Özdemir, Behlül Numan
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Ozdemir, B. Numan Ozdemir, B. N. Ozdemir, B.N. Özdemir, B. N. Özdemir, B.N. Ozdemir, Behlul Numan Özdemir, Behlül N. Ozdemir, Behlul N. Özdemir, B. Numan
Job Title
Email Address
bnozdemir@ktun.edu.tr
Main Affiliation
02.08. Department of Geomatic Engineering
Status
Current Staff
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Turkish CoHE Profile ID
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WoS Researcher ID
Research Topics
Domains
Physical Sciences
Fields
EngineeringPhysics and AstronomyEarth and Planetary Sciences
Subfields
Aerospace EngineeringAstronomy and AstrophysicsOceanographyElectrical and Electronic EngineeringAtomic and Molecular Physics, and Optics
Specific Research Areas
GNSS positioning and interference
Ionosphere and magnetosphere dynamics
Geophysics and Gravity Measurements
Indoor and Outdoor Localization Technologies
Advanced Frequency and Time Standards
Sustainable Development Goals
1NO POVERTY
0
Research Products
2ZERO HUNGER
0
Research Products
3GOOD HEALTH AND WELL-BEING
0
Research Products
4QUALITY EDUCATION
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5GENDER EQUALITY
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6CLEAN WATER AND SANITATION
0
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7AFFORDABLE AND CLEAN ENERGY
0
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8DECENT WORK AND ECONOMIC GROWTH
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
0
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10REDUCED INEQUALITIES
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11SUSTAINABLE CITIES AND COMMUNITIES
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12RESPONSIBLE CONSUMPTION AND PRODUCTION
0
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13CLIMATE ACTION
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14LIFE BELOW WATER
2
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15LIFE ON LAND
0
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
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17PARTNERSHIPS FOR THE GOALS
0
Research Products
Documents
10
Citations
53
h-index
4
Documents
9
Citations
46
Publication Collaboration
| Affiliation Name | Count |
|---|---|
| Konya Technical University | 14 |
| Necmettin Erbakan University | 11 |
| Sivas Cumhuriyet Üniversitesi | 7 |
| Niğde Ömer Halisdemir Üniversitesi | 3 |
| TU Wien | 1 |
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Data obtained from OpenAlex
Scholarly Output
15
Articles
14
Views / Downloads
39/127
Supervised MSc Theses
0
Supervised PhD Theses
1
WoS Citation Count
46
Scopus Citation Count
53
Patents
0
Projects
0
WoS Citations per Publication
3.07
Scopus Citations per Publication
3.53
Open Access Source
7
Supervised Theses
1
| Journal | Count |
|---|---|
| Advances in Space Research | 5 |
| Atmosphere | 1 |
| Earth Science Informatics | 1 |
| El-Cezeri Journal of Science and Engineering | 1 |
| Gps Solutions | 1 |
Current Page: 1 / 2
Scopus Quartile Distribution
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15 results
Scholarly Output Search Results
Now showing 1 - 10 of 15
Article Towards Geodetic-Level Accuracy in Low-Cost GNSS: Tectonic Velocity Determination Capabilities of the U-Blox Zed-F9p Over a Year Multi-GNSS PPP-AR Time Series(Elsevier Sci Ltd, 2026-01-01) Duman, Huseyin; Ogutcu, Sermet; Alcay, Salih; Ozdemir, Behlul Numan; Atiz, Omer Faruk; Bulbul, SercanThe growing availability of low-cost dual-frequency GNSS receivers is enhancing their suitability for various kinds of geodetic applications. Geodetic monitoring of the continuous crustal deformation using GNSS time series analysis is one of the commonly used geodetic applications. To maintain the most accurate estimated parameters such as secular velocity, seasonal signal parameters and offsets, geodetic-grade GNSS receivers are commonly used in the GNSS time series analysis. However, due to the increasing availability of low-cost dual-frequency GNSS receivers and advancements in software and hardware, these receivers have now reached a level that supports the GNSS time series analysis. In this study, over a year of multi-GNSS PPP-AR time series of the u-blox ZED-F9P low-cost GNSS receiver are investigated by