Apparatus for offshore GNSS reference station, offshore GNSS positioning system, method for generating offshore positioning reference data and method for determining a position

Abstract

Apparatus for offshore GNSS reference station; offshore RTK and PPP GNSS reference stations; offshore GNSS positioning systems, real-time kinematic and real-time kinematic network; method for generating offshore positioning reference data and real-time kinematic reference data; method for determining a position; and method for determining the position of an underwater communications unit. Apparatus for offshore GNSS reference station (102), comprising: a processing feature (118) and an acoustic unit for underwater communications (115). The acoustic unit for underwater communications (115) comprising an underwater acoustic transducer (116), the acoustic unit for underwater communications (115) being arranged to cooperate with the processing feature (118) in order to calculate a position.the equipment (102) further comprising a GNSS antenna location (128) and an orientation determination unit (124) operationally coupled to the processing device (118). The orientation determination unit (124) is arranged to determine an orientation associated with the GNSS antenna location (128) and the acoustic transducer (116) of the acoustic unit for underwater communications (115).

Description

1 / 50 “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, OFFSHORE GNSS POSITIONING SYSTEM, METHOD FOR GENERATING OFFSHORE POSITIONING REFERENCE DATA AND METHOD FOR DETERMINING A POSITION. PREAMBLE

[0001] This patent application relates to an apparatus for an offshore GNSS reference station of the type that, for example, can support offshore geolocation. This patent application also relates to an offshore GNSS positioning system of the type that, for example, supports offshore GNSS geolocation. This patent application further relates to a method for generating offshore positioning reference data, the method being of the type that, for example, supports offshore GNSS geolocation. STATE OF THE ART

[0002] In the field of geolocation, Global Navigation Satellite Systems (GNSS) have been developed so that the position of an individual and / or vehicle can be determined. In such systems, geolocation devices are carried by the individual or vehicle and receive spread spectrum signals that are broadcast from a subset of a constellation of satellites orbiting the Earth. The signals received by the geolocation device are processed according to a known technique, applying an unambiguous code, pseudorange observations, and the principle of trilateration, in order to determine the location of the geolocation device. Petition 870240097696, dated 11 / 14 / 2024, page 16 / 143 2 / 50, thus allowing the position of the individual or vehicle to be determined. The intrinsic accuracy of a typical GNSS is a few meters, which is adequate for a wide variety of positioning applications. However, some applications require positioning at the decimeter or centimeter level. In this regard, there are so-called "GNSS augmentation" techniques for better accuracy.

[0003] In this regard, for applications requiring a higher level of precision, a Real-Time Kinematic (RTK) positioning technique can be employed. The technique requires a “fixed base station on solid ground equipped with a GNSS receiver capable of geolocation, the location of the GNSS receiver antenna being known. The RTK technique is based on removing common errors from both the roving geolocation device and the GNSS receiver at the base station. More specifically, the RTK technique uses ambiguous carrier phase observations that are orders of magnitude more precise than the aforementioned technique, which employs unambiguous code observations.Observations of the codes and carrier phase associated with the base station are transmitted to the roving geolocation device, whose GNSS receiver then processes its own observations and the received observations of the codes and carrier phase associated with the base station, resolving relative carrier phase ambiguities and providing the exact position in centimeters of the geolocation device relative to the base station. In this respect, high-precision GNSS receivers can quickly resolve carrier phase ambiguities, for example. Petition 870240097696, dated 11 / 14 / 2024, p. 17 / 143 3 / 50 example, within one minute.

[0004] A variant of the RTK technique is known as “network RTK” and employs multiple base stations, which allows for more accurate modeling of distance-dependent errors caused by atmospheric variations, and errors in orbital satellite models disseminated by GNSS satellites. The geolocation device can therefore be provided with ideal location-specific data, for example, observations corresponding to the so-called “Virtual Reference Station” in the vicinity of the geolocation device. As such, Network RTK can be used to provide a service equivalent to that provided when using the RTK technique described above, but using fewer base stations than a set of independent RTK base stations.

[0005] However, the ability to resolve carrier phase ambiguities depends on the distance between a given base station or Virtual Reference Station and the geolocation device (known as the baseline). For example, where the baseline between the base station and the geolocation device exceeds approximately 40 km, the resolution of carrier phase ambiguities may be impeded.

[0006] When the distance from a geolocation device to a ground-based RTK GNSS base station prevents the so-called fixed ambiguity solution by the RTK technique, the GNSS receiver of the geolocation device, if properly equipped, can revert to employing a differential 'floating' GNSS technique, which is an order of magnitude less Petition 870240097696, dated 11 / 14 / 2024, page 18 / 143 4 / 50 requires what the fixed ambiguity solution by the RTK technique mentioned above requires.

[0007] Alternatively, if registered, the geolocation device may employ a GNSS Precise Point Positioning (PPP) technique. PPP employs a global network of ground-based reference stations to compute corrections to the GNSS satellite clock and orbit models (ephemeris data). The corrections are disseminated to the geolocation device, typically via satellite or internet, and applied by the geolocation device's GNSS receiver to calculate a decimetric level or the geolocation device's best position without the need for a GNSS base station. The PPP technique may also support modeling and dissemination of total ionospheric electron content and tropospheric delays.

[0008] The PPP technique requires a conversion time to achieve decimeter accuracy, for example, between about 20 and 40 minutes, in order to reduce the effects of, inter alia, local atmospheric effects and multipath signal effects. More recently, the so-called “Ambiguity Resolved by PPP” has demonstrated greater accuracy.

[0009] However, both the PPP technique and the Differential GNSS floating positioning technique are, in general, significantly less accurate than the RTK “short baseline” technique. In an offshore geolocation context, reverting to the use of such lower-precision techniques may, for example, limit the accuracy of seabed transponder surveys and / or extend the duration of measurement collection. Petition 870240097696, dated 11 / 14 / 2024, page 19 / 143 5 / 50 BRIEF DESCRIPTION OF THE INVENTION

[0010] According to a first aspect of the present patent application, an apparatus for an offshore GNSS reference station is provided, comprising: a processing feature; an acoustic unit for underwater communications, comprising an underwater acoustic transducer, the acoustic unit for underwater communications being arranged to cooperate with the processing feature to calculate, when in use, a position.

[0011] The apparatus may further comprise: a GNSS antenna location; and a unit for determining orientation operationally coupled to the processing resource; the unit for determining orientation may be arranged to determine an orientation associated with the GNSS antenna location and the acoustic transducer of the acoustic unit for underwater communications.

[0012] The position can be associated with a location of the GNSS antenna.

[0013] The device may also comprise: a module for wireless communications operationally coupled to the processing resource.

[0014] The calculated position can be the position of the underwater acoustic transducer; and the processing feature can be arranged to calculate a vector that extends between the position of the underwater acoustic transducer and the position of the GNSS antenna site; the vector can be calculated using a predetermined lever arm displacement and the orientation determined by Petition 870240097696, dated 11 / 14 / 2024, page 20 / 143 6 / 50 unit for orientation determination.

[0015] The processing feature can be arranged to translate the position of the underwater acoustic transducer using the calculated vector, in order to produce a position of the GNSS antenna site; the position of the GNSS antenna site can be a three-dimensional position of the GNSS antenna site relative to a seabed reference point.

[0016] The apparatus may further comprise: a GNSS receiver disposed to make observations of the GNSS signal, comprising a pseudorange measurement and a carrier phase measurement; characterized in that the processing capability may be disposed to store data generated by the GNSS receiver, representing the observations of the GNSS signal as GNSS observation data.

[0017] GNSS signal observations may include a signal-to-noise ratio. GNSS signal observations may include a frequency measurement using the Doppler effect.

[0018] The acoustic unit for underwater communications can be arranged to make distance-related measurements.

