Observation of the GNSS jamming sources during commercial flights

Observation of the GNSS jamming sources during commercial flights | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Observation of the GNSS jamming sources during commercial flights Saulius Rudys, Jūras Banys This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8944498/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Russia invasion to Ukraine and Middle East conflicts provides problems for Global Navigation Satellite System (GNSS) based navigation systems in aviation because various GNSS jamming and spoofing systems are using as electronic warfare. Navigation systems make an important contribution to the safety of flights. Thus, it is important to know where jamming or spoofing stations are located and what kind of signals are using. This information can help to develop interference mitigation strategies. Signals on GNSS frequencies were safely received during flights on commercial airlines. The location (in Belorussia territory) of the GNSS jamming signal was estimated by using signal strength and aircraft position information. We propose several methods to locate the source of the interfering signal. In addition, we have suggested location of aircraft GNSS antennas to mitigate GNSS jamming and spoofing. GNSS jamming spoofing ADS-B antenna flight mode DoA Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 1 Introduction During war actions, electronic countermeasures such as spoofing and jamming against GNSS are widely used. After Russia invasion to Ukraine and conflicts in Middle East, the operation range of electronic warfare reach lines of commercial airflights. Since GNSS is one of the radio navigation systems, disturbing or disabling GNSS negatively affects aircraft navigation. Moreover, GNSS is a key component of Automatic Dependent Surveillance - Broadcast (ADS-B) system which is a part Traffic Collision Avoidance System (TCAS). Thus, GNSS is very important for flight safety. Unfortunately, due to the conflicts, the quality of GNSS navigation is low in some regions. Map of the level of GNSS interference is presented in Fig. 1 (GPSJAM). This map is colored by using a parameter of navigation quality (GPSJAM), which was transmitted in ADS-B data. Area A corresponds to the jammer affected area, considered in this paper. Area B is example of spoofing, when some information about GNSS signal condition is plotted over Ukraine territory, where no commercial flights are conducted. Using this data from ADS-B system we can approximately estimate positions and density of Russian military objects, covered by spoofing systems. Much more dangerous than jamming is the appearance of “ghost planes” in ADS-B map. “Ghosts” can be inserted basically in two ways: by transmission of synthesized ADS-B signal, or by legal ADS-B transmitter of the aircraft when its GNSS receiver is spoofed. Last case example with the “ghost plane” is presented in Fig. 2 where data are taken from open Flightradar24 source (Flightradar24). Most relevant explanation of Fig. 2 is following – AFL2173 aircraft receive GNSS spoofing signal from transmitter in occupied Ukraine territory with coordinates above Ukraine, then aircraft’s ADS-B transmits these coordinates, whereas ground ADS-B receiver provides these coordinates for mapping. When aircraft leaves area, covered by spoofer, then ADS-B transmits real coordinates of aircraft (right picture). This case is only one example of multiple cases during only one day gathered in area B in Fig. 1 . To avoid synthesized “ghost planes”, we need to authenticify transmitters. Due to well-known vulnerability of ADS-B (Wu et al. 2020 ), there are limited abilities to identify a “ghost”. Among the recently proposed solutions to ADS-B security issues, covered in a surveys (Wu et al. 2020 , Strohmeier et al. 2015 ), most are targeted at ground Air Traffic Control (ATC) centers. Most notably, multilateration systems (Nijsure et al. 2016 , Monteiro et al. 2015 ) have been proposed and already implemented at a number of airports. Some ideas based on signal encryption (Baek et al. 2017 ), or adding time stamps (Kim et al. 2017 ) requires changes in ADS-B standard. Ideas of authentication of ADS-B signal on aircraft side without changing ADS-B standard are presented in (Rudys et al. 2020). It seems, authentication of the ADS-B signals is not widely used in aviation yet. Another kind of counter measure which allows to avoid situation presented in Fig. 2 (spoofing of GNSS) is using anti-spoofing solutions in GNSS receivers (Yuan et al. 2018 ), (Magiera 2019 , Jafarnia-Jahromi et al. 2012 ). Most reliable principle of operation of these system can be based on comparison of DoA from GNSS and spoofing signals when positions of satellites are known. Estimation of direction of arrival (DoA) or spatial selection of satellites require directional antennas or arrays of antennas (1 Stenberg et al.2020, Montgomery et al. 2009 ). It can be implemented by using only 2x2 array and 4 receivers as presented in (Razgunas et al. 2023). If DoA of spoofing source(s) was spatially detected, then beamforming technique can be used to reject interfering signal sources. In this paper we provide experimental results of receiving jamming signals during flight by commercial airlines. These results may be useful for situational awareness in aircraft GNSS navigation, make some transparency in situation about jamming and probably will inspire further crowded investigations of this problem. The remainder of this paper is organized as follows. Section 2 introduces the methodology of receiving jamming signals during flight and methodology of finding location of the jammer. The results of receiving and locating jamming signals are presented in Section 3 whereas further jamming signals receiving and locating approach is presented in Section 4 . Suggestions for jamming and spoofing mitigation in aviation are presented in Section 5 . Finally, conclusions and discussion are provided in Section 6. 2 Methods and materials 2.1 Receiving hardware and data logging The Signal hound BB60C receiver was used with Spike software (Signal Hound). The receiver was connected to a tablet computer via USB port. To save battery power of computer, the second power USB connector of receiver’s cord was connected to power bank. We used a simple ceramic 25x25x4 mm patch antenna with 6x7 cm reflector made from copper foil. The radiation pattern of antenna was simulated by Ansys HFSS software (Ansys). Radiation pattern and drawing of the patch antenna are presented in Fig. 4 . Since we are interested in robustness to interferences which polarization may be unknown and can be different, in this and further simulations we calculate total directivity which contains different polarizations. The presence of the reflector slightly increases gain and reduces interferences from computer or other sources inside the cabin. Despite the antenna being without filters and amplifiers, it provides sufficient frequency selection as presented in Fig. 3 . It allows to suppress potential interference from aircraft navigation, broadcasting and telecommunication signals. Although antenna is designed for circular polarization, ellipticity (further it allows us to estimate polarization of the jammer) was clearly presented. Measured antenna gain is 0 dBi. Before measurements, a wide spectrum up to 6GHz was recorded on board to ensure in presence strong potentially interfering signals. This spectrum presented in Fig. 5 . Radiation in 2.4–2.5 GHz band is strongest. The sources from Bluetooth devices are prevailing here. While receiving signals, we have logged video from screen with time and signal strength, but do not log GNSS position. Positions (related to time) were taken from ADS-B logs provided by local communication authorities. Obviously, it is more convenient to make our own real time logs of GNSS position. Automated logging of time, signal and position will be implemented in further experiments. In the case of strong jamming or spoofing, a logging device of position (for example – a smartphone) can be located near the window of opposite side. For safety, all computers and phones must be switched (and was switched) into the “Flight mode”. The receivers as itself are no (negligible) radiating devices and are safe for use in flights. 