Demodulation of complex baseband radar signals for the analysis of multiple narrow spectral lines
Demodulation of complex baseband radar signals for the analysis of multiple narrow spectral lines
复制标题
复杂基带雷达信号的解调，用于分析多个窄谱线
DOI：
10.1029/96rs03580
复制
发表时间：
1997
期刊：
影响因子：
1.6
通讯作者：
R. Woodman
中科院分区：
文献类型：
--
作者：
E. Ragaini;R. Woodman
本文提出了一种处理信号的技术，其中相关的频谱特征由一条或多条相对于参考频率具有非零多普勒频移的窄线组成。所提出的技术包括将第二次解调过程应用于作为接收机输出的解调信号。这种解调的目的是去除观测到的光谱线和观测到的光谱带中心之间的频移。这样，选定的光谱线被带到基带，允许研究其包络作为一个缓慢变化的过程。执行第二解调步骤的一种有效方法是通过正交解调器的数字版本。这个想法被转化为一个有效的算法，使用真正的乘法和累加器。该算法的优点是，为了观察相对于中心频率对称位置的两条谱线，可以使用普通乘法和累加器。讨论了一种可能的简化算法，其中用于解调的正弦波被方波取代，以便乘法减少为同步符号反转。文中还提到了这种简化算法可能造成的失真。最后讨论了在数字信号处理系统中实现双解调的可能性。
This paper proposes a technique for processing signals in which the relevant spectral feature consists of one or more narrow lines which have a nonzero Doppler shift with respect to the reference frequency. The proposed technique consists of applying a second demodulation process to the demodulated signal obtained as the receiver output. The purpose of such a demodulation is to remove the frequency shift between the observed spectral line and the center of the observed spectral band. This way, the selected spectral line is brought to baseband, allowing the study of its envelope as a slowly varying process. One efficient way to perform the second demodulation step is by a digital version of a quadrature demodulator. This idea is translated into an efficient algorithm, employing real multiplications and accumulators. An advantage of such an algorithm is that in order to observe two spectral lines in symmetrical positions with respect to the center frequency, common multiplication and accumulators can be used. A possible simplification of the algorithm is discussed in which sinusoids used for demodulation are replaced by square waves, so that multiplication reduces to a synchronous sign reversal. Possible distorsions due to this simplified algorithm are mentioned. Possible implementations of double demodulation in a digital signal processing system are discussed in the final part of the paper.