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Akos, Dennis
Publications (10 of 35) Show all publications
Axell, E., Eklöf, F. M., Alexandersson, M., Johansson, P. & Akos, D. (2015). Jamming detection in GNSS receivers: Performance evaluation of field trials (ed.). Paper presented at International technical meeting of the Satellite Division of the Institute of Navigation : 16/09/2013 - 20/09/2013. Navigation, 62(1), 73-82
Open this publication in new window or tab >>Jamming detection in GNSS receivers: Performance evaluation of field trials
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2015 (English)In: Navigation, ISSN 0028-1522, E-ISSN 2161-4296, Vol. 62, no 1, p. 73-82Article in journal (Refereed) Published
Abstract [en]

We evaluate the detection performance of several commercial interference detectors and of a detector that uses the automatic gain control (AGC) level as a test statistic. The evaluations are based on actual measurements of GPS signals and different types of jamming signals, and were performed at the Vidsel test range in northern Sweden.The AGC detector and the Chronos CTL-3500 were shown to work well for all types of jamming signals. The J-alert was able to detect a wideband (20 MHz) signal but not the narrow band (<2 MHz) signals. By contrast, the jamming indicator on a Ublox 6H receiver was only able to detect a slowly varying modulated CW signal, but not signals with larger bandwidth (>2 MHz). We confirmed that C/N0-based Android application detectors could work well in static scenarios but are not suitable in dynamic scenarios, since they cannot distinguish between decreased GPS signal strength and increased interference

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-9928 (URN)10.1002/navi.74 (DOI)000352013600005 ()2-s2.0-84925775476 (Scopus ID)8a2b14b8-a2ba-4b73-822b-3fc1342c961b (Local ID)8a2b14b8-a2ba-4b73-822b-3fc1342c961b (Archive number)8a2b14b8-a2ba-4b73-822b-3fc1342c961b (OAI)
Conference
International technical meeting of the Satellite Division of the Institute of Navigation : 16/09/2013 - 20/09/2013
Note
Validerad; 2015; Nivå 2; 20150331 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Isoz, O., Buehler, S., Kinch, K., Bonnedal, M. & Akos, D. (2014). Interference from terrestrial sources and its impact on the GRAS GPS radio occultation receiver (ed.). Radio Science, 49(1), 1-6
Open this publication in new window or tab >>Interference from terrestrial sources and its impact on the GRAS GPS radio occultation receiver
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2014 (English)In: Radio Science, ISSN 0048-6604, E-ISSN 1944-799X, Vol. 49, no 1, p. 1-6Article in journal (Refereed) Published
Abstract [en]

It is well known that terrestrial GPS/Global Navigation Satellite Systems (GNSS) receivers are vulnerable and have suffered from intentional and unintentional interference sources. Unfortunately, space-based GPS/GNSS receivers are not exempt from radio frequency interference originating from the Earth. This paper explores data recorded by the GNSS Receiver for Atmospheric Sounding (GRAS) instrument onboard MetOp-A in September 2007, which is assumed to be representative of the typical environment for GPS/GNSS instrumentation in LEO orbit. Within these data it is possible to detect both pulsed interference and variations in the background noise. One plausible source of the pulsed interference is identified. We also show that neither the pulsed interference nor the variations in the background noise degrades the performance of the higher level products from GRAS.

National Category
Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-11945 (URN)10.1002/2013RS005243 (DOI)000333023400001 ()2-s2.0-84891794195 (Scopus ID)afdbd932-5a6f-4958-a5f8-858d51b67bc2 (Local ID)afdbd932-5a6f-4958-a5f8-858d51b67bc2 (Archive number)afdbd932-5a6f-4958-a5f8-858d51b67bc2 (OAI)
Note