2.1 Transmitter location finding During the flight we permanently recorded the signal strength of the jammer. Also, we know the position of the aircraft. Since we used receiving antenna with low directivity, the strategy of jammer’s location finding was based on signal strength and position measurements by using multilateration principle. According to the Friis equation (Stutzman at al. 1980), voltage at the receiver input U R is inverse proportional to distance R to transmitter and vice versa. $$\:R=\sqrt{{G}_{R}{G}_{T}\:{P}_{T}{Z}_{R}}\frac{\lambda}{\text{4}\pi}\frac{\text{1}}{{\text{U}}_{\text{R}}}$$ 1 There G R and G T are the gain of receivers and transmitters antennas, P T is a power of transmitter, Z R is input impedance of receiver, λ is a wavelength. By measuring signal voltage, we can find coordinates x and y of the transmitter when transmission power, antennas gain, and frequency are known by solving system of equations (2). ( x − x n ) 2 +(y − y n ) 2 =R n 2 (2) There, x n and y n are coordinates of receiver, R n is distance to transmitter which can be found from (1). In this case we are using the assumption that receiving and transmitting antennas are omnidirectional. We need only two equations (receiver positions) to find 2D transmitter coordinates. It can be done ambiguously if the direction (side) of signal arrival is approximately known. When antennas parameters and transmission power are unknown, then we know not distances, but quasi ranges which are equal to unknown parameter k divided by voltage in the receiver U Rn . Where: $$\:k=\sqrt{{G}_{R}{G}_{T}\:{P}_{T}{Z}_{R}}\frac{\lambda}{4\pi}$$ 3 Since an additional unknown parameter appears, we need additional equation in the system: ( x − x n ) 2 +(y − y n ) 2 =(k/U Rn ) 2 (4) The situation is like in GNSS, when additional satellite is required to solve range - quasi range problem. Due to the flight trajectory near the jamming source was a straight line, it is possible to find jammer location without solving system of equations. 3 Results 3.1 Estimation of jammer’s location A good tool for presentation of measurement results is Google Earth. We used airplane track .kml extension file, but imputed receiver’s voltage here instead of altitude of aircraft. Results are presented in Fig. 6 . Voltage dependance on coordinate is presented on 3D map. Voltage dependance on flying distance is presented on the lower part of Fig. 6 . Since we are using software for presentation of geospatial data, the voltage is presented as altitude. 1 m of altitude corresponds to 10 nV. Thanks to straight trajectory, it is possible instantly find direction to the jammer. This direction is perpendicular to the trajectory line, starting from position with maximum signal (yellow line in Fig. 6 ). Sometimes jamming signal comes from Kaliningrad (Russia) side in opposite direction. To ensure that this signal comes from Belarus we tried to receive signals from the opposite side window. No signal from Russia side was received at this time. Due to strong oscillations of signal level, the average curve was derived (red curve). The position of signal maximum (point A) was taken from this averaged curve. Now it remains to calculate distance (in our consideration we make assumption that difference between slant and ground rages is negligible) to the jamming transmitter. It can be done by finding angle α when distance | AB | is known. Distances | AC | and |BC| are k/U A and k/U B respectively (Fig. 6 ). Where U A and U B are voltages in receiver input on point A and point B respectively. Despite k is unknown, it is possible to find cosine of angle α: cos(α)=|AC|/|BC|=k*U B /(k*U A )= U B /U A (5). Hence, the distance to the transmitter |AC| is |AC|=|AB|/tg(α) (6) It is convenient to take U B /U A =1/2 , then α = 60 degrees. As mentioned above, assumption about omnidirectional radiation patterns is made for transmitter position finding. Our receiving antenna was directional, pointed perpendicular to flight direction. If the transmitter is not located to this perpendicular direction, then voltage in our directional antenna output will be lower than in the case of omnidirectional antenna. We can estimate this voltage drop using antenna radiation pattern data. The radiation pattern of the receiving antenna is presented in Fig. 4 . To correct voltage by using radiation pattern data, we need to choose the angle to the transmitter, but this angle is not known precisely yet. In point B when U B /U A =1 /2, in the case of omnidirectional receiving antennas this angle is equal to 60 o . We may consider that the angle to transmitter is known approximately. In the case of omnidirectional antennas, in the point B, U B will be higher, ratio U B /U A will be higher than ½ and real angle to the transmitter will be smaller than 60. Let’s choose this angle as 50 o . According to Fig. 4 , antenna gain loses at 50 o is 2.5 dB or 1.333 times by voltage. Then cos(α) = 1.333*U B /U A =0.666 . Arc cos(0.666)=48 o . This angle is close to chosen above 50 o for U B correction. If higher accuracy is required, further iterations of correction can be performed. Distance |AB| is 154 km. Hence, from (6), jamming transmitter range |AC| is 137.6 km. Transmitter position presented as red circle C in Fig. 6 . Location of transmitter is on Belarus territory, close to Poland border and in vicinity of Hrodna city. We may consider, this transmitter is responsible at least for five red cells in Fig. 1 on zone A. Mention should be made, method used above is useful under assumption that the radiated power is the same in all measured directions, therefore this method is less accurate than methods using directional antennas where assumption above is not necessary. We will consider directional antenna in Chap. 4. 3.2 Jamming signals The spectrum of jamming signal which considered above is presented in the Fig. 7 . This signal consists of two temporal parts: narrowband, slowly sweeping carrier and wide band signal, whit the spectrum close to Global Positioning System (GPS) L1 Coarse Acquisition (C/A) signal. The period of this signal is 8100 ms, and the wideband signal duration is 2500 ms. We suppose this signal is composed with the intention to implement two different strategies of jamming. Due to ellipticity of polarization of receiving antenna (Fig. 3 ), the signal level was different at perpendicular orientation of the antenna. The polarization of the jamming signal was measured as horizontal. Some weaker signal (Fig. 8 ) was detected during flight over southern Lithuanian territory. This signal performs at least three components for the jamming of several GNSS systems: for Beidou at 1561.098 MHz, for various systems at 1575.42 MHz and wideband multicarrier signal for Glonass. Due to signal weakness, we don’t try to estimate transmitter location. 