• Journal of Aerospace System Engineering
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• v.2 no.3
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• pp.33-39
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• 2008

VDL Mode 2 is one of air-to-ground VHF digital data link technologies. The VDL Mode 2 system is designed to be an air-to-ground subnetwork of the Aeronautical Telecommunication Network (ATN) using the AM(R)S band and it is organized according to the Open System Interconnection (OSI) model (defined by ISO). It can be used in ATS Applications especially for ATC communication such as CPDLC and ADS as well. And It is expected VDL Mode 2 replaces ACARS(Aircraft Communications Addressing and Reporting System) which has broadly been used for over 20 years. This paper presents the result of design of operational test equipments for the validation of VDL Mode 2 system under development in KARI.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.30-39
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• 2008

This paper presents the result of VDL Mode 2 system design and implementation with AOA (ACARS Over AVLC) protocol based on international VDL Mode 2 specifications for the bit-oriented ATS applications. The designed VDL Mode 2 system is composed of airborne and ground subsystem. Airborne subsystem consists of VDR, CMU and Ground system consists of Ground Station and DSP. For the test of whole system, simplified CPDLC, ADS and AFN applications are implemented in test equipments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.10
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• pp.28-33
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• 2009

In this paper, we propose the receiver algorithms suitable for the VHF (Very High Frequency) digital link mode-2(VDL Mode-2) system. Unlike conventional digital communication systems using the root raised cosine filter as a transmit and receive filter, raised cosine filter is used as a transmit filter in the VDL Mode-2 system. Hence, it is crucial to design and implement the optimum lowpass receive filter by considering inter-symbol interference and noise performance. On the other hand, due to the short preamble pattern, it is crucial to develop an efficient packet detection algorithm for reliable communication link for the VDL Mode-2 system. Also, frequency offset due to the carrier frequency difference between transmitter and receiver and doppler frequency shift must be estimated and compensated for reliable communication. In this paper, the optimum receive filter, packet detection and frequency offset compensation algorithms are proposed and the performance of the VDL system employing the proposed algorithms are evaluated.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.173-175
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• 2013

최근 AIS 기술을 적용한 MOB(Man Overboard) 장치가 개발되고 있으나 이에 대한 국제적인 기술표준 뿐만 아니라 우리나라의 기술기준도 아직까지 마련되어 있지 않다. MOB가 사용하는 주파수가 AIS 주파수와 동일하기 때문에 AIS VDL(VHF Data Link)에 미치는 영향이 파악되지 않았기 때문이다. 본 연구에서는 AIS 기술을 적용한 MOB가 AIS VDL에 미치는 영향을 분석하고 기술기준을 마련하는데 있어서 고려해야 할 사항을 제시하였다.

• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.41-53
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• 2009

This study describes to design the interface between VDL (VHF Digital Link) Mode 2 system and AOA (ACARS Over AVLC) network. KARI-Wrapper using aircraft and ground station design requirements should be designed to the system configuration of the in-out interface of the components and analyzed with the ARINC 618, 620, 622 documentations. According to the system interface test, we are verified the satisfactions of uplink and downlink VDL Mode 2 requirements.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.11-20
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• 2008

The current air-to-ground communication between aircraft pilots and ground controllers is done by voice communication and text-based data communication. International Civil Aviation Organization (ICAO) suggested the digital data communication techniques to improve accuracy and effectiveness of the current air-to-ground communication. As one of them, VDL M2, a VHF band digital data communication link, is expected to substitute the voice communication and text-based ACARS data communication. In this paper, the software design and implementation of the VDL M2 system developed by Korea Aerospace Research Institute.

• Journal of Aerospace System Engineering
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• v.1 no.4
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• pp.13-21
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• 2007

As one of YHF digital data link technologies, VDL Mode 2 is designed to be an air-to-ground subnetwork of the Aeronautical Telecommunication Network (ATN) based on the Open System Interconnection (OSI) architecture. VDL Mode 2 can be used in ATS Applications especially for CPDLC and ADS. And it is also expected to replace ACARS (Aircraft Communications Addressing and Reporting System) which has broadly been used in AOC for over 20 years. This paper presents the design result of VDL Mode 2 system under AOA (ACARS Over AVLC) environment for the implementation of bit-oriented ATS applications. The system is composed of airborne and ground subsystem. Airborne subsystem consists of VDR, CMU and an aircraft test equipment with CPDLC/ADS client applications for operational test and ground system consists of Ground Station which includes ground VDR and ground communication controller, simple DSP (Datalink Service Processor) and a ground test equipment with CPDLC/ADS server applications.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.9-16
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• 2007

In this paper, the Bit Error Ratio (BER) performances of the D8PSK modulation schemes for VDL Mode-2 are analyzed according to the matched and unmatched cases of the channel filters. The carrier frequency and phase offset effects are analyzed with unmatched case. Generally in digital transmission techniques, the Root Raised Cosine filters which are used as channel filters are applied to both sides at transmitter and receiver in order to achieve no ISI, but in VDL Mode-2, the Raised Cosine Filter is used only in transmission section and the receiver section uses general low pass filter, therefore we could not achieve ISI reduction effects but can have better spectrum quality. From the simulation results, the error probability is increased slightly (1~2dB) with use of un-matched channel filter, we got the conclusions that carrier phase offset do not effect to bit error ratio, but the frequency offset effect is so serious. Finally, narrow band D8PSK modulation signals are generated by the use of Digital Up-Converter and then its features are compared with analog modulator.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.337-343
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• 2009

In this paper, we proposed a burst mode symbol timing recovery unit that is applicable to the VDL Mode-2 using D8PSK modulation. A method that IIR loop filter is used to minimize symbol timing error is hard to apply to burst mode because its convergence time is long. That is, the fast convergence property is important. In this paper, the proposed method takes one sample which has maximum symbol power after the initial synchronization has been achieved by using preambles. The main principle of operation is that the unit moves one sample clock to advance or retard according to symbol power. We verify that the proposed method is operated well in ${\pm}100$ ppm or greater through the test results between Australia ADS Corp. transmitter and the designed receiver.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.6-8
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• 2009

In this paper. we propose receiver algorithms for VHF(Very High Frequency) digital link mode-2(VDL Mode-2) systems. Unlike conventional digital communication systems using the root raised cosine filter as a transmit and receive filter, raised cosine filter is used as a transmit filter in VDL Mode-2 systems. Hence, it is crucial to design and implement the optimum lowpass receive filter by considering the amount of inter-symbol interference and noise performance. On the other hand, due to the short preamble pattern, it is crucial to develop an efficient packet detection algorithm for reliable communication link. In this paper, we design the optimum receive filter and packet detection algorithm and evaluate the performance of receiver adopting the proposed receive filter and packet detection algorithm.