Validerad; 2014; 20140115 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-05-06Bibliographically approved
Axell, E., Eklöf, F. M., Alexandersson, M., Johansson, P. & Akos, D. (2013). Jamming detection in GNSS receivers: Performance evaluation of field trials (ed.). In: (Ed.), (Ed.), Proceedings of the 26th international technical meeting of the Satellite Division of The Institute of Navigation, ION GNSS+ 2013, Sept. 16 - 20, 2013, Nashville Convention Cener, Nashville, Tennessee: . Paper presented at International technical meeting of the Satellite Division of the Institute of Navigation : 16/09/2013 - 20/09/2013 (pp. 2542-2551). Manassas, VA: Institute of Navigation, The, 3
Open this publication in new window or tab >>Jamming detection in GNSS receivers: Performance evaluation of field trials
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2013 (English)In: Proceedings of the 26th international technical meeting of the Satellite Division of The Institute of Navigation, ION GNSS+ 2013, Sept. 16 - 20, 2013, Nashville Convention Cener, Nashville, Tennessee, Manassas, VA: Institute of Navigation, The , 2013, Vol. 3, p. 2542-2551Conference paper, Published paper (Refereed)
Abstract [en]

In this work, we evaluate the detection performance of a number of commercial interference detectors and, in addition, of a detector that uses the automatic gain control (AGC) levels as test statistic. The AGC detector has been implemented on a Novatel GPS receiver and on a Universal Software Radio Peripheral (USRP). The evaluations are based on actual measurements of GPS signals and different types of jamming signals, which have been performed at the Vidsel test range in northern Sweden. The AGC detector was shown to work well for all types of jamming signals, in particular the one implemented on the USRP. The Chronos CTL-3500 was also shown to perform quite well for all kinds of signals, although not as good as the USRP with an AGC detector. Quite surprisingly, the J-alert was only able to detect the wideband (20 MHz) signal but not the narrow band (<2MHz) signals. By contrast, the jamming indicator on the Ublox 6 receiver was only able to detect a slowly varying modulated CW (MCW) signal, but not the signals with larger bandwidth (2 and 20 MHz). We confirmed that C/N0-based detectors could work well in a static scenario, but are not suitable in a dynamic scenario, since they cannot distinguish between decreased GPS signal strength (e.g. indoors) and an increased interference level.

Place, publisher, year, edition, pages
Manassas, VA: Institute of Navigation, The, 2013
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-37003 (URN)adfb5e20-7630-45a2-b776-c8f5fb361ba9 (Local ID)adfb5e20-7630-45a2-b776-c8f5fb361ba9 (Archive number)adfb5e20-7630-45a2-b776-c8f5fb361ba9 (OAI)
Conference
International technical meeting of the Satellite Division of the Institute of Navigation : 16/09/2013 - 20/09/2013
Note
Godkänd; 2014; 20140509 (andbra)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Powell, S. J., Akos, D. & Backén, S. (2012). Altimetry using gnss reflectrometry for L5 (ed.). In: (Ed.), (Ed.), 2012 6th ESA Workshop on Satellite Navigation Technologies (Navitec 2012) & European Workshop on GNSS Signals and Signal Processing: Noordwijk, 5 - 7 December 2012. Paper presented at European Workshop on GNSS Signals and Signal Processing : 05/12/2002 - 07/12/2002. Piscaaway, NJ: IEEE Communications Society
Open this publication in new window or tab >>Altimetry using gnss reflectrometry for L5
2012 (English)In: 2012 6th ESA Workshop on Satellite Navigation Technologies (Navitec 2012) & European Workshop on GNSS Signals and Signal Processing: Noordwijk, 5 - 7 December 2012, Piscaaway, NJ: IEEE Communications Society, 2012Conference paper, Published paper (Refereed)
Abstract [en]

GNSS reflectrometry offers a low cost alternative for Earth remote sensing and is used to measure, for example, ocean altimetry, wind speed, wind direction and modeling of the ocean surface state. A bistatic configuration, using one right-handed circular polarized and one left-handed circular polarized antenna, was built for this experiment in order to measure direct and reflected L1 and L5 signals. The direct and reflected signals were compared and the path difference between them calculated, leading to altitude measurements with both L1 and L5 signals. Compared to publicly available signals on L1, the higher code rate of L5 will provide higher measurement sensitivity

