现代电子技术
現代電子技術
현대전자기술
MODERN ELECTRONICS TECHNIQUE
2014年
16期
21-23
,共3页
正交幅度调制%扫频%极性判决%载波恢复
正交幅度調製%掃頻%極性判決%載波恢複
정교폭도조제%소빈%겁성판결%재파회복
quadrature amplitude modulation%frequency sweep%polarity decision%carrier recovery
针对高阶QAM调制解调系统对载波偏移的敏感性问题,采用一种基于导频、扫频环路和载波恢复环路的高阶QAM载波恢复方法。这里设计的扫频环路是由帧检测、扫频、频率校正三个模块组成,载波恢复环路由极性判决算法模块和判决导向模块组成。扫频和极性判决算法都具有较大的频偏捕获能力。两者联合用于载波频偏的捕获阶段,既克服了一般扫频算法残留频偏大的困难,也解决了极性算法可用角点少的问题。
針對高階QAM調製解調繫統對載波偏移的敏感性問題,採用一種基于導頻、掃頻環路和載波恢複環路的高階QAM載波恢複方法。這裏設計的掃頻環路是由幀檢測、掃頻、頻率校正三箇模塊組成,載波恢複環路由極性判決算法模塊和判決導嚮模塊組成。掃頻和極性判決算法都具有較大的頻偏捕穫能力。兩者聯閤用于載波頻偏的捕穫階段,既剋服瞭一般掃頻算法殘留頻偏大的睏難,也解決瞭極性算法可用角點少的問題。
침대고계QAM조제해조계통대재파편이적민감성문제,채용일충기우도빈、소빈배로화재파회복배로적고계QAM재파회복방법。저리설계적소빈배로시유정검측、소빈、빈솔교정삼개모괴조성,재파회복배로유겁성판결산법모괴화판결도향모괴조성。소빈화겁성판결산법도구유교대적빈편포획능력。량자연합용우재파빈편적포획계단,기극복료일반소빈산법잔류빈편대적곤난,야해결료겁성산법가용각점소적문제。
In order to solve the sensitivity problem of high-order quadrature amplitude modulation(QAM)modulation and demodulation system for carrier offset,a new high-order QAM carrier recovery method based on pilot frequency,frequency sweep loop and carrier recovery loop is proposed. The frequency sweep loop is comprised of three modules of frame detection, frequency sweep and frequency correction. The carrier recovery loop contains the polarity decision algorithm module and decision-directed(DD)module. The frequency sweep and polarity decision algorithm both have large frequency offset acquisition ability. If They are applied jointly to the stage of frequency offset acquisition,the difficulty of larger residual frequency offset caused by general sweep algorithm can be overcome and the problem of polarity algorithm with little available corner can be solved.