GNSS Receiver Research Articles

Comprehensive Analysis of BDS/GNSS Differential Code Bias and Compatibility Performance

High-precision DCBs are essential for effective multi-frequency and multi-constellation GNSS integration, especially in processing compatible signal observations. This study utilizes data from MGEX, iGMAS, and CORS stations to estimate and analyze long time series of BDS/GNSS DCBs, focusing on stability and influencing factors. Results indicate that DCBs for the same signal, but different channels exhibit similar ranges and trends. Among BDS DCBs, those from satellites with rubidium atomic clocks are more stable than those with hydrogen atomic clocks. An upgrade and maintenance of BDS in late 2022, reported by NABU, likely contributed to DCB jumps. BDS-compatible signal DCBs show weaker stability compared to GPS and Galileo. Variations in GNSS signal processing and receiver algorithms also impact DCB stability. Converting DCBs to OSBs and performing RMS statistics revealed that smaller differences between signals increase the susceptibility of observation equations to observation quality.

Assessing jamming and spoofing impacts on GNSS receivers: Automatic gain control (AGC)

Assessing jamming and spoofing impacts on GNSS receivers: Automatic gain control (AGC)

Mid‐Latitude Study of Ionospheric Variation Over Iran Associated With Equatorial Ionization Anomaly (EIA), and Artificial Neural Networks Model Development

AbstractThe ionosphere over Iran is located on the upper edge of equatorial ionization anomaly (EIA). The Equatorial Electrojet (EEJ) as the proxy of temporal evolution of the EIA is explored using the MAGDAS stations near the magnetic equator during quiet and active geomagnetic conditions. The possible impact of EIA on Total Electron Content (TEC) over Iran is investigated. Analyzing data from 140 stations over 7 months, it is found that EEJ influences TEC and its latitudinal penetration. During geomagnetically active days, EEJ's behavior and TEC's latitudinal variations are investigated. Diurnal EEJ patterns and counter electrojets (CEJ) are analyzed, alongside solar wind timing effects on EEJ and TEC using data from stations in Brazil, Peru, the Philippines, and Sri Lanka. Statistical correlations between maximum TEC and parameters extracted from the daily EEJ profile, including EEJ, integrated EEJ (IEEJ), and IEEJ—highlight Iran's position at the EIA's upper edge, indicating high susceptibility to equatorial dynamics. In addition, the Rate of Total Electron Content Index (ROTI) has been analyzed under geomagnetic active conditions. The results demonstrate that ROTI exhibits good agreement with TEC in terms of latitude penetration and the detected gradient in TEC. Employing Artificial Neural Networks (ANN) for local TEC prediction, Iran is segmented into eight regions based on GNSS receiver distribution. Each region's ANN model, trained during the quiet geomagnetic condition, assesses predictability and accuracy. The ANN model demonstrates reliable local TEC forecasting and confirms the direct impact of equatorial dynamics on Iran's ionosphere.

Concept of Sporadic E Monitoring Using Space-Based Low Power Multiple Beacon-Systems

Current monitoring systems to detect sporadic E use ground-based setups, ionosondes, and the network of GNSS satellites in order to assess the phenomenon of sporadic E. This paper aims to monitor sporadic E using a miniature space-based platform in an atypical way. The setup consists of multiple radio-amateur beacon systems aboard satellites, each having a specific modulation and transmission scheme. This Radio Amateur Beacon System for the Investigation of the Ionosphere (RABSII) is coupled to a GNSS receiver, revealing the location of the platform. Multiple beacon data streams are sequentially sent from a satellite platform towards the Earth. By receiving and comparing the Signal-to-Noise ratios of these streams using a dedicated ground-based radio-amateur network of receiving stations, the presence of sporadic E can be determined, and a location-based model can be built. The advantage of this miniaturized, low-power, low-cost instrument is its ability to be put on any satellite platform in the future in order to map sporadic E.