Place, publisher, year, edition, pages
Piscaaway, NJ: IEEE Communications Society, 2012
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-26931 (URN)03219a9c-52ba-4e2c-8653-0ede611b2fe6 (Local ID)9781467320108 (ISBN)03219a9c-52ba-4e2c-8653-0ede611b2fe6 (Archive number)03219a9c-52ba-4e2c-8653-0ede611b2fe6 (OAI)
Conference
European Workshop on GNSS Signals and Signal Processing : 05/12/2002 - 07/12/2002
Note
Godkänd; 2012; 20150325 (andbra)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Borowski, H., Isoz, O., Lo, S., Eklöf, F. & Akos, D. (2012). Detecting false signals with automatic gain control (ed.). Paper presented at . GPS World, 23(4), 38-43
Open this publication in new window or tab >>Detecting false signals with automatic gain control
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2012 (English)In: GPS World, ISSN 1048-5104, Vol. 23, no 4, p. 38-43Article in journal (Refereed) Published
Abstract [en]

A component of most GPS receiver front-ends, the automatic gain control (AGC) can flag potential jamming and spoofing attacks. The detection method is simple to implement and accessible to most GPS receivers. It may be used alone or as a complement other anti-spoofing architectures. This article presents results from a baseline AGC characterization, develos a simple spoofing detection method, and demonstrate the results of that method on receiver data gathered in the presence of a live spoofing attack.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-2519 (URN)023ce73d-bd07-475b-88a7-41f7b1decaab (Local ID)023ce73d-bd07-475b-88a7-41f7b1decaab (Archive number)023ce73d-bd07-475b-88a7-41f7b1decaab (OAI)
Note
Validerad; 2012; 20120403 (osciso)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Isoz, O., Akos, D., Lindgren, T., Sun, C.-C. & Jan, S.-S. (2011). Assessment of GPS L1/Galileo E1 interference monitoring system for the airport environment (ed.). In: (Ed.), (Ed.), Proceedings of the 23rd international technical meeting of the Satellite Division of the Institute of Navigation, ION GNSS 2011: Sept. 19 - 23, 2011, Oregon Convention Cener, Portland, Oregon. Paper presented at ION GPS GNSS : 19/09/2011 - 23/09/2011 (pp. 1920-1930). Manassas, Va: Inst. of Navigation, 3
Open this publication in new window or tab >>Assessment of GPS L1/Galileo E1 interference monitoring system for the airport environment
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2011 (English)In: Proceedings of the 23rd international technical meeting of the Satellite Division of the Institute of Navigation, ION GNSS 2011: Sept. 19 - 23, 2011, Oregon Convention Cener, Portland, Oregon, Manassas, Va: Inst. of Navigation , 2011, Vol. 3, p. 1920-1930Conference paper, Published paper (Refereed)
Abstract [en]

How does the GPS Ll spectrum look like at a commercial airport? How frequently do radio frequency interference (RFI) incidents occur? To answer this, the GPS Ll/Galileo El band was monitored at two different airports for an extended period of time. The monitor stations continuously recorded the noise level using the automatic gain control (AGC) in the frontend. Also, the raw intermediate frequency (IF) signal was recorded at regular intervals as well as when the AGC level dropped below a certain threshold. In this paper the analysis of long-term measurements of the spectrum and AGC level at Luleå Airport outside Luleå, Sweden, and Kaohsiung International Airport in Kaohsiung City, Taiwan, is presented. The results shows that RFI incidents did occur at both airports, although more frequent at Kaohsiung International Airport. The measurements also show that the AGC level is useful in systems monitoring the RFI environment. Importantly, the measured data could be utilized for analyses toward the future introduction of GBAS for civil aviation authorities.

