CROSS REFERENCE TO RELATED APPLICATION [S]

[0001] This application claims priority to U.S. Provisional Patent Application

"TRANSLATION OF KINEMATIC GNSS DATA TO AN ALTERNATE LOCATION," serial number 62/173,728 filed June 10, 2015, the disclosure of which is hereby incorporated entirely herein by reference.

BACKGROUND OF THE INVENTION

Technical Field

[0002] This invention relates generally to GNSS positioning and more particularly to a system for performing translation of kinematic GNSS data to an alternate location.

[0003] The following terms are used in the foregoing application, and will hereinafter be referred to using the designated acronyms: Global Navigation Satellite System (GNSS), Satellite-based Augmentation System (SBAS), Radio Technical Commission for Maritime Services (RTCM), National Marine Electronics Association (NMEA), Receiver Independent Exchange Format (RINEX), and Binary Exchange Format (BINEX).

State of the Art

[0004] GNSS positioning can be performed using a wide variety of corrections and in a variety of modes. One of the more common methods is Real Time Kinematic, whereby the data from a stationary reference station is sent as observations or corrections to a mobile, kinematic GNSS receiver and are processed in combination with the kinematic GNSS receiver's data to produce a precise position solution.

[0005] A similar method is also commonly used where instead of a stationary reference station, the data from a kinematic GNSS receiver, known as the Master, is sent to a second kinematic or static GNSS receiver, known as the Rover, to be processed in combination. In this case, the precise relative position between the two receivers can be calculated however the precision and accuracy of the Rover' position is dependent on the precision and accuracy of Master's positioning. Due to this limitation, this processing is typically only used for heading and pitch calculations between the reference stations.

[0006] In the case where the Rover's position is desired, the Master is required to transmit synchronously both its position in addition to either observation or observation correction information to the Rover. The observation or observation corrections is typically used to provide relative information between the Master and Rover, while the Master's position is used to provide an absolute position frame for the relative baseline. The need to frequently transmit the Master's position requires additional communication bandwidth and can lead to the previously mentioned synchronization problem if not managed correctly.

[0007] Accordingly, there is a need for an improved system for translation of kinematic GNSS data to an alternate location in order to remove the necessity to transmit and synchronize the Master's position.

SUMMARY OF THE INVENTION

[0008] The present invention relates to a system for performing translation of kinematic GNSS data to an alternate location using a Kinematic Master and a Rover, wherein the observations from the Kinematic Master receiver can be translated to a static location before being transmitted to the Rover receiver for processing. This makes the Master appear to be static to the Rover and eliminates the need to frequently communicate the Master's position.

[0009] An embodiment includes a method of translating data from a kinematic GNSS receiver to an alternate location, the method comprising: using observations of the kinematic GNSS receiver to calculate the position of the kinematic GNSS receiver; determining an alternate location; translating the observations to the alternate location; and making available translated receiver data, wherein the translated receiver data includes at least the translated observations.

[0010] Another embodiment includes a system for performing translation of kinematic GNSS data to an alternate location, the system comprising: a Master receiver; a Rover receiver; and GNSS satellites, wherein the Master receiver generates its position in response to observations, determines an alternate location, translates the observations to the alternate location, and provides the translated data to the Rover receiver.

[0011] Another embodiment includes a method of translating data from a kinematic GNSS receiver to an alternate location, the method comprising: using observations of the kinematic GNSS receiver to calculate the position of the kinematic GNSS receiver;

determining an alternate location; translating the observations to the alternate location; and making available translated receiver data, wherein the translated receiver data includes the translated observations, the translated location and the original location, and wherein the translated observations are converted into an altered representation of the full translated observations.

