Theme 5 Research Page

THEME 5: GNSS RECEIVER DESIGN & SIGNAL PROCESSING

Academic staff members of the School of Surveying & Spatial Information Systems, University of New South Wales, now undertake research and teaching in areas beyond just the narrow areas of "satellite navigation and positioning" of the original SNAP group of the 1990s, to also embrace what may be referred to as "earth observation" (geodesy, airborne and satellite remote sensing and imaging). To better describe the range of activities in the exciting fields of satellite and ground-based wireless positioning, our research projects are grouped into several themes. Download our SNAP Lab Research Directions document to see what we'll be researching over the next few years. The SNAP Lab has also produced a Research Brochure that explains the range of research topics being undertaken, identifying opportunities for potential graduate students as well as research collaboration with external partners. ...email us for a hardcopy, or download a PDF version.

Theme 5 deals with a range of research topics that are comparatively recent initiatives of the SNAP Lab. For many years academic researchers (especially if they came from university surveying/geomatics departments) have treated GPS as a "black box", focussing instead on data modelling investigations (such as in Theme 1) or multi-sensor integration challenges (Theme 3). In 1999 the SNAP Lab made a strategic decision to initiate research into GPS/GNSS receiver hardware design, the only Australian academic research group to do so. Associate Professor Andrew Dempster heads up SNAP's research in this area. For SNAP papers dealing with this topic area click here ...

Two important investment decisions were made in 1999. Firstly, in May 1999 SNAP purchased its first pseudolite (PL), and launched research activity into non-GPS/GNSS positioning technologies such as pseudolites and Locata (see Theme 4). Secondly, in August 1999 a Mitel GPS Receiver Software Development Kit (SDK) was purchased, initially to support receiver customisation for the UNSW BlueSat microsatellite project, but subsequently to initiate GNSS receiver design. In summary, the SNAP Lab:

has designed and built its own GPS/GNSS receiver - the "Namuru" - based on reconfigurable FPGA hardware
owns several GPS/GNSS receiver software development kits, SW receivers and Matlab GNSS receiver toolkits
owns a Spirent 6560 RF signal simulator
undertakes research into receiver design for acquisition and tracking of the modernised GPS and Galileo signals, and will progressively research other signals such as from Russia’s Glonass (including the new CDMA signals), Europe’s Galileo and China’s Compass system, as well as Regional Navigation Satellite Systems (RNSS) under development by Japan and India
is one of the few research labs that has successfully tracked the new GPS L2C signal as well as the E1 signal transmitted by the GIOVE-A prototype Galileo satellite... click here
is undertaking innovative research into RF interference effects on GNSS receivers, and developing an RFI detection device based on the Namuru FPGA board
is investigating new applications of GNSS signal tracking, including bistatic radar (GPS reflectometry)

Research was first conducted on the Locata technology (see Theme 4) using the Mitel SDK. The first step was to create a number of hardware platforms that could be used for R&D as well as for undergraduate and graduate student projects. The original Mitel SDK was purchased with a single HW board, as part of a product known as the "Architect". Multiple HW was developed by hacking into several Canadian Marconi Corporation (CMC) Allstar single-frequency GPS receivers. The Mitel SDK provided all the source code for the customisation of receiver firmware that was based on the Mitel (later Zarlink) GP2021 baseband processor chip. The CMC Allstars also used the GP2021 chip. Although this SDK and HW platform combination was used for a number of student projects, the Zarlink GP2021 chip was an old design and was superseded by the Zarlink GP4020.

In mid-2002 the SNAP Lab purchased a SDK from SigNav Pty Ltd (Canberra) - the MG5021 (right). This SDK used the Zarlink GP4020 chip, and could be used to modify the firmware resident in receiver boards such as the MG5001 and MG5003. However, unlike the Mitel SDK, not all the source code is provided. Peter Mumford in 2003 succeeded in porting the old Mitel SDK to the new MG5001/5003 HW, enabling continued research using this relatively open SDK (e.g. into a spaceborne receiver for the UNSW BlueSat project).

Former research associate Joel Barnes had also been working closely with the Open Source GPS movement to test the firmware on Zarlink GP2021/GP4020-based receivers. A paper was prepared for the 2002 U.S.ION-GPS conference ... click here. In 2005 the MATLAB Data Fusion software GPS receiver toolkit was purchased.