[0019] The processing feature can be arranged to modify the data generated by the GNSS receiver, representing the GNSS signal observations, in order to match the measurements made from a predetermined static pseudo-observation position and store the modified data as GNSS observation data. Petition 870240097696, dated 11 / 14 / 2024, page 21 / 143 7 / 50

[0020] The predetermined static pseudo-observation position can be the center of a predetermined area in a substantially horizontal plane.

[0021] The unit for determining orientation can be a unit for inertial measurement.

[0022] The unit for inertial measurement may comprise an accelerometer and a gyroscope.

[0023] The orientation determination unit can be configured to calculate the orientation of the GNSS antenna site from the GNSS observation data.

[0024] GNSS observation data can be received from a GNSS receiver operating coupled to a first GNSS antenna and a second GNSS antenna, or another GNSS receiver operating coupled to a third GNSS antenna and a fourth GNSS antenna.

[0025] The underwater acoustic transducer can be an acoustic transceiver.

[0026] The position may be an acoustically derived position.

[0027] The processing resource can be arranged to support a unit for reference frame translation; the unit for reference frame translation can be arranged to receive the position and to translate the position from the expression in a first reference frame to a second reference frame.

[0028] The wireless communications module can be arranged to broadcast GNSS observation data. The wireless communications module can be Petition 870240097696, dated 11 / 14 / 2024, page 22 / 143 8 / 50 configured to broadcast the location of the GNSS antenna.

[0029] The wireless communication module can be arranged to broadcast modified data and the predetermined static pseudo-observation position. The wireless communication module can be arranged to receive other GNSS observation data and other position data from other base stations.

[0030] The GNSS receiver can be configured to receive precise point positioning data; and the processing feature can be arranged to support a unit for precise point positioning processing; the unit for precise point positioning processing can be arranged to receive the precise point positioning data and use the precise point positioning data to calculate a GNSS-derived position of the GNSS antenna location.

[0031] The GNSS receiver can be a dual-frequency GNSS receiver.

[0032] The GNSS receiver can be configured to receive precise point positioning data; and the processing feature can be arranged to support a unit for precise point positioning processing; the unit for precise point positioning processing can be arranged to receive the precise point positioning data and use the precise point positioning data to calculate a GNSS-derived position of the GNSS antenna location; and the processing feature can be arranged to calculate an offset between the GNSS-derived position of the location of the Petition 870240097696, dated 11 / 14 / 2024, page 23 / 143 9 / 50 GNSS antenna calculated using precise point positioning data and the location of the GNSS antenna.

[0033] The apparatus may also comprise an enclosure, the enclosure being arranged to support the respective movement in an aquatic environment. The enclosure may comprise a tie rod anchor point.

[0034] The apparatus may also comprise a motorized locomotion unit.

[0035] The processing feature can be arranged to estimate an average speed of sound in water, the average speed of sound being monitored over time.

[0036] The processing feature can be arranged to calculate a depth of the underwater acoustic transducer, and the processing feature can be arranged to estimate refraction corrections to the speed of sound in a water column from a predetermined approximate speed of sound profile.

[0037] According to a second aspect of the present patent application, an offshore RTK GNSS reference station is provided, comprising the apparatus for an offshore GNSS reference station as set out above in relation to the first aspect of the present patent application.

[0038] According to a third aspect of the present patent application, an offshore POR PPP GNSS reference station is provided, comprising the apparatus for an offshore GNSS reference station as set out above in relation to the first. Petition 870240097696, dated 11 / 14 / 2024, page 24 / 143 10 / 50 aspect of the present patent application.

[0039] According to a fourth aspect of the present patent application, an offshore GNSS positioning system is provided, comprising: the apparatus for an offshore GNSS reference station, as set forth above in relation to the first aspect of the present patent application; and a plurality of acoustic transponders for underwater reference; characterized in that the acoustic unit for underwater communications is arranged to measure a respective bidirectional travel time in relation to each of the plurality of acoustic transponders for underwater reference.

[0040] The plurality of acoustic transponders for underwater reference may comprise at least four acoustic transponders for underwater reference.

[0041] The plurality of acoustic transponders for underwater reference may comprise at least six acoustic transponders for underwater reference.

[0042] The processing feature can be arranged to estimate a spatial gradient of average speed of sound.

[0043] The offshore GNSS reference station can be arranged to maintain a position close to a center of the plurality of acoustic transponders for underwater reference.

[0044] The processing resource can be arranged to cooperate with the acoustic unit to Petition 870240097696, dated 11 / 14 / 2024, p. 25 / 143 11 / 50 underwater communications, in order to estimate the position of the acoustic transducer in relation to the plurality of acoustic transponders for underwater reference.

[0045] The estimated position of the acoustic transducer can be given at a reference point defined by the plurality of acoustic transponders for underwater reference.

[0046] The system may further comprise: a roving GNSS device disposed to receive GNSS observation data and the position of the GNSS antenna site relative to the reference point defined by the plurality of acoustic transponders for underwater reference; and the roving GNSS device may be disposed to calculate a relative position vector associated with the position of a GNSS antenna site of the roving GNSS device relative to the position of the GNSS antenna of the GNSS reference station.

[0047] The system may also comprise: a remote processing resource designed to receive broadcast GNSS observation data and broadcast position data.

[0048] The system may also include: another device for an offshore GNSS reference station, including remote processing capability.

[0049] The system may also include: a GNSS reference station on land.

[0050] The equipment for a GNSS reference station on land may include: the remote processing feature.

[0051] The apparatus for the station of Petition 870240097696, dated 11 / 14 / 2024, page 26 / 143 A 12 / 50 GNSS reference on land may have a system-wide reference point, and the land-based GNSS reference station apparatus may be arranged to translate the position of the GNSS antenna location from the offshore GNSS reference station apparatus to the system-wide reference point used by the land-based GNSS reference station apparatus.

[0052] The onshore GNSS reference station may have a system-wide reference point and the offshore GNSS reference station apparatus may be arranged to translate the position of the GNSS reference antenna location from the offshore GNSS reference station apparatus to the system-wide reference point used by the onshore GNSS reference station apparatus.

[0053] The system may also comprise: a plurality of devices for offshore GNSS reference station; the plurality of devices for offshore GNSS reference station may comprise the device for offshore GNSS reference station.

[0054] A plurality of offshore GNSS reference station devices may have a common reference point assigned to them; and the offshore GNSS reference station device may be arranged to translate the position of the GNSS antenna from the offshore GNSS reference station device to the common reference point assigned to the plurality of offshore GNSS reference station devices.

[0055] The system may also include: a device for a GNSS reference station on land. Petition 870240097696, dated 11 / 14 / 2024, page 27 / 143 13 / 50 firm.

[0056] The plurality of devices for an offshore GNSS reference station may comprise: at least three devices for an offshore GNSS reference station.

[0057] The land-based GNSS reference station device and the plurality of offshore GNSS reference station devices can provide at least three reference station devices.

[0058] The GNSS roving device may be arranged to receive broadcast GNSS observation data and broadcast antenna position data, respectively, from at least three reference station devices and to use the received broadcast GNSS observation data and the respective received broadcast position data to estimate a position of the GNSS roving device.

[0059] According to a fifth aspect of the present patent application, a real-time kinematic GNSS positioning system is provided, comprising the apparatus for an offshore GNSS reference station as set out above in relation to the first aspect of the present patent application.

[0060] According to a sixth aspect of the present patent application, a real-time kinematic GNSS positioning system is provided, comprising the offshore GNSS positioning system as set forth above in relation to the fourth aspect of the present patent application. Petition 870240097696, dated 11 / 14 / 2024, page 28 / 143 14 / 50

[0061] According to a seventh aspect of the present patent application, a real-time kinematic positioning system for the GNSS network is provided, comprising the apparatus for an offshore GNSS reference station as set forth above in relation to the first aspect of the present patent application.