4 Array antennas for direction finding In Section 3 we have found the location of transmitter by using a low directivity antenna and assumption about omnidirectional radiation of transmitter. In general cases it leads to errors in estimating of transmitter’s coordinates. More universal method is instant finding of DoA by using directional antenna. Unfortunately using directional antenna (for example Yagi antenna) in passenger seat is inconvenient. Small window aperture can disorder antenna radiation pattern and limits angles of view. Most problematic is implementation of measurement of the antenna’s pointing angle. To eliminate the drawbacks of Yagi antenna, we suggest using two conventional patch antennas (for example, one as was used above) system. Antennas should be arranged on the neighboring windows. Distance between antennas is chosen 500 mm - close to distance between windows in Boeing-737. Simulated by HFSS radiation patterns with different phasing are presented in Fig. 9 . Antennas pointing direction is to horizon, perpendicular to direction of flight. Due to the distance between antennas is much greater than half of wavelength, grating lobes are highly expressed. This system is very sensitive to the DoA angle, but due to grating lobes the angles are ambiguous. Angles of lobes α can be expressed analytically by Eq. (7). α = arcsin(-λ(Δϕ/360 0 \(\:\pm\:\) n)/d ) (7) \(\:n=\) 0,1,2…. There Δϕ is a difference of antennas, excitation phases. Both antennas should be connected by cables of equal length (if we need no phase shift between antennas) to power splitter or divider, then splitter can be connected to receiver by cable of arbitrary length. The strategy of transmitter location finding can be the following: Using logged data (signal strength, aircraft position, time, course) we can build voltage (in the receiver input) dependance vs. time. Then, we can calculate voltage dependance vs. time using Friis equation, substituting receiving antenna gain (depends on angle and receiver coordinates) and unknown parameters for fitting as radiated transmitter power and transmitter coordinates. The best fit of both curves will give the transmitter’s location. If both antennas are arranged on the same window and the distance between antennas is less than half a wavelength, we can get radiation pattern without grating lobes. It allows us to find direction to transmitter unambiguously but less accurate than in the case above. Simulated radiation patten (directivity) of two antennas array when distance d between antennas is 100 mm in the cases of different phasing is presented in Fig. 10 . DoA can be finded automatically by using small synchronous radio receiver set (for example RTL-SDR, Kerbeross, HackRF one, etc.) using Multiple Signal Classification (MUSIC)-like algorithms or by using manually tuned phase shifter. When DoA is known, the location of transmitter can be found by using multiangulation principle. To not scratch the inner plastic cabin window, the surface of an antenna should be soft, or antennas should be placed into the plastic bags. 5 Mitigation of GNSS spoofing and jamming in aviation As presented in Fig. 1 and Fig. 2 , airplanes fly around dangerous zones, but signals of jammers and spoofers interfere with the GNSS navigation system. Most of the time of flight near the dangerous zone, interfering transmitters are in directions close to perpendicular to fuselage. Thus, suppression of the signals exactly from these directions is highly desirable. We suggest adding an additional two GNSS antennas (and receivers). Antennas should be arranged on the wings, close to fuselage on both opposite sides as presented on insets of fig, 11. The horizontal surface of the wing will serve as a screen from ground located signals. Fuselage will serve as a very effective screen from the signals from the opposite side. Obviously, the fuselage will screen not only interfering signals, but also GNSS satellites in the sector close to the hemisphere. It will lead to dilution of precision of positioning. Modern multisystem receivers provide sufficient number of satellites for navigation. At higher altitudes, where the vulnerability of GNSS is highest, there are no so high requirements for positioning accuracy as in the case of approaching. Thus, some dilution of precision at high altitudes can be acceptable with significantly increased robustness to spoofing and jamming. At low altitudes, where higher positioning precision is required, it can be switched to conventional top mounted GNSS antennas. Then, antennas on the wings can serve as supplementary antennas for jamming and spoofing detection. Simulation of antennas’ directivity is presented in Fig. 11 . Due to very big (expressed in wavelengths) aircraft dimension, only part of aircraft body (length of 4m) with simplified geometry was considered. Thus, the sense of this simulation is on approximal estimation of the efficiency of proposed configuration of antennas. According to Fig. 11 , isolation of unwanted direction is -20dB as difference in directivity between top mounted antenna (solid red curve) and wing mounted antenna (blue curve) at -90 o direction. In real life, due to limited simulation and wider fuselages, we can expect even more suppression of unwanted signal from the opposite side. 5 Conclusions and discussion Interferences to GNSS navigation in aviation are increasing in the modern world. Navigation systems make an important contribution to the safety of flights. Thus, it is important to know where jamming or spoofing stations are located and what kind of signals are using. This information can help to develop strategies for interference mitigation. The possibility of safe receiving GNSS jamming signals during commercial flight was demonstrated. Small low weight and in most cases low-cost equipment is required for signals reception and estimation of transmitter’s location. Equipment can be easily placed into the hand luggage and taken to the passenger seat. The location (in Belarus territory) of the GNSS jamming signal was estimated by using signal strength and aircraft position information using multilateration principle. Jamming signal performs narrowband and wideband (like GPS C/A) signals changing each other in time. This signal probably is composed to implement two different strategies of jamming and is responsible for interferences described in area A in Fig. 1 . We propose simple two antenna array for implementation of different multiangulation principles for location finding of the jamming transmitters. In addition, we have suggested using two additional aircraft GNSS antennas placed on both wings close to fuselage to mitigate GNSS jamming and spoofing. We hope these results will inspire scientific and engineering communities to make their own measurements or even further crowded investigations on interferences to aviation. It may be helpful for situational awareness in aircraft GNSS navigation, make some transparency in situations about jamming and finally increase safety of flights. Declarations Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author Contribution **SR** : Formal analysis, Conceptualization. Writing – original draft, Methodology, Investigation, Data curation. **JB** : Writing – review & editing, Project administration, Funding acquisition, Resources. Acknowledgement Thanks to Communications Regulatory Authority of the Republic of Lithuania and Saulius Gelzinis for consulting and providing of flight logs. Data availability Data will be made available on request. 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Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 08 Mar, 2026 Reviewers agreed at journal 07 Mar, 2026 Reviewers invited by journal 05 Mar, 2026 Editor assigned by journal 26 Feb, 2026 Submission checks completed at journal 24 Feb, 2026 First submitted to journal 23 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8944498","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":602679079,"identity":"bf955f55-66c6-404c-8987-8d6ffed4530a","order_by":0,"name":"Saulius Rudys","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAs0lEQVRIiWNgGAWjYHACAwaGCgYZBmY2krScYeAhUQtjG1ALA7FazGckb5P8Oc+GR7edLfEDQ41NNEEtMjfSyqR5t6XxmB1mOyzBcCwtt4GQFgmJHDNpxm2HgVrYGyQYGw4Tp0Xy55z/IC3NP4jWIsHbcADksGNE2sLzrNia51gySEuaRQJRfmFP3njzR42dnNn5Y8Y3PtTYENYCBCwScGYCEcpBgPkDkQpHwSgYBaNgpAIA1hw3QuQhPscAAAAASUVORK5CYII=","orcid":"","institution":"Vilnius Gediminas Technical University","correspondingAuthor":true,"prefix":"","firstName":"Saulius","middleName":"","lastName":"Rudys","suffix":""},{"id":602679080,"identity":"0bc044fc-8cca-45f6-ac75-e1bd42bc0be7","order_by":1,"name":"Jūras Banys","email":"","orcid":"","institution":"Vilnius University","correspondingAuthor":false,"prefix":"","firstName":"Jūras","middleName":"","lastName":"Banys","suffix":""}],"badges":[],"createdAt":"2026-02-23 08:09:57","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8944498/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8944498/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104393748,"identity":"e76a05b9-1446-4c0d-b44e-54a9d3dd92fe","added_by":"auto","created_at":"2026-03-11 10:44:05","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":323166,"visible":true,"origin":"","legend":"\u003cp\u003eMap of the level of GNSS interference (GPSJAM).