Methods: We observe the effect of using Intravenous Catheter System with PRN 139 cases and analyse the factors which influence it.
方法：观察139例浅静脉留置针临床使用效果，分析其影响因素。
2
PRN combined feature selection algorithm is proposed.
并提出改进的PRN组合特征选择算法。
3
The former is used to achieve the fine estimation of the carrier frequency while the later is used to achieve the fine estimation of the code delay of the PRN code.