한국정보통신학회:학술대회논문집 (Proceedings of the Korean Institute of Information and Commucation Sciences Conference)
- 한국해양정보통신학회 2007년도 추계종합학술대회
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- Pages.693-697
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- 2007
디지털 SSB 모뎀 개발에 관한 연구
A Study on the Development of SSB Modem
- Jin, Heung-Du (Mokpo Maritime University, Division of Maritime and Communication Engineering) ;
- Choi, Jo-Cheon (Mokpo Maritime University, Division of Maritime and Communication Engineering)
- 발행 : 2007.10.26
초록
SSB 무선모뎀은 데이터의 디지털 전압레벨을 가청주파수로 변환하는 변조와 역으로 가청주파수를 데이터의 디지털 전압레벨로 변환하는 복조과정을 거치는데 변
The SSB modem performs the modulation process which converts the digital voltage level to the audible frequency band signal and the demodulation process which converts reversely the audible frequency signal to the digital voltage level. The modulator and the demodulator are implemented with a single DSP chip. Because of the SSB specific character, the distortion occurs when the frequency is changed. This distortion has no effect on voice communication, but it has an significant effect on data communication. In other words, it is impossible to send data stream with adjacent 2 periods. Therefore, in case of using 2-tone FSK, it is needed to send at least 3 periods to transmit 1 bit. Therefore we implemented the modem using modified phase-delay shift keying to transmit 1 tone signal for high speed transmission. In the 1200[bps] mode, it generates 0,