evaluating the accuracy of the estimated parameters, comparing them with data from a geodetic-grade GNSS receiver monumented on a building roof. The results show that the minimum detrended standard deviation obtained from White Noise (WN) estimation is achieved using GPS + GLONASS + Galileo PPP for both receivers. The computed annual velocity and amplitude differences obtained from the GNSS time series between the u-blox ZED-F9P and the geodetic-grade GNSS receivers using GPS + GLONASS + Galileo PPP-AR are found as 0.6 mm / 0.4 mm / 0.8 mm and 1.5 mm / 0.4 mm / 0.2 mm for north, east, and up components, respectively. (c) 2025 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.Article Citation - WoS: 9Citation - Scopus: 11Constructing a Precise Radio Map and Application of Indoor Positioning With Dual-Frequency Wi-Fi Fingerprinting Method(ELSEVIER SCI LTD, 2020-10-01) Özdemir, Behlül Numan; Ceylan, AyhanLocation-based services provide information about objects and people primarily including their location. While their location can be easily estimated outdoors using GNSS, satellite signals are unable to reach indoor spaces such as buildings. Thus, to provide the position information indoors, several technologies have been proposed. Wi-Fi, which is a wireless communication technology offers a wide range of applications for indoor positioning. One of them is the fingerprinting method that uses the diversity of RSS measurements from different wireless access points for each location in indoor space. Here, we constructed a precise radio map with a measuring tool and compared the 2.4 GHz and 5 GHz frequencies with the dual-band fingerprint dataset. Experimental results show that, even if they do not represent a different location, the incorporation of these two frequencies with different characteristics into a single fingerprint dataset improves the overall positioning accuracy. (C) 2020 Elsevier Ltd. All rights reserved.Article Assessing the Reliability of the GNSS Loss of Lock Indicator (LLI) Index for PPP across Different Types of GNSS Receivers(Elsevier Sci Ltd, 2026-03-01) Alcay, Salih; Duman, Huseyin; Oztan, Gurkan; Ogutcu, Sermet; Bulbul, Sercan; Wareyka-Glaner, Marcus Franz; Ozdemir, Behlul NumanCycle slips are events in which a receiver experiences a disruption in its carrier phase lock to a Global Navigation Satellite System (GNSS) signal. Accurate detection of cycle slips is essential to prevent degradation of positioning accuracy when carrier-phase observations are used. In this study, the reliability of the Loss of Lock Indicator (LLI) index in RINEX observation files from six different receiver types was investigated and compared with the Phase Geometry-Free and Hatch-Melbourne-Wu & uml;bbena (GF + HMW) cycle slip detection algorithm. Precise Point Positioning (PPP) in stand-alone mode was performed using GPS, GLONASS, Galileo, and BDS-3 observations, applying either the LLI index alone or the GF + HMW cycle slip detection algorithm. The resulting RMSEs and overlaps between the methods were analyzed based on receiver types. The results show that the most reliable LLI data comes from LEICA and TRIMBLE receivers, while SEPTPOLARX5-TR, SEPTPOLARX5, and JAVAD receivers exhibited relatively poor LLI performance. PPP results showed that the LLI, which outperforms GF + HMW on the ionospherically quiet days for some receivers and GNSS constellations, performs worse on ionospheric scintillation days. (c) 2026 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.Article Citation - WoS: 10Citation - Scopus: 12Static and Kinematic Ppp-Ar Performance of Low-Cost Gnss Receiver in Monitoring Displacements(Elsevier Ltd, 2023-12-01) Ogutcu, S.; Alcay, S.; Duman, H.; Ozdemir, B.N.; Konukseven, C.Recently, low-cost GNSS receivers have played a significant role in displacement monitoring studies due to the increasing availability of mass-market applications. In this work, the performance of static and kinematic PPP-AR using a low-cost u-blox ZED-F9P GNSS receiver in monitoring displacements is investigated by comparing it with a geodetic-grade GNSS receiver using a displacement simulation apparatus. The capability to determine the horizontal displacement direction is also investigated for both receivers. The results showed that