The present invention refers to an ice buoy to be placed on ice in order to measure movements of ice.

Ice buoys are used in the Artie area for reporting ice movements on a small or a large scale. The ice buoys are deployed on the ice. Each buoy is provided with equipment to receive GPS signals to determine the position of the buoy and a transmitter arranged to transmit the position of the buoy to a base station via AIS (Automatic Identification System) or through satellite networks. There is a problem with both of these methods since they yield inadequate accuracy for ice drift calculations and are very expensive.

The problem with an inadequate accuracy is due to that the AIS system transmits the position of the buoy depending on the speed of the movement of the buoy. Since the ice moves slowly, such as 0.1 to 1 knot, the transmitter will send a new position after for example 50 meters from the latest position. Ice that moves may move in spirals and other patterns and fairly sharp turns, where the extension of such a spiral or turn is less than 50 meters. This gives that when making mathematical prognosis for the movement of the ice, the input values for different parameters such as how the ice actually moves, the buoys yield incorrect positions on how the ice actually has moved, which incorrect values will be used as input values. Such bouys are deployed in different ways. One way is that a person manually place the bouy on the ice. Another way is to deploy the bouy by a low altitude drop, such as 20 to 100 feet, from a helicopter. For example information about the movements of the ice is used to predict where icebreakers shall break ice in relation to the position of a ship for offshore drilling. Ice movements prognoses are made and are fed into among others the navigation system of a ship. This enables the crew to see on a screen how the ice has moved and how it is expected to move. Hereby the crew can move the ship to a good position relative to the ice.

The navigation systems of ships are designed to mark the position of a ship or a buoy on a screen on the bridge of the ship according to the A1S standard. Such buoys are normally deployed by a person placing the buoy on the ice. This is costly and time consuming since a ship must manoeuvre to the location where the buoy shall be placed. Normally at least 3 to 7 buoys have to be deployed in order to make it possible to make a prognosis of the move- ments of the ice.

The present invention refers to an ice buoy which can be put on the ice in a more efficient way and to a lower cost. Thus, the present invention relates to an ice buoy to be placed on ice in order to measure movements of ice, which buoy is provided with a GPS device and a transmitter for transmitting its position and identity to a receiving party, such as a ship or vessel, which is provided with a navigation system that is adapted to receive signals according to AIS standard, and is characterized in, that the ice buoy has an elongated tube like housing, in that the buoy has a barb at a first end of the housing, which barb has a sharp front point, in that a power package, a transmitter package containing said transmitter, an electronics package and said GPS device are located on top of each other inside said housing.

Below the present invention is described in greater detail together with an exemplifying embodiment of the invention, where

- Figure 1 is a block diagram

- Figure 2 shows a buoy.

In Figure 1 an ice buoy 1 according to the invention is shown. The ice buoy 1 is to be placed on ice in order to measure movements of ice. The ice buoy is provided with a GPS device 11 and a transmitter 9 for transmitting its position and identity to a receiving party, such as a ship or vessel, which is provided with a navigation system 6 that is adapted to receive signals according to AIS standard.

According to the invention the ice buoy 1 has an elongated tube like housing 7. The buoy 1 has a barb 17 at a first end of the housing, which barb 17 has a sharp front point.

A power package 8, a transmitter package containing said transmitter 9, an electronics package 10 and said GPS device 11 are located on top of each other inside said housing 7.

According to a preferred embodiment of the invention there is a damper 18 provided close to the first end of the housing 7 and there is a damper 19, 20, 21 located between the power package 8 and the transmitter package 9, between the transmitter package 9 and the electronics package 10 and a between the electronics package 10 and the GPS device 11. The dampers 18-21 are made of a foam material that will compress to a certain extent when the barb 17 of the ice buoy hits the ice.

According to a preferred embodiment of the invention the housing 7 is made of fibre glass or aluminium.

The barb is preferably a metal barb 16 suitable for putting the buoy 1 in the ice so that the buoy 1 is sitting in the ice in an upright position.

It is preferred that the length of the ice buoy 1 is about 1 meter and has a diameter of about 50 millimeters.

The length of the dampers (18-21) is preferably 30 - 60 millimeters .

According to still another preferred embodiment of the invention the location of the different parts in the housing is from the said first end towards the opposite second end of the housing the power package 8, the transmitter package 9, the electronics package 10 and said GPS device (11) .

The power package 8 consists of a battery pack of Lithium-Ion or low temperature Lithium batteries or any other suitable battery that operate at low temperatures.

The transmitter 9 has an output power of 1 to 10 W. The transmitter uses a direct digital modulation technique. Demodulation is handled by said receiver having digital signal processors . The electronic package is arranged, to handle and create the signal to be transmitted by the transmitter 9. Said signal contains the coordinates of the buoy created by means of a proprietary signal protocol. The electronic package is ar- ranged to receive the GPS signals, assemble data packages and to control a transmitter section in order to deliver messages regarding the position.

The electronic package is designed to deliver a position two times a minute.

The received GPS signal contains a clock signal giving actual time. Each of the buoys 1 is programmed to transmit its position within a time window when no other buoy is transmitting its position.

The buoy according to the invention can be placed on the ice in different ways. One way is to manually place the buoy on the ice.

However, due to the design of the ice buoy 1 it can dropped from a helicopter from an altitude of 20 to 100 feet.

Alternatively the ice buoy can be propelled into a ballistic path from a launch tube by means of compressed air.

To drop the ice buoy from a helicopter or to launch it into a ballistic path means that a ship does not have to be manoeuvred to the position where the ice buoy shall be placed in order to monitor the ice movements in order to be- able to make prognosis regarding the ice movements. According to yet another preferred embodiment said GPS device 11 is arranged to produce unfiltered position information as regards so called Speed filtering, in that the unfiltered position information is caused to be transmitted by the transmitter 9 to a base station onboard a ship or vessel.

This gives that the transmitter 9 can be caused to transmit the position of the buoy 1 with a predetermined time frequency regardless of the speed of movement of the buoy.

In Figure 1 an ice buoy 1 is shown together with a receiver 3 of a base station on a ship or vessel. In figure 1 reference numeral 6 designates a navigation system of the ship or vessel and the reference numeral 12 designates a screen showing the positions of ice buoys 1 or their movements .

In case the ice buoys transmits a position information signal that has not been Speed filtered the receiver 3 of the base station is connected to a converter 5 arranged to covert the received position information to a signal protocol according to AIS (Automatic Identification System) . Thereafter the converter 5 in caused to feed the converted signal into said navigation system 6 of the ship or vessel.

The converter 5 can be a computer or it could be integrated in the navigation system 6,

The above mentioned converted signal which is fed by the converter 3 to the navigation system of the ship or vessel is caused to be a signal according to Ν ΕΆ standard. This means that the position of the buoys 1 will appear with their respective identity on a screen 12 on the bridge of the ship or vessel as if the position information had been transmitted according to the A1S standard. In Figure 1 the stars 13, 14 mark two respective buoys 1. The navigation system 6 may also display the movements of the respective buoys during a certain time back. In Figure 1 the curves 15, 16 illustrates the movements of the buoys 1 and thereby the ice from a certain time back in time.

Above several embodiments of the invention has been described. However, the present invention can be varied as to materials and dimensions .

Thus, the present invention shall not be restricted to the above described embodiments, but can be varied within the scope of the claims.