• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.11
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• pp.945-951
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• 2021

The SOQPSK-TG is a modulated signal for aeronautical telemetry with a very good bandwidth efficiency. In this paper, the frequency waveform filter of the SOQPSK-TG is linearly approximated and modeled with a duobinary precoder and a modified frequency waveform filter having a phase transition period of about 1T_b. In combination with the existing precoder, the SOQPSK-TG is modeled by a double duobinary MSK. Comparing the SOQPSK-TG signal and the newly modeled double duobinary MSK signal in time domain and frequency domain, it is confirmed that the two signals are almost identical and there is virtually no performance difference. Moreover, we can attain 0.1 dB BER performance improvement compared to the existing cosine filter when the filter of the IQ-detector is implemented with a cosine sum filter taking into account the change in the modulation index by the new double doubinary precoder.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.6 s.360
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• pp.64-70
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• 2007

This paper presents a novel unified DC offset cancellation and I/Q regeneration for five-port junction based direct receivers. It utilizes the symmetry characteristics of the single-frequency continuous-wave (CW) signal, making it possible that the proposed method can be used regardless of carrier phase offset. The proposed method eliminates the additional DC offset cancellation and reduces the I/Q regeneration parameter estimation time. Since the proposed method employs a single-frequency CW signal independent of the modulation scheme, five-port junction based direct receivers can be used for the demodulation of orthogonal frequency-division multiplexing and continuous phase modulation as well as phase shift-keying.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.125-133
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• 2016

As one of solutions to pursue the efficient use of spectrum resource, we proposed the methodology for the co-channel multi-site radar operations with the synchronous GPS clock. The proposed algorithm, based on a quasi orthogonal property, find a candidate set of the time shifted linear frequency modulation(TSLFM) signals with the minimum acceptable level of the correlation among selected TSLFM signals. To check suggested algorithm, numerical analysis for several radars operating in the same channel with a sawtooth waveform has been performed by using range-Doppler processing for the given system parameters, and computational results are presented and examined in terms of range profile and doppler shift for a targets with velocity and distance. Simulated results have a good agreement with assumed target distance and its velocity, within the error of resolution.