one-sigma horizontal / vertical RMSEs computed from the true displacements and computed displacements are 1.4 / 5.6 mm and 2.6 / 8.4 mm for the geodetic and u-blox receivers, respectively, using 24-h data with static GPS + GLONASS PPP-AR. It is found that GLONASS contribution to GPS-only static PPP is more evident for the u-blox receiver compared with the geodetic one. RMSEs are found to be higher as observation times are decreased. The post-processed kinematic test results showed that minimum 10 / 20 and 20 / 30 mm horizontal / vertical dynamic displacements can be visually detected as an offset from the daily time series for the geodetic and u-blox receivers, respectively. © 2023 COSPARArticle Effect of Calibration Point Density on Indoor Positioning Accuracy: a Study Based on Wi-Fi Fingerprinting Method(Atlas Akademi, 2021) Özdemir Behlül Numan; Ceylan AyhanIndoor positioning refers to all methods used in areas(indoor) where GNSS signals are too weak or non-existent for position determination, using various signals (Signals of Opportunity) and various sensor data. The availability of these signals and sensors for general navigation use is an important factor in terms of cost and feasibility. Considering the diversity of smart mobile devices and the technologies they contain; it is clear that they are perfect candidates for this job. Signals of Opportunity (SoOP) are intended for purposes other than navigation and Wi-Fi is a great example for this. Since majority of mobile devices have built-in Wi-Fi hardware, many studies focused on Wi-Fi positioning. This study used the fingerprint approach, which is among the most successful methods of indoor positioning using this technology. The number of calibration points to be marked in the calibration phase, which is the first of the two stages of this method, affects both the position accuracy and the time and effort spent. In this study, location accuracy was studied using NN, KNN and WKNN algorithms on a radio map with low calibration point density and it was discovered that the NN method provides both simplicity and satisfactory results in all scenarios. It was determined that the mean errors were minimal at the 2-meter point density and better results were obtained with the weighted-KNN algorithm compared to the KNN.Article Citation - WoS: 3Citation - Scopus: 3Gps + Galileo + Bds-3 Medium To Long-Range Single-Baseline Rtk: an Alternative for Network-Based Rtk?(Cambridge University Press, 2023-07-01) Ogutcu, S.; Alcay, S.; Ozdemir, B.N.; Duman, H.; Koray, U.; Konukseven, C.; Bilal, N.G.Thanks to the development of the real-time kinematic (RTK) algorithm and the emerging Global Navigation Satellite System (GNSS), especially for Galileo and BeiDou-3, reliable positioning accuracy for medium and long-baseline RTK became possible globally. Moreover, with the development of the GNSS receiver hardware, baseline length limitations due to radio-based communications are removed thanks to internet-based communication. In this work, single-baseline RTK, incorporated partial ambiguity resolution with troposphere and ionosphere weighting, using GPS (G), Galileo (E), BeiDou-3 (C3) and multi-GNSS (GE and GEC3), is conducted with real GNSS data of EUREF Permanent GNSS network under three different cutoff angles (10°, 20°, and 30°) for six different lengths of baselines (∼50, ∼150, ∼250, ∼350, ∼450, and ∼550 km). The results show that the multi-GNSS RTK solution significantly contributed to the positioning accuracy and convergence time of the single-system RTK solutions. Based on the results, non-available epoch-wise solutions for the high-degree cutoff angles are more obvious for the single-system RTK, whereas multi-GNSS solutions provide 100% solutions for each cutoff angle and baseline. The results indicate that instantaneous and a few epochs single-epoch ambiguity resolution is feasible for 50, 150, 250 and 350 km baseline lengths for multi-GNSS RTK. Based on the positioning results, horizontal-vertical positioning improvements of multi-GNSS RTK (GEC3) compared with the single-system GPS RTK are found as 50%-37%, 40%-35%, 55%-47%, 53%-54%, 57%-49% and 57%-49% for 50, 150, 250, 350, 450 and 550 km, respectively, under a 10° cutoff angle. For 20° and 30° cutoff angles, the accuracy