Expecting the expected – learning from the past to provide forward scenarios through geomorphic change detection, monitoring and modeling

This paper tells the story of a landslide, its origins, its activity and the actions undertaken to mitigate the risks that it poses. The Rotolon landslide is a large Deep-seated Gravitational Slope Deformation (DGSD), located in the Eastern Italian Alps, whose unremitting movements provide a sediment supply for large-scale debris flow events. It has been active since at least 1789, threatening the valley where the thermal baths town of Recoaro Terme is located. In 2010, a major reactivation of the landslide channelled 320,000 m3 of material towards the town causing significant concern, the evacuation of the exposed population and threatening several buildings. A few days after the emergency, the personnel of the Research Institute for Geo-Hydrological Protection of the Italian Research Council (IRPI-CNR) deployed a monitoring system consisting of an automatic total station, several extensometers and web cameras to monitor the evolution of the unstable slope and set up an early warning and alarm system equipped with sirens to warn the local population. Subsequently, after the emergency phase, the 2010 event was studied through multi-temporal LiDAR Digital Terrain Models (DTMs) and modeling. The authors have continued monitoring and actively studying this landslide ever since. In 2020, a new LiDAR survey of the area allowed assessment of the sediment dynamics within the catchment through the comparison with the post-2010 event LiDAR DTM. Based on DEM of difference maps, new insight into the behaviour of the catchment emerged, which appears to be influenced both by natural processes and anthropic activities. The authors were able to assess the amount of sediment that could be stored in the channel without causing overflooding and to calculate the expected damage to the built environment should another event occur. Furthermore, the considerable amount of data collected by the monitoring system throughout the years has allowed identification of two active sectors of the DGSD that may be prone to detachment, and through numerical modeling, future hazard scenarios were produced. Based on these outcomes, a second-tier targeted monitoring campaign was implemented, consisting of a network of four permanent GNSS receivers, additional topographic benchmarks and web cameras, and a new early warning protocol, in an ever-updating cycle of monitoring, modeling and mitigation.

Software-Defined Platform for Global Navigation Satellite System Antenna Array Development and Testing

With the increasing demand for accurate and robust positioning solutions, the use of GNSS antenna arrays has gained significant attention. However, their development and testing are frequently constrained by the inflexibility of traditional hardware platforms, often requiring extensive reconfiguration throughout the development cycle. This paper presents a platform based on a system on chip to develop a highly flexible software-controlled system that is capable of directly sampling up to 16 antenna elements. Multibeam digital beamforming is implemented using the available FPGA resources and the resulting signal is reproduced by the integrated DAC and can be connected to any conventional single antenna GNSS receiver. This paper presents the architecture of the platform, detailing its components and capabilities. Our experimental results demonstrate that the system can phase shift every channel with errors of less than 0.5° and can reconfigure 4 simultaneous beams of a 16-antenna array at speeds of 1.2 kHz, and 20 beams at around 400 Hz. The average delay introduced by each channel of the system is around 381 ns with a maximum deviation of 1.05 ns. The delay was also measured for the implementation using 4 beams, which achieves a slightly bigger average delay of 384.6 ns while keeping the variation to 5 to 6 ns. This system is intended to be used as the backbone for the development of antenna arrays and beamforming algorithms. Given its flexibility, it is not necessary to develop new hardware between development iterations or even for different systems, as only the software layer needs to be modified. Consequently, it is possible to expedite the development stage before producing dedicated solutions for industrial applications.