[0012] The foregoing and other features and advantages of the present invention will be apparent from the following more detailed description of the particular embodiments of the invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar items throughout the Figures, and:

[0014] Figure 1 is a diagrammatic view of a kinematic master and a rover;

[0015] Figure 2 is a diagrammatic view of a translation of kinematic master signals;

[0016] Figure 3 is a diagrammatic view of a minimum configuration using the translated alternate location;

[0017] Figure 4 is a flow chart of a master receiver process;

[0018] Figure 5 is a diagrammatic view of translated observation along with additional information;

[0019] Figure 6 is a diagrammatic view of the translated observation through differencing with other observations;

[0020] Figure 7 is a diagrammatic view of the translated observation through removal of model values;

[0021] Figure 8 is a diagrammatic view of the translated observations through removal of an observation ambiguity;

[0022] Figure 9 is a diagrammatic view of calculating the Master's position using SB AS satellites;

[0023] Figure 10 is a diagrammatic view of calculating the Master's position using global corrections;

[0024] Figure 11 is a diagrammatic view of calculating the Master's position using local corrections; [0025] Figure 12 is a diagrammatic view of methods of calculating the Master receiver's position;

[0026] Figure 13 is a diagrammatic view of translated alternate location moving to a new location;

[0027] Figure 14 is a diagrammatic view of potential translated alternate locations arranged in a predefined grid;

[0028] Figure 15 is a diagrammatic view of translated observation information used by multiple Rovers; and

[0029] Figure 16 is a diagrammatic view of translated observation information used by a processing server.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0030] Embodiments of the present invention relate to a system for performing translation of kinematic GNSS data to an alternate location using a Kinematic Master and a Rover, wherein the observations from the Kinematic Master receiver can be translated to a static location before being transmitted to the Rover receiver for processing. This makes the Master appear to be static to the Rover and eliminates the need to frequently communicate the Master's position.

[0031] Referring to Figures 1-16, depict an embodiment of a system 10 for performing translation of kinematic GNSS data to an alternate location. The translation of the Master's 20 position to a static location may occur at different rates. The translation rate may be at least equal to or greater than the rate of the transmitted message, since every transmitted message needs to be created based on a translated observation epoch. Additionally, the translation rate may also be equal to or less than the receiver measurement rate since measurements are needed for the translation. Therefore the translation can occur at any rate between the receiver observation rate, and the message transmission rate.

[0032] The translation must account for position-dependent effects that will be applied by the Rover receiver 30. The most common of these are the calculated satellite 40 coordinates, and the troposphere correction. [0033] There may be other effects that could be coordinated between the rover 30 and the reference station that are position dependent. These may include other effects including ionosphere models, multipath models, antenna models, and orbit error models,

[0034] The Master 20 calculates the difference between effects at their current location and the new location 22. This effect is then projected into the vector between the receiver 20 and satellite 40 and the difference is applied to the measurement. When the rover receiver 30 applies their models for the translated location 22, although they perceive the translated location, they will still have measurements for the original location. This allows this translation to have a minimal impact on the performance of the Rover 30 position processing and, therefore, the resulting accuracy. Figure 1 shows the translation of the kinematic data to the translated alternate location.

[0035] Once the measurements have been translated, then synchronous position and measurement information are no longer required, as shown in Figure 2. The translated alternate position 24 can be pre-determined between the Master 20 and Rover 30 and would not need to be transmitted at all (see Figure 3). This significantly reduces the complexity of the system by removing the necessity to transmit and synchronize the Master's 20 position.

[0036] The operational flow or method 50 at the Master 20 is shown in Figure 4. The process includes performing an observation calculation (Step 51); performing a position calculation (Step 52); determining a translated location (Step 53); translating the observations to the translated location (Step 54); and making the translated observations available (step 55). The translation operation may be triggered by an event or status, such as, but not limited to, waiting for the receiver position quality to be better than a certain level. For instance, one could require that translation and respective data transmission only occurs whenever the receiver position is known with a certain level of accuracy. The observation and position calculations (Steps 51 and 52) are typical for all GNSS receivers and remain unchanged in this method. Once the calculations are made, the observations and positions would be made available to the Rover 30 through the remaining process steps. This may be accomplished by execution of an algorithm, wherein after the position is calculated an alternate position is determined. The observations are then translated to the alternate location. These translated observations are then made available to the Rover receiver 30. It will be understood that the calculations may be similar to those calculations performed with regard to other GNSS devices, for example, but not limited to, calculations similar to what is done in virtual base station applications.