Abstract [en]

How does the GPS L1 spectrum look like at a commercial airport? How frequently do radio frequency interference (RFI) incidents occur? To answer this, the GPS L1/Galileo E1 band was monitored at two different airports for an extended period of time. The monitor stations continuously recorded the noise level using the automatic gain control (AGC) in the frontend. Also, the raw intermediate frequency (IF) signal was recorded at regular intervals as well as when the AGC level dropped below a certain threshold. In this paper the analysis of long-term measurements of the spectrum and AGC level at Luleå Airport outside Lueå Sweden, and Kaohsiung International Airport in Kaohsiung City, Taiwan, is presented. The results shows that RFI incidents did occur at both airports, although more frequent at Kaohsiung International Airport. The measurements also show that the AGC level is useful in systems monitoring the RFI environment. Importantly, the measured data could be utilized for analyses toward the future introduction of GBAS for civil aviation authorities.

Place, publisher, year, edition, pages
Manassas, Va: Inst. of Navigation, 2011
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-27335 (URN)0c059292-cbd3-4d09-beda-8e9e5de8108b (Local ID)9781618394750 (ISBN)0c059292-cbd3-4d09-beda-8e9e5de8108b (Archive number)0c059292-cbd3-4d09-beda-8e9e5de8108b (OAI)
Conference
ION GPS GNSS : 19/09/2011 - 23/09/2011
Note
Godkänd; 2011; Bibliografisk uppgift: 1 CD-ROM; 20111021 (osciso)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Backén, S., Akos, D. & Wilson, S. G. (2011). RF replay system for narrowband GNSS if signals (ed.). Paper presented at . IEEE Transactions on Aerospace and Electronic Systems, 47(1), 586-595
Open this publication in new window or tab >>RF replay system for narrowband GNSS if signals
2011 (English)In: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 47, no 1, p. 586-595Article in journal (Refereed) Published
Abstract [en]

Although GNSS RF signal simulators have long possessed the capability to generate scenarios they are, for example, not yet able to model a realistic scenario with complex multipath. Software defined receivers bridge the gap between simulated and real data to the extent that they may offer a replay capability, where a data set is first recorded to disk and later can be processed several times. Unfortunately, the recorded data generally can not be used by other GNSS receivers, making receiver to receiver comparisons difficult and time consuming.This paper describes a system capable of replaying recorded IF data into any narrow bandwidth L1 GNSS receiver, including an evaluation of the difference (position, timing and SNR) between live and replayed data using a high sensitivity, consumer grade receiver. The performance of the replayed data set was found to match that of the live data.

Keywords
Information technology - Signal processing, Informationsteknik - Signalbehandling
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-14241 (URN)10.1109/TAES.2011.5705693 (DOI)000286931800039 ()2-s2.0-79551630620 (Scopus ID)d97e7590-77e2-11dc-80da-000ea68e967b (Local ID)d97e7590-77e2-11dc-80da-000ea68e967b (Archive number)d97e7590-77e2-11dc-80da-000ea68e967b (OAI)
Note
Validerad; 2011; 20071011 (staffan)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Isoz, O. & Akos, D. (2010). Development of a deployable low cost interference detection and localization system for the GNSS L1/E1 band (ed.). In: (Ed.), (Ed.), 5th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing (NAVITEC): . Paper presented at ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing : 08/12/2010 - 10/12/2010. Piscataway, NJ: IEEE Communications Society
Open this publication in new window or tab >>Development of a deployable low cost interference detection and localization system for the GNSS L1/E1 band
2010 (English)In: 5th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing (NAVITEC), Piscataway, NJ: IEEE Communications Society, 2010Conference paper, Published paper (Refereed)
Abstract [en]