[0062] According to an eighth aspect of the present patent application, a method for generating offshore positioning reference data is provided, the method comprising: acoustically determining a position through the water; making a GNSS observation regarding the position; determining an orientation associated with a GNSS antenna location and the acoustically determined position.

[0063] GNSS observation data may include pseudorange measurement data and carrier phase measurement data.

[0064] The acoustically determined position through the water can be determined in relation to a plurality of acoustic transponders for underwater reference.

[0065] According to a ninth aspect of the present patent application, a method for generating real-time kinematic reference data is provided, comprising the method for generating offshore positioning reference data as set forth above in relation to the eighth aspect of the present patent application.

[0066] The method may also include: diffusion of GNSS observation and associated position. Petition 870240097696, dated 11 / 14 / 2024, page 29 / 143 15 / 50

[0067] The method may also include: the generation of GNSS observations, which involves modifying GNSS observations to match measurements taken from a predetermined static pseudo-observation position.

[0068] According to a tenth aspect of the present patent application, a method for determining a position is provided, the method comprising: the method of generating offshore positioning reference data, as set out above in relation to the eighth aspect of the present patent application; broadcasting GNSS observation and position; receiving the broadcast GNSS observation and position at a position to be determined; making a local GNSS observation relative to the position to be determined; and using the received broadcast GNSS observation and position with the local GNSS observation data to estimate a relative position vector.

[0069] According to an eleventh aspect of the present patent application, a method is provided for determining the position of an underwater communications unit, the method comprising: the method of generating a real-time kinematic reference signal as set forth above in relation to the eighth aspect of the present patent application; a roving GNSS apparatus receiving broadcast GNSS observation and position; determining the position of the roving GNSS apparatus using the received broadcast GNSS observation and position and a locally generated GNSS observation; and the roving GNSS apparatus. Petition 870240097696, dated 11 / 14 / 2024, page 30 / 143 16 / 50 perform the acoustic variation in relation to the underwater communications unit.

[0070] The method may further comprise: the GNSS roving apparatus circumnavigating one or more underwater reference acoustic transponder(s) according to a boxing scheme; performing bidirectional travel time measurements respectively with respect to one or more underwater reference acoustic transponder(s); and estimating an average speed of sound relative to a water column comprising one or more underwater reference acoustic transponder(s).

[0071] The average speed of sound can be a harmonic mean between an underwater acoustic transducer and the underwater reference acoustic transponder.

[0072] The method may also include: determining a spatial variation of the average speed of sound using an inverted echo sounder.

[0073] The method may further comprise: tracking one or more underwater reference acoustic transponder(s) with a corresponding number of sound velocity sensors; measuring a bidirectional travel time between a pair of sound velocity sensors; refining the positions of an underwater reference acoustic transponder using the measured bidirectional travel time.

[0074] According to a twelfth aspect of the present patent application, a method is provided for calculating the position of an acoustic transponder for underwater reference used by an apparatus for an offshore GNSS reference station, the method comprising: carrying out the topographic survey of Petition 870240097696, dated 11 / 14 / 2024, page 31 / 143 17 / 50 an underwater reference acoustic transponder from among a plurality of underwater reference acoustic transponders using a roving GNSS device, in order to calculate a position of the underwater reference acoustic transponder, using a first positioning technique; the offshore GNSS reference station device that communicates GNSS reference data and an acoustically derived position that corresponds to a position of a GNSS antenna of the offshore GNSS reference station device, the position being acoustically derived based on the respective positions of the plurality of underwater reference acoustic transponders; perform a topographic survey of the underwater reference acoustic transponder in order to determine an updated position of the underwater reference acoustic transponder using a second positioning technique.

[0075] The second acoustic positioning technique can be employed after the first acoustic positioning technique, and the second acoustic positioning technique is a real-time kinematic positioning technique.

[0076] The method may also comprise: receiving GNSS reference data and the acoustically derived position remotely from the device to an offshore GNSS reference station; characterized by determining the updated position of the acoustic transponder for underwater reference comprising the use of the received GNSS reference data and the acoustically derived position.

[0077] The first technique of Petition 870240097696, dated 11 / 14 / 2024, page 32 / 143 18 / 50 positioning can be a precise spot positioning technique.

[0078] The method may also include: providing the updated position of the acoustic transponder for underwater reference to the device for offshore GNSS reference station.

[0079] The method may also include: calculating the position corresponding to the GNSS antenna with the device for offshore GNSS reference station, using the updated position of the acoustic transponder for underwater reference.

[0080] The method may also include: calculating the updated position of the acoustic transponder for underwater reference remotely from the GNSS roving device.

[0081] The calculation of the updated position of the acoustic transponder for underwater reference can be done at a land-based processing station.

[0082] The updated position of the acoustic transponder for underwater reference can be calculated on the device for offshore GNSS reference station.

[0083] The updated position of the acoustic transponder for underwater reference can be calculated on another device for offshore GNSS reference station.

[0084] The topographic survey of the acoustic transponder for underwater reference may include the calculation of a plurality of bidirectional travel times in relation to the acoustic transponder for Petition 870240097696, dated 11 / 14 / 2024, page 33 / 143 19 / 50 underwater reference.

[0085] The topographic survey of the acoustic transponder for underwater reference to determine the updated position may involve employing a boxing scheme.

[0086] The plurality of acoustic transponders for underwater reference may comprise another submerged acoustic transponder at a given position using the first positioning technique; the method may further comprise: carrying out a topographic survey of another underwater acoustic transponder in order to determine an updated position of the other underwater acoustic transponder using the second positioning technique.

[0087] The topographic survey of the acoustic transponder for underwater reference may comprise the GNSS roving apparatus following a substantially circular path around the acoustic transponder for underwater reference.

[0088] Determining the updated position of the acoustic transponder for underwater reference using the second positioning technique may include: calculating a position of the GNSS rover, an orientation of the GNSS rover, and a velocity of the GNSS rover.

[0089] The method may also include: communicating the position calculated using the second positioning technique, the orientation of the GNSS rover and the acoustic measurements made to calculate the position of the GNSS rover using the second positioning technique. Petition 870240097696, dated 11 / 14 / 2024, page 34 / 143 20 / 50

[0090] The method may also include: communicating the GNSS observation data collected by the mobile GNSS unit, the orientation of the mobile GNSS unit, and the acoustic measurements made and associated with the collected GNSS observation data.

[0091] The updated position of the acoustic transponder for underwater reference can be calculated in real time or near real time.

[0092] The calculation of the updated position of the acoustic transponder for underwater reference may be temporally deferred.

[0093] The method may also include: recording GNSS observation data, orienting the GNSS mobile unit and the acoustic measurement data associated with the GNSS mobile unit.

[0094] The updated position of the acoustic transponder for underwater reference can be a three-dimensional position.

[0095] The topographic survey of the acoustic transponder for underwater reference may include estimating the speed of sound between a transducer on the GNSS mobile unit and the acoustic transponder for underwater reference.

[0096] The method may also comprise: using a predetermined sound velocity profile to apply a refraction compensation for the estimation of the speed of sound.

[0097] The topographic survey of the acoustic transponder for underwater reference to determine the updated position may include: following a Petition 870240097696, dated 11 / 14 / 2024, page 35 / 143 21 / 50 path that varies spatially with time, thus allowing us to estimate the temporal and spatial variation of the speed of sound in relation to vertical distance.

[0098] The method may also include: independently determining the average speed of sound using an inverted echo sounder.

[0099] The method may further comprise: selecting at least three from a plurality of underwater reference acoustic transponders; and using at least three underwater reference acoustic transponders to calculate the speed of sound.

[0100] The method may further comprise: selecting at least six from a plurality of underwater reference acoustic transponders and using at least six underwater reference acoustic transponders to calculate the speed of sound.

[0101] The method may also include: another mobile GNSS device to perform a topographic survey of the underwater acoustic reference transponder, in order to determine the updated position of the underwater acoustic reference transponder using the second positioning technique.