\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/1e95cf395bf32eed9cc876fd.jpeg"},{"id":104393749,"identity":"24f61400-05be-4b09-abe3-cd7c1c50c80e","added_by":"auto","created_at":"2026-03-11 10:44:05","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":254701,"visible":true,"origin":"","legend":"\u003cp\u003e“Ghost plane” appearance in the Flightradar24 map- left, no “ghost” - right (Flightradar24).\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/1ac3f7e1b2670cff301ff71a.jpeg"},{"id":104393750,"identity":"09e8eea0-7a6a-413d-989e-b3b279a49f6c","added_by":"auto","created_at":"2026-03-11 10:44:05","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":82314,"visible":true,"origin":"","legend":"\u003cp\u003eReturn loss of GNSS antenna – upper chart, Transmission loss between log-periodic (frequency range from 800MHz) and ceramic GNSS antenna in different polarization – lower chart. Chart with lower transmission loss corresponds to horizontal polarization.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/c2c5df407815b36e2e33079c.jpeg"},{"id":104393747,"identity":"2566a840-9497-4c04-8693-9a3d21dd8104","added_by":"auto","created_at":"2026-03-11 10:44:05","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":373385,"visible":true,"origin":"","legend":"\u003cp\u003ePatch antenna structure (right) and simulated radiation pattern of directivity in orthogonal planes (left).\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/649d9508038c1851a8a29372.jpeg"},{"id":104405901,"identity":"0fcb355a-6007-45e3-b81f-2b018b86f74c","added_by":"auto","created_at":"2026-03-11 12:24:07","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":164743,"visible":true,"origin":"","legend":"\u003cp\u003eWideband spectrum received onboard using GNSS antenna.\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/ac50644ac617aab1a48c2c9b.jpeg"},{"id":104406324,"identity":"44029cf8-9697-4fb9-bf97-526a621a29d3","added_by":"auto","created_at":"2026-03-11 12:25:20","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":355734,"visible":true,"origin":"","legend":"\u003cp\u003eVoltage in the receiver’s input dependance on coordinate (upper chart) and voltage dependance on flying distance (lower chart).\u003c/p\u003e","description":"","filename":"floatimage6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/b6cae8c2fc49e640d3d05381.jpeg"},{"id":104393755,"identity":"aa066831-aa1b-4198-9265-1e39e0b9e4fd","added_by":"auto","created_at":"2026-03-11 10:44:06","extension":"jpeg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":273143,"visible":true,"origin":"","legend":"\u003cp\u003eSpectrum of the jamming signal from Belarus. A full period of 8100 ms is presented in waterfall.\u003c/p\u003e","description":"","filename":"floatimage7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/f12018fef5974e28a6a4e5ed.jpeg"},{"id":104393753,"identity":"41cc10be-421b-4faf-93ff-f91c43c7ba1d","added_by":"auto","created_at":"2026-03-11 10:44:05","extension":"jpeg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":246945,"visible":true,"origin":"","legend":"\u003cp\u003eSpectrum of the jamming signal for multiple GNSS systems.\u003c/p\u003e","description":"","filename":"floatimage8.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/a55a8e19844d442f32347458.jpeg"},{"id":104393752,"identity":"1e93e95d-36bb-4a07-a374-600628b02af0","added_by":"auto","created_at":"2026-03-11 10:44:05","extension":"jpeg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":722527,"visible":true,"origin":"","legend":"\u003cp\u003eSimulated radiation pattern in horizontal (solid lines) and vertical (dashed line) planes of two antenna array, when distance \u003cem\u003ed\u003c/em\u003e between antennas is 500mm in different \u0026nbsp;\u003cem\u003eΔϕ. Δϕ=0\u003c/em\u003e\u003csup\u003e\u003cem\u003eo\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e \u003c/em\u003e-red\u003cem\u003e, Δϕ=90\u003c/em\u003e\u003csup\u003e\u003cem\u003e o\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e -\u003c/em\u003eblue\u003cem\u003e, Δϕ=180\u003c/em\u003e\u003csup\u003e\u003cem\u003e o\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e -\u003c/em\u003egreen\u003cem\u003e.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage9.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/f8ffba3c519d58bec9c5a759.jpeg"},{"id":104393756,"identity":"446407f8-7598-47ba-8203-7641b0ddbee5","added_by":"auto","created_at":"2026-03-11 10:44:06","extension":"jpeg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":481752,"visible":true,"origin":"","legend":"\u003cp\u003eSimulated radiation pattern in horizontal plane of two antenna array, when distance d between antennas is 100 mm in different\u0026nbsp; \u003cem\u003eΔϕ. Δϕ=0\u003c/em\u003e\u003csup\u003e\u003cem\u003eo\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e \u003c/em\u003e-red\u003cem\u003e, Δϕ=45\u003c/em\u003e\u003csup\u003e\u003cem\u003eo\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e -\u003c/em\u003epink\u003cem\u003e, \u0026nbsp;Δϕ=90\u003c/em\u003e\u003csup\u003e\u003cem\u003e o\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e -\u003c/em\u003eblue\u003cem\u003e, Δϕ=180\u003c/em\u003e\u003csup\u003e\u003cem\u003e o\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e -\u003c/em\u003egreen\u003cem\u003e.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage10.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/ab45de9720022bdde062747b.jpeg"},{"id":104393754,"identity":"f5843a5d-9687-4717-b33d-ffac819e8b19","added_by":"auto","created_at":"2026-03-11 10:44:06","extension":"jpeg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":165968,"visible":true,"origin":"","legend":"\u003cp\u003eRadiation patterns in vertical planes of top mounted antenna -red and wing mounted antenna- blue. Solid lines – roll plane, dashed lines – yaw plane. Simplified model of simulation with positions of antennas is in the lower inset. Possible mounting of antennas on aircraft is presented in upper inset.\u003c/p\u003e","description":"","filename":"floatimage11.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/cba44a95a9b8b4857eef0453.jpeg"},{"id":104779881,"identity":"2d60e7bd-abf0-480f-834d-f066fcbd71b0","added_by":"auto","created_at":"2026-03-17 07:47:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4019059,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8944498/v1/26b29862-a88a-45d5-9257-86851ed107d1.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Observation of the GNSS jamming sources during commercial flights","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eDuring war actions, electronic countermeasures such as spoofing and jamming against GNSS are widely used. After Russia invasion to Ukraine and conflicts in Middle East, the operation range of electronic warfare reach lines of commercial airflights. Since GNSS is one of the radio navigation systems, disturbing or disabling GNSS negatively affects aircraft navigation. Moreover, GNSS is a key component of Automatic Dependent Surveillance - Broadcast (ADS-B) system which is a part Traffic Collision Avoidance System (TCAS). Thus, GNSS is very important for flight safety. Unfortunately, due to the conflicts, the quality of GNSS navigation is low in some regions. Map of the level of GNSS interference is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (GPSJAM). This map is colored by using a parameter of navigation quality (GPSJAM), which was transmitted in ADS-B data. Area A corresponds to the jammer affected area, considered in this paper. Area B is example of spoofing, when some information about GNSS signal condition is plotted over Ukraine territory, where no commercial flights are conducted. Using this data from ADS-B system we can approximately estimate positions and density of Russian military objects, covered by spoofing systems.