Smartphone GPS Systems as Precision Locators for Advanced Positioning
In the realm of global navigation satellite systems (GNSS), smartphone devices equipped with GNSS receivers have become increasingly common. However, their use in high-precision geomatics work remains limited, as compared to dedicated surveying-grade GNSS receivers.
Limitations of Smartphone GNSS for High-Precision Geomatics
Accuracy and Precision
While modern smartphones can achieve meter-level accuracy under optimal conditions, this is insufficient for applications requiring centimeter- to millimeter-level precision, such as cadastral surveys, construction layout, or deformation monitoring.
Sensor Quality
Smartphone GNSS chipsets are typically low-cost, consumer-grade components, designed for power efficiency rather than high-precision navigation. They lack advanced features found in professional receivers, such as multi-frequency (L1/L2/L5) tracking, wide-area correction service compatibility (e.g., RTK, PPP), and robust anti-jamming/spoofing capabilities.
Signal Processing and Tracking
Professional geomatics GNSS receivers employ advanced signal processing, multi-constellation support (GPS, GLONASS, Galileo, BeiDou), and continuous tracking of carrier phase measurements for precise positioning. Most smartphones do not provide raw GNSS measurements to the application layer, and their software often applies heavy filtering or averaging for smoothness at the expense of accuracy.
Environmental Challenges
Like all GNSS systems, smartphone positioning degrades in urban canyons, under dense foliage, or near large structures where signals are occluded or multipath effects are severe. However, smartphones are more susceptible due to their smaller, less sensitive antennas and lack of sophisticated multipath mitigation.
Integration with Geomatics Workflows
Geomatics applications often require seamless integration with other sensors (e.g., LiDAR, IMU, total stations) and post-processing software. Smartphone GNSS data quality and interoperability are usually inadequate for these advanced workflows.
Calibration and Stability
Professional systems are meticulously calibrated for sensor alignment and temporal synchronization—features absent in smartphones. Even modular LiDAR systems face calibration challenges when sensors are reconfigured; smartphone GNSS, as part of a tightly integrated, non-modular device, cannot be recalibrated or optimized for geomatics applications.
Temporal and Spatial Resolution
For regional height reference maintenance or deformation monitoring, GNSS stations must provide millimeter-level precision over time and be sensitive to local mass changes within ~100 km. Smartphone GNSS, with its lower accuracy and lack of carrier phase tracking, cannot meet these demands.
Summary Table
| Limitation | Smartphone GNSS | Professional Geomatics GNSS | |-----------------------------------|----------------------------|-------------------------------------| | Accuracy | Meter-level | Centimeter- to millimeter-level | | Sensor Quality | Consumer-grade, single-freq| Survey-grade, multi-frequency | | Signal Processing | Basic, no raw measurements | Advanced, carrier phase tracking | | Environmental Robustness | Poor in challenging areas | Better, with advanced mitigation | | Integration with Workflows | Limited | Extensive, with multiple sensors | | Calibration | Fixed, non-reconfigurable | Precisely calibrated, modular | | Temporal/Spatial Resolution | Insufficient for monitoring| Suitable for deformation studies |
Conclusion
While smartphone GNSS receivers are convenient and increasingly capable for everyday navigation, they are not suitable for high-precision geomatics work due to limitations in accuracy, sensor quality, signal processing, environmental robustness, integration, calibration, and temporal/spatial resolution. Professional surveying-grade GNSS equipment remains essential for applications demanding millimeter- to centimeter-level precision.
For applications requiring greater accuracy in the positioning of points, users have geodetic receivers that allow the generation of the signal in the L1 and L2 or L1, L2 and L5 frequencies. Some smartphone and tablet devices, in their latest versions and equipped with low-cost GNSS micro receivers, have the ability to track the GPS signal and generate the L1 and L5 carrier observables.
The main causes of the low quality of measurements with mobile devices in Geomatics work are the duty cycling process and antennas with little capacity to attenuate the multipath effect of the signal. The use of cell phones in place of precision trackers can be invalidated when analyzing the uncertainty and accuracy of the tracked points, based on the normative documents of the Brazilian Navy for the use of trackers in topogeodesic activities.
The processing for both the smartphone observables and the Emlid RS2 tracker was carried out using frequencies L1 to L5, observables from all currently available GNSS systems, and using a 10o elevation mask in static positioning mode. Atmospheric corrections were turned off during the processing.
The GPS system is widely used in several areas such as aviation, land and sea navigation, precision agriculture, topographic and geodetic mapping, among others. A great advantage of devices with two or more frequencies is the possibility of performing combinations between the observables of different carriers, which serve as an improvement for further application of ionospheric and tropospheric models during data processing.
The Global Navigation Satellite System (GNSS) geotechnology demand has increased greatly over the last decades, primarily due to the applicability of the Global Positioning System (GPS) in smartphone devices. The seven points tracked, of which five for processing with a reference station in RJNI and four in ONRJ, presented fixed solutions (fix) and deviations in the millimeter, infers the correct processing of the data by the RTKLIBR software. Among the limitations presented by RTKLIB, there is the unavailability of processing adjustment for a 95% confidence interval, which is possible in GrafNet.
The Plane Coordinate System UTM (Universal Transverse Mercator) and the Datum SIRGAS 2000 will be used in the preparation of this work from this point. During processing, a trend of reduction of the standard deviation in both coordinates along the sections could be observed, indicating that the longer the smartphone tracking time, the better its accuracy. However, most of the time the float solution was obtained, including for the last coordinate generated in the processing. Topographic receivers are currently able to generate the L1 carrier phase and its code.
- The hydrographic survey field, being dependent on high-precision geomatics work, benefits more from professional surveying-grade GNSS equipment, as smartphone GNSS receivers lack the centimeter- to millimeter-level precision required for applications like cadastral surveys and deformation monitoring.
- In terms of science, the integration of smartphone GNSS data with other sensors and post-processing software is usually inadequate for advanced geomatics workflows, while professional geomatics GNSS receivers offer extensive support for multiple sensors.
