• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.573-575
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• 2015

Positioning system using satellite GPS is used at positioning, navigation, acquisition time information and other various field and taking an important part precision guided weapon such as missile. But commercial code(C/A code) do not have ECCM. Therefore commercial code is vulnerable to various jamming techniques and noise jamming from near station can attack even the encrypted military code(P code) GPS. In this paper, GPS jamming techniques, North Korean GPS jamming cases and anti-jamming GP S technologies are surveyed and described.

• Korean Journal of Geomatics
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• v.2 no.1
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• pp.65-73
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• 2002

GPS in the United States and GLONASS of the old Soviet Union are used currently as satellite navigation systems. Plans are being made to use the Galileo satellite system in Europe, and these plans focus on a combined application of the satellite navigation systems. In this study, we examined the possibility of effective application of a combination of GPS/GLONASS in urban areas, where 3-dimensional positioning is impossible with GPS alone. We analyzed the 3-D coordinate deviation of a GLONASS satellite by integration interval and compared it with GLONASS satellite coordinates in precise ephmerides by transforming it into WGS84. We also programmed GPS/GLONASS, analyzed 3-D positioning accuracy by static surveying and kinematic surveying with Ashtech Z18 receivers and Legacy receivers, and then compared the results to those of GPS surveying. As a result, we are able to decide the integration interval for producing GLONASS satellite coordinates in navigation and geographical information and construct a GPS/GLONASS data processing system by developing a DGPS/DGLONASS positioning program. If more than four GLONASS satellites are observed, the accuracy of GPS/GLONASS is better than that of GPS positioning. As a result of kinematic surveying in a congested urban area with skyscrapers, we discovered that the GPS/LONASS combination is very effective.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.161-169
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• 2008

This paper introduces test configuration and operation method for the GPS receiver system under electromagnetic test of KSLV-I upper-stage as a system qualification level and describes performance analysis of the test results. The GPS receiver system has clearly passed the electromagnetic test specifications of component level which is based on MIL-STD-461E through several design changes. Under electromagnetic test as a system qualification level, the GPS receiver system normally operates in spite of electromagnetic interferences with other systems. Performance of the GPS receiver system is also, not degraded on the condition of electromagnetic field incidence and electrostatic discharge. The KSLV-I GPS receiver system, as a result, is verified on the electromagnetic condition of the KSLV-I upper-stage.

• Journal of Navigation and Port Research
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• v.29 no.10 s.106
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• pp.877-882
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• 2005

It is necessary that Fail-Safe Seaway technology providing a continuous navigation solution though fault of navigation system is occurred in sea. This paper focus on signal processing of GPS receiver, one of receivers using the software radio technology to implement a integrated radio navigation system including satellite-based and ground-based navigation systems. It is difficult to implement the software GPS receivers using a commercial processor because of the heavy computational burden for processing the GPS signals in real time. This paper proposes an efficient multi-bit GPS signal processing scheme to reduce the computational burden for processing the GPS signals in the software GPS receiver. The proposed scheme uses a compression concept of the multi-bit replica signals and patterned look-up table method to generate the correlation value between the GPS signals and the replica signals.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.7
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• pp.737-745
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• 2010

This paper describes the operation results of the GPS receiver system for KSLV (Korea Space Launch Vehicle)-I on the launch site at Naro Space Center that is the first spaceport of South Korea located at Goheung. All equipments of KSLV-I including the GPS receiver system should be monitored and controlled through hard-wired interface during KSLV-I is on standby at the launch pad. The GPS receiver for KSLV-I is connected to triple almost omni-directional patch antennas mounted on the cylindrical surface of KSLV-I that should be erected vertically on the launch pad until lift-off. Signal interference and multipath effects observed in the GPS receiver on the launch site are analyzed in this paper based on the GPS signals received from each GPS antenna.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.2 s.20
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• pp.107-114
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• 2002