Dual-Band Low-Noise Amplifier for GNSS Applications

A new dual-band low-noise amplifier (LNA) operating at L1/E1 1.575 GHz and L5/E5 1.192 GHz center frequencies for global navigation satellite system receivers is proposed. A doubled common-source amplifier architecture is used with a single input, shared gate inductor, and two outputs to split the RF signal into separate RX channels. The main advantage of the proposed circuit is compatibility with widespread multi-band antennas with single RF connectors dedicated to high-precision applications, as well as the possibility to use cheap SAW filters with small footprints to build low-cost, highly accurate GNSS receiver modules. The input and both outputs are well matched to 50 Ω impedance. The LNA is designed with a 110 nm CMOS process, consuming 6.13 mA current from a 1.5 V supply. The measured noise figures and voltage gains of the dual-band LNA are, respectively, NF1/NF5 = 3.23/3.5 dB and G1/G5 = 21.22/18.2 dB in the band of interest for each channel. The measured impedance matching at the input (S11) and output (S22) of the dual-band low-frequency amplifier is as follows: S11_L1 = −23.89, S11_L5 = −8.42, S22_L1 = −12.65, S22_L5 = −15.08. The one-decibel compression points are L1 band PdB1 = −37.71 dBm and L5 band PdB5 = −34.72 dBm, respectively.

Imaging the May 2024 Extreme Aurora With Ionospheric Total Electron Content

AbstractThe continental United States is well instrumented with facilities for mid‐latitude upper atmosphere research that operate on a continuous basis. In addition, citizen scientists provide a wealth of information when unusual events occur. We combine ionospheric total electron content (TEC) data from distributed arrays of GNSS receivers, magnetometer chains, and auroral observations obtained by citizen scientists, to provide a detailed view of the intense auroral breakup and westward surge occurring at the peak of the 10–11 May 2024 extreme geomagnetic storm. Over a 20‐min interval, vertical TEC (vTEC) increased at unusually low latitude (∼45°) and rapidly expanded azimuthally across the continent. Individual receiver/satellite data sets indicate sharp bursts of greatly elevated of vTEC (∼50 TECu). Intense red aurora was co‐located with the leading edge of the equatorward and westward TEC enhancements, indicating that the large TEC enhancement was created by extremely intense low‐energy precipitation during the rapid substorm breakup.

On the applicability of low-cost GNSS antennas to precise surveying applications

Abstract This study addresses the scientific question of the applicability of low-cost antennas to the most precise GNSS applications. First of all, we inspect the implications of the availability and quality of low-cost antenna PCC models for precise positioning. From this point of view, we analyze the selected performance indicators of multi-constellation positioning with the representative set of low-cost mass-market GNSS receiver antennas. The processing strategy was based on the relative positioning model, considered the most reliable and precise one. To isolate the antenna-related errors from atmospheric propagation ones, we conducted an experiment based on an ultra-short baseline. As the main indications of low-cost antenna performance, we considered distance and height residuals, defined as the difference between benchmarks and the retrieved from GNSS measurements. We found that the low-cost antenna's PCV effect may significantly affect the final results. On the other hand, the results obtained using certain configurations of low-cost antennas were characterized by only slightly higher standard deviations and discrepancies with respect to benchmark values than those obtained with surveying or geodetic equipment. We identify several sets of low-cost antennas where distance residuals do not exceed 4 mm and height residuals do not exceed 6 mm, which shows the low-cost antenna performance comparable to those achieved using high-grade antennas. On this basis, we conclude that selected low-cost antennas can meet the requirements of high-precision surveying applications.

Evaluating antenna phase center variation effects on tropospheric delay retrieval using a low-cost dual-frequency GNSS receiver