In mid-2005 the NordNav R30 software receiver system (right) was purchased. This has been of great value for both teaching and research.

The SNAP laboratory is well equipped with several different receiver development options, from Open Source, to full SW-based, to Zarlink chip-based and FPGA.

SigNav MG5021 SDK

NordNav R30 attached to laptop

(1) Namuru Receiver Board Development

In 2004 research commenced on the development of a GPS receiver using reconfigurable hardware - Field Programmable Gate Arrays (FPGAs). Graduate student Kevin Parkinson was the first to use FPGAs in a research project, and his experience encouraged the rapid uptake of this new technology. Peter Mumford is assisting in FPGA research efforts, initially working on a Pilot Project funded jointly by SNAP and NICTA (National ICT Australia) at UNSW. Followon ARC-funded FPGA research ("Designing Next Generation GNSS Receivers Using the Software Approach" 2005-2007) supported the enhancement of the SNAP-designed FPGA-based GPS receiver known as the Namuru (L1 and L1/L2 versions shown right).

In late-2007 Namuru version 2 was completed. It has dual frontends, and can track the L2 frequency. The SNAP Lab now has ten of these boards for use by its researchers. Over 20 Namuru boards have also been sold to research organisations in the UK, New Zealand, Germany, Australia, Japan, Spain and the US. New RF frontends are being developed to track frequencies other than L1/E1 and L2. The Namuru version 3 design has not been completed yet.

Namuru version 1: L1 FPGA-based GPS Receiver

Namuru version 2: L1/L2 GPS Receiver

(2) GNSS Receiver Design

The appointment of Assoc. Prof. Andrew Dempster in mid-2004 was crucial to SNAP's plans to ramp up research into GNSS receiver design. The purchase in 2005 of a pair of SPIRENT 6560 RF signal simulators (right), funded by an ARC-LIEF grant, was also a significant milestone. This equipment allows laboratory testing of new signal tracking and navigation solution algorithms, under different scenarios. Simulation of the operation of current and future GPS satellites, and of new GNSSs, is vital for testing new receiver designs. This L1-only simulator can be programmed to generate GPS satellite signals with user-selectable physical variations in the signal path, including the presence of RF jamming sources, high atmospheric disturbances, diffraction effects and multipath. As many of the signal variations are rare and/or unpredictable, the Signal Simulator is the only means to carry out such tests. Current and future constellations of GPS and SBAS satellites can be simulated.

Much of the GNSS receiver design research is being conducted either by Matlab-based SW receivers, or increasingly with the Namuru version 2 board (see above). Collaboration is underway with the SigNav Pty Ltd company (Canberra) - Australia's only GPS receiver design company.

Several graduate students were (and are) engaged on various aspects of GNSS receiver design: Bilal Amin, Faisal Khan, Jinghui Wu, Sana Qaisar, Nagaraj Shivaramaiah and Omer Mubarak.

Spirent 6560 signal simulator

Namuru version 1 setup to track the GPS L2C signal

(3) GPS Interference Detection

Research is being conducted into the detection of RF interference of GPS (& GNSS) receivers. Former graduate student Asghar Tabatabaei was engaged on this topic, funded under Project 1.1 of the CRC for Spatial Information for the period 2005-2007. An FPGA-based RFI detection device was developed by research assistant Peter Mumford, using Asghar's algorithms. This work was also undertaken in collaboration with Ms Beatrice Motello, a PhD student in Electronic and Communication Engineering at the Politecnico di Torino, Italy (who worked in the SNAP Lab for 9 months from mid-2006). An ARC-Linkage project (2008-2010), "Locating Interference to GPS: Protecting the World's Aircraft landing Systems", with AirServices Australia as Industry Partner, will continue this research. Testing of a network of RFI detection device will be undertaken.