This study aimed to estimate accuracy of GPS/Leveling and to present availability of GPS/Leveling in public surveying. For this purpose, we carried out GPS survey for bench marks and control points of Hongsung area. Orthometric heights calculated by two GPS/Leveling methods were compared to reference height. The one is calculated by base of geoid models such as EGM96, OSU91A, KGEOID99, and the other is calculated by network adjustment using fixed point. The results of GPS/Leveling by geoid models show that RMSE of EGM96 is ${\pm}0.061m,\;OSU91A\;{\pm}0.725m,\;KGEOID99\;{\pm}0.598m$. The results of GPS/Leveling by network adjustment show that the best RMSE is ${\pm}0.043m$ in case of using three fixed bench mark, and this method can be used for leveling effectively. GPS/Leveling would be able to apply in forth order public leveling and height determination of public control points.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.4
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• pp.65-70
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• 2011

National Geographic Information Institute provides VRS service using permanent GPS networks. VRS-RTK(Virtual Reference System-Real Time Kinematic)GPS surveying which enable to accomplish the real time-based GPS surveying has been increasingly popular. However the positioning accuracy tends to deteriorate as the distance between the rover and base station increases in the VRS-RTK GPS surveying. To analysis this problem in this study, the accuracy of VRS-RTK data was analyzed with 2 different test sites of Geoje city, Gyeongnam province within and without the permanent GPS networks in order to accomplish the cadastral supplementary control surveying. As a result of surveying accuracy analysis at two test sites, positioning errors were ${\pm}0.03m$(RMSE) in both sites. The result was that within the tolerance specified in cadastral surveying law, and indicated the possibility of VRS-RTK GPS surveying in cadastral surveying.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.133-140
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• 2015

In this paper, a roll angle estimation method of a rolling airframe using a low grade GPS and a roll rate gyro is proposed. The strength of the received signal of the GPS antenna attached on the rolling airframe is maximized when the GPS satellite is placed on the plane determined by the x-axis of the rolling airframe and the GPS antenna axis. Under the assumption that the x-axis of the rolling airframe is coincident with its velocity vector, the roll angle of the rolling airframe is calculated from the relative position vector of the satellite to the GPS when the GPS signal strength becomes maximum. The Kalman filter combined with a roll rate gyro is introduced to increase the determination accuracy of the roll angle. The performance of the proposed method is verified via 6-DOF simulations.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.5
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• pp.565-574
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• 2009

The water vapor weighted vertically mean temperature(Tm) models, which were developed by the consideration of seasonal characteristics over the Korea, was used in the retrieval of precipitable water vapor (PWV) from GPS data which were observed at four GPS permanent stations. Since the weighted mean temperature relates to the water vapor pressure and temperature profile at a site, the accuracy of water vapor information which were estimated from GPS tropospheric wet delay is proportional to the accuracy of the weighted mean temperature. The adaption of Korean seasonal weighted mean temperature model, as an alternative to other formulae which are suggested from other nation, provides an improvement in the accuracy of the GPS PWV estimation. Therefore, it can be concluded that the seasonally appropriate weighted mean temperature model, which is used to convert actual zenith wet delay (ZWD) to the PWV, can be more reduced the relative biases of PWV estimated from GPS signal delays in the troposphere than other annual model, so that it would be useful for GPS PWV estimation with high accuracy.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.138-146
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• 2011

With the increased use of GPS in the field of various applications including surveying, the request for fast and precise positional information has increased. Several countries such as USA, Canada, and Australia have already been operating Internet-based automatic GPS data analysis system using e-mail and FTP. Expanding GPS market, it is necessary to establish automatic GPS baseline processing system that is accessible via Internet. The system developed in this study is operating on the web, and it allows the users to access easily regardless of time and place. The main processing engines are Bernese V5.0 and PAGES. They process user data with three GPS CORS(Continuously Operating Reference Station), and then send the report to the users through e-mail. This system allows users to process high accurate GPS data easily. It is expected that this system will be used for various GPS applications such as monitoring large-scale structures and providing spatial information services in private sector.