碩士 / 國立海洋大學 / 電機工程學系 / 91 / The underwater acoustic channel is characterized as a time-varying multipath environment, which in addition to possible Doppler effect make developing an underwater communication system a very challenging task. Digital communication technology was used popularly to deal with these problems in recent years. Underwater communication systems generally use phase-shifting-keying (PSK) modulation/demodution techniques.
In conventional receiver, carrier recovery is conducted by controlling the frequency and phase of the voltage controlled oscillator (VCO) in the phase-locked loop. The QPSK modulation techniques for all-digital underwater acoustic transceiver are investigated in this thesis. An all-digital PLL (ADPLL) for QPSK carrier recovery is employed to overcome the channel effect. The frequency offset estimator is also included in the ADPLL to enhance the performance. The TMS320 C6711 DSK module with the A/D converter circuit was used to build up a fundamental hardware architecture. The QPSK modulator/demodulator with ADPLL will be realized by software on DSP. And we use TI C6X assembly language and C language to complement the system programs on CCS. The experiment results from ideal channel and UW channel show that all-digital underwater transceiver is practicable.
| Identifer | oai:union.ndltd.org:TW/091NTOU0442031 |
| Date | January 2003 |
| Creators | 呂友翔 |
| Contributors | 呂福生 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 66 |
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