[0102] The method may further comprise: using the updated position of the underwater reference acoustic transponder determined using the GNSS roving instrument and the updated position of the underwater reference acoustic transponder determined using the other GNSS roving instrument to calculate an updated average position of the underwater reference acoustic transponder. Petition 870240097696, dated 11 / 14 / 2024, p. 36 / 143 22 / 50

[0103] According to a thirteenth aspect of the present patent application, a system for determining the position of the transponder is provided, comprising: a mobile offshore GNSS device; a device for an offshore GNSS reference station; and a plurality of acoustic transponders for underwater reference, comprising an acoustic transponder for underwater reference having a known position determined using a first positioning technique; characterized in that the acoustic transponder for underwater reference is arranged to communicate acoustically with the mobile offshore GNSS device and with the device for an offshore GNSS reference station;The offshore GNSS reference station apparatus being arranged to communicate GNSS reference data and an acoustically derived position corresponding to the position of a GNSS antenna of the offshore GNSS reference station apparatus and an orientation associated with the GNSS antenna, the position being acoustically derived at the respective positions of a plurality of underwater acoustic transponders; and the roving GNSS apparatus being arranged to topographically survey the underwater acoustic transponder in order to determine an updated position of the underwater acoustic transponder using a second positioning technique.

[0104] Thus, it is possible to provide a device and method capable of supporting offshore GNSS positioning with greater accuracy over existing systems and reducing the device convergence time to accuracy. Petition 870240097696, dated 11 / 14 / 2024, page 37 / 143 23 / 50 centimetric. In fact, for hydrocarbon fields and sites (and other applications), it is possible to maintain a GNSS reference asset for the lifetime of the field. It is also possible to position a variety of reference beacons far from the area of ​​a site subject to settlement and transfer precise three-dimensional positioning to the site subject to settlement. Furthermore, low-cost beacons can be used, which can be replaced regularly if necessary. The apparatus and method also allow underwater positioning to be achieved at a lower cost and with greater accuracy than other known systems, for example, so-called underwater GNSS (GPS) systems. It is also possible to augment or extend existing PPP and RTK systems using the method and apparatus. DESCRIPTION OF THE FIGURES

[0105] At least one application of the present patent application will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a system for an offshore reference station, comprising an apparatus for an offshore GNSS reference station and constituting an application of the present patent application; Figure 2 is a schematic flowchart diagram of a method for generating positioning reference data, constituting another application of the present patent application; Figure 3 is a schematic diagram of an itinerant vessel, constituting another application of the present application. Petition 870240097696, dated 11 / 14 / 2024, page 38 / 143 24 / 50 of invention patent; Figure 4 is a schematic diagram of an offshore positioning system; Figure 5 is a flowchart of a method for determining position, employing the system of Figure 4; and Figure 6 is a schematic diagram of a network of base stations in a positioning system and constitutes another application of the present patent application. REFERENCE SIGNS

[0106] The “OFFSHORE GNSS REFERENCE STATION APPARATUS, OFFSHORE GNSS POSITIONING SYSTEM, OFFSHORE POSITIONING REFERENCE DATA GENERATING METHOD AND METHOD FOR DETERMINING A POSITION” being best described based on the following reference signals: (100) vessel; (102) device for offshore GNSS reference station; (104) seabed; (106) acoustic transponders for underwater reference; (108) first acoustic transponder; (110) second acoustic transponder; (112) third acoustic transponder; (114) fourth acoustic transponder; (115) first acoustic unit for underwater communications; (116) first acoustic transceiver / transducer; (118) first processing resource; (120) first module for wireless communications; (122) GNSS receiver; (124) first unit for inertial measurement; Petition 870240097696, dated 11 / 14 / 2024, pp. 39 / 143 25 / 50 (126) first communications antenna; (128) first GNSS antenna; (130) mass of water; (132) unit for translation of the reference frame; (200) Stage; (202) Stage; (204) Stage; (206) Stage; (208) Stage; (210) Stage; (212) Stage; (300) maritime itinerant vessel; (302) transponder; (304) first inverted echo sounder; (306) second inverted echo sounder; (308) second processing resource; (310) GNSS receiver; (312) second unit for inertial measurement; (313) second acoustic unit for communications underwater; (314) second acoustic transceiver / transducer; (316) second communications module; (318) second communications antenna; (320) GNSS antenna; (500) Step; (502) Step; (504) Step; (506) Step; (508) Step; (510) Step; Petition 870240097696, dated 11 / 14 / 2024, page 40 / 143 26 / 50 (512) Stage; (600) network of base stations; (602) first GNSS reference station on land; (604) second GNSS reference station on land; (606) third GNSS reference station on land; (608) central processing resource; and (610) VRS; DETAILED DESCRIPTION OF THE INVENTION

[0107] Throughout the following description, identical reference numbers will be used to identify identical parts.

[0108] With reference to Figure 1, a vessel (100) comprises an apparatus for an offshore GNSS reference station (102). In this example, the vessel (100) is a ship, but the expert should understand that the vessel need not be limited to a ship and that other types of vessels may be employed. In this respect, instead of the vessel, the offshore GNSS reference station may comprise an enclosure capable of supporting the respective movement in an aquatic environment. In fact, the apparatus for an offshore GNSS reference station (102) may comprise any suitable vessel capable of carrying the apparatus for an offshore GNSS reference station (102) in an aquatic environment, for example, a hermetically sealed enclosure that is floating. In some examples, the vessel (100) may be anchored to a seabed (104). In such examples, the enclosure may comprise a tie-rod anchor point.In other applications, the offshore GNSS reference station apparatus (102) is powered by a locomotion unit. Petition 870240097696, dated 11 / 14 / 2024, page 41 / 143 27 / 50 for example, a form of propulsion and / or steering, such as an electric motor or mechanism coupled with suitable steering features.

[0109] An offshore reference system comprises the apparatus for offshore GNSS reference station (102) and a plurality of underwater reference acoustic transponders (106) which are disposed on the seabed (104), being, for example, at least four transponders, as well as at least six transponders. In this example, a first acoustic transponder (108) on the seabed, a second acoustic transponder (110) on the seabed, a third acoustic transponder (112) on the seabed and a fourth acoustic transponder (114) on the seabed. The plurality of underwater reference acoustic transponders (106) disposed on the seabed (104) are spaced from each other and are within the communication range of the vessel (100).The plurality of acoustic transponders for underwater reference (106) constitutes a transponder network and resides in a reference plane, here designated as the seabed reference frame.

[0110] The apparatus for offshore GNSS reference station (102) comprises a first acoustic unit for underwater communications (115), comprising a first acoustic transducer, for example, a first acoustic transceiver (116), capable of communicating with a plurality of acoustic transponders for underwater reference (106). The first acoustic transceiver (116) is operationally coupled to a first processing resource (118), the first resource of Petition 870240097696, dated 11 / 14 / 2024, pp. 42 / 143 28 / 50 processing (118) supporting a unit for reference frame translation (132). The first processing feature (118) is operatively coupled to a first module for wireless communications (120), a GNSS receiver (122), and a first unit for orientation determination, for example, a first unit for inertial measurement (124), which in this example comprises an accelerometer and a gyroscope. In this example, the GNSS receiver (122) is a single-frequency GNSS receiver. However, in other examples, a dual-frequency GNSS receiver may be employed. It should be appreciated that the first processing feature (118) may be distributed in nature and may encompass the processing capabilities of the GNSS receiver (122).

[0111] The first communications module (120) is operationally coupled to a first communications antenna (126) for RF communications. In this example, the first module for wireless communications (120) comprises some components and logic to support the dissemination of position-related data according to one or more of the RTCM SC-104 standards. The GNSS receiver (122) is operationally coupled to a first GNSS antenna (128) disposed at a first antenna location (not shown) on the vessel (100). As will be appreciated, there is a relative positional relationship between the first antenna location and the first acoustic transceiver (116), and this is known as the so-called lever arm, which is a translation that describes the difference in position between the first antenna location and the first acoustic transceiver (116).