improvements are much higher. The convergence time improvements (n/e/u) of multi-GNSS RTK (GEC3) compared with the single-system GPS RTK are found as 86/92/75%, 77/67/72%, 75/77/83%, 53/56/52%, 69/49/62%, and 52/45/39% for 50, 150, 250, 350, 450 and 550 km, respectively, under a 10° cutoff angle. Copyright © The Author(s), 2023. Published by Cambridge University Press on behalf of The Royal Institute of Navigation.Article Citation - WoS: 1Citation - Scopus: 2Rinex Scan: Open-Source Rinex Epoch and Frequency Scanning Software(Springer Heidelberg, 2025-02-25) Ozdemir, Behlul NumanSince the introduction of the Receiver Independent Exchange Format (RINEX) version 2 in 1990, the community of Global Navigation Satellite System (GNSS) rapidly adapted to its use and continued to develop the RINEX format. Because of its widespread adoption and user-friendly format across all GNSS receivers, GNSS companies typically offer conversion software that enables users to convert raw receiver-dependent data into the RINEX observation format. As new GNSS signals and constellations continue to emerge, revising the RINEX format has become a necessary requirement over time. RINEX SCAN is a new open-source software for multi-GNSS epoch and frequency (GNSS observation codes) scanning, providing availability information for epochs and frequencies in RINEX files. This software is free and open source, released under the MIT License., and written in object-oriented programming language C#. The software supports GPS, GLONASS, Galileo, BeiDou-2, BeiDou-3, and QZSS constellations data in RINEX observation 2.xx and 3.xx formats. Thanks to parallel computing architecture, users can easily obtain large-scale data quantity results for epochs and multi-GNSS frequencies when working with big data sets.Article Citation - WoS: 1Data Integrity and Quality Analysis of Low Cost Zed-F9p U-Blox Gnss Receiver(Konya Teknik Univ, 2023-05-10) Öğütcü, Sermet; Alçay, Salih; Duman, Hüseyin; Özdemir, Behlül Numan; Koray, ÜlkünurThanks to the rapidly emerging low-cost dual-frequency GNSS receivers, a feasible alternative for geodetic-grade GNSS receivers became available for some GNSS applications. In this study, the performance of data integrity and quality of a low-cost ZED-F9P u-blox GNSS receiver was investigated by comparing it with a geodetic-grade GNSS receiver. Availability of the epoch and phase/code signal channels, signal-to-noise ratio (SNR), code multipath, and cycle slips were analyzed for the geodetic-grade and low-cost ZED-F9P u-blox GNSS receivers. One month’s data of GPS, GLONASS, and Galileo constellations were analysed using the RINEX files of the receivers. The results showed that the epoch availability of the geodetic-grade and u-blox GNSS receiver is comparable to each other, while the availability of phase/code signal channels of the geodetic-grade receiver is higher than the u-blox receiver. In terms of data quality, SNR values from both receivers are comparable, while the multipath level of the u-blox GNSS receiver is significantly higher than the geodetic-grade one. The results also showed that the number of cycle slips of the u-blox receiver is significantly higher than the geodetic-one.Article Citation - WoS: 4Citation - Scopus: 4Analysis of Ionospheric Vtec Retrieved From Multi-Instrument Observations(MDPI, 2024-06-09) Öztan, Gürkan; Duman, Huseyin; Alçay, Salih; Öğütçu, Sermet; Özdemir, Behlül NumanThis study examines the Vertical Total Electron Content (VTEC) estimation performance of multi-instruments on a global scale during different ionospheric conditions. For this purpose, GNSS-based VTEC data from Global Ionosphere Maps (GIMs), COSMIC (F7/C2)-Feng-Yun 3C (FY3C) radio occultation (RO) VTEC, SWARM-VTEC, and JASON-VTEC were utilized. VTEC assessments were conducted on three distinct days: geomagnetic active (17 March 2015), solar active (22 December 2021), and quiet (11 December 2021). The VTEC values of COSMIC/FY3C RO, SWARM, and JASON were compared with data retrieved from GIMs. According to the results, COSMIC RO-VTEC is more consistent with GIM-VTEC on a quiet day (the mean of the differences is 4.38 TECU), while the mean of FY3C RO-GIM differences is 7.33 TECU on a geomagnetic active day. The range of VTEC differences between JASON