Location correction through differential networks system

A method may be executed by a base station or mobile device to improve accuracy of a global positioning system (GPS)-based position or “geoposition” of the mobile device. A time-stamped first set of GPS data may be received via a GPS receiver, e.g., of the base station. A second set of GPS data describing a geoposition of the mobile device is received from the mobile device by the base station. A time of collection of the base station and mobile device GPS data coincides. The GPS data includes code phase and pseudo-range data from each of the GPS satellites, and may include carrier phase data. A predetermined GPS position correction technique is used to generate a corrected geoposition of the mobile device using the GPS data. The corrected geoposition is then transmitted to the mobile device and/or an external response system such as a drone or first responder.

BACKGROUND OF THE INVENTION

Mobile devices such as cell phones and tablet computers may be equipped with Global Positioning System (GPS) chipsets and receivers, and thus are able to use built-in GPS capabilities for a variety of beneficial purposes. GPS is a worldwide satellite-based navigation system that relies on an earth-orbiting constellation of satellites to facilitate precise geoposition identification of GPS-equipped devices. Each GPS satellite continuously broadcasts data in the form of a navigation message containing pseudo-range, code phase, and carrier phase information. Timing of the GPS data is driven by an atomic clock, with an encoded time in the form of a GPS time stamp received by the GPS-equipped device. The time difference between broadcast and receipt of the time-stamped GPS data is used to calculate approximate distances between the GPS-equipped device and the orbiting GPS satellites. Determination of a position of the device is thus possible in two or three dimensions (latitude and longitude, and possibly altitude) when a corresponding distance is known for three or four GPS satellites, respectively.

The quantity and variety of mobile applications using onboard GPS capabilities has exploded in recent years. However, the functionality of the types of GPS receivers and associated chipsets typically used in modern mobile devices is limited by the reduced size, weight, power, and cost requirements of the receiving device. Research suggests that the available positioning accuracy for a typical handheld mobile device is around 5-15 meters (m) or 8-20 m depending on the device. While such levels of accuracy may be more than adequate for general navigation and other common GPS-based applications, higher levels of accuracy may be required, for instance in drone-based package delivery, gaming, or search-and-rescue/first responder dispatch efforts.

SUMMARY OF THE INVENTION

A method is disclosed herein for situationally increasing the available global positioning system (GPS) positioning accuracy of a global positioning system (GPS)-equipped and internet-enabled mobile device, e.g., a cell phone or tablet computer. The disclosed method takes advantage of systems and techniques associated with high-accuracy GPS positioning in combination with relatively low-quality GPS-related hardware components of the mobile device so as to situationally increase positional accuracy, and to thereby enable applications that require more a precise GPS position or “geoposition.”

The mobile device is in remote communication with multiple earth-orbiting GPS satellites and a fixed (stationary) base station having a reference geoposition. In some embodiments, the mobile device may be in communication with a deployable response system, e.g., a first responder vehicle or a package delivery drone. In other embodiments, the mobile device may effectively function as the response system, such as when a user of the mobile device views the improved geoposition via a display screen of the mobile device and conducts any number of possible automated operations or manual activities with the benefit of more precise knowledge of the user's true geoposition.

The method according to an example embodiment includes determining a geoposition of the fixed base station as a reference GPS position using a time-stamped first set of GPS data from each of the GPS satellites, and establishing an internet connection between the fixed base station and the mobile device. The method may include determining, over the established internet connection, a time-stamped second set of GPS data describing the geoposition of the mobile device. A time of collection of the time-stamped first and second sets of GPS data coincide, i.e., are the same, and include code phase data and pseudo-range data from each of the GPS satellites. The method may include generating a corrected geoposition of the mobile device using a predetermined GPS position correction technique, the time-stamped first and second sets of GPS data, and a chipset or processor of the base station or the mobile device. Thereafter, the method may include using the corrected geoposition to control an action of the mobile device and/or an external response system.

Generating the corrected geoposition may include using a differential GPS technique, a Real Time Kinematic (RTK) technique, or techniques similar to those used in a Local Area Augmentation System (LAAS)/Ground Based Augmentation System (GBAS) in different embodiments. Thereafter, an action of the response system may be requested and/or controlled responsive to the corrected geoposition of the mobile device.

