Ocean-travel configuration of asset tracking devices
Methods and systems for controlling an asset tracking device and, in particular, determining when an asset tracking device is aboard a ship. The device may have a ship mode in which the device determines it has been loaded onto a ship and in which geolocation is not determined. The device may further have an ocean mode to which it transitions from the ship mode in which it ceases to look for a cellular connection in order to send location reports. The device may detect a beacon signal from a ship-mounted base-station to trigger the ship mode and may detect, or fail to detect, one or more wireless signals or identifiers as the trigger to transition to ocean mode.
1 . A computer-implemented method of operating an asset tracking device, the method comprising:
detecting, at the asset tracking device, using a short-range communication system, a beacon signal broadcast by a base station on a ship;
in response to detecting the beacon signal,
entering a ship mode in which the asset tracking device does not determine its location using a global navigation satellite system (GNSS) chip,
determining whether the ship is in motion based on data from an inertial measurement unit,
setting an interval based on the determination of whether the ship is in motion, and
periodically powering a cellular transceiver to seek a mobile network connection according to the interval; and
determining, based on whether the asset tracking device detects a real-time kinematics (RTK) correction signal, that the ship is at sea and, in response to determining that the ship is at sea, entering an ocean mode in which the asset tracking device does not determine its location using the GNSS chip and does not power the cellular transceiver to seek a mobile network connection.
2 . The method of claim 1 , wherein the beacon signal includes an identifier, wherein the detecting of the beacon signal includes comparing the identifier to stored data listing ship-borne beacon identifiers and locating a match, and wherein the interval is decreased in response to detecting that the ship is in motion based on the data from the inertial measurement unit.
3 . The method of claim 1 , further comprising ascertaining that the asset tracking device is located in a shipping yard but not on the ship, in response to detecting the beacon signal and determining that a received signal strength intensity of the beacon signal is below a minimum threshold level.
4 . The method of claim 1 , wherein determining that the ship is at sea is based on data in the beacon signal.
5 . The method of claim 1 , further comprising detecting the RTK correction signal using an RTK receiver, and causing the asset tracking device to use the short-range communication system to look for the beacon signal after detection of the RTK correction signal.
6 . The method of claim 5 , wherein determining that the ship is at sea includes determining that the RTK receiver no longer detects the RTK correction signal.
7 . The method of claim 5 , wherein detecting the RTK correction signal includes decoding the RTK correction signal to obtain an RTK base-station identifier, and matching the RTK base-station identifier to an identifier in a set of port-associated RTK base-station identifiers.
8 . The method of claim 5 , further comprising, after entering the ocean mode, during a subsequent wake-up time:
detecting the beacon signal using the short-range communication system;
detecting a new RTK correction signal using the RTK receiver; and
in response to the new RTK correction signal, switching from the ocean mode to the ship mode.
9 . The method of claim 8 , further comprising, during a further wake up time, attempting and failing to detect the beacon signal using the short-range communication system and, in response, switching the device from the ship mode to a normal mode of operation in which the device uses the GNSS chip to determine its location.
10 . The method of claim 1 , wherein determining that the ship is at sea includes determining that the device cannot detect any cellular tower signals using the cellular transceiver.
11 . The method of claim 1 , further comprising first using the GNSS chip to determine a geolocation for the device, determining that the geolocation matches a geofence defined for a port area and, in response, causing the device to use the short-range communication system for detecting the beacon signal.
12 . An asset tracking device comprising:
a short-range communication system;
a global navigation satellite system (GNSS) chip;
a cellular transceiver;
a controller; and
a memory storing processor executable instructions that, when executed by the controller, cause the controller to:
detect, using the short-range communication system, a beacon signal broadcast by a base station on a ship;
in response to detecting the beacon signal, enter a ship mode in which the asset tracking device does not determine its location using the GNSS chip and periodically powers the cellular transceiver to seek a mobile network connection;
determine, in response to receiving a real-time kinematics (RTK) correction signal, that the ship is at port, wherein the RTK correction signal comprises a base- station identifier:
identify the port by referencing the base-station identifier with data stored in the memory comprising a set of RTK base station identifiers and respective ports associated with the RTK base station identifiers; and
determine, in response to ceasing to detect the RTK correction signal, that the ship is at sea and, in response to determining that the ship is at sea, enter an ocean mode in which the asset tracking device does not determine its location using the GNSS chip and does not power the cellular transceiver to seek a mobile network connection.
13 . The asset tracking device of claim 12 , wherein the beacon signal includes an identifier.
14 . The asset tracking device of claim 12 , wherein the instructions, when executed, cause the controller to detect the beacon signal by determining that a received signal strength intensity of the beacon signal is above a minimum threshold level.
15 . The asset tracking device of claim 12 , wherein the instructions, when executed, cause the controller to determine that the ship is at sea is based on data in the beacon signal.
16 . The asset tracking device of claim 12 , wherein the instructions, when executed, further cause the controller to detect the RTK correction signal using an RTK receiver, and cause the asset tracking device to use the short-range communication system to look for the beacon signal after detection of the RTK correction signal.
17 . The asset tracking device of claim 12 , wherein, when in the ship mode the asset tracking device powers an RTK receiver to receive the RTK correction signal without powering the GNSS chip.
18 . The asset tracking device of claim 12 , wherein the data is periodically updated by transmissions from a central server to the asset tracking device.
19 . The asset tracking device of claim 16 , wherein the instructions, when executed, further cause the controller to, after entering the ocean mode, during a subsequent wake-up time:
detect the beacon signal using the short-range communication system;
detect a new RTK correction signal using the RTK receiver; and
in response to the new RTK correction signal, switch from the ocean mode to the ship mode.
20 . The asset tracking device of claim 19 , wherein the instructions, when executed, further cause the controller to, during a further wake up time, attempt and fail to detect the beacon signal using the short-range communication system and, in response, switch the device from the ship mode to a normal mode of operation in which the device uses the GNSS chip to determine its location.
21 . The method of claim 5 , further comprising determining that the asset tracking device is in a port or a harbor, in response to detecting both the beacon signal and the RTK correction signal.
22 . The method of claim 5 , wherein the determining that the ship is at sea comprises determining that the ship is at sea, in response to detecting the beacon signal and determining that the RTK correction signal is not detected.
23 . The method of claim 1 , wherein the determining that the ship is at sea comprises determining that the ship is at sea, in response to receiving a flag in the beacon signal.
24 . The method of claim 6 , wherein the RTK correction signal is from an RTK base station at a harbor area.