[0112] The first unit for measurement Petition 870240097696, dated 11 / 14 / 2024, pp. 43 / 143 29 / 50 inertial (124) is provided to calculate the orientation of the lever arm between the first antenna location and the first acoustic transceiver (116). In this respect, the orientation is associated with the first antenna location and the first acoustic transducer (116). In some applications, the orientation of the first antenna location can alternatively be determined by employing a first GNSS receiver and a second GNSS receiver (not shown), the first GNSS receiver being operationally coupled to a first GNSS antenna (not shown) and a second GNSS antenna (not shown), and the second GNSS receiver being operationally coupled to a third GNSS antenna (not shown) and a fourth GNSS antenna (not shown). In this respect, the first, second, third, and fourth GNSS antennas are arranged in a spaced relationship.In this example, the first orientation determination unit receives GNSS observation data from the first and second GNSS receivers and determines the orientation of the first antenna location using the received GNSS observation data. Although four GNSS antennas were employed in this example, the specialist must assess which orientation can be determined using the GNSS signals received by three antennas.

[0113] As mentioned above, the vessel (100) is an offshore vessel and is therefore placed in a body of water, for example, the sea (130) and, in fact, in this example, the vessel (100) floats on the surface of the sea.

[0114] In operation (Figure 2), the vessel (100) is deployed in the body of water, for example, Petition 870240097696, dated 11 / 14 / 2024, page 44 / 143 30 / 50 at sea, and is positioned above the plurality of acoustic transponders for underwater reference (106) that are calibrated Step (200). This initial calibration involves conventional boxing of each transponder, or any other suitable pattern, to determine the transponder coordinates, using an acoustic distance and GNSS observations by PPP (real-time or post-processed) by a surface vessel, and may include an acoustic distance from transponder to transponder (Figure 1). The offshore GNSS reference station apparatus needs to be within communication range of at least four pluralities of acoustic transponders for underwater reference (106).The plurality of acoustic transponders for underwater reference (106) may be specifically deployed for the purpose of serving the offshore GNSS reference station apparatus (102) as part of the offshore GNSS reference system, or may be deployed for other purposes, for example, for other underwater applications, but capable of communicating acoustically with the offshore GNSS reference station apparatus (102). However, the offshore GNSS reference system comprises the seabed transponders, regardless of their initial purpose.

[0115] The first processing resource (118) instructs the first acoustic transceiver (116) to interrogate the plurality of underwater reference acoustic transponders (106) and each of the underwater reference acoustic transponders (106) respectively transmits a response to the first acoustic transceiver (116). The acoustic unit for Petition 870240097696, dated 11 / 14 / 2024, pp. 45 / 143 31 / 50 underwater communication (115) operates internal clocks to determine flight times and calculate the bidirectional travel time Step (202), taking into account the response times of the reference transponders. Any suitable technique for determining distances can then be used to determine individual distances from the first acoustic transceiver (116) to each plurality of underwater reference acoustic transponders 106 that respond to an interrogation signal broadcast by the first acoustic transceiver (116). Using known processing techniques, the first processing feature (118) calculates the position of the first acoustic transceiver (116) within the reference frame defined by the plurality of underwater reference acoustic transponders (106) and thus the position of the first acoustic transducer (116) is calculated relative to the plurality of underwater reference acoustic transponders (106).Since the techniques applied are not key to an understanding of the inventive concepts exemplified here, the processing to determine the location of the first acoustic transceiver (116) in the acoustic transponder reference frame for underwater reference will not be described in detail.

[0116] At the same time, the first processing feature (118) obtains Step (204) the GNSS data from the GNSS receiver (122). The GNSS data comprise signal observation data, for example, a pseudorange measurement and a carrier phase measurement. The GNSS data may comprise other signal observations, for example, a signal-to-noise ratio and / or a frequency measurement by the Doppler effect. Petition 870240097696, dated 11 / 14 / 2024, pp. 46 / 143 32 / 50

[0117] Furthermore, the first unit for inertial measurement (124) obtains Step (206) a measure of the vessel orientation (100) and therefore the orientation of the first antenna location and the orientation of the first acoustic transceiver (116) at the time of performing the acoustic measurements and obtaining the GNSS data.

[0118] The lever arm between the first antenna location and the first acoustic transceiver (116) is known to exhibit a fixed relationship between the two entities and, thus, this a priori information is stored as a parameter for use by the first processing feature (118). If the a priori information is not available, it should be appreciated that the lever arm can be determined using any suitable post-processing technique, for example, using an appropriately designed method. Thus, the position of the first acoustic transceiver (116) is associated with the position of the first antenna location.Using the obtained orientation measurement and the known lever arm, the first processing feature (118) calculates a vector between the position of the first acoustic transceiver (116) and the position of the first antenna site, so that the antenna site position can be determined in the reference frame of the acoustic transponder plurality for underwater reference (106) Step (208). In another example, if activated, the reference frame translation unit (132) transforms Step (208), then, the antenna position expressed in the reference frame of the acoustic transponder plurality for underwater reference (106) to a position expressed in a second reference frame, for example, the Terrestrial Reference Frame. Petition 870240097696, dated 11 / 14 / 2024, pp. 47 / 143 33 / 50 International Terrestrial Reference Frame (ITRF). This is an example of the unit of reference frame translation, translating an acoustically derived position from a first reference frame to a second reference frame. The translation, for example, a coordinate vector, to translate from an acoustic reference frame to the ITRF, can be obtained as the average difference between the acoustically derived positions and the GNSS positions by PPP (in real time or post-processed, for example, using the so-called final orbit products available from the International GNSS Service (IGS)) observed during a sustained period, for example, one day. The acoustically derived position of the first antenna location is a three-dimensional position of the first antenna location relative to a seabed reference frame.

[0119] GNSS data obtained from the GNSS receiver (122) are communicated to the first wireless communications module (120), together with the acoustically derived position of the GNSS antenna location, and the first wireless communications module (120) broadcasts Step (210) the GNSS observation data and the acoustically derived position of the GNSS antenna location, which can be used by other offshore geolocation hardware employing different GNSS principles.

[0120] To improve the accuracy of the acoustically derived position of the GNSS antenna location, the first processing feature (118), in this example, estimates a speed of sound in water, for example, an average speed of sound Step (208). In this respect, the Petition 870240097696, dated 11 / 14 / 2024, pp. 48 / 143 34 / 50 first processing feature (118) keeps a record of the calculated sound velocities in order to monitor changes in the speed of sound over time. The monitored sound velocity data can be used to improve accuracy when determining the height of the first acoustic transceiver (116) above the seabed (104), i.e., the depth of the first acoustic transducer (116). In this respect, as the average speed of sound in water varies over time, the calculated height of the first acoustic transducer reduces accuracy, since the average speed of sound varies. In addition to estimating the temporal variation of the average speed of sound, the first processing feature (118) can estimate the spatial variation of the average speed of sound to further improve accuracy. The spatial variation can be modeled, for example, using average sound velocity gradients relative to the relative north and east coordinates of the seabed transponders.

[0121] The geometry of the first acoustic transceiver (116) in relation to the plurality of acoustic transponders for underwater reference (106) is such that the average speed of sound and the depth of the vessel can be estimated distinctly, since there is significant variation in the angles between the transceiver / transponder vectors and the vertical. The estimate of the average speed of sound (harmonic mean) refers to an acoustic signal moving vertically to a reference depth and is the geometric distance (straight line) divided by the one-way travel time. The process of estimating the speed of sound compensates for the variation in the depths of the acoustic transponders to Petition 870240097696, dated 11 / 14 / 2024, pp. 49 / 143 35 / 50 underwater reference (106) at a nominal depth and compensates for acoustic path refraction caused by the horizontal displacement of each of the several underwater reference acoustic transponders (106) relative to the first acoustic transceiver (116). The refraction and depth variation corrections for the speed of sound are small, for example, typically a few centimeters per second, and can be estimated from an approximate speed of sound profile, for example, from a worldwide ocean model. The continuous estimation of the average speed of sound ensures that a three-dimensional position estimate, especially the vertical estimate (which is highly correlated with the speed of sound), is independent of the variation in the speed of sound. With six or more underwater reference acoustic transponders, the spatial gradient of the average speed of sound variation can also be continuously estimated.