A base station is also disclosed herein that has a fixed geoposition. The base station may also include a GPS receiver configured to receive a time-stamped first set of GPS data from each of the GPS satellites, a chipset or processor in communication with the GPS receiver, and memory containing recorded instructions. When executed by the processor, the instructions cause the base station to receive a second set of GPS data from a mobile device in networked connection with the base station. The second set of GPS data describes a geoposition of the mobile device and has a time of collection that coincides with a time of collection of the time-stamped first set of GPS data. The first and second sets of GPS data include code phase data and pseudo-range data from each of the GPS satellites. Using a predetermined GPS position correction technique, the base station generates a corrected geoposition of the mobile device via the processor and the first and second sets of GPS data. Thereafter, the base station transmits the corrected geoposition to the mobile device and/or an external response system.

A mobile device is also disclosed. In a possible embodiment, the mobile device includes a GPS receiver configured to receive a time-stamped set of GPS data from each of a plurality of GPS satellites, a chipset or processor in communication with the GPS receiver, and memory on which is recorded instructions that, when executed by the processor, cause the mobile device to execute a method. In various steps, the method may include establishing an internet connection with the base station, and receive another time-stamped set of GPS data from the base station describing a fixed geoposition of the base station. A time of collection of the time-stamped sets of GPS data from the mobile device and the base station coincide, and include at least code phase data and pseudo-range data from each of the GPS satellites. The mobile device also generates, via a predetermined GPS position correction technique, a corrected geoposition of the mobile device using the processor and the first and second sets of GPS data. A control action is then executed over the mobile device and/or an external response system using the corrected geoposition.

These and other features, advantages, and objects of the present disclosure will be further understood and readily apparent from the following detailed description of the embodiments and best modes for carrying out the disclosure by referring to the specification, claims, and appended drawings.

The present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments are shown by way of example in the drawings. It should be understood that novel aspects of this disclosure are not limited to the particular forms illustrated in the appended drawings. Rather, the disclosure is intended to cover all modifications, equivalents, combinations, and alternatives falling within the scope and spirit of the disclosure as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein are method and system for increasing global positioning system (GPS)-based position accuracy of internet-capable cell phones, tablet computers, or other mobile devices. The disclosed method takes advantage of available GPS data and other measurements such as pseudo-range, code phase, and/or carrier phase data, combined with corresponding GPS data and other measurement information provided over an internet or other wireless connection from one or more stationary base stations. For example, the method may take advantage of the Continuously Operating Reference Stations (CORS) operated by the U.S. National Geodetic Survey, and as typically used for positioning, meteorology, weather, and geophysical applications, or the Networked Transport of Radio Technical Commission for Maritime Services (RTCM) via Internet Protocol, i.e., the NTRIP protocol. The separate base station and mobile device data is processed using a predetermined GPS positional correcting technique, e.g., Differential GPS, Real-Time Kinematic (RTK) GPS, and/or using techniques similar to or variants of those used in the Local Area Augmentation System (LAAS) in three possible embodiments. Such techniques are able to remove atmospheric distortion and other errors common to coinciding GPS measurements of the base station and mobile device to the extent such errors correlate, thereby increasing the level of accuracy of position estimates of the mobile device.

As is well known in the art, a typical GPS receiver uses a self-generated pseudo-random code or “pseudo-code” to determine the time of propagation of unique pseudo-random codes emitted by each orbiting GPS satellite. The term “pseudo-range” as used herein refers to uncorrected distance measurements that are based on a correlation between the satellite-emitted pseudo-codes and the GPS receiver's locally-generated code. Carrier-phase processing techniques use the GPS satellite's carrier frequency, which is typically higher than the pseudo-random code frequency. This is done to more accurately calculate the geoposition of the GPS receiver. The carrier frequencies may be 1575.42 MHz, i.e., the L1 carrier frequency, and 1227.60 MHz (the L2 carrier frequency). While carrier frequency-based correction techniques such as RTK or LAAS tend to be more accurate than pure differential techniques that rely solely on the code phase and pseudo-range information, the possible distances between the mobile device and the base station are more limited with such techniques. For example, differential techniques may be used up to about 90-100 km on certain applications, while RTK techniques and techniques used in LAAS may be usable up to about 30 km for similar applications, albeit at additional cost and complexity relative to implementation of basic differential techniques.

