spectrum limitation

In order to obtain lower SNR estimation, spectrum accumulation average technique ( AAT) and cross-correlation accumulation technique ( CCAT) are added to the output of CDM processing, several improved methods are proposed, and obtain lower SNR limitation effectively.

为获得更低的信噪比容限，提出了在平方倍频处理后端加入频谱集平均技术和互相关积累技术的若干改进方法，成功实现更低信噪比下的估计。

In MSK modulation, due to the discontinuous slope during the switch time of the phasic path, the dropping velocity of the modulation spectrum is affected, and IJF-OQPSK is introduced to solve the limitation, smooth the phasic path and improve the spectrum.

MSK调制技术中，由于其相位路径在转换时刻的斜率不连续，影响了已调信号频谱的衰减速度，针对这一缺陷引入IJF-OQPSK，使得相位路径平滑，频谱特性有所提高。

Results show the imaging quality is near the diffraction-limitation in visible spectrum and arrived in infrared spectrum. So the off-axis three-mirror reflective is able to work in the multi-band from the visible spectral region to infrared range.

从评价结果来看，在可见光波段，像质接近衍射极限，在红外波段成像质量基本达到了衍射极限，充分说明了离轴三反射光学系统具备从可见光到红外多波段工作的能力。