[0122] Using a predetermined approximate speed of sound profile, depth variations and sound velocity refraction corrections in a water column are estimated by the first processing feature.

[0123] When available to the device for offshore GNSS reference station (102), the first communications module (120) can receive, in this example, other GNSS observation data and other position data from base stations in a positioning system network. Similarly, the GNSS receiver (122) can receive precise point positioning data. In such examples, the first processing feature (118) supports Petition 870240097696, dated 11 / 14 / 2024, pp. 50 / 143 36 / 50 a unit for precise point positioning processing (not shown), the unit for precise point positioning processing being arranged to receive precise point positioning data and use the precise point positioning data to calculate a GNSS-derived position of the GNSS antenna location.

[0124] As mentioned above, the use of the offshore GNSS reference station apparatus (102) with the plurality of acoustic transponders for underwater reference (106) constitutes an offshore reference system. The offshore GNSS reference station apparatus (102) can serve as an offshore RTK POR GNSS reference station or an offshore PPP POR GNSS reference station.

[0125] In another application, if necessary, the first processing resource (118) can modify Step (212) the GNSS data generated by the GNSS receiver (122), representing the GNSS signal observations in a way that corresponds to measurements made from a predetermined static pseudo-observation position. The modified data can be stored as GNSS observation data. For example, the predetermined static pseudo-observation position can be the center of a predetermined area on a substantially horizontal plane. When this is done, the wireless communications module (120) broadcasts the modified Step (210) data and the predetermined static pseudo-observation position. The broadcast, therefore, does not require continuous updates of the acoustically derived position from the device to the offshore GNSS reference station (102) to keep up with the Petition 870240097696, dated 11 / 14 / 2024, page 51 / 143 37 / 50 diffusions of GNSS data, and the offshore GNSS reference station apparatus (102) can be used in a similar manner to a conventional land-based GNSS reference station.

[0126] In another application, if fitted with the locomotion unit described above, the offshore GNSS reference station apparatus (102) can maintain a position close to a center of the plurality of acoustic transponders for underwater reference (106). Maintaining the position of the offshore GNSS reference station apparatus (102) restricts the positioning error of the acoustically derived position of the GNSS antenna location caused by errors in the initial calibration of the plurality of acoustic transponders for underwater reference (106).

[0127] In another application (Figure 3), a maritime roving vessel (300) is placed at sea or in another suitable body of water and is capable of moving above (not necessarily directly) a transponder (302) installed on the seabed, for example, a transponder whose position needs to be determined precisely. The maritime roving vessel (300) may be, for example, an unmanned propelled surface vehicle, for example, a so-called wave glider, a manned vehicle, for example, a survey vessel or drilling rig, or an anchoring vessel, for example, a buoy. In addition to the transponder (302) that is installed on the seabed (104), other devices may also be installed on the seabed (104), for example, a first inverted echo sounder (304) and a second inverted echo sounder (306). Petition 870240097696, dated 11 / 14 / 2024, page 52 / 143 38 / 50

[0128] The maritime itinerant vessel (300) comprises a second processing resource (308) operationally coupled to another GNSS receiver (310) and a second unit for orientation determination, for example, a second unit for inertial measurement (312). It should be appreciated that the second processing resource (308) may be distributed in nature and may encompass the processing capabilities of the other GNSS receiver (310). In this example, the other GNSS receiver (310) is a single-frequency GNSS receiver. However, in other examples, a dual-frequency GNSS receiver may be employed. The maritime itinerant vessel (300) also comprises a second acoustic unit for underwater communications (313), comprising a second acoustic transducer, for example, a second acoustic transceiver (314), capable of communicating with the transponder (302) installed on the seabed and the first and second inverted echo sounders (304) and (306).The second acoustic transceiver (314) is operationally coupled to the second processing device (308).

[0129] A second communications module (316) is operationally coupled to a second communications antenna (318) for RF communications, the communications module (316) also being operationally coupled to the other GNSS receiver (310). In this example, the second communications module (316) comprises components and logic for supporting broadcast position data in accordance with one or more of the RTCM SC-104 standards. The other GNSS receiver (310) is operationally coupled to another GNSS antenna (320) disposed at a second antenna location (not Petition 870240097696, dated 11 / 14 / 2024, pp. 53 / 143 39 / 50 shown) on the maritime itinerant vessel (300). As will be appreciated, there is also a relative positional relationship between the second antenna location and the second acoustic transceiver (314), and this is known as the so-called lever arm, which in this example is a translation or displacement describing the difference in position of the second antenna location and the second acoustic transceiver (314).

[0130] The second unit for inertial measurement (312) is provided for calculating the orientation of the lever arm between the second antenna location and the second acoustic transceiver (314). In some applications, the orientation of the antenna location may alternatively be determined by employing multiple GNSS receivers and multiple GNSS antennas, as described above in relation to the apparatus for offshore GNSS reference station (102).

[0131] In this example, the maritime itinerant vessel (300) has a propulsion system so that it can move across the sea surface, according to a research route.

[0132] With reference to Figure 4, in an application related to an offshore positioning system, combining the use of the offshore GNSS reference station device (102) and the maritime roving vessel (300), the maritime roving vessel (300) is located at sea, for example, within a radius of 30 km from the offshore reference station device (102). As described in the previous examples, the offshore GNSS acoustic reference station device (102) is capable of being Petition 870240097696, dated 11 / 14 / 2024, page 54 / 143 40 / 50 communicate acoustically with the first acoustic transponder on the seabed (108), with the second acoustic transponder on the seabed (110), with the third acoustic transponder on the seabed (112) and with the fourth acoustic transponder on the seabed (114). Similarly, the maritime itinerant vessel (300) is able to communicate acoustically with the transponder (302) installed on the seabed, for example, the transponder whose position needs to be determined precisely, and the first inverted echo sounder (304) and the second inverted echo sounder (306).

[0133] In operation (Figure 5), the maritime roving vessel (300) operates in combination with the offshore GNSS reference station apparatus (102) described above. The offshore GNSS reference station apparatus (102) determines the acoustically derived position and obtains the associated GNSS observation data, which are broadcast, as described above in relation to a previous example.

[0134] On the maritime roving vessel (300), the second communications module (316) of the maritime roving vessel (300) receives Step (500) the acoustically derived position data and the broadcast GNSS observation data from the device to the offshore GNSS reference station (102). The other GNSS receiver (310) of the maritime roving vessel (300) also obtains Step (502) more GNSS observation data, comprising another pseudorange measurement and another carrier phase measurement from the GNSS satellite network orbiting the Earth, i.e., a local GNSS observation. Petition 870240097696, dated 11 / 14 / 2024, page 55 / 143 41 / 50

[0135] Using the information received by the second communications module (316) from the offshore GNSS reference station device (102) and the information obtained from another GNSS receiver (310), the second processing feature (308) calculates Step (504) a position of the second antenna location where the other GNSS antenna (320) is positioned relative to the seabed reference point used by the offshore GNSS reference station device (102) using a differential GNSS, for example, an RTK computer technique. In this respect, the second processing feature (308) is arranged to calculate a relative position vector associated with the position of the second GNSS antenna location relative to the position of the first antenna location of the offshore GNSS reference station device (102).