Referring toFIG. 1, a Location Corrections Through Differential Networks or “LOCD-IN” system10includes a stationary base station12in remote networked communication with a global positioning system (GPS)-equipped mobile device14, e.g., a tablet computer14A, cell phone14B, or other portable electronic device equipped with a chipset or processor (P1), memory (M1), and a GPS antenna or receiver15. The base station12and the mobile device14are in remote communication with a plurality of GPS satellites11, shown as four representative GPS satellites11A,11B,11C, and11D.

Depending on orbital path, time of day, and line of sight obstructions, more or fewer GPS satellites11may be in view at a given time and thus usable by the base station12and the mobile device14at a given time. The base station12is stationary and thus has a relatively well known three-dimensional reference geospatial position or “geoposition” in terms of latitude, longitude, and altitude. The base station12includes an antenna or other GPS receiver13that, along with a processor P2and memory M2, enables the base station12to accurately identify its geospatial position or “geoposition” to a first level of accuracy. Similarly, the mobile device14, being handheld, typically has a time-varying geoposition as a user of the mobile device14moves relative to the fixed base station12.

A single base station12and mobile device14are shown inFIG. 1solely for the purpose of illustrative simplicity. Those of ordinary skill in the art will appreciate that multiple base stations12and mobile devices14may be used in other embodiments, with an example of such an embodiment shown inFIG. 3and described below. Therefore, singular descriptions provided herein with respect to the number of base stations12or mobile devices14are intended to apply equally to multiple base stations12or mobile devices14when used as part of the system10.

The LOCD-IN system10ofFIG. 1, as with the alternative LOCD-IN systems10A and10B ofFIGS. 2 and 3, is configured to situationally improve upon existing levels of GPS location accuracy of the mobile device14. As noted above, the accuracy or resolution of the mobile device14may be limited due to restrictions on packaging size, weight, or power requirements of the mobile device14. Such restrictions tend to result in use of a lower cost, lower performance receiver15and processor (P1) aboard the mobile device14. For everyday GPS applications such as turn-by-turn navigation or social media-based location reporting, the uncorrected GPS-based positional resolution may be sufficient. However, situations may periodically arise in which the available GPS position accuracy of the mobile device14is inadequate.

An example of such a situation is a scheduled aerial delivery of a package to a specific mailing address, e.g., via an autonomous or remotely piloted drone30. Another example may be that of a first responder40, such as a police squad car as shown, search and rescue teams, firefighters, or emergency medical services requiring a more precise knowledge of the geoposition of the mobile device14. When improved accuracy is required, whether prompted by the base station12or initiated by a user of the mobile device14, the user may request execution of a method50for processing on the mobile device14and/or via the processor (P2) or chipset of the base station12, or via a server or another remote device. Although not necessary, such an accuracy improvement request may be generated in some embodiments by touching a touch screen-displayed activation icon25on the mobile device14or by pressing a physical button (not shown).

The base station12and the mobile device14separately receive GPS data signals (arrows S1, S2, S3, S4) from the receptive GPS satellites11A,11B,11C, and11D. The receiver15and processor (P1) of the mobile device14together identify an uncorrected geoposition of the mobile device14to a second level of accuracy that, due to the lower cost and size of the receiver15and processor (P1), is less than the first level of accuracy of the base station12. Thus, the base station12serves herein as reference geoposition and data source to situationally correct for errors in the available geoposition accuracy of the mobile device14, doing so without requiring hardware modification to the low-cost receiver15and associated processor (P1) of the mobile device14.

In the depicted embodiment ofFIG. 1, the mobile device14determines its geoposition via communication with each GPS satellite11that is in view of the mobile device14at a given moment. Thereafter, the mobile device14automatically refines the GPS-based position estimates using unprocessed measurements (arrows20A and20B) as transmitted by the base station12through an internet connection16. In other embodiments, onboard processing may be performed by the mobile device14, such that the base station12relays its own geoposition as a set of GPS measurements and the mobile device14performs the necessary correction techniques using the processor (P1).