Abstract This study examines the impact of Phase Center Variation (PCV) corrections on Zenith Wet Delay (ZWD) accuracy using a low-cost U-blox ZED-F9P receiver paired with three different antenna configurations: the high-grade TRM57971 antenna, the moderate-grade AS-ANT3BCAL antenna, and the low-cost ANN-MB-00 antenna. Among the three antennas evaluated, the low-cost antenna exhibited the largest PCV magnitude and a pronounced elevation angle dependence. In contrast, the other two antennas demonstrated lower levels of PCV variation. Without PCV corrections, the low-cost antenna showed significant ZWD biases compared to reference values. Applying PCV corrections significantly improved its accuracy, reducing bias and RMS by 88% and 79%, respectively. Moderate- and high-grade antennas experienced minimal improvement with correction. All antennas exhibited remarkable day-to-day repeatability in their residual patterns, despite variations observed in the RMS of phase residuals. This observed repeatability is likely attributable to the presence of unmodeled multipath contributions. The variations in RMS, in turn, can be primarily ascribed to inherent differences in multipath resistance among the antenna designs. This study highlights the critical role of PCV corrections for accurate ZWD estimation with low-cost GNSS receivers. Future research should prioritize the acquisition of manufacturer-provided calibration data for low-cost antennas to streamline and enhance the accuracy of PCV correction applications. Moreover, efforts should be directed toward developing innovative solutions, such as low-cost, multipath-resistant antennas or advanced signal processing algorithms, to mitigate the impact of multipath errors. By addressing these areas, low-cost GNSS solutions can become more reliable and cost-effective tools for tropospheric delay estimation.

Estimation of Surface Water Level in Coal Mining Subsidence Area with GNSS RTK and GNSS-IR

Ground subsidence caused by underground coalmining result in the formation of ponding water on the ground surface. Monitoring the surface water level is crucial for studying the hydrologic cycle in mining areas. In this paper, we propose a combined technique using Global Navigation Satellite System Real-Time Kinematic (GNSS RTK) and GNSS Interferometric Reflectometry (GNSS-IR) to estimate the surface water level in areas of ground subsidence caused by underground coal mining. GNSS RTK is used to measure the geodetic height of the GNSS antenna, which is then converted into the normal height using the local height anomaly model. GNSS-IR is employed to estimate the height from the water surface to the GNSS antenna (or, the reflector height). To enhance the accuracy of the reflector height estimation, a weighted average model has been developed. This model is based on the coefficient of determination of the signal fitted by the Lomb-Scargle spectrogram and can be utilized to combine the reflector height estimations derived from multiple GNSS system and band reflection signals. By subtracting the GNSS-IR reflector height from the GNSS RTK-based normal height, the proposed method-based surface water level estimation can be obtained. In an experimental campaign, a low-cost GNSS receiver was utilized for the collection of dual-frequency observations over a period of 60 days. The collected GNSS observations were used to test the method presented in this paper. The experimental campaign demonstrates a good agreement between the surface water level estimations derived from the method presented in this paper and the reference observations.

Development of Cost-Effective GPS Receiver for Ionospheric Scintillation Monitoring Aided with IoT System

One of the applications of GPS receiver is to detect and measure the irregularities in satellites communication. Many of the studies conducted the research to analyses the transmission data through ionosphere layers. One of the subjects of the research is scintillation. One of the ionosphere scintillation parameters used for measuring the irregularities is amplitude scintillation (S4). However, the survey-grade or GISTM receiver, which is expensive, was commonly used to monitor the parameter. The other alternative is to used common geodetic GPS receiver that capable of collecting the parameters. This study used ZED-F9P with ANN-MB antenna and Raspberry Pi as the prototype to operate. The data collected during the autumnal equinox showed a pattern of strong ionospheric scintillation effects in the post-midnight hours. The study demonstrates the feasibility of using low-cost GNSS receivers for ionospheric monitoring, which has important implications for various applications such as navigation, communication, and space weather monitoring.

Developing a new interface for Qibla direction application based on MATLAB GUI

In this study, a MATLAB GUI-based interface has been developed that can be integrated with GNSS receivers. Through this interface developed for calculation and querying purposes, Qibla direction application with geodetic precision can be achieved using coordinate information of a corner of the mosque and its facade length, without the need for auxiliary geodetic measurement devices and computational burden. Furthermore, interface allows users to query the Qibla directions in mosques for inspection. It has been found that 2% of the mosques are outside the Qibla direction, 51% are outside the Miqat boundaries, and 8% are within the Haram boundaries.

