摘要
理想周期伪随机序列的异相自相关全为零,被称为完美序列。然而已证明在周期为4<n<12100范围内不存在完美序列,因此,异相自相关系数中除中间的一点外全为零的近完美序列在一定条件下可替代完美序列。与常用的m序列相比,近完美序列可以实现无旁瓣测距,从而有效解决近区大功率回波旁瓣淹没远区小功率回波主瓣的问题。同样长度的m序列和近完美序列被用于武汉电离层斜向返回探测系统进行实测比较,结果显示,在同样的发射功率和探测波形参数下,近完美序列探测获得的后向散射回波具有更高的信噪比。
The out-of-phase autocorrelation of ideal periodic pseudorandom sequence, namely perfect sequence, is zero. However, no other binary perfect sequences of length 4〈n〈12100 have been found. The almost perfect sequences exhibiting zero out-of-phase autocorrelation except one value in the middle can replace perfect sequences under certain conditions. Compared with rn sequences, almost perfect sequences can detect without sidelobes, and solve the problem that the sidelobes of the echoes with high power submerge the main lobes of the echoes with low power. The almost perfect sequence and rn sequence with same length are used in Wuhan Ionospheric Oblique Backscattering Sounding System （WIOBSS） for real detection. The detecting results show that the echoes of almost perfect sequence have higher SNR with the same transmitting power and detecting waveform parameters.
出处
《电波科学学报》
EI
CSCD
北大核心
2008年第1期68-73,共6页
Chinese Journal of Radio Science
基金
国家自然科学基金资助项目(40474066)
博士后科学基金(20070420919)
关键词
近完美序列
M序列
衰落
多普勒频移
almost perfect sequence
m sequence
fading
Doppler frequency shift
