频率源特性对CEI精度影响分析

Impact of Frequency Characteristics on the Accuracy of Connected-Element Interferometry

频率源特性导致的误差是影响干涉测量精度的因素之一,基于频率源稳定性详细分析了频率基准对CEI(Connected-Element Interferometry,连线端站干涉测量)精度的影响机理,针对差分单向测距/双差分单向测距、本地相关/互相关等各种干涉测量模式,给出了频率源稳定性对测量精度影响的解析表达式,并基于典型条件量化了频率源不稳定带来的误差大小,给出了能够满足CEI的频率源稳定性指标的建议。分析计算结果表明:如果要解出载波相位延迟量,在其他误差因素不会导致相位模糊的情况下,针对X频段差分单向测距,频率源稳定性优于8.5×10-12/s即可;针对双差分单向测距,对频率源稳定性的要求可进一步放宽。由此可以认为:在CEI模式下,较好的铷频标即可满足测量要求。

Errors resulted from frequency characteristics are one of the factors that impact the accuracy of interferom- etry. Based on analysis of the stability of frequency source, this paper explores the mechanism of impact of frequen- cy reference on the accuracy of CEI （Connected-Element Interferometry）. An accuracy expression related to frequen- cy stability is given for DOR （Differential One-Way Ranging）/delta-DOR, local correlation/cross correlation scenar- ios. A quantificational error analysis result due to frequency stability is also given based on typical conditions and a frequency stability suggestion for CEI measurement is presented. Calculation results show that if other factors do not result in phase ambiguity, the frequency stability value should be better than 8.5 × 10^-12/s to get the delay of carrier phase for X-band DOR. However, the value can be relaxed for delta-DOR. So we can get the conclusion that a good rubidium frequency reference is enough for measurement in CEI mode.