GNSS系统中预积分时间内基带信号的功率谱密度研究

目前在进行全球卫星导航无线频率兼容性评估时,由于忽略了接收端预积分时间对基带信号截断作用的事实,导致采用的短码功率谱密度计算方法有误,这将影响到评估结果的精确性。针对这个问题,分预积分时间大于等于和小于伪码周期两种情况,对基带信号的功率谱解析式进行推导,然后仿真不同预积分时间内实际信号的功率谱以及解析式的功率谱,比较这两者的谱分离系数。仿真结果表明,预积分时间对短码的谱分离系数影响很大,这正确反映了预积分时间对功率谱密度的影响。该功率谱解析式有助于精确估计无线射频干扰。

GNSS baseband signal power spectrum in pre-integration time

The correct analysis of power spectrum density is very critical when assessing the radio frequency compatibility. Among a number of papers on this research, however,the fact that pre integration time in time domain is equivalent to the product of rectangular window multiplied by PRN code is ignored, and some present assessment results with deviation. The above problems, instead, are given close attention by this paper. This paper firstly presents the detail derivation process in two cases. In the first case pre integration time is greater than or equal to the pseudo code period and in the second case the pre integration time is less than the pseudorandom code period.And then the real power spectrum and the analytical power spectrum are compared in different pseudo code period to verify the correctness of derivation results.It is concluded that the derivation results are proved to be correct, and the pre integration time should be regarded as an important parameter of short code when accurate assessing the radio frequency compatibility.