(4) Bistatic Radar Studies

The Bistatic Radar project is an example of the "inside-the-receiver" type research that has commenced. This ARC-funded project "Remote Sensing Based on Indirect GPS Signals" (2003-2006) sought to utilise signals from the GPS satellite system, reflected from stationary objects (walls and water surfaces), to detect deformation or changed surface characteristics using the 'bistatic radar principle'. Use of this principle over the oceans (e.g. where the receiver antenna points downwards from a LEO satellite) is also known as "GPS reflectometry" or "GPS scatterometry". This research was commenced in partnership with Prof. Kurt Kubik at the Univ. of Queensland. The first graduate student was Yonghong Li, followed by Eamonn Glennon, who developed algorithms for extracting weak signals (in this case reflected signals) in the presence of strong (direct) signals. It is proposed to advance this research using the Namuru platform in the coming years as part of ARC project (2008-2012) "Environmental Geodesy: Variations of Sea Level and Water Storage in the Australian Region".

The current activities and challenges in Theme 5 can be summarised as:

FPGA-based GNSS receiver board design: a NICTA funded pilot project (2004.5-2005.5) has resulted in the SNAP Lab designing and building its own FPGA-based GPS receiver known as the 'Namuru'. This is quite a significant achievement. Currently Namuru version 2 is available, and is generating a lot of interest from other research organisations. SNAP Lab researchers will use FPGAs also as a platform for new GNSS receiver design and for multi-sensor integration projects.

GPS interference studies is an important research area that takes advantage of the Namuru FPGA-based GPS receiver. In 2005 a project commenced to develop algorithms for the detection of RFI, as part of a CRC for Spatial Information funded project. Former graduate student Asghar Tabatabaei and student Faisal Khan were engaged on this activity. Asghar is now a Research Associate on this RFI detection project.

GNSS receiver signal processing algorithm studies for acquisition and tracking of the modernised GPS and Galileo signals, as well as other signals from Russia’s Glonass (including the new CDMA signals), Europe’s Galileo and China’s Compass system, and Regional Navigation Satellite Systems (RNSS) under development by Japan and India. In addition, weak signal and multipath mitigation algorithms are also being investigated. This is a "hot" topic attracting much attention, as the Namuru platform is ideal for such research.

A Short History ...

The following is a sample of SNAP "GNSS Receiver Design & Signal Processing" project work carried out by SNAP researchers:

Customising GPS Receivers Using SDKs: Joel Barnes and Chris Rizos, supported by research assistant Peter Mumford, have been primarily responsible for supervising undergraduate EE and TE projects that use the Mitel or SigNav Software Development Kits (SDKs) to customise L1-tracking GPS receivers for such applications as the UNSW Bluesat microsatellite project; to track pseudolite signals; to develop an Assisted-GPS receiver; for "indirect" GPS signal studies; high-sensitivity carrier phase tracking receiver, to name a few. Graduate students Eamonn Glennon and Kevin Parkinson, and former graduate students Ravi Babu, and Asghar Tabatabaei, have also used SDKs in their research projects.

HARPER, N., NICHOLSON, P., MUMFORD, P., & POON, E., 2004. Process for improving GPS acquisition assistance data and server-side location determination for cellular networks. Journal of GPS, 3(1-2), 132-142. (Download PDF)
KOORVARJEE, N., ZHENXIANG, P., HUANG, T.S., & DEMPSTER, A.G., 2006. A-GPS for firefighting. Symp. on GPS/GNSS (IGNSS2006), Surfers Paradise, Australia, 17-21 July, CD-ROM procs. (Download PDF)
SABELLA, D.A., 2003. GPS usage aboard the BlueSat microsatellite mission. 10th Australian Int. Aerospace Conf., Brisbane, Australia, 29 July Ð 1 August, CD-ROM proc., paper 93. (Download PDF)
WALTERS, L., 200. Development of a GRAS Network Receiver, EE/TE final year thesis project.
FPGA GNSS Receiver Design: Graduate student Kevin Parkinson has been responsible for the overall board design of the Namuru GNSS receiver, assisted by Peter Mumford. Papers include:

ENGEL, F., HEISER, G., MUMFORD, P., PARKINSON, K., & RIZOS, C., 2004. An open GNSS receiver platform architecture. Int. Symp. on GNSS/GPS, Sydney Australia, 6-8 December. (Download PDF)
MUMFORD, P.J., PARKINSON, K., & DEMPSTER, A.G., 2006. Open GNSS receiver platform. IEEE/ION PLANS, San Diego, California, 25-27 April, 1108-1113. (Download PDF)
MUMFORD, P.J., PARKINSON, K., & DEMPSTER, A.G., 2006. The Namuru Open GNSS Research Receiver. 19th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Fort Worth, Texas, 26-29 September, 2847-2855. (Download PDF)
PARKINSON, K., DEMPSTER, A.G., MUMFORD, P.J., & RIZOS, C., 2005. FPGA based GPS receiver design considerations. Int. Symp. on GPS/GNSS, Hong Kong, 8-10 December, paper 8C-05, CD-ROM procs. (Download PDF)
PARKINSON, K., MUMFORD, P.J., DEMPSTER, A.G., & RIZOS, C., 2006. Improving signal quality in FPGA based GPS receiver designs. Symp. on GPS/GNSS (IGNSS2006), Surfers Paradise, Australia, 17-21 July, CD-ROM procs. (Download PDF)
QZSS Time Synchronisation Design: the work of graduate student Fabrizio Tappero on the design of a satellite clock system based on low-cost onboard clocks synchronised to atmoic clocks on the ground for Japan's Quasi-Zenith Satellite System (QZSS). Papers include:

IWATA, T., TAPPERO, F., TAKASAKI, N., IWASAKI, A., IMAE, M., SUZUYAMA, T., MURAKAMI, H., KAWASKI, Y., & DEMPSTER, A.G., 2006. Simulation and ground experiments of remote synchronization system for on-board crystal oscillator of quasi-zenith satellite. Navigation, Journal of the U.S. ION, 53(4), 231-236. (Download PDF)
IWATA, T., IMAE, M., SUZUYAMA, T., HASHIBE, Y., FUKUSHIMA, S., IWASAKI, A., KOKUBU, K., TAPPERO, F., & DEMPSTER, A.G., 2007. Remote synchronisation of onboard crystal oscillator for QZSS using L1/L2/L5 for error adjustment. IEEE Int. Frequency Control Symp. TimeNav07 , Geneva, Switzerland, 29 May - 1 June, 1312-1317. (Download PDF)
IWATA, T., KAWASKI, Y., IMAE, M., SUZUYAMA, T., MATSUZAWA, T., FUKUSHIMA, S., HASHIBE, Y., TAKASAKI, N., KOKUBU, K., IWASAKI, A., TAPPERO, F., DEMPSTER, A.G., & TAKAHASI, Y., 2007. Remote synchronisation system for Quasi-Zenith satellites using multiple positioning signals for feedback control. Navigation, 54(2), 99-108. (Download PDF)
TAPPERO, F., DEMPSTER, A.G., & IWATA, T., 2006. Space-based positioning system with no on-board atomic clocks. Coordinates, 2(6), 26-28. (Download PDF)
TAPPERO, F., DEMPSTER, A.G., & IWATA, T., 2007. SBAS with ground based atomic reference station. Location, 2(1), 46-48. (Download PDF)
TAPPERO, F., DEMPSTER, A.G., & IWATA, T., 2007. Phase error reduction method for free-run QZSS clock. IEEE Int. Frequency Control Symp. TimeNav07 , Geneva, Switzerland, 29 May - 1 June, 529-534. (Download PDF)
TAPPERO, F., DEMPSTER, A.G., & IWATA, T., 2007. Positioning performance study of the RESSOX system with hardware-in-the-loop clock. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 30, CD-ROM procs. (Download PDF)
TAPPERO, F., DEMPSTER, A.G., IWATA, T., & TORTORA, P., 2007. Low earth orbit satellite positioning system with remotely controlled onboard clocks. 3rd Workshop for Space, Aeronautical & Navigational Electronics, Perth, Australia, 15-18 April, procs in IEICE Tech. Rept. 107(2), 145-150. (Download PDF)
TAPPERO, F., IWATA, T., IMAE, M., SUZUYAMA, T., IWASAKI, A., & DEMPSTER, A.G., 2006. Remote control system for the Quasi-Zenith Satellite crystal oscillator based on the two-way time transfer method. Symp. on GPS/GNSS (IGNSS2006), Surfers Paradise, Australia, 17-21 July, CD-ROM procs. (Download PDF)
TAPPERO, F., IWATA, T., DEMPSTER, A.G., IMAE, M., IKEGAMI, T., FUKUYAMA, K., IWASAKI, A., & HAGIMOTO, K., 2006. Proposal for a novel remote synchronization system for the on-board crystal oscillator of the Quasi-Zenith Satellite System. U.S Institute of Navigation's Journal of Navigation, 53(4), 219-229. (Download PDF)
GNSS Receiver Design: important (and growing) area of research into new signal acquisition/tracking algorithms. Past and current graduate students Eamonn Glennon, Bilal Amin, Jinghui Wu, Sana Qaisar and Nagaraj Shivaramaiah , have contributed, or are contributing, to a variety of research projects. Papers include:

