ephemeris time

The evolution of time measurement system has experienced the following stages in general: the ancient time measurement systems, universal time, ephemeris time, atomic time and universal time coordinated.

时间计量系统的演变大致经历了如下几个阶段：古代的时间计量系统、世界时、历书时、原子时、协调世界时。

The broadcast ephemeris, which is the basic of satellite navigation, must be precise and real time.

导航卫星广播星历是卫星导航定位的基础, 要求有较高的精度和实时性.

In his free time, Banneker wrote the Pennsylvania, Delaware , Maryland, and Virginia Almanac and Ephemeris.

闲暇之时, 班尼卡撰写有关宾州 、 德拉瓦 、 马里兰和维吉尼亚的农民历及星象历书.

The emphasis is given on analysis to relationship of error sources to location accuracy on platform ephemeris, echo time delays, target elevation, Doppler center frequency and time clock etc.

着重分析了平台星历、回波时延、目标高度、多普勒中心频率和时钟等误差源与定位精度的关系。