When using code phase-based data, the receivers13and15are used to establish the respective geopositions of the base station12and the mobile device14by determining pseudo-ranges to each of the orbiting GPS satellites11as noted above. The base station12may thereafter transmit its determined pseudo-ranges and/or code phase information to the mobile device14, or vice versa, with subsequent calculations thereafter performed by the processor of the receiving device, for instance the processor P1of the mobile device14. The base station12and/or the mobile device14may thereafter execute a suitable control action using the corrected geoposition of the mobile device14. For example, a response system45may be embodied as the drone30or the first responder40, in which case the corrected geoposition (arrow PE) may be transmitted to the drone30or first responder40to more accurately direct the drone30or first responder40to the user of the mobile device14, or a location specified by the user of the mobile device14.

Alternatively, the base station12ofFIG. 1may use Real-Time Kinematic (RTK) correction to improve geoposition accuracy of the mobile device14. As is known in the art, RTK functions by determining a number of carrier cycles between the GPS satellites11and each of the mobile device14and base station12, and thereafter multiplying the number of carrier cycles by the known carrier wavelength as reported by the GPS satellites11. The optional RTK embodiment of the present system10thus adds carrier-phase GPS information to the available pseudo-range and code phase information noted above.

RTK techniques may be used to help remove errors that are common to both the base station12and the mobile device14, such as clock errors of the GPS satellites11or the base station12or mobile device14, ionosphere errors, and/or atmospheric noise. Phase measurements may be used after correcting for such common errors in order to determine the geoposition of the mobile device14in a Cartesian reference frame, within a few centimeters of accuracy in some instances depending on the quality of the GPS receiver15and the chipset (P1). In the present application, GPS accuracies of 1-2 meters or less may be possible and sufficient without modifying the low-cost receiver15and processor P1of the mobile device14.

FIG. 2depicts another example embodiment utilizing correction techniques similar to those of the Local Area Augmentation System (LAAS) to improve GPS accuracy relative to the differential and RTK techniques described above. LAAS, now more commonly referred to as the Ground Based Augmentation System (GBAS), is most often used to provide corrections to aircraft in the vicinity of an airport. A typical LAAS/GBAS facility may include collocated GPS receivers, a processor/CPU/chipset, and a VHF Data Broadcast (VDB) transmitter. Orbiting aircraft include a GPS receiver, VHF antenna, and an associated chipset. The base station thus uses the available VHF link to transmit GPS corrections to the aircraft. For instance, the base station is able to average the slightly different GPS position measurements from each of the multiple receivers13A,13B,13C, and13D to thereby minimize common error between the receivers13A,13B,13C, and13D.

In an example system10A, the mobile device14refines its GPS-based position estimates using corrections for a local area computed and transmitted by the base station12, e.g., via data broadcast or other networked devices. The base station12A in this embodiment includes a plurality of collocated GPS receivers, i.e., the receivers13A,13B,13C, and13D noted above. The receivers are in close proximity to each other, such as within a few meters, so as to function as a larger and more accurate base station12A relative to the more limited configuration ofFIG. 1. As with RTK, the correction processes used by LAAS/GBAS are more accurate but also tend to be more expensive than basic differential correction techniques. Therefore, the example embodiment ofFIG. 2may be used when increased accuracy is required and justified by the tradeoff in cost.

FIG. 3illustrates any of the above-described geoposition correction techniques using a system10B with multiple GPS receivers13A,13B,13C,13D,13E,13F, and13G corresponding to a given base station12ofFIGS. 1 and 2, sequentially numbered #1-7 inFIG. 3for clarity, respectively for the above-noted receivers, and distributed across a wider geographic area relative toFIGS. 1 and 2. In an example drone-based package delivery application, for instance, the various base stations12may be arranged on the roofs of package distribution facilities spread across a wide distribution region. Using two-way communication between the mobile device14and the base stations12, the GPS locational accuracy is maximized by selecting the nearest base station12based off of the geoposition of the mobile device14working in a standalone fashion.