A Lightweight, Polarization-Camera Equipped Sensor Rig for the Development of Autonomous Surface Vehicles

Abstract Situational Awareness (SITAW) of Autonomous Surface Vessels (ASV) is critical for safe and efficient maritime operations, enabling these vehicles to understand their environment better and make informed decisions. High-quality data sets from relevant maritime environments are needed to advance the development of SITAW, as it is both the backbone of any learning-based method and the development and validation of classical methods. Research vessels such as the full-scale ferry milliAmpere2 provide such data, but there tends to be a considerable labor cost associated with their operation. With this in mind, we have developed a portable sensor rig that makes collecting sensor data significantly easier. The sensor rig is designed for easy transport and operation by a single individual. It can also be temporarily attached to an existing vessel, making it versatile for a wide range of data collection scenarios. The sensor rig is equipped with a Jetson Orin AGX computer, two dual-band GNSS receivers, a high-quality IMU, and two color polarization cameras. Accurate synchronization of all sensors and the computer to UTC is achieved using a microcontroller for triggering and a custom Pulse Per Second (PPS)-enabled Linux kernel on the Jetson. The sensor rig is controlled and monitored by connecting a smartphone to its hosted web app, which provides a live stream from the cameras and information about the sensors. We present a new dataset from the river Nidelva in Trondheim, Norway, to demonstrate the sensor rig’s potential and the benefit of color polarization cameras in the maritime domain. We show how the data from color polarization cameras can be used directly to make the water surface more visibly distinct and remove reflections and sun glare. This new data set consists of synchronized stereo color polarization video, raw IMU data, and raw GNSS data, and it is made publically available to the research community.

Comprehensive Study of Large‐Scale Traveling Ionospheric Disturbances (LSTIDs) Observed Over Iran

AbstractA dense network of GNSS receivers is employed to study temporal and spatial characteristics of large‐scale traveling ionospheric disturbances (LSTIDs) in Iran. Three geomagnetic storms in 2021 are selected. To determine LSTID propagation, an eighth‐order Butterworth bandpass filter was applied to the data to remove the diurnal variability of the total electron content (TEC). Moreover, two‐dimensional TEC perturbation maps are provided to explore the meridional and zonal structures of the LSTIDs. Analysis of a major storm on November 4 (Kp = 7, Dst = −99 nT) revealed two single LSTIDs and three groups of multiple LSTIDs. The phase velocity and wavelength of LSTIDs in this event varied between 190 and 930 m/s and 1,030–5,022 km, respectively. Southward propagating LSTIDs appeared to be more frequent than northward. The complex propagation of two simultaneous LSTIDs is resolved. A large‐amplitude mixed front showing broadening both latitudinally and meridionally is revealed. No nighttime propagating LSTID is reported. In addition, global differential TEC data are explored to examine the detection of LSTID propagation. The global data validates the timing, direction of propagation, and strength of LSTIDs detected over Iran. The auroral oval extension is consistent with generating and propagating reported LSTIDs. The second storm studied occurred on August 27 (Kp = 4, Dst = −82 nT). This storm exhibited weaker LSTIDs in terms of both observed numbers and amplitude. Finally, the storm case of May 12 (Kp = 7, Dst = −61 nT) was examined. The results underscores the vital role of the Dst index in studying LSTIDs.

Plakun Burial Ground: a new discovery of the well-known site based on the results of the aerial lidar and ground penetrating radar research