[0136] As mentioned above, the maritime roving vessel (300) communicates with the transponder (302) deployed on the seabed, whose position needs to be precisely determined. The second acoustic transceiver (314) communicates acoustically with the transponder (302) in order to obtain Step (506) bidirectional travel time observations which are communicated to the second processing device (308). The second processing device 308 also obtains Step (508) the calculated orientation of the lever arm between the second antenna location and the second acoustic transceiver (314). Using the orientation data and the bidirectional travel time data obtained, the second processing device (308) calculates Step (510) a three-dimensional position of the seabed transponder (302) on the reference frame used by the device for Petition 870240097696, dated 11 / 14 / 2024, page 56 / 143 42 / 50 offshore GNSS reference station (102).

[0137] When one or more underwater reference acoustic beacon(s) is / are available, the maritime itinerant vessel (300) may navigate within the area of ​​one or more underwater reference acoustic beacon(s), in accordance with a boxing of each transponder or any other suitable pattern. The second underwater communications acoustic unit (313) cooperates with the second processing resource (308) of the maritime itinerant vessel (300) in order to make measurements of bidirectional travel time relative to one or more underwater reference acoustic beacon(s). As part of a computation process of measured bidirectional travel time variation data, the average speed of sound relative to the water column is estimated Step (510), the water column comprising one or more underwater reference acoustic beacon(s).In this example, the average speed of sound is a harmonic mean between the second acoustic transceiver (314) and the transponder (302). A model of average speed of sound can be augmented by further estimating spatial and temporal average speed gradients of sound.

[0138] Alternatively, by communicating with one or both of the first inverted echo sounder (304) and the second inverted echo sounder (306), the second acoustic unit for underwater communications (313) is able to make Step (512) observations on the pressure in the inverted echo sounder, which can be used by the second processing feature (308) to calculate Step (510) the Petition 870240097696, dated 11 / 14 / 2024, page 57 / 143 43 / 50 data on spatial speed of sound variation mentioned above.

[0139] In another example, one or more acoustic beacon(s) for underwater reference may be provided or accompanied by a respective series of sound velocity sensors, which may, in pairs, estimate distances between them, from bidirectional travel times measured between them, in order to refine the measurement of the seabed transponder position (302).

[0140] Although, in the example above, a single maritime roving vessel (300) was employed, the expert should appreciate that multiple roving vessels may be employed and their data collected to determine the three-dimensional position of one or more underwater reference acoustic transponder(s) mentioned above.

[0141] The GNSS reference station apparatus (102) can be used in any suitable RTK GNSS positioning system. Similarly, a GNSS positioning system comprising the GNSS reference station apparatus (102) and the plurality of acoustic transponders for underwater reference (106) can also be used in any suitable RTK GNSS positioning system.

[0142] In another example, one or more itinerant maritime vessel(s)(300) may be employed for the topographic survey of the plurality of acoustic transponders for underwater reference (106), in order to refine the initial calibration coordinates mentioned above in Step (200). Petition 870240097696, dated 11 / 14 / 2024, pp. 58 / 143 44 / 50

[0143] In another application (Figure 6), a network of base stations (600) can be provided. For example, the network may comprise the offshore GNSS reference station apparatus (102), a first onshore GNSS reference station (602), a second onshore GNSS reference station (604) and a third onshore GNSS reference station (606). In this example, the first, second and third onshore GNSS reference stations (602), (604) and (606) are conventional GNSS reference stations used in RTK GNSS geolocation networks. The onshore reference stations (602), (604) and (606) employ a predetermined system-wide reference frame, for example, the European Terrestrial Reference Frame (ETRF).A central processing resource (608) is also located on land and is capable of receiving GNSS observation data broadcast by any of the first, second and third land-based GNSS reference stations (602), (604), (606) and / or the offshore GNSS reference device (102). The central processing resource (608) is also capable of communicating with the maritime roving vessel (300).

[0144] The first processing feature (118) of the offshore GNSS reference station apparatus (102) is arranged to translate the position of the first antenna location, for example, a pseudostatic observation position, to the reference point of the entire system used by the onshore reference stations (602), (604) and (606). The reference point of the first antenna location is translated before diffusion. Petition 870240097696, dated 11 / 14 / 2024, pp. 59 / 143 45 / 50 of the acoustically derived position of the first antenna location. Alternatively, when the central processing feature (608) is located on land, for example, at one of the land-based reference stations, the central processing feature (608) is arranged to receive the position data for the first antenna location from, and for diffusion by, the device to the offshore GNSS reference station (102) and translate the position data from the seabed reference points where it is expressed to the system-wide reference point for land-based reference stations (602), (604) and (606). Although pseudostatic observation positions are described as used in this example, the expert should understand that the use of observation positions, for example, acoustically derived positions that change over time, is contemplated and not excluded from use in an appropriately configured geolocation network.

[0145] In common with other RTK GNSS geolocation networks, in this example, the GNSS and RTK network (600) supports the Virtual Reference Station (VRS) functionality, whereby the GNSS reference stations are in communication with the central processing resource (608) and the central processing resource (608) can create a VRS (610) located in the vicinity of the maritime roving vessel (300), or any other roving vessel, as needed. This functionality can be optional to improve accuracy, depending on the application requirements.

[0146] In operation, the network of base stations (600) operates to provide a GNSS service. Petition 870240097696, dated 11 / 14 / 2024, pp. 60 / 143 46 / 50 differential to the maritime roving vessel (300), so that the position of the maritime roving vessel (300) can be determined with improved accuracy in an offshore environment. The shore reference stations (602), (604) and (606) can be useful when the maritime roving vessel (300) is sufficiently close to the coast where one or more shore reference station(s) is located, in this example.

[0147] Although, in this example, most GNSS reference stations are located on land, it should be appreciated that in other suitable examples the RTK GNSS network (600) requires at least three reference stations, and that these may be a mixture of land-based and offshore GNSS reference station instruments, or at least exclusively three offshore GNSS reference stations, for example, such as the offshore GNSS reference station instrument (102).In the example of the exclusive use of offshore GNSS reference stations, a common reference point can be assigned to the plurality of offshore GNSS reference stations, comprising the offshore GNSS reference station apparatus (102), and the offshore GNSS reference station apparatus (102) can be arranged to translate the acoustically derived position of the first antenna location of the offshore GNSS reference station apparatus (102) to the common reference point assigned to the plurality of offshore reference stations. Even in this example, an onshore reference station can participate in the network that includes the plurality of offshore GNSS reference stations. Petition 870240097696, dated 11 / 14 / 2024, pp. 61 / 143 47 / 50

[0148] In relation to the determination of the position of the maritime roving vessel (300), the maritime roving vessel (300) receives transmitted GNSS observation data and transmitted antenna position data from at least three reference stations mentioned above. The second processing feature (308) of the maritime roving vessel (300) uses the respective transmitted GNSS observation data and the respective received position data to estimate a position of the second antenna location of the maritime roving vessel (300) using the so-called Master Auxiliary Concept (MAC).

[0149] With respect to the central processing resource (608), although the central processing resource (608) is, in this example, independent of the GNSS reference stations and located on land, the expert should appreciate that the central processing resource (608) may alternatively be located offshore and / or colocated with one of the GNSS reference stations, for example, the offshore GNSS reference station apparatus (102) or another offshore GNSS reference station apparatus (not shown). In this respect, the central processing resource constitutes a remote processing resource and may be arranged to broadcast GNSS observation data and antenna position data which may correspond to VRS data, a single reference station or multiple reference stations using the Main Auxiliary Concept.

[0150] The specialist should appreciate that the applications described above are merely examples of Petition 870240097696, dated 11 / 14 / 2024, pp. 62 / 143 48 / 50 various applications that are conceivable within the scope of the appended claims. In fact, for example, although the use of VRS (610) has been described herein, the base station network (600) or the GNSS positioning system may additionally or alternatively support the so-called Nearest Reference Station and / or the Main Auxiliary Functionality.