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMuch more dangerous than jamming is the appearance of \u0026ldquo;ghost planes\u0026rdquo; in ADS-B map. \u0026ldquo;Ghosts\u0026rdquo; can be inserted basically in two ways: by transmission of synthesized ADS-B signal, or by legal ADS-B transmitter of the aircraft when its GNSS receiver is spoofed. Last case example with the \u0026ldquo;ghost plane\u0026rdquo; is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e where data are taken from open Flightradar24 source (Flightradar24). Most relevant explanation of Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e is following \u0026ndash; AFL2173 aircraft receive GNSS spoofing signal from transmitter in occupied Ukraine territory with coordinates above Ukraine, then aircraft\u0026rsquo;s ADS-B transmits these coordinates, whereas ground ADS-B receiver provides these coordinates for mapping. When aircraft leaves area, covered by spoofer, then ADS-B transmits real coordinates of aircraft (right picture). This case is only one example of multiple cases during only one day gathered in area B in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eTo avoid synthesized \u0026ldquo;ghost planes\u0026rdquo;, we need to authenticify transmitters. Due to well-known vulnerability of ADS-B (Wu et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), there are limited abilities to identify a \u0026ldquo;ghost\u0026rdquo;. Among the recently proposed solutions to ADS-B security issues, covered in a surveys (Wu et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Strohmeier et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), most are targeted at ground Air Traffic Control (ATC) centers. Most notably, multilateration systems (Nijsure et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2016\u003c/span\u003e, Monteiro et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) have been proposed and already implemented at a number of airports. Some ideas based on signal encryption (Baek et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), or adding time stamps (Kim et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) requires changes in ADS-B standard. Ideas of authentication of ADS-B signal on aircraft side without changing ADS-B standard are presented in (Rudys et al. 2020). It seems, authentication of the ADS-B signals is not widely used in aviation yet. Another kind of counter measure which allows to avoid situation presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e (spoofing of GNSS) is using anti-spoofing solutions in GNSS receivers (Yuan et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), (Magiera \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Jafarnia-Jahromi et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Most reliable principle of operation of these system can be based on comparison of DoA from GNSS and spoofing signals when positions of satellites are known. Estimation of direction of arrival (DoA) or spatial selection of satellites require directional antennas or arrays of antennas (1 Stenberg et al.2020, Montgomery et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). It can be implemented by using only 2x2 array and 4 receivers as presented in (Razgunas et al. 2023). If DoA of spoofing source(s) was spatially detected, then beamforming technique can be used to reject interfering signal sources.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn this paper we provide experimental results of receiving jamming signals during flight by commercial airlines. These results may be useful for situational awareness in aircraft GNSS navigation, make some transparency in situation about jamming and probably will inspire further crowded investigations of this problem.\u003c/p\u003e \u003cp\u003eThe remainder of this paper is organized as follows. Section \u003cspan refid=\"Sec2\" class=\"InternalRef\"\u003e2\u003c/span\u003e introduces the methodology of receiving jamming signals during flight and methodology of finding location of the jammer. The results of receiving and locating jamming signals are presented in Section \u003cspan refid=\"Sec5\" class=\"InternalRef\"\u003e3\u003c/span\u003e whereas further jamming signals receiving and locating approach is presented in Section \u003cspan refid=\"Sec8\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Suggestions for jamming and spoofing mitigation in aviation are presented in Section \u003cspan refid=\"Sec9\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Finally, conclusions and discussion are provided in Section 6.\u003c/p\u003e"},{"header":"2 Methods and materials","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Receiving hardware and data logging\u003c/h2\u003e \u003cp\u003eThe Signal hound BB60C receiver was used with Spike software (Signal Hound). The receiver was connected to a tablet computer via USB port. To save battery power of computer, the second power USB connector of receiver\u0026rsquo;s cord was connected to power bank. We used a simple ceramic 25x25x4 mm patch antenna with 6x7 cm reflector made from copper foil. The radiation pattern of antenna was simulated by Ansys HFSS software (Ansys). Radiation pattern and drawing of the patch antenna are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Since we are interested in robustness to interferences which polarization may be unknown and can be different, in this and further simulations we calculate total directivity which contains different polarizations.\u003c/p\u003e \u003cp\u003eThe presence of the reflector slightly increases gain and reduces interferences from computer or other sources inside the cabin. Despite the antenna being without filters and amplifiers, it provides sufficient frequency selection as presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. It allows to suppress potential interference from aircraft navigation, broadcasting and telecommunication signals.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAlthough antenna is designed for circular polarization, ellipticity (further it allows us to estimate polarization of the jammer) was clearly presented. Measured antenna gain is 0 dBi.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBefore measurements, a wide spectrum up to 6GHz was recorded on board to ensure in presence strong potentially interfering signals. This spectrum presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Radiation in 2.4\u0026ndash;2.5 GHz band is strongest. The sources from Bluetooth devices are prevailing here.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWhile receiving signals, we have logged video from screen with time and signal strength, but do not log GNSS position. Positions (related to time) were taken from ADS-B logs provided by local communication authorities. Obviously, it is more convenient to make our own real time logs of GNSS position. Automated logging of time, signal and position will be implemented in further experiments. In the case of strong jamming or spoofing, a logging device of position (for example \u0026ndash; a smartphone) can be located near the window of opposite side. For safety, all computers and phones must be switched (and was switched) into the \u0026ldquo;Flight mode\u0026rdquo;. The receivers as itself are no (negligible) radiating devices and are safe for use in flights.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Transmitter location finding\u003c/h2\u003e \u003cp\u003eDuring the flight we permanently recorded the signal strength of the jammer. Also, we know the position of the aircraft. Since we used receiving antenna with low directivity, the strategy of jammer\u0026rsquo;s location finding was based on signal strength and position measurements by using multilateration principle.\u003c/p\u003e \u003cp\u003eAccording to the Friis equation (Stutzman at al. 1980), voltage at the receiver input \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eR\u003c/em\u003e\u003c/sub\u003e is inverse proportional to distance \u003cem\u003eR\u003c/em\u003e to transmitter and vice versa.