The article presents findings of complex interdisciplinary researches of a group of sopkas in the Plakun terrain feature. The monument is part of the Staroladozhky archaeological complex located in Volk- hovsky district, Leningrad region, 120 km east of St. Petersburg. The sopkas are one of the main landmarks of the region. They are high steep embankments 11 – 30 m in diameter and 3 – 8 m high. They date back to the 8th – 10th centuries. The ethnicity of their makers is uncertain. Historiographical data suggest that the monu- ment consisted of 6 sopkas divided into clusters 3 embankments each. In 1955, the southernmost sopka was excavated for demolition. In 2022 – 2023, scheduled scientific researches and Russian Science Foundation Grant No. 23-18-00515 implied an aerial laser scanning of the monument territory. The area was scanned at the attitude of 70 – 90 m with a DJI Matrice 300 RTK drone and an L1 LiDAR from a DJI D-RTK ground station. The coordinates are referenced in LCS-47 Zone 2 with Spectra Epoch 50 GNSS receiver and amended by Geospider survey station network. The findings allow to distinguish a range of small hills in two groups of remaining sopkas. The standard presentation of Digital Elevation Model (DEM) clearly distinguishes 5 remaining large rounded embankments and piles of the excavated southernmost one. However, the research matches several relief color gradations. The study combines several DEM copies in QGIS geographic information system. Consequently, it is revealed that the chain of remaining embankments includes 4 rounded elevations. 3 of them resemble ploughed embankments. In 2023, two identified elevations were studied with OKO-2 ground penetrating radar equipped with a probe antenna which radiates 100 and 700 MHz pulses. The research involves gridding the area of the alleged lost ploughed sopkas and one apparent embankment. The profiles of the site were double-scanned. The radargrams reveal common structure features in the hills and sopka such as contrast mound foundations, heterogeneous centers, multi-layered structures and local depressions in the top layer around 0.5 meters thick. The findings suggest that 3 out of 4 hills can be viewed as demolished embank- ments of a sopka burial. The fourth one requires additional research.

Twenty years of volcano data at GeoNet—collection, custodianship, and evolution of open data on New Zealand’s volcanoes

The GeoNet programme at GNS Science has monitored and managed data for volcanoes, earthquakes, landslides, and tsunami in Aotearoa New Zealand since 2001. Volcano monitoring data are collected from seismometers, acoustic sensors, GNSS receivers, webcams, remote gas monitoring sensors, and a range of environmental sensors, as well as manually during visits to volcanoes. The primary user of volcano data is the internal cross-specialised Volcano Monitoring Group (VMG), which fulfils the role of the national volcano observatory. GeoNet concentrates on automatic data collection and analysis, while supporting members of the VMG with manual data collection and interpretation. The application of open-data principles to both data and metadata has always been a core aspect of GeoNet; responses have been overwhelmingly positive, despite concerns regarding some high value, manually collected datasets. The website www.geonet.org.nz represents the primary data access portal. Data analysis and delivery applications are organised by data type rather than hazard, with no volcano-specific data applications. Most datasets have web-based and API delivery application options; both provide standard data formats from a cloud-based archive. One of the challenges for volcano data collection and management has been shifting from a reliance on manually collected data to automatic collection. Additionally, awareness of important questions related to Indigenous Māori data governance is increasing, although the associated impact is not yet understood. Overall, the current centralised, cooperative volcano monitoring and data collection and management system, which benefits from improved efficiency, interoperability, and data quality, has proved effective in Aotearoa New Zealand. Ongoing work aims to ensure optimal data collection and management for volcano monitoring and downstream activities.

Tropospheric delay retrieval using cost-effective single-frequency GNSS receivers with established reference stations

This study explores the feasibility of using single-frequency (SF) receivers to achieve Zenith Total Delay (ZTD) retrievals with existing reference stations via the Satellite-specific Epoch-differenced Ionospheric delay (SEID) model. Over 30 days, data from a low-cost SF receiver was collected under varying ionospheric conditions. Two reference network configurations were tested: scheme 1 with an average inter-station distance of 138 km and scheme 2 with a distance of 431 km. The GPS-only solution exhibited Root Mean Square (RMS) of 4.2 mm and 11.3 mm for schemes 1 and 2, respectively. Incorporating GLONASS data had minimal impact on scheme 1 but increased the mean bias in scheme 2, likely due to residual ionospheric delays over the larger area. ZTD estimates from reanalysis products fell between those of the two schemes. This study demonstrates the viability of cost-effective, single-frequency receivers for precise ZTD estimation, advocating for network expansion through additional low-cost receivers.

Study of Global Navigation Satellite System Receivers' Accuracy for Unmanned Vehicles.