[0151] The apparatus, systems, networks and methods of example above have numerous applications. For example, one or more underwater acoustic reference transponder(s) may be used to monitor tectonic plates. For such an application, a first underwater acoustic reference transponder may be placed on the seabed on one side of a seismic fault and a second underwater acoustic reference transponder may be placed on the other side of the seismic fault. The movement of the first and second underwater acoustic reference transponders relative to each other may be monitored using one or more roving vehicle(s). In another application, a set of underwater acoustic transponders may be monitored by one or more roving vehicle(s) in order to determine the state of a hydrocarbon field relative to seabed movement.In this regard, seabed monitoring may be required from field exploration to development, production, and decommissioning. Indeed, if the field is subsequently reused as a carbon sequestration site, additional field monitoring may be necessary. Therefore, at different stages, for example, during oil field development, there is a need for such monitoring. Petition 870240097696, dated 11 / 14 / 2024, pp. 63 / 143 49 / 50 precision at the top and near the seabed in specific areas. Another example is the connection of pipelines to underwater settlements. Furthermore, the examples described above can be used for routine pipeline inspection. It should be appreciated that these applications described here are established only as examples and are representative of a large number of possible applications for the methods and equipment described herein.

[0152] The devices, systems and methods, according to the above applications, can be implemented in a computer system (in particular, in computer hardware or computer software) or in specifically manufactured or adapted integrated circuits, in addition to the structural components and user interactions, as described herein.

[0153] The methods, according to the above applications, may be provided as computer programs, as products of a computer program, or as a computer-readable medium carrying a computer program which is arranged, when run on a computer or other processor, so as to perform the method described above.

[0154] Alternative applications of the present patent application may be implemented as a computer program product for use with a computer system, the computer program product being, for example, a series of computer instructions stored on a tangible data recording medium, such as a floppy disk, CD-ROM, ROM or hard disk, or incorporated into a computer data signal, the signal being transmitted by Petition 870240097696, dated 11 / 14 / 2024, pp. 64 / 143 50 / 50 a tangible medium or a wireless medium, for example, microwave or infrared. The computer instruction set may constitute all or part of the functionality described above, and may also be stored in any volatile or non-volatile memory device, such as a semiconductor, magnetic, optical or other memory device. Petition 870240097696, dated 11 / 14 / 2024, pp. 65 / 143

Claims

1 / 5 CLAIMS 1. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, having a first processing feature (118); a wireless communications module (120) operably coupled to the processing feature (118); and a GNSS antenna location (128); characterized in that it has a first acoustic unit for underwater communications (115), having an underwater acoustic transducer (116), the first acoustic unit for underwater communications (115) being arranged to cooperate with the first processing feature (118) to calculate, when in use, a position; a first orientation determination unit (124) operationally coupled to the first processing feature (118), the first orientation determination unit (124) being arranged to determine an orientation associated with the location of the first GNSS antenna (128) and the acoustic transducer of the first acoustic unit for underwater communications (115);the processing resource (118) being arranged to calculate an acoustically derived position of the GNSS antenna location using the calculated position and the determined orientation; and the wireless communications module (120) being arranged to transmit the received GNSS observation data and the acoustically derived position of the GNSS antenna location.

2. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, according to claim 1, characterized in that: the calculated position being a position of the underwater acoustic transducer (116); and the first processing feature (118) being arranged to calculate a vector extending between the position of the underwater acoustic transducer (116) and the position of the location of the first GNSS antenna (128), the vector being calculated using a predetermined lever arm displacement and the orientation determined by the first orientation determination unit (124) .

3. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, according to claim 2, characterized in that the first processing feature (118) is arranged to translate the position of the underwater acoustic transducer (116), using the calculated vector to obtain a position of the location of the first GNSS antenna (128), the position of the location of the first GNSS antenna (128) being a three-dimensional position of the location of the first GNSS antenna (128) relative to a reference point on the seabed (104) .

4. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, according to any of the preceding claims, further having: a GNSS receiver (122) arranged to make observations of the GNSS signal, comprising a pseudorange measurement and a carrier phase measurement; characterized in that: the first processing feature (118) is arranged to store data generated by the GNSS receiver (122) representing the observations of the GNSS signal as GNSS observation data.

5. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, according to claim 4, characterized in that the first processing feature (118) is arranged to modify the data generated by the GNSS receiver (122) representing the GNSS signal observations, so as to correspond with the measurements made from a predetermined static pseudo-observation position, and Petition 870240097696, dated 11 / 14 / 2024, page 67 / 143 3 / 5 store the modified data as GNSS observation data.

6. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, according to claim 4, when dependent on claim 2, characterized in that the first module for wireless communications (120) is arranged to disseminate GNSS observation data.

7. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, according to claim 5, characterized in that the first module for wireless communications (120) is arranged to broadcast modified data and the predetermined static pseudo-observation position.

8. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, according to claim 4, characterized in that: the GNSS receiver (122) is arranged to receive precise point positioning data; and the first processing feature (118) is arranged to support a precise point positioning processing unit, the precise point positioning processing unit being arranged to receive precise point positioning data and using the precise point positioning data to calculate a GNSS-derived position of the location of the first GNSS antenna (128).

9. “APPARATUS FOR OFFSHORE GNSS REFERENCE STATION, according to claim 4, characterized in that: the GNSS receiver (122) is arranged to receive precise point positioning data; the first processing feature (118) is arranged to support a precise point positioning processing unit, the precise point positioning processing unit being arranged to receive the precise point positioning data and using the precise point positioning data to calculate a GNSS-derived position of the location of the first GNSS antenna (128); and the first processing feature (118) is arranged to calculate an offset between the GNSS-derived position of the location of the first GNSS antenna (128) calculated using the precise point positioning data and the position of the location of the first GNSS antenna (128).

10. “OFFSHORE GNSS POSITIONING SYSTEM, having: the apparatus for an offshore GNSS reference station (102), defined in any one of claims 1 to 9; and a plurality of underwater reference acoustic transponders (106); characterized in that: the first acoustic unit for underwater communications (115) is arranged to measure a respective bidirectional travel time in relation to each of a plurality of underwater reference acoustic transponders (106).

11. “OFFSHORE GNSS POSITIONING SYSTEM, according to claim 10, characterized in that the first processing feature (118) is arranged to cooperate with the first acoustic unit for underwater communications (115) to estimate the position of the acoustic transducer unit (115) with respect to the plurality of underwater reference acoustic transponders (106).

12. “OFFSHORE GNSS POSITIONING SYSTEM, according to claim 10, characterized in that it also has: a roving GNSS device (300) arranged to receive GNSS observation data and the location of the first GNSS antenna (128) in relation to the reference point defined by the plurality of underwater reference acoustic transponders (106); and the roving GNSS device (300) being arranged to calculate a relative position vector associated with a location of the first GNSS antenna (320) of the roving GNSS device (300) in relation to the location of the first GNSS antenna (320) of the GNSS reference station (102).

13. “OFFSHORE POSITIONING REFERENCE DATA GENERATION METHOD, the method characterized by comprising: determining (200) a position acoustically through the water; making a GNSS observation (204) relative to the position; and determining an orientation (208) associated with a location of the first GNSS antenna (128) and the acoustically determined position; calculating an acoustically derived position of the GNSS antenna location (128) using the determined orientation and the acoustically determined position; and transmitting the GNSS observation and the acoustically derived position.

14. “METHOD FOR DETERMINING A POSITION, the method characterized by comprising: the method of generating offshore positioning reference data, defined in claim 13; receiving (500) the GNSS diffusion observation and diffusion position at a position to be determined; making a local GNSS observation (504) relative to the position to be determined; and using the received GNSS diffusion observation and diffusion position with the local GNSS observation data to estimate (510) a relative position vector. Petition 870240097696, dated 11 / 14 / 2024, p. 70 / 143

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