中圖分類號： TN927 文獻標識碼： A DOI：10.16157/j.issn.0258-7998.201221 中文引用格式： 羅強. 一種G比特可變編碼調(diào)制的解調(diào)方法設(shè)計與實現(xiàn)[J].電子技術(shù)應(yīng)用，2021，47(6)：126-130. 英文引用格式： Luo Qiang. Design and implementation of a demodulation method of G-bit variable coding modulation[J]. Application of Electronic Technique，2021，47(6)：126-130.
Design and implementation of a demodulation method of G-bit variable coding modulation
Luo Qiang
Southwest China Institute of Electronic Technology，Chengdu 610036，China
Abstract： With the development of satellite communication technology, the broadband spectrum is becoming less and less, so it is more and more important to improve the spectrum efficiency. The variable code modulation technology is a solution. According to the definition of modulation signal format in DVB-S2 standard, when the modulation mode is switched in QPSK, 8PSK, 16APSK and 32APSK, ?仔/2BPSK is still used for frame head and pilot. Based on this, a carrier synchronization and equalization processing based on pilot and frame header with variable coding rate is proposed. The results show that different modulation modes can be demodulated normally, while maintaining the same time. The test results show that the demodulation performance deviates from the theoretical value by less than 3 dB. Because only one carrier synchronization method and equalization method are used, which is simple and which saves the whole FPGA resource.
Key words : pilot；variable code modulation；FPGA implementation；high-speed data receiver
0 引言
伴隨衛(wèi)星通信技術(shù)應(yīng)用的發(fā)展，頻段資源越來越緊缺，提高頻帶利用率就越來越重要。提高衛(wèi)星過境期間總的傳輸數(shù)據(jù)量可以通過提高調(diào)制階數(shù)，從QPSK提高到8PSK，進而到16APSK和32APSK可以明顯提高數(shù)據(jù)量，調(diào)制階數(shù)越高對傳輸?shù)妮d噪比要求就越高，而衛(wèi)星過境期間的載噪比隨著衛(wèi)星仰角的不斷增加而不斷提高，過頂后仰角的不斷減小而減小。2005年，歐洲電信標準化協(xié)會(European Telecommunication Standards Institute，ETSI)頒布了新一代數(shù)字衛(wèi)星廣播標準DVB_S2[1](Digital Video Broadcasting-Second Generation Satellite，第二代數(shù)字衛(wèi)星廣播標準)。在此標準中增加了可變編碼調(diào)制(Variable Coding and Modulation，VCM)，此種傳輸方式可以根據(jù)衛(wèi)星仰角的不斷改變相應(yīng)地改變調(diào)制編碼方式，在低仰角時采用QPSK調(diào)制方式，隨著仰角的提高調(diào)制方式不斷改變?yōu)?PSK和16APSK，在接近過頂時載噪比較高，可以采用32APSK調(diào)制方式，這種VCM方式既保證在低仰角時能夠進行傳輸，又保證了高仰角時的數(shù)據(jù)傳輸速率。