and GIM is relatively smaller on a quiet day, and the mean of differences on active/quiet days is less than 6 TECU. Besides the daily comparison, long-term results (1 January-31 December 2015) were also analyzed by considering active and quiet periods. Results show that Root Mean Square Error (RMSE) values of COSMIC RO, FY3C RO, SWARM, and JASON are 5.02 TECU, 6.81 TECU, 16.25 TECU, and 5.53 TECU for the quiet period, and 5.21 TECU, 7.07 TECU, 17.48 TECU, and 5.90 TECU for the active period, respectively. The accuracy of each data source was affected by solar/geomagnetic activities. The deviation of SWARM-VTEC is relatively greater. The main reason for the significant differences in SWARM-GIM results is the atmospheric measurement range of SWARM satellites (460 km-20,200 km (SWARM A, C) and 520 km-20,200 km (SWARM B), which do not contain a significant part of the ionosphere in terms of VTEC estimation.Doctoral Thesis Kapalı Mekânlarda Rss Tabanlı Konum Belirleme Yaklaşımı: Parmak İzi Metodunun Uygulanması ve Performans Analizi(Konya Teknik Üniversitesi, 2020) Özdemir, Behlül Numan; Ceylan, AyhanKablosuz iletişimi sağlayan Wi-Fi teknolojisi günümüzde oldukça yaygın olan, her geçen yıl güncellenerek yenilenen ve çeşitli alanlarda insan yaşamına fayda sağlayan bir araç olmuştur. Ortaya çıkış amacı her ne kadar iletişim olsa da araştırmacılar tarafından yapılan çalışmalar neticesinde bir yan görev olarak Wi-Fi sinyallerinden konum belirleme amacıyla da faydalanılmaktadır. Günümüzde çok popüler ve güncel bir araştırma konusu olmasında bu teknolojinin Dünya genelinde oldukça yaygın olması, neredeyse tüm kamu binaları, alışveriş merkezleri, hastaneler, kütüphaneler vb. tüm binalarda altyapısının hazır olarak kurulmuş olmasından kaynaklanmaktadır. Sinyal parmak izi, işte bu binalarda bulunan birçok kablosuz Wi-Fi erişim noktasının oluşturduğu sinyal vektörleridir ve bu parmak izleri adından anlaşılacağı üzere yalnızca bulunduğu konuma özeldir. Bu tez çalışmasında alınan sinyal gücü (RSS) bilgisi ile parmak izi konum belirleme yöntemi gerçek koşullarda uygulanmış, konum doğrulukları çeşitli kriterler dikkate alınarak analiz edilmiştir. Bu amaç doğrultusunda bir veri toplama yazılımı, öne sürülen 3 veri türü ve bir analiz yazılımı geliştirilmiştir. Parmak izi yönteminin en zaman alıcı aşaması olan kalibrasyon aşaması için kullanılan ölçü düzeneği ve güzergâhlar şeklinde oluşturulan kalibrasyon noktaları ile yüksek doğrulukta ve hızlı bir şekilde parmak izi veritabanının oluşturulması sağlanmıştır. Yapılan çalışmalarda en yakın komşu yönteminin konum doğruluğunun kalibrasyon nokta sıklığına bağlı olduğu görülmüştür. Birden çok noktadan aday nokta konumunun hesabında ağırlıkların göz önüne alınması gerektiği, ancak komşu sayısının seçiminde sabit bir değer yerine dinamik bir değer kullanılmasının farklı tipte kapalı mekânlar için daha uygun olacağı anlaşılmaktadır. Radyo haritasında nokta sıklığına bağlı olarak veri boşlukları mevcut ise, algoritma aday noktanın konumunu, fiziksel olarak o noktadan daha uzakta bulunan kalibrasyon noktası ile eşleştirebileceği nedeniyle bu boşlukların enterpolasyon yöntemleri ile doldurulmasının konum doğruluklarına fayda sağlayacağı belirtilmektedir. Parmak izi konum belirleme uygulamalarında kullanılabilecek yazılımsal çözümler, süreci oldukça hızlandırmakta ve çeşitli analizlerin istenilen parametreler ile gerçekleştirilmesini sağlamaktadır. Bu tez çalışması ile ortaya çıkan analiz ve veri toplama yazılımları, geliştirme süreçleri devam eden, bir kapalı mekânda konum belirleme uygulaması yapılması istenildiğinde bir bütün olarak ihtiyaçları karşılayan iki program haline gelmiştir. Bölüm 4.1'de belirtilen problem gibi henüz cevap bulunamamış, farklı kapalı mekân tiplerinde konum doğruluğuna etkisi gerçek ortam şartlarında incelenerek analiz edilmesi gereken birçok konuda katkı sağlayacağı düşünülmektedir. Bu tez çalışmasının sonlarında ortaya çıkan Wi-Fi 6 teknolojisi ile 6GHz ve üzerindeki frekanslar ile kapalı mekân konum belirleme çalışmalarında yeni ufuklar açılacağı düşünülmektedir. Ayrıca yine çalışmanın sonlarında ortaya çıkan Covid-19 pandemisi sebebiyle bu gibi durumlarda kapalı mekânlarda belki de temas, yakınlık gibi durumların belirlenebilmesinde fayda sağlanabileceği düşünülmektedir.