This is the second session of our student paper presentations where students from the University of Calgary present thier work from ION GNSS+ 2025 held in Baltimore Maryland.
Presentations
Title: Hardware Simulation of Low-Earth-Orbit GNSS for Carrier Phase Ambiguity Resolution
Author: Claire Mah
Bio:Claire Mah is a master’s student at the University of Calgary. She has a background in geomatics engineering, and her current research focuses on GNSS positioning and estimation for low earth orbit satellite systems.
Abstract: This paper details a hardware in-the-loop simulation of single frequency RTK positioning for GPS augmented with low-earth-orbit (LEO) satellites to demonstrate how carrier phase ambiguity resolution is impacted by LEO satellites. Ambiguity resolution is dependent on satellite geometry and therefore benefits from how fast the geometry of LEO satellites changes. Findings include an average improvement of 29% in the time taken for the probability of correct fix to reach a threshold of 99.9999% in a scenario simulated with only one added LEO satellite, compared to GPS only. The LEO satellites were found to have the strongest impact on scenarios with poor initial GPS geometry but still improved the convergence times in all test cases. Additionally, some common GNSS equipment and tools are shown to be capable of handling simulated LEO satellites for research and testing purposes.
Title: Investigating Cycle Slip Repair for Single and Multi-Frequency Smartphone GNSS
Author: Naman Agarwal
Bio: Naman Agarwal is a PhD student in the Department of Geomatics Engineering at the University of Calgary. He works in the PLAN lab under the supervision of Dr. Kyle O’Keefe. His main research area is Precise Smartphone Positioning.
Abstract: Smartphone carrier-phase measurements are highly prone to cycle slips, degrading the performance of Precise Point Positioning (PPP) and Real-time Kinematics (RTK) on smartphones. This paper investigates the impact of cycle slip detection and repair (CSDR) across both single and dual-frequency undifferenced uncombined ionosphere-constrained PPP on smartphones. A cycle slip detection and repair (CSDR) methodology proposed in our earlier works is further investigated upon single and multifrequency smartphone GNSS data. Among five different ambiguity resolution techniques, a modified partial ambiguity resolution with fixed failure-rate ratio test (PAR-FFRT) method is identified to be the most effective for cycle slip repair and is integrated within the PPP framework. Extensive validation is conducted against high-quality IGS station data (using artificial slips) and four real-world static smartphone datasets spanning different handsets (Google Pixel 4, Pixel 7 Pro, Samsung Galaxy S20+ 5G) and environments, including open sky and urban conditions. Preliminary results are promising, showing improvement in PPP position convergence when cycle slips repair is performed, with the most substantial gains found in the vertical component, though benefits vary with slip density and signal redundancy. Despite promising findings, further validation on additional datasets and environments is required to establish the robustness and general efficacy of instant cycle slip repair compared to conventional ambiguity resetting. This study underscores the potential of advanced CSDR for enabling precise smartphone-based GNSS applications.
Location:
Room 112 – Engineering Block B (ENB), University of Calgary Campus
Date: Friday, November 28, 2025
Time: Meeting will open at 11:45am, presentations to begin shortly after 12:00
Cost: $20 non-members, $18 members, $15 graduate students, $10 undergraduate students, includes a light lunch and refreshments. All proceeds go towards two annual scholarships for students attending the University of Calgary