论文部分内容阅读
本文介绍了一种用于一点多址TDMA系统中的高速OQPSK全数字突发 MO-DEM的实现。该 MODEM采取边调制载波恢复方案,能同时实现载波的快速恢复和极低的载波跳周率性能。为了实现这些性能,该MODEM采用 CCCS(ConcurrentCarrier and Cbck Synchronization)技术,使得载波和时钟恢复能同时进行,加快捕获和同步时间;同时,采用一种新的报头信息来加快同步速率和消除相位模糊;另外,其数字式载波滤波电路也具有一定的独特性,既能有效地滤除噪声又能抵消滤波电路所引入的时延。计算机模拟结果显示该MODEM在输入中频频差高达 17kHz时,在 Eb/N0=8dB时,其同步时间不到/60个符号,其误比特率接近理论值。这些性能使得该MODEM既有良好的性能又易于实现,很适于一点多址TDMA系统。
This paper presents an implementation of a high-speed OQPSK all-digital burst MO-DEM for a one-point multiple access TDMA system. The MODEM adopts a side-modulated carrier recovery scheme, which can simultaneously achieve carrier fast recovery and very low carrier hop rate performance. In order to achieve these performances, the MODEM uses the CCCS (ConcurrentCarrier and Cbck Synchronization) technology to enable carrier and clock recovery to be performed at the same time to speed up the capture and synchronization time; at the same time, a new header information is adopted to speed up the synchronization rate and eliminate the phase ambiguity; In addition, its digital carrier filter circuit also has a certain uniqueness, both to effectively filter out the noise but also to filter the delay introduced by the filter circuit. Computer simulation results show that the MODEM input IF frequency difference up to 17kHz, at Eb / N0 = 8dB, the synchronization time less than / 60 symbols, the bit error rate close to the theoretical value. These properties make the MODEM both good performance and easy to implement, it is suitable for TDMA TDMA system.