The development of unmanned ground vehicles and unmanned aerial vehicles requires high-precision navigation due to the autonomous motion and higher traffic intensity. The existing L1 band GNSS receivers are a good and cheap decision for smartphones, vehicle navigation, fleet management systems, etc., but their accuracy is not good enough for many civilian purposes. At the same time, real-time kinematic (RTK) navigation allows for position precision in a sub-centimeter range, but the system cost significantly narrows this navigation to a very limited area of applications, such as geodesy. A practical solution includes the integration of dual-band GNSS receivers and inertial sensors to solve high-precision navigation tasks, but GNSS position accuracy may significantly affect IMU performance due to having a great impact on Kalman filter performance in unmanned vehicles. The estimation of dilution-of-precision (DOP) parameters is essential for the filter performance as the optimality of the estimation in the filter is closely connected to the quality of a priori information about the noise covariance matrix and measurement noise covariance. In this regard, the current paper analyzes the DOP parameters of the latest generation dual-band GNSS receivers and compares the results with the L1 ones. The study was accomplished using two types of antennas-L1/L5 band patch and wideband helix antennas, which were designed and assembled by the authors. In addition, the study is extended with a comparison of GNSS receivers from different generations but sold on the market by one of the world's leading GNSS manufacturers. The analyses of dilution-of-precision (DOP) parameters show that the introduction of dual-band receivers may significantly increase the navigation precision in a sub-meter range, in addition to multi-constellation signal reception. The fast advances in the performance of the integrated CPU in GNSS receivers allow the number of correlations and tracking satellites to be increased from 8-10 to 24-30, which also significantly improves the position accuracy even of L1-band receivers.

Decimeter-Level Accuracy for Smartphone Real-Time Kinematic Positioning Implementing a Robust Kalman Filter Approach and Inertial Navigation System Infusion in Complex Urban Environments.

New smartphones provide real-time access to GNSS pseudorange, Doppler, or carrier-phase measurement data at 1 Hz. Simultaneously, they can receive corrections broadcast by GNSS reference stations to perform real-time kinematic (RTK) positioning. This study aims at the real-time positioning capabilities of smartphones using raw GNSS measurements as a conventional method and proposes an improvement to the positioning through the integration of Inertial Navigation System (INS) measurements. A U-Blox GNSS receiver, model ZED-F9R, was used as a benchmark for comparison. We propose an enhanced ambiguity resolution algorithm that integrates the traditional LAMBDA method with an adaptive thresholding mechanism based on real-time quality metrics. The RTK/INS fusion method integrates RTK and INS measurements using an extended Kalman filter (EKF), where the state vector x includes the position, velocity, orientation, and their respective biases. The innovation here is the inclusion of a real-time weighting scheme that adjusts the contribution of the RTK and INS measurements based on their current estimated accuracy. Also, we use the tightly coupled (TC) RTK/INS fusion framework. By leveraging INS data, the system can maintain accurate positioning even when the GNSS data are unreliable, allowing for the detection and exclusion of abnormal GNSS measurements. However, in complex urban areas such as Qazvin City in Iran, the fusion method achieved positioning accuracies of approximately 0.380 m and 0.415 m for the Xiaomi Mi 8 and Samsung Galaxy S21 Ultra smartphones, respectively. The subsequent detailed analysis across different urban streets emphasized the significance of choosing the right positioning method based on the environmental conditions. In most cases, RTK positioning outperformed Single-Point Positioning (SPP), offering decimeter-level precision, while the fusion method bridged the gap between the two, showcasing improved stability accuracy. The comparative performance between the Samsung Galaxy S21 Ultra and Xiaomi Mi 8 revealed minor differences, likely attributed to variations in the hardware design and software algorithms. The fusion method emerged as a valuable alternative when the RTK signals were unavailable or impractical. This demonstrates the potential of integrating RTK and INS measurements for enhanced real-time smartphone positioning, particularly in challenging urban environments.