• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.61-69
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• 2006

Position determination accuracy is strongly depending on how much precisely and frequently satellite receiver measures transmitted signals from terminals on target animals when Doppler effect is applied for position determination. ARGOS satellite system has shown relatively high position determination accuracy by operating multiple satellites, which enable operator to get more Doppler shift data from terminals. In case of animal tracking mission with single satellite, however, it is difficult for the satellite receiver to receive transmitted signals from terminals frequently during short period that satellite passes over ground terminals. This is one of the main sources to decrease position accuracy on target animals. In this paper, the Doppler rate estimation is implemented to increase the number of Doppler shift data received by single satellite. It is proved that the relatively high position determination accuracy with increased number of estimated data can be obtained. We also suggest that the Doppler rate estimation is applicable for position determination system with single satellite.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.103-104
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• 2014

Wide Area Differential GNSS(WA-DGNSS) was developed in order to improve the accuracy and integrity performance of GNSS. In Korea, WA-DGNSS development project, which aims to develop core algorithms and verify the performance using pseudolite-based demo system, is currently in progress. In this paper, overall structure of developed system and experimental methods which enables the post-processing test with commercial receiver will be described. In this system, pseudolite is used to broadcast augmenting signal and RF signal logger and broadcaster were used to test the performance. Performance test was conducted broadcasting the logged RF signal and pseudolite signal to commercial receiver and those results will be described.

• Journal of Advanced Navigation Technology
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• v.28 no.1
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• pp.1-14
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• 2024

Global navigation satellite system (GNSS) providing position, navigation and timing (PNT) services consist of satellite, ground, and user systems. Monitoring stations, a key element of the ground segment, play a crucial role in continuously collecting satellite navigation signals for service provision and fault detection. These stations detect anomalies such as threats to the signal-in-space (SIS) of satellites, receiver issues, and local threats. They deliver received data and detection results to the master station. This paper introduces the main monitoring algorithms and measurement pre-processing processes for quality assessment and fault detection of received satellite signals in current satellite navigation system monitoring stations. Furthermore, it proposes a strategy for the development of components, architecture, and algorithms for the new regional navigation satellite system (RNSS) monitoring stations.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.18-22
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• 2016

In this paper, we proposed a scheme for signal detection based on average of detected energy of frequencies for backscatter communications. We applied this scheme on the bistatic backscatter radio architecture for RF energy harvesting. Tags reflected entire RF signals on a same bandwidth when transmitted energy signals. Receivers can optimal switching antenna by this scheme. Simulation results show that the proposed scheme can precisely detect signals from tag with properly calculated parameters.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.80-84
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• 2014

As an integrated technology with IT and biomedical sciences, U-health offers various healthcare services without time and space limit. In order to make a proper diagnosis, doctors need two key technologies: biosignal measurement and high reliability communication technologies. In this paper, we introduce an implementation process of a bio signal system with using an electrocardiography(ECG) sensor, video, global positioning system(GPS), communication module and micro controller unit(MCU).

• Journal of Navigation and Port Research
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• v.38 no.4
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• pp.391-397
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• 2014

Wide Area Differential GNSS(WA-DGNSS) was developed in order to improve the accuracy and integrity performance of GNSS. In this paper, overall structure of Pseudolite-Based Augmentation System(PBAS) and experimental methods which enables the post-processing test with commercial receiver will be described. For generating augmenting message, GPS measurement collected from five NDGPS reference stations were processed by reference station S/W and master station S/W. The accuracy of augmenting message was tested by comparing SP3, IONEX data. In the test, RF signal of user was collected and correction data were generated. After that, RF signal was broadcasted with pseudolite signal. Test was conducted using three commercial receiver and the performance was compared with MSAS and standalone user. From the position output of each receiver, it was shown that improved position was obtained by applying augmenting message.

• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.58-65
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• 2009

The paper identifies noise characteristics of a nonliner image sensor model which reflects a saturation effect of each detector pixel and extends the result to estimate an image SNR (Signla-to-Noise Ratio) distribution over all the pixels in a detector. In particular, nonlinearity of a pixel is studied from two perspectives of including asymmetry of a noise PDF (Probability Distribution Function) and enhancing a pixel SNR value, in comparison to a linear model. It is noted that the proposed image SNR distribution function is useful to effectively select new optimal operation parameter values: an integration time and an pixel-summing number, even after a launch campaign, assuming sensor gain degradation in orbit or inevitable modification of some operation parameter values due to space contingency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6C
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• pp.502-511
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• 2012

As the importance of GNSS system increases, the necessity of independent system is increased also. When the independent GNSS system is required, GNSS signal design is necessary with requirement definition. This paper suggests the design method of GNSS signal using the analysis result of receiver performance. First, the candidates are defined based on the design elements. Then the receiver performance of the candidates is analyzed based on the performance evaluation parameters. The weights of performance evaluation parameter are defined in order to consider the receiver performance in a various aspects. Finally, the calculation of normalized performance evaluation parameters and weights are derived to obtain the compared value for signal selection. Spreading code, modulation method and carrier frequency are considered as design parameters. Also, correlation width, DLL PLL thermal noise jitter, frequency bandwidth and side lobe peak ratio are considered as performance evaluation parameters. And positioning performance, robustness to noise, bandwidth efficiency are considered as the performance aspects. This paper analyzes the performance of each candidate using software based simulator and suggest the method to compare objectively the performance of each candidates.

• 전기의세계
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• v.39 no.5
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• pp.10-18
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• 1990

위성통신의 이용과 기술발전 추세를 살펴보면, 1950/60년대에는 미국, 프랑스 소련 및 영국을 중심으로 국방 및 과학기술측면에서 위성을 보유운용 하였으나, 1970/80년대에는 브라질, 호주, 중국, 인도 및 인도네시아와 같이 국토면적이 넓거나 섬이 많은 국가에서 위성의 특징을 활용하였다. 그리고 1990년대 이후에는 새로운 정보통신 및 방송서비스 영역을 확장하기 위해 개발도상국에 이르기까지 위성의 이용은 상당히 증대될 것으로 기대된다. 또한 선진각국들은 최근 급속한 발전을 이룩한 디지틀 신호처리기술, 부품 및 소자기술 등을 이용하여 다기능 및 고효율성을 갖는 위성시스팀 개발을 진행해오고 있다.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.120-124
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• 2017

This paper describes the product of search and rescue system with dynamic model. This spread spectrum system based new standard of COSPAS-SARSAT is results of RF signal generation and transmission. we will test performance evaluation which implement signal process adapting Dynamic model and we will adapt the CAF model using TDOA and FDOA relationship.