For instance, a first mobile device140A may be paired with a base station (#6), a second mobile device140B may be paired with a base station (#3), and a third mobile device140C may be paired with a base station (#5). Pairing may occur automatically via the processors P1and/or P2based on closest proximity, i.e., using the calculated geoposition. By way of illustrative example, the mobile device140A may conceivably communicate with base stations #4 at a distance D4′ and with base station #6 at a distance D6. By simple comparison, the distance D6may be selected by the mobile device14as the closest of the base stations12, thereafter initiating geoposition correction using the base station #6. In the same way, mobile device140B may determine that distance D3to base station #1 is shorter than the distances D1, D4, and D5to base stations #4 and #5, respectively. Similarly, the mobile device140C may determine that the distance D5′ to base station #5 is shorter than distance D2to base station #2 and thereafter select base station #5 responsive to this determination.

FIG. 4is a flow chart describing an example embodiment of the method50. Beginning with step S51, and with reference to the systems10,10A, and10B ofFIGS. 1-3, the method50commences after or shortly before establishing an internet connection between the fixed base station12and the mobile device14. As part of step S51, the method50may include determining a geoposition of the fixed base station12as a reference GPS position, doing so using a time-stamped first set of GPS data from each of the GPS satellites11. Step S51may include receipt of the GPS signals S1, S2, S3, and S4via the GPS receiver13of the base station12shown inFIG. 1, for instance, concurrently with receipt of the signals S1, S2, S3, and S4by the GPS receiver15of the mobile device14. The method50then proceeds to step S52.

At step S52, the method50includes detecting or otherwise determining whether an accuracy refinement request was made indicative of a need for improved accuracy of the GPS location of the mobile device14. Step S52may include a user of the mobile device14touching or swiping the icon25shown inFIG. 1in a user-initiated action. In other embodiments the request may be generated automatically and/or remotely, e.g., by the response system45, the base station12, or another remote entity such as a web site, warehouse, police dispatcher, etc. The method50repeats step S51when a need has not presented itself that refinement of the GPS accuracy of the mobile device14is needed. The method50continues to step S53when the request for improved accuracy of the GPS location of the mobile device14is detected.

Step S53includes refining the GPS location estimates of the mobile device14using any of the GPS position correction techniques noted above, i.e., Differential Correction, RTK, or LAAS. The method50proceeds to step S54after the mobile device14and/or the base station12have executed the geoposition correction technique.

At step S54, the method50may include executing a control action, e.g., of the mobile device14or the external response system(s)45using the refined or corrected geoposition from step S53. For example, step S54may include controlling an action of the response system45ofFIGS. 1 and 2responsive to the corrected geoposition.

As a non-limiting example illustration of the method50, a user of the mobile device14ofFIGS. 1-3may request delivery of a package from an online supplier. The supplier notifies the user via SMS text message to the mobile device14when delivery has been scheduled. The text message may include a request to input a one-time request for enhanced geoposition, such as a text prompt to the user to touch the icon25when the user is present at a desired point of delivery of the package. The user then touches the icon25, thus triggering execution of step S53.

Once the geoposition of the mobile device14is corrected via the techniques described above, the corrected geoposition may be recorded in memory M1or M2, and/or transmitted to the online supplier. In turn, the online supplier may transmit the refined geoposition information to the drone30, such that the drone30is able to schedule flight operations accordingly. Similar approaches may be used with the first responder40or other external response system45. In this manner, systems and techniques typically associated with high-accuracy, high-cost GPS positioning systems may be used in combination with low-cost, low-quality GPS hardware of the type typically found in a mobile device such as the mobile devices14described herein.

The detailed description and the drawings or figures are supportive and descriptive of the disclosure, but the inventive scope is defined solely by the claims. While some of the best modes and other embodiments for carrying out the disclosure have been described in detail herein, various alternative designs and embodiments exist within the intended scope of this disclosure. Furthermore, the embodiments shown in the drawings or the characteristics of various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of an embodiment can be combined with one or a plurality of other desired characteristics from other embodiments, resulting in other embodiments not described in words or by reference to the drawings. Accordingly, such other embodiments fall within the framework of the scope of the appended claims.