DCSK的反相叠加相关解调方案

基于DCSK的类重传特点提出了反相叠加相关解调方案。第一种方案将同一码元前后半段的信号反相叠加后与前半个码元信号进行相关运算，其结果作为判决量;第二种方案将第一种解调方案的判决量与前后半个码元信号直接相关运算的结果进行反相叠加后再作为判决量。只要同一码元的前后半段内的噪声具有正相关性，与将前后半个码元信号直接相关运算的结果作为判决量的现有解调方案相比，所提方案均可有效抑制噪声的影响。而第二种方案在噪声相关系数小于0.5的条件下进一步提高了系统的噪声容限。

Reversed-phase overlay demodulation scheme of DCSK

In order to reduce the side effects of noise correlation on DCSK system,the reversed-phase overlay demodulation scheme is put forward in this paper based on the retransmission characteristic of DCSK.In the first scheme,the first and the second half-symbol signals within a code period are reversed-phase overlapped firstly.Then the variable for judgments is got- ten from the related operations results of the overlaid signal with the first half-symbol signal.In the second scheme,the judgment variable is gotten by subtracting the related operation results of the first and the second half-symbol signals from the judgment variable of the first scheme.As long as the noises within the first and the second half-symbol have the positive correlation characteristic, the proposed schemes can effectively suppress noise impact than the existing scheme whose judgments variable is directly calculated by the correlation of the first and the second half-symbol of received signals.Besides, the noise tolerance is further improved in the second scheme when the noise correlation coefficient is less than 0.5.