\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:R=\\sqrt{{G}_{R}{G}_{T}\\:{P}_{T}{Z}_{R}}\\frac{\\lambda}{\\text{4}\\pi}\\frac{\\text{1}}{{\\text{U}}_{\\text{R}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThere \u003cem\u003eG\u003c/em\u003e\u003csub\u003e\u003cem\u003eR\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eG\u003c/em\u003e\u003csub\u003e\u003cem\u003eT\u003c/em\u003e\u003c/sub\u003e are the gain of receivers and transmitters antennas, \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eT\u003c/em\u003e\u003c/sub\u003e is a power of transmitter, \u003cem\u003eZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eR\u003c/em\u003e\u003c/sub\u003e is input impedance of receiver, \u003cem\u003eλ\u003c/em\u003e is a wavelength. By measuring signal voltage, we can find coordinates \u003cem\u003ex\u003c/em\u003e and \u003cem\u003ey\u003c/em\u003e of the transmitter when transmission power, antennas gain, and frequency are known by solving system of equations (2).\u003c/p\u003e \u003cp\u003e(\u003cem\u003ex\u0026thinsp;\u0026minus;\u0026thinsp;x\u003c/em\u003e\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e)\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e+(y\u0026thinsp;\u0026minus;\u0026thinsp;y\u003c/em\u003e\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e)\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e=R\u003c/em\u003e\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e (2)\u003c/p\u003e \u003cp\u003eThere, \u003cem\u003ex\u003c/em\u003e\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ey\u003c/em\u003e\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e are coordinates of receiver, \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e is distance to transmitter which can be found from (1).\u003c/p\u003e \u003cp\u003eIn this case we are using the assumption that receiving and transmitting antennas are omnidirectional. We need only two equations (receiver positions) to find 2D transmitter coordinates. It can be done ambiguously if the direction (side) of signal arrival is approximately known. When antennas parameters and transmission power are unknown, then we know not distances, but quasi ranges which are equal to unknown parameter k divided by voltage in the receiver \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eRn\u003c/em\u003e\u003c/sub\u003e. Where:\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:k=\\sqrt{{G}_{R}{G}_{T}\\:{P}_{T}{Z}_{R}}\\frac{\\lambda}{4\\pi}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eSince an additional unknown parameter appears, we need additional equation in the system:\u003c/p\u003e \u003cp\u003e(\u003cem\u003ex\u0026thinsp;\u0026minus;\u0026thinsp;x\u003c/em\u003e\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e)\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e+(y\u0026thinsp;\u0026minus;\u0026thinsp;y\u003c/em\u003e\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e)\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e=(k/U\u003c/em\u003e\u003csub\u003e\u003cem\u003eRn\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e)\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e (4)\u003c/p\u003e \u003cp\u003eThe situation is like in GNSS, when additional satellite is required to solve range - quasi range problem.\u003c/p\u003e \u003cp\u003eDue to the flight trajectory near the jamming source was a straight line, it is possible to find jammer location without solving system of equations.\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Results","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Estimation of jammer\u0026rsquo;s location\u003c/h2\u003e \u003cp\u003eA good tool for presentation of measurement results is Google Earth. We used airplane track .kml extension file, but imputed receiver\u0026rsquo;s voltage here instead of altitude of aircraft. Results are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. Voltage dependance on coordinate is presented on 3D map. Voltage dependance on flying distance is presented on the lower part of Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. Since we are using software for presentation of geospatial data, the voltage is presented as altitude. 1 m of altitude corresponds to 10 nV.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThanks to straight trajectory, it is possible instantly find direction to the jammer. This direction is perpendicular to the trajectory line, starting from position with maximum signal (yellow line in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Sometimes jamming signal comes from Kaliningrad (Russia) side in opposite direction. To ensure that this signal comes from Belarus we tried to receive signals from the opposite side window. No signal from Russia side was received at this time. Due to strong oscillations of signal level, the average curve was derived (red curve). The position of signal maximum (point A) was taken from this averaged curve. Now it remains to calculate distance (in our consideration we make assumption that difference between slant and ground rages is negligible) to the jamming transmitter. It can be done by finding angle α when distance |\u003cem\u003eAB\u003c/em\u003e| is known. Distances |\u003cem\u003eAC\u003c/em\u003e| and \u003cem\u003e|BC|\u003c/em\u003e are \u003cem\u003ek/U\u003c/em\u003e\u003csub\u003e\u003cem\u003eA\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ek/U\u003c/em\u003e\u003csub\u003e\u003cem\u003eB\u003c/em\u003e\u003c/sub\u003e respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Where \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eA\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eB\u003c/em\u003e\u003c/sub\u003e are voltages in receiver input on point A and point B respectively. Despite \u003cem\u003ek\u003c/em\u003e is unknown, it is possible to find cosine of angle α:\u003c/p\u003e \u003cp\u003e \u003cem\u003ecos(α)=|AC|/|BC|=k*U\u003c/em\u003e \u003csub\u003e \u003cem\u003eB\u003c/em\u003e \u003c/sub\u003e \u003cem\u003e/(k*U\u003c/em\u003e \u003csub\u003e \u003cem\u003eA\u003c/em\u003e \u003c/sub\u003e \u003cem\u003e)= U\u003c/em\u003e \u003csub\u003e \u003cem\u003eB\u003c/em\u003e \u003c/sub\u003e \u003cem\u003e/U\u003c/em\u003e \u003csub\u003e \u003cem\u003eA\u003c/em\u003e \u003c/sub\u003e (5).\u003c/p\u003e \u003cp\u003eHence, the distance to the transmitter |AC| is\u003c/p\u003e \u003cp\u003e \u003cem\u003e|AC|=|AB|/tg(α)\u003c/em\u003e (6)\u003c/p\u003e \u003cp\u003eIt is convenient to take \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eB\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/U\u003c/em\u003e\u003csub\u003e\u003cem\u003eA\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e=1/2\u003c/em\u003e, then \u003cem\u003eα\u0026thinsp;=\u0026thinsp;60\u003c/em\u003e degrees. As mentioned above, assumption about omnidirectional radiation patterns is made for transmitter position finding. Our receiving antenna was directional, pointed perpendicular to flight direction. If the transmitter is not located to this perpendicular direction, then voltage in our directional antenna output will be lower than in the case of omnidirectional antenna. We can estimate this voltage drop using antenna radiation pattern data. The radiation pattern of the receiving antenna is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. To correct voltage by using radiation pattern data, we need to choose the angle to the transmitter, but this angle is not known precisely yet. In point B when \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eB\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/U\u003c/em\u003e\u003csub\u003e\u003cem\u003eA\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e=1\u003c/em\u003e/2, in the case of omnidirectional receiving antennas this angle is equal to 60\u003csup\u003eo\u003c/sup\u003e. We may consider that the angle to transmitter is known approximately. In the case of omnidirectional antennas, in the point B, \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eB\u003c/em\u003e\u003c/sub\u003e will be higher, ratio \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eB\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/U\u003c/em\u003e\u003csub\u003e\u003cem\u003eA\u003c/em\u003e\u003c/sub\u003e will be higher than \u0026frac12; and real angle to the transmitter will be smaller than 60. Let\u0026rsquo;s choose this angle as 50\u003csup\u003eo\u003c/sup\u003e. According to Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, antenna gain loses at 50 \u003csup\u003eo\u003c/sup\u003e is 2.5 dB or 1.333 times by voltage. Then \u003cem\u003ecos(α)\u0026thinsp;=\u0026thinsp;1.333*U\u003c/em\u003e\u003csub\u003e\u003cem\u003eB\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/U\u003c/em\u003e\u003csub\u003e\u003cem\u003eA\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e=0.666\u003c/em\u003e. \u003cem\u003eArc cos(0.666)=48\u003c/em\u003e\u003csup\u003e\u003cem\u003eo\u003c/em\u003e\u003c/sup\u003e. This angle is close to chosen above 50\u003csup\u003eo\u003c/sup\u003e for \u003cem\u003eU\u003c/em\u003e\u003csub\u003e\u003cem\u003eB\u003c/em\u003e\u003c/sub\u003e correction. If higher accuracy is required, further iterations of correction can be performed. Distance \u003cem\u003e|AB|\u003c/em\u003e is 154 km. Hence, from (6), jamming transmitter range \u003cem\u003e|AC|\u003c/em\u003e is 137.6 km. Transmitter position presented as red circle C in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. Location of transmitter is on Belarus territory, close to Poland border and in vicinity of Hrodna city. We may consider, this transmitter is responsible at least for five red cells in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e on zone A. Mention should be made, method used above is useful under assumption that the radiated power is the same in all measured directions, therefore this method is less accurate than methods using directional antennas where assumption above is not necessary. We will consider directional antenna in Chap.\u0026nbsp;4.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Jamming signals\u003c/h2\u003e \u003cp\u003eThe spectrum of jamming signal which considered above is presented in the Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. This signal consists of two temporal parts: narrowband, slowly sweeping carrier and wide band signal, whit the spectrum close to Global Positioning System (GPS) L1 Coarse Acquisition (C/A) signal. The period of this signal is 8100 ms, and the wideband signal duration is 2500 ms. We suppose this signal is composed with the intention to implement two different strategies of jamming.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eDue to ellipticity of polarization of receiving antenna (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), the signal level was different at perpendicular orientation of the antenna. The polarization of the jamming signal was measured as horizontal.\u003c/p\u003e \u003cp\u003eSome weaker signal (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e) was detected during flight over southern Lithuanian territory. This signal performs at least three components for the jamming of several GNSS systems: for Beidou at 1561.098 MHz, for various systems at 1575.42 MHz and wideband multicarrier signal for Glonass.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eDue to signal weakness, we don\u0026rsquo;t try to estimate transmitter location.\u003c/p\u003e \u003c/div\u003e"},{"header":"4 Array antennas for direction finding","content":"\u003cp\u003eIn Section \u003cspan refid=\"Sec5\" class=\"InternalRef\"\u003e3\u003c/span\u003e we have found the location of transmitter by using a low directivity antenna and assumption about omnidirectional radiation of transmitter. In general cases it leads to errors in estimating of transmitter\u0026rsquo;s coordinates. More universal method is instant finding of DoA by using directional antenna. Unfortunately using directional antenna (for example Yagi antenna) in passenger seat is inconvenient. Small window aperture can disorder antenna radiation pattern and limits angles of view. Most problematic is implementation of measurement of the antenna\u0026rsquo;s pointing angle.\u003c/p\u003e \u003cp\u003eTo eliminate the drawbacks of Yagi antenna, we suggest using two conventional patch antennas (for example, one as was used above) system. Antennas should be arranged on the neighboring windows. Distance between antennas is chosen 500 mm - close to distance between windows in Boeing-737. Simulated by HFSS radiation patterns with different phasing are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e. Antennas pointing direction is to horizon, perpendicular to direction of flight. Due to the distance between antennas is much greater than half of wavelength, grating lobes are highly expressed. This system is very sensitive to the DoA angle, but due to grating lobes the angles are ambiguous. Angles of lobes α can be expressed analytically by Eq.\u0026nbsp;(7).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eα\u0026thinsp;=\u0026thinsp;arcsin(-λ(Δϕ/360\u003c/em\u003e \u003csup\u003e \u003cem\u003e0\u003c/em\u003e \u003c/sup\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:\\pm\\:\\)\u003c/span\u003e \u003c/span\u003e \u003cem\u003en)/d ) (7)\u003c/em\u003e \u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:n=\\)\u003c/span\u003e \u003c/span\u003e \u003cem\u003e0,1,2\u0026hellip;.\u003c/em\u003e \u003c/p\u003e \u003cp\u003eThere \u003cem\u003eΔϕ\u003c/em\u003e is a difference of antennas, excitation phases.\u003c/p\u003e \u003cp\u003eBoth antennas should be connected by cables of equal length (if we need no phase shift between antennas) to power splitter or divider, then splitter can be connected to receiver by cable of arbitrary length.\u003c/p\u003e \u003cp\u003eThe strategy of transmitter location finding can be the following:\u003c/p\u003e \u003cp\u003eUsing logged data (signal strength, aircraft position, time, course) we can build voltage (in the receiver input) dependance vs. time. Then, we can calculate voltage dependance vs. time using Friis equation, substituting receiving antenna gain (depends on angle and receiver coordinates) and unknown parameters for fitting as radiated transmitter power and transmitter coordinates. The best fit of both curves will give the transmitter\u0026rsquo;s location.\u003c/p\u003e \u003cp\u003eIf both antennas are arranged on the same window and the distance between antennas is less than half a wavelength, we can get radiation pattern without grating lobes. It allows us to find direction to transmitter unambiguously but less accurate than in the case above. Simulated radiation patten (directivity) of two antennas array when distance \u003cem\u003ed\u003c/em\u003e between antennas is 100 mm in the cases of different phasing is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eDoA can be finded automatically by using small synchronous radio receiver set (for example RTL-SDR, Kerbeross, HackRF one, etc.) using Multiple Signal Classification (MUSIC)-like algorithms or by using manually tuned phase shifter. When DoA is known, the location of transmitter can be found by using multiangulation principle.\u003c/p\u003e \u003cp\u003eTo not scratch the inner plastic cabin window, the surface of an antenna should be soft, or antennas should be placed into the plastic bags.\u003c/p\u003e"},{"header":"5 Mitigation of GNSS spoofing and jamming in aviation","content":"\u003cp\u003eAs presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, airplanes fly around dangerous zones, but signals of jammers and spoofers interfere with the GNSS navigation system. Most of the time of flight near the dangerous zone, interfering transmitters are in directions close to perpendicular to fuselage. Thus, suppression of the signals exactly from these directions is highly desirable.