• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.2
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• pp.222-231
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• 2011

In this paper, we have proposed a method which can make it possible to stably transmit and receive data like the ARC-164 radio frequency hopping environment as a S/W packet modem with PSK modulation. This is a method that the S/W packet modem with PSK digital modulation and the use of PC sound cards change over from data to voice signals and then transmit/receive data. We confirmed not only that it is possible to solve the slow speed communication with the use of sending data through multi-channels and PSK modulation that has the ability to methodically improve transmission rates, but also that it is possible to send the state of frequency hopping stably. In conclusion, we've confirmed both tactical values that though the transmission rate may be a tad slow, a state of frequency hopping of more than 94% confidence plus voice and data can be sent via radio at the same time. In this paper, the proposed S/W packet modem is only an implemented S/W component, so when we apply it to aircraft that we don't consider EMC problems with, then we have the advantage of a wider use of conventional UHF/VHF/HF radio that is possible to voice communication. If we recognize these operational requirements, we can apply for a lot of field equipment efficiently.

• Journal of Advanced Navigation Technology
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• v.6 no.4
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• pp.318-325
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• 2002

In this paper, the effects of the interference environments on the performance of the time hopping(TH) binary PPM impulse radio(IR) system are presented. Based on the monocycle pulse available within the frequency of 3.1~10.6 GHz permitted for application by FCC, a PPM-modulated TH IR system simulator was designed and followed by the analysis of the monocycle pulse characteristics as well as the system performance. Particularly for the evaluation of the system performance, the multiple access interference and the narrowband system interference signals were considered as the interference signals. Since the narrowband system interference signal has very narrow bandwidth and very large amplitude compared with those of IR system, the analysis of the IR system performance was implemented by considering the interference power and band fraction ratio of the narrowband interference signal.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.988-995
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• 2019

In this paper, we propose the Tile Based Frequency Hopping - Chirp Spread Spectrum(TBFH-CSS) technique, which has excellent Low Probability of Intercept(LPI)/Anti-Jamming(AJ) performance. Conventional Frequency Hopping - Chirp Spread Spectrum(FH-CSS) technique uses only single chirp signal, that makes the follower jammer easy to find and jam. However, proposed TBFH-CSS uses various kind of chirp signals which are generated according to the structure of basis tile, it is composed the basis time unit and the basis bandwidth unit. The TBFH-CSS signal has variety signal period and signal bandwidth. Therefore, the follower jammer hard to find and difficult to jam the TBFH-CSS signal. We analysis the LPI/AJ performance of the TBFH-CSS technique when the follow jamming attack exist and compared with the performance of the conventional FH-CSS technique. From the analysis, we can see the proposed TBFH-CSS technique has better LPI/AJ performance than conventional technique.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.141-150
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• 2002

In this paper, we composed orthogonal multi carrier FH/CDMA system using frequency hopping sequence. Considering hit possibilities by delayed other user's signals we searched the optimal number of user access carrier slots not to influence on performance deterioration with the variation of number of carrier slots according to the number of user access carrier slots. A]io, we evaluated the BER performance improvement due to TCM and Concatenated coding technique by computer simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.802-809
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• 2001

A linear power amplifier for the VHF frequency-hopping(FH) transmitter using an adaptive predistortion linearizer is designed. An analog polynomial linearizer as predistorter is employed. The recursive least square(RLS) algorithm is employed in the optimization process to minimize the errors between the predistorter and postdistorter output signals. Experimental results show that the adjacent channel power of the designed power amplifier is reduced by of 10 dB.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.520-523
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• 2001

In this paper, a system that transmits ECG signals which get from hand baggage ECG is implemented by using Bluetooth technology. Bluetooth technology is a close range wireless communication used wireless frequency 2.4GHZ bandwidth. This technology consumes very small power and provides high reliability also self error correction with high speed frequency hopping. Because every device which uses Bluetooth protocol can communicate each other. These can connect between the system implemented and any devices such as mobile telephone with Bluetooth module, notebook, and the personal mobile device. Also, the paper proposes capability of transmission to the sever of hospital through each type of wireless communication device that acquired medical information signals in mobile medical machine. The system consists of hardware parts with Bluetooth module and host part, and software parts with bluetooth protocol stacks. The host precesses a connection with other device and transmits ECG signals with bluetooth frequency hopping sequence.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.297-301
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• 2001

In this paper, a system that transmits ECG signals which get from hand baggage ECG is implemented by using Bluetooth technology. Bluetooth technology is a close range wireless communication used wireless frequency 2.4GHz bandwidth. This technology consumes very small power and provides high reliability also self error correction with high speed frequency hopping. Because every device which uses Bluetooth protocol can communicate each other. These can connect between the system implemented and any devices such as mobile telephone with Bluetooth module, notebook, and the personal mobile device. Also, the paper proposes capability of transmission to the sever of hospital through each type of wireless communication device that acquired medical information signals in mobile medical machine. The system consists of hardware parts with Bluetooth module and host part, and software parts with blutooth protocol stacks. The host precesses a connection with other device and transmits ECG signals with bluetooth frequency hopping sequence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2188-2195
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• 2015

In tactical wireless local area networks, jamming attack can easily occur by sending out continuous radio signals. The damage will be serious when the channel frequency is identical. Since wireless channel environment is open to everyone, the perfect solution for jamming attack does not exist. However, a channel-hopping scheme is well known for mitigating those jamming attacks. In this paper, I consider various channel-hopping schemes in order to analyze the throughput and fairness performance under smart jammer attack. Also an analytical model is introduced to evaluate the throughput performances of channel-hopping schemes. After analyzing well known channel-hopping schemes, I propose a simple channel-hopping scheme that can enhance fairness significantly at minimal throughput degradation expense.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11A
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• pp.924-932
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• 2011

In this paper, we propose a possibility of usage of carrier superpositioning scheme for a specific slow frequency hopping(SFH) transmission method for the satellite data link in which all of hopping carriers have to be synchronized to DSM transponder of our previous work and usage of frequency diversity in the saved frequency to overcome the SFH disadvantage against jammer. We have analyzed anti-jamming performance and LPI performance and confirmed that the proposed scheme can support data service with 18.5dB processing gain against the worst case partial band jamming and give 2.5dB gain in the LPI performance against D&M detector which can estimate the data rate of unknown signals.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.8 s.338
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• pp.25-32
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• 2005

Frequency hopping system has been adopted to many communication systems in order to overcome the inferior situation such as jamming environment. But typically its processing gain being limited, data interfered by jamming signal could not be fully recovered. This can be enhanced by combing FH system with spatial interference canceller which is a kind of active beamformer In this Paper, we proposed the compensation method of weight vector discrepancy according to the hopped frequencies and the PMBF method which is able to eliminate the inference effectively with less computational complexity. That is, the steering vector of wanted signals can be calculated from the frame without jamming signals using eigen analysis. New projection matrix extracted by the steering vector of wanted signal eliminates the interferences from the covariance matrix of received signal including wanted signal and jamming signals. This PMBF has similar performance of SINR beamformer with less computational complexity.