assigned location circle.

The “Off Position” function is useful for both mariners and the authorities in charge, as it provides remote access to this information, allowing appropriate action to be taken.

A Real AIS AtoN may be used to broadcast one or more virtual or Predicted Synthetic AIS AtoN.

Section 5.2. Virtual and Synthetic AIS AtoN

Virtual AIS AtoN can be deployed quickly, and the accuracy of their positions allows them to be used in various situations for the benefit of mariners.

The Canadian Coast Guard is not currently conducting any tests with Monitored Synthetic AIS AtoN. However, tests with Predicted Synthetic AIS AtoN are underway across Canada. These are broadcast on fixed aids to navigation and help to locate them, even in situations where the radar screen is cluttered.

Section 5.2.1. Reference Points - Virtual and Synthetic AIS AtoN

Virtual and Predicted Synthetic AIS AtoN can help validate the accuracy of navigation equipment, particularly in situations where a discrepancy is observed between the radar echo and the position of the AIS AtoN symbol (refer to the validation process at Section 4.4). To this end, a diamond-shaped schematic has been developed using Virtual and Predicted Synthetic aids to navigation (see Figure 5-5). This schematic contains the following information to help validate broadcast positions:

• The name of the AIS AtoN;
• The geographical coordinates; and
• The azimuth and distance between each point.

The schematic of the four reference points is oriented toward True North.

An initial test bed was made with this schematic at the entrance to the Halifax Harbour in Nova Scotia. The diamond shape is displayed on ECDIS as well as on radars. On-board instruments make it possible to check whether the displayed information is identical to that shown on the schematic.

This test bed revealed that the only use of Virtual AIS AtoN did not detect a radar positioning error, as no echo is reflected by the V-AtoN (see Figure 5-8).

To overcome this deficiency, the reference point schematic was modified to include a Predicted Synthetic AIS AtoN broadcast on a fixed aid to navigation that will reflect the radar signal (see Figure 5-9).

In collaboration with the pilots, it was agreed to broadcast the reference point schematics near the pilot boarding stations to optimize their use quickly.

Section 5.2.2. Identification of Radar Marks

Virtual AIS AtoN can also make it easier to identify radar marks used by mariners, but that are not considered as aids to navigation. A test bed was initiated at Sainte-Croix along the St. Lawrence River where a Virtual AIS AtoN is broadcast from a cell tower (see Figure 5-10). Given that the tower is far from shore, the radar echoes from surrounding objects make it difficult to locate. The Virtual AIS AtoN symbol displayed on the tower allows to quickly detect the targeted location. Other similar examples are being tested across Canada.

Figure 5-11 illustrates the test bed conducts in Halifax Harbour at the Bedford Institute of Oceanography wharf. The fixed aid to navigation at the end of the wharf is a good radar mark. The symbol for the Synthetic AIS AtoN “OCEANO WHARF” helps to identify the aid to navigation, especially on the radar image where the diffused echo from the wharf prevents the fixed aid from being identified.

At Lac Saint-Louis (in the St. Lawrence Seaway, Figure 5-12), Synthetic AIS AtoN are broadcast on the front and rear ranges in the Kahnawake area. Figure 5-13 illustrates the benefit of using the Predicted Synthetic AIS AtoN to help locate fixed aids to navigation on the radar. The photo was taken in December 2017 as the ice cover began to form. The AIS AtoN symbols help to rapidly locate the position of fixed aids to navigation on the radar screen cluttered with ice echoes.

A similar test bed was set up on ranges in the Fraser River in British Columbia, and pilots observed the added value of the Predicted Synthetic AIS AtoN for gyro error detection and validation of the course made good (Figure 5-14).

Figure 5-15 illustrates again the range tracking enhancement on the radar using AIS AtoN symbols.

Section 5.2.3. Protecting Whales - Identification of Dynamic Sectors

Virtual AIS AtoN have also been used in the Gulf of St. Lawrence as a complementary measure to limit the risk of collisions between transiting vessels and North Atlantic right whales. Virtual AIS AtoN have been positioned at all four corners of each dynamic speed reduction zones. Virtual AIS AtoN were broadcast only when the speed reduction was in effect in one or more zones. By clicking one of the symbols, a message was displayed indicating the zone and the speed limit (see Figure 5-17).

This application enabled rapid interaction with mariners and informed them of the status of the zone through which they were transiting.

Section 5.3. Conclusion

Various test beds were used to validate the reliability of the broadcasted AIS AtoN signal. In addition, the AIS AtoN facilitated the detection of potential errors on shipboard equipment by comparing the displayed information between the systems (PPU, ECDIS, radar). Another significant benefit is that it makes it easier to locate the radar echo in all weather and traffic conditions.

These preliminary observations justify the proposal to gradually introduce AIS AtoN in the Aids to Navigation service. However, continued validation on the various equipment on board vessels is essential to familiarize users with the new technology and instill confidence in it.

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