The differential code bias (DCB) of the global navigation satellite system (GNSS) receiver onboard a low earth orbit (LEO) satellite is one of the crucial hardware error sources in ionospheric estimation. In common practice, LEO DCBs are considered as constant within a single day. However, since such receivers are installed on moving platforms, they are subjected to the ever-changing space environment, and thus, LEO DCBs are prone to more frequent fluctuations than receiver DCBs of ground GNSS stations. We estimate the LEO GPS receiver DCBs and plasmaspheric vertical total electron content by using inequality constrained least square and a multi-layer mapping function (MF) approach to minimize mapping errors. The GPS receiver DCBs onboard constellation observing system for meteorology, ionosphere, and climate satellites (COSMIC) is investigated and analyzed during the January 2008 period. The results show that in most cases the multi-layer MF approach performs better than the commonly used single-layer MF. The mapping error from an inaccurately fixed single-layer height can be considerably reduced. Meanwhile, with the help of a multi-layer MF, the mean deviations of DCBs for five receivers compared with those based on a geometric MF at 1400 km are significantly decreased by 59%, 15%, 26%, 47%, and 22%, respectively.

中文翻译：

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基于不等式约束最小二乘和多层映射函数的LEO-GPS接收机差分码偏差估计

低地球轨道（LEO）卫星上的全球导航卫星系统（GNSS）接收机的差分代码偏差（DCB）是电离层估算中至关重要的硬件误差源之一。通常，LEO DCB在一天之内是恒定的。但是，由于这种接收器安装在移动平台上，因此它们经受着不断变化的空间环境的影响，因此，LEO DCB的波动比地面GNSS站的接收器DCB更为频繁。我们通过使用不等式约束最小二乘和多层映射函数（MF）方法来最小化映射误差，从而估计LEO GPS接收器DCB和等离子层垂直总电子含量。GPS接收器DCB车载星座观测系统，用于气象，电离层，在2008年1月，对气候卫星（COSMIC）进行了调查和分析。结果表明，在大多数情况下，多层MF方法的性能要优于常用的单层MF。来自不正确固定的单层高度的映射误差可以大大降低。同时，借助多层MF，五个接收机的DCB的平均偏差与基于几何MF在1400 km的接收机的平均偏差相比，分别降低了59％，15％，26％，47％和22％ ， 分别。