There have already been a number of well documented cases where the GNSS signals have been interfered by different sources. A number of different methods has been developed to counteract this. One problem with doing experiments to validate the accuracy of interference detection system is that the GPS L1 band is protected, therefore it is difficult to get permission to deliberately broadcast on those frequencies. In this paper we present a novel way to test such a system. The proposed method will be validated by deploying a number of low cost nodes and then an attempt to localize the interference will be made.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2010
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-37244 (URN)10.1109/NAVITEC.2010.5708043 (DOI)2-s2.0-79952492474 (Scopus ID)b38d0fcc-e3ca-4672-a85d-86d7bf1cd841 (Local ID)978-1-4244-8740-0 (ISBN)b38d0fcc-e3ca-4672-a85d-86d7bf1cd841 (Archive number)b38d0fcc-e3ca-4672-a85d-86d7bf1cd841 (OAI)
Conference
ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing : 08/12/2010 - 10/12/2010
Note
Godkänd; 2011; 20110207 (osciso)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-07-10Bibliographically approved
Chu, T., Vinande, E., Akos, D. & Weinstein, B. (2010). GNSS receiver evaluation: record-and-playback test methods (ed.). GPS World, 21(1), 28-34
Open this publication in new window or tab >>GNSS receiver evaluation: record-and-playback test methods
2010 (English)In: GPS World, ISSN 1048-5104, Vol. 21, no 1, p. 28-34Article in journal (Refereed) Published
Abstract [en]

Researchers at the university of Colorado have successfully used radio frequency record-and-playback systems (RPS) have gathered importance commercially because it offers the best way to test hardware receivers. RPS constitutes a stark contrast to more traditional signal simulators that use pre-defined trajectories and mathematical models to determine appropriate RF output. Positioning performance of a satellite navigation receiver under test (RUT) is coupled with its RF front-end system and local oscillator quality. The required equipment and connections are minimal when performing RPS drive testing, as no RUTs are included. It overcomes the fidelity limits of simulator-based testing, especially when considering the difficult-to-model urban environment. During receiver development, it requires only a single drive test for each location, as sampled RF data can be replayed from disk

National Category
Embedded Systems
Research subject
Embedded System
Identifiers
urn:nbn:se:ltu:diva-4810 (URN)2ccda510-6730-11df-ab16-000ea68e967b (Local ID)2ccda510-6730-11df-ab16-000ea68e967b (Archive number)2ccda510-6730-11df-ab16-000ea68e967b (OAI)
Note

Validerad; 2010; 20100524 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-12-20Bibliographically approved
Isoz, O., Akos, D. & Balaei, A. (2010). Interference detection and localization in GPS L1 band (ed.). In: (Ed.), (Ed.), Proceedings of the 2010 International Technical Meeting of The Institute of Navigation: . Paper presented at International Technical Meeting of The Institute of Navigation : 25/01/2010 - 27/01/2010 (pp. 925-929). Manassas, VA: Institute of Navigation, The
Open this publication in new window or tab >>Interference detection and localization in GPS L1 band
2010 (English)In: Proceedings of the 2010 International Technical Meeting of The Institute of Navigation, Manassas, VA: Institute of Navigation, The , 2010, p. 925-929Conference paper, Published paper (Refereed)
Abstract [en]

The GNSS signals are very weak and therefore sensitive to interference. Since the usage of GNSS based services continues to increase, there is a need to develop a cost effective method to detect and localize interference sources. In this paper one such system will be presented. The system uses independent front ends that collects raw IF data. After the collection is done, the files are synchronized in time and frequency so that they can be cross correlated and the time difference of arrival of the interference signal is estimated. This paper will present the initial results from a test in May 2009 where the four stations were deployed and exposed to interference. It will be shown that the system is capable of both detection and localization of wide band interference.

Place, publisher, year, edition, pages
Manassas, VA: Institute of Navigation, The, 2010
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-28326 (URN)218bb4e0-5cee-11df-ab16-000ea68e967b (Local ID)978-161738115-7 (ISBN)218bb4e0-5cee-11df-ab16-000ea68e967b (Archive number)218bb4e0-5cee-11df-ab16-000ea68e967b (OAI)
Conference
International Technical Meeting of The Institute of Navigation : 25/01/2010 - 27/01/2010
Note
Godkänd; 2010; 20100511 (osciso)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
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