AMIN, B., 2007. Jitter analysis of QPSK and BOC(n,n) GNSS signals. 20th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Fort Worth, Texas, 25-28 September, 1543-1548. (Download PDF)
AMIN, B., & DEMPSTER, A.G., 2006. Sampling and jitter considerations for GNSS software receivers. Symp. on GPS/GNSS (IGNSS2006), Surfers Paradise, Australia, 17-21 July, CD-ROM procs. (Download PDF)
DEMPSTER, A.G., 2004. New GNSS signals: Receiver design challenges. 2004 Int. Symp. on GNSS/GPS, Sydney, Australia, 6-8 December. (Download PDF)
DEMPSTER, A.G., 2006. Correlators for L2C: Some considerations. Inside GNSS, 1(7), 32-37. (Download PDF)
DEMPSTER, A.G., & HEWITSON, S., 2007. The “System of Systems” receiver: An Australian opportunity? IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 95, CD-ROM procs. (Download PDF)
FANTINO, M., DOVIS, F., PRESTI, L.L., & WANG, J., 2004. Acquisition performance analysis for BOC modulated signals. Int. Symp. on GNSS/GPS, Sydney Australia, 6-8 December. (Download PDF)
QAISAR, S.U., & DEMPSTER, A.G., 2007. Receiving the L2C signal with ‘Namuru' GPS L1 receiver. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 53, CD-ROM procs. (Download PDF)
WU, J., & DEMPSTER, A.G., 2007. Galileo GIOVE-A acquisition and tracking analysis with a new unambiguous discriminator. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 75, CD-ROM procs. (Download PDF)
GPS Signal Propagation Studies: includes weak signal studies; multipath; and propagation of GPS signals through foliage. This research was/is being conducted by former and past graduate students Azzam Barakat, Xiaodong Jia, Eamonn Glennon and Omer Mubarak. Papers include:

FANTINO, M., DOVIS, F., & WANG, J., 2004. Quality monitoring for multipath affected GPS signals. Int. Symp. on GNSS/GPS, Sydney Australia, 6-8 December. (Download PDF)
GLENNON, E.P., & DEMPSTER, A.G., 2004. A review of GPS cross correlation mitigation techniques. 2004 Int. Symp. on GNSS/GPS, Sydney, Australia, 6-8 December. (Download PDF)
GLENNON, E.P., & DEMPSTER, A.G., 2006. Cross correlation mitigation by adaptive orthogonalization using constraints - new results. 19th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Fort Worth, Texas, 26-29 September, 1811-1820. (Download PDF)
GLENNON, E.P., & DEMPSTER, A.G., 2007. Cross correlation mitigation techniques for software GPS C/A code receivers. IGNSS2007 Symposium on GPS/GNSS, Sydney, Australia, 4-6 December, paper 51, CD-ROM procs. (Download PDF)
GLENNON, E.P., BRYANT, R.C., & DEMPSTER, A.G., 2006. Delayed parallel interference cancellation for GPS C/A code receivers. 12th IAIN Congress & 2006 Int. Symp. on GPS/GNSS, Jeju, Korea, 18-20 October, 261-266. (Download PDF)
GLENNON, E.P., BRYANT, R.C., DEMPSTER, A.G., & MUMFORD, P., 2007. Post correlation CWI and cross correlation mitigation using delayed PIC. 20th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Fort Worth, Texas, 25-28 September, 236-245. (Download PDF)
JIA, X., BABU, R., BARNES, J., RIZOS, C., GLENNON, E., & BRYANT, R., 2004. Study on carrier phase tracking receiver for difficult GPS environments - issues on signal to noise ratio and signal acquisition. Int. Symp. on GNSS/GPS, Sydney Australia, 6-8 December. (Download PDF)
MUBARAK, O.M., & DEMPSTER, A.G., 2007. Carrier phase analysis to mitigate multipath effect. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 64, CD-ROM procs. (Download PDF)
QAISAR, S.U., & DEMPSTER, A.G., 2007. An analysis of L1-C/A cross correlation and acquisition effort in weak signal environments. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 107, CD-ROM procs. (Download PDF)
SRIVASTAV, M., LEE, J., BHOLA, N., & DEMPSTER, A.G., 2006. The effectiveness of GPS multipath mitigation techniques on BOC signals. Symp. on GPS/GNSS (IGNSS2006), Surfers Paradise, Australia, 17-21 July, CD-ROM procs. (Download PDF)
THEO, J., MAZAHERI, M., TABATABAEI, A., & DEMPSTER, A.G., 2007. The application of a multicorrelator receiver in bistatic radar. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 71, CD-ROM procs. (Download PDF)
GPS Signal Interference Studies: research was/is being conducted by former graduate students Asghar Tabatabaei and Faisal Khan. This is now continued with a new group of researchers. Papers include:

DEMPSTER, A.G., 2005. How vulnerable is GPS? Position, 20, 64-67. (Download PDF)
TABATABAEI, A., 2006. Statistical inference technique in pre-correlation interference detection in GPS receivers. 19th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Fort Worth, Texas, 26-29 September, 2232-2240. (Download PDF)
KHAN, F., 2007. GPS-based synchronisers in the presence of interference. Inside GNSS, Fall 2007 issue, 46-49. (Download PDF)
KHAN, F.A., 2007. Behavior of GPS timing receivers in the presence of interference. 20th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Fort Worth, Texas, 25-28 September, 1977-1982. (Download PDF)
KHAN, F.A., & DEMPSTER, A.G., 2007. Effects on CDMA network performance due to degradation of GPS based synchronization. Int. Symp. on Communications & Information Technologies (ISCIT), Sydney, Australia, 16-19 October, CD-ROM procs, paper T3B6. (Download PDF)
MUMFORD, P., TABATABAEI, A., & DEMPSTER, A.G., 2007. UNSW GNSS interference detection device. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 12, CD-ROM procs. (Download PDF)
TABATABAEI, A., & DEMPSTER, A.G., 2006. A novel approach in detection and characterization of CW interference of GPS signal using receiver estimation of CNo. IEEE/ION PLANS, San Diego, California, 25-27 April, 1120-1126. (Download PDF)
TABATABAEI, A., & MOTELLA, B., 2007. Satellite exclusion zone in the presence of CW interference - Experimental results. ENC-GNSS2007, Geneva, Switzerland, 29 May - 1 June 1179-1190. (Download PDF)
TABATABAEI, A., DEMPSTER, A.G., & BARNES, J., 2006. Application of post-correlation interference detection and characterization in reconfiguration of GPS receivers. 12th IAIN Congress & 2006 Int. Symp. on GPS/GNSS, Jeju, Korea, 18-20 October, 347-352. (Download PDF)
TABATABAEI, A., MOTELLA, B., & DEMPSTER, A.G., 2007. GPS interference detected in Sydney-Australia. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 74, CD-ROM procs. (Download PDF)
TABATABAEI, A., WU, J., & DEMPSTER, A.G., 2007. Comparison between GPS and Galileo satellite availability in the presence of CW interference. IGNSS2007 Symp. on GPS/GNSS, Sydney, Australia, 4-6 December, paper 73, CD-ROM procs. (Download PDF)
TABATABAEI, A., DEMPSTER, A.G., THAN, N.T., & BARNES, J., 2006. An application of post-correlation GPS receiver interference detection and characterization. Symp. on GPS/GNSS (IGNSS2006), Surfers Paradise, Australia, 17-21 July, CD-ROM procs. (Download PDF)
TABATABAEI, A., DEMPSTER, A.G., MOTELLA, B., & RIZOS. C., 2007. Mutual effects of satellite signal quality and satellite geometry on positioning quality. 20th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Fort Worth, Texas, 25-28 September, 1182-1190. (Download PDF)

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