[0037] In addition to the translated observations, additional supporting information can be transmitted to the Rover 30 to assist with positioning and reporting. This information could be comprised of the following: the translated location; the original location; the difference between the translated and original location; datum transformation information; coordinate system information; time system information; position accuracy or precision information; atmosphere information; orbit information; and multipath information. For example, and without limitation, the translated location with coordinate system and datum transformation information can be sent periodically at a low rate in addition to the translated observations. This would allow the Rover 30 to calculate its position and report the coordinate system of that position. The system 10 could also then transform that position into other coordinates systems using the additional information.

[0038] The communication format used to transmit the translated observations shown in Figure 5 could be in one or more of the following recognized formats: RTCM Version 2; RTCM Version 3; MEA 0183; MEA 2000; RINEX; and BINEX.

[0039] The additional information, also shown in Figure 5, possibly including the translated location, could be transmit in one or more of the following formats: RTCM

Version 2; RTCM Version 3; NMEA 0183; NMEA 2000; RF EX; BINEX; or any other GNSS observation record format.

[0040] The two data streams depicted in Figure 5 could be the same data stream or the information could be divided between any number of data streams using any of the of the following communication formats: an L-band satellite; a GNSS satellite; a radio transmitter; the internet; Wifi network; cellphone network; Bluetooth; satellite radio; satellite telephone; television signal; local radio signal; and a physical cable.

[0041] There are many representations that can be used to reduce the magnitude of the translated observations. These include, but are not limited to, differences between the original observations (or other observations) and translated observations as shown in Figure 6. The differences between the original observations and the translated observations allow the data size to be small in cases where the original data is required for other applications on the same stream, as an example. [0042] The translated observations can also be reduced by models that are known to both the Master 20 and Rover 30 receiver. For example, Figure 7 depicts a model that is known to both the Master 20 and the Rover 30 is used to reduce the translated observations by the model value. The Rover 30 can then choose to reapply the model values or use the residual translated observations directly.

[0043] The translated observations can also be reduced by a predetermined ambiguity value. For example, referring to Figure 8, if the position can be determined to an accuracy of 100m then the translated observation can be reduced to be less than 200m in range.

[0044] The Master receiver's 20 position can be calculated autonomously using only a view of the GNSS satellites 40 or it can be further improved by the introduction of external correction sources. These sources could be SBAS satellites 42 (see Figure 9), global corrections 44 (see Figure 10), local corrections 46 (see Figure 11), or a combination of more than one set of corrections (see Figure 12). At this point the system 10 runs multiple processors, each of them responsible for dealing with each of the correction sources. Those processors are part of a unique overall processor framework in certain cases, thus making it easier to integrate their results. The combination of correction streams form various correction sources occur by combining each of the processors' results in different ways. Other embodiments may utilize multiple correction sources within a unique processor.

[0045] The translated alternate location 24 can remain in the same location or move periodically at regular or irregular intervals, as depicted in Figure 13. If the translated alternate location 24 is predetermined then it does not need to be transmitted at all. This can be the case if the alternate location is static or if its position is scheduled.

[0046] The translated alternate location 24 can also be one of the locations within a predefined grid 60 as shown in Figure 14. Only the grid index or ID needs to be transmitted, which requires significantly less data because the entire alternate location resolution needs to be transmitted. This provides a lot of flexibility because many locations are available with significantly reduced data requirements.

[0047] Once the translated observations are made available they can be used by a variety of sources, alone or in combination. Figure 15 shows the translated observation information being used by multiple rovers 30 at the same time. Alternatively, and referring to Figure 16, the translated observation information could be processed by a processing server 70 to generate local, regional, or global corrections in combination with other translated GNSS data, non-translated GNSS data, or GNSS reference station data.

[0048] The embodiments and examples set forth herein were presented in order to best explain the present invention and its practical application and to thereby enable those of ordinary skill in the art to make and use the invention. However, those of ordinary skill in the art will recognize that the foregoing description and examples have been presented for the purposes of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the teachings above without departing from the spirit and scope of the forthcoming claims.