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe suggest adding an additional two GNSS antennas (and receivers). Antennas should be arranged on the wings, close to fuselage on both opposite sides as presented on insets of fig, 11. The horizontal surface of the wing will serve as a screen from ground located signals. Fuselage will serve as a very effective screen from the signals from the opposite side. Obviously, the fuselage will screen not only interfering signals, but also GNSS satellites in the sector close to the hemisphere. It will lead to dilution of precision of positioning. Modern multisystem receivers provide sufficient number of satellites for navigation. At higher altitudes, where the vulnerability of GNSS is highest, there are no so high requirements for positioning accuracy as in the case of approaching. Thus, some dilution of precision at high altitudes can be acceptable with significantly increased robustness to spoofing and jamming. At low altitudes, where higher positioning precision is required, it can be switched to conventional top mounted GNSS antennas. Then, antennas on the wings can serve as supplementary antennas for jamming and spoofing detection.\u003c/p\u003e \u003cp\u003eSimulation of antennas\u0026rsquo; directivity is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e. Due to very big (expressed in wavelengths) aircraft dimension, only part of aircraft body (length of 4m) with simplified geometry was considered. Thus, the sense of this simulation is on approximal estimation of the efficiency of proposed configuration of antennas. According to Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e, isolation of unwanted direction is -20dB as difference in directivity between top mounted antenna (solid red curve) and wing mounted antenna (blue curve) at -90\u003csup\u003eo\u003c/sup\u003e direction. In real life, due to limited simulation and wider fuselages, we can expect even more suppression of unwanted signal from the opposite side.\u003c/p\u003e"},{"header":"5 Conclusions and discussion","content":"\u003cp\u003eInterferences to GNSS navigation in aviation are increasing in the modern world. Navigation systems make an important contribution to the safety of flights. Thus, it is important to know where jamming or spoofing stations are located and what kind of signals are using. This information can help to develop strategies for interference mitigation.\u003c/p\u003e \u003cp\u003eThe possibility of safe receiving GNSS jamming signals during commercial flight was demonstrated. Small low weight and in most cases low-cost equipment is required for signals reception and estimation of transmitter\u0026rsquo;s location. Equipment can be easily placed into the hand luggage and taken to the passenger seat.\u003c/p\u003e \u003cp\u003eThe location (in Belarus territory) of the GNSS jamming signal was estimated by using signal strength and aircraft position information using multilateration principle. Jamming signal performs narrowband and wideband (like GPS C/A) signals changing each other in time. This signal probably is composed to implement two different strategies of jamming and is responsible for interferences described in area A in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eWe propose simple two antenna array for implementation of different multiangulation principles for location finding of the jamming transmitters.\u003c/p\u003e \u003cp\u003eIn addition, we have suggested using two additional aircraft GNSS antennas placed on both wings close to fuselage to mitigate GNSS jamming and spoofing.\u003c/p\u003e \u003cp\u003eWe hope these results will inspire scientific and engineering communities to make their own measurements or even further crowded investigations on interferences to aviation. It may be helpful for situational awareness in aircraft GNSS navigation, make some transparency in situations about jamming and finally increase safety of flights.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eDeclaration of Competing Interest\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003e**SR** : Formal analysis, Conceptualization. Writing \u0026ndash; original draft, Methodology, Investigation, Data curation. **JB** : Writing \u0026ndash; review \u0026amp; editing, Project administration, Funding acquisition, Resources.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThanks to Communications Regulatory Authority of the Republic of Lithuania and Saulius Gelzinis for consulting and providing of flight logs.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eData will be made available on request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAnsys (2025) Ansys HFSS: Full-wave 3D electromagnetic simulation software. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ansys.com/products/electronics/ansys-hfss\u003c/span\u003e\u003cspan address=\"https://www.ansys.com/products/electronics/ansys-hfss\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Accessed 13 March 2025)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBaek J, Hableel E, Byon YJ, Wong DS, Jang K, Yeo H (2017) How to protect ADS-B: Confidentiality framework and efficient realization based on staged identity-based encryption. 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Chin J Electron 27:213\u0026ndash;222. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1049/cje.2017.11.001\u003c/span\u003e\u003cspan address=\"10.1049/cje.2017.11.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"gps-solutions","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"gpss","sideBox":"Learn more about [GPS Solutions](http://link.springer.com/journal/10291)","snPcode":"10291","submissionUrl":"https://submission.nature.com/new-submission/10291/3","title":"GPS Solutions","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"GNSS, jamming, spoofing, ADS-B, antenna, flight mode, DoA","lastPublishedDoi":"10.21203/rs.3.rs-8944498/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8944498/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eRussia invasion to Ukraine and Middle East conflicts provides problems for Global Navigation Satellite System (GNSS) based navigation systems in aviation because various GNSS jamming and spoofing systems are using as electronic warfare. Navigation systems make an important contribution to the safety of flights. Thus, it is important to know where jamming or spoofing stations are located and what kind of signals are using. This information can help to develop interference mitigation strategies. Signals on GNSS frequencies were safely received during flights on commercial airlines. The location (in Belorussia territory) of the GNSS jamming signal was estimated by using signal strength and aircraft position information. We propose several methods to locate the source of the interfering signal. In addition, we have suggested location of aircraft GNSS antennas to mitigate GNSS jamming and spoofing.\u003c/p\u003e","manuscriptTitle":"Observation of the GNSS jamming sources during commercial flights","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-11 10:43:58","doi":"10.21203/rs.3.rs-8944498/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-03-08T19:19:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"37691594484936175344323242834153135705","date":"2026-03-07T13:32:19+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-05T13:36:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-26T19:48:25+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-24T11:47:42+00:00","index":"","fulltext":""},{"type":"submitted","content":"GPS Solutions","date":"2026-02-23T08:03:53+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"gps-solutions","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"gpss","sideBox":"Learn more about [GPS Solutions](http://link.springer.com/journal/10291)","snPcode":"10291","submissionUrl":"https://submission.nature.com/new-submission/10291/3","title":"GPS Solutions","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d29b021d-9440-4a82-8f8d-b0eba2a77617","owner":[],"postedDate":"March 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-11T10:43:58+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-11 10:43:58","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8944498","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8944498","identity":"rs-8944498","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}