GPS 初学之一 ： 热启动 冷启动，暖启动



关于冷启动、暖启动和热启动的一种解释 （ 转自指北针导航）

 
GPS接收机的启动时间是一个目前比较混乱，同时如果不具备一定的GPS知识比较难以理解的一个概念。本文借助于外文的一些解释，希望能够用比较简单的语言让GPS爱好者们加深认识。关于几个启动时间的解释也只是一家之言，大家还可以进一步探讨。GPS的启动是一个比较有趣的话题，因为通过这个话题，可以作为深入了解GPS专业知识的一个门径。 

 
Hot Start - The GPS receiver remembers its last calculated position and which satellites were in view, the almanac used, and the UTC Time. It then performs a reset and attempts to acquire satellites and calculate a new position based upon the previous information. This is the quickest re-acquisition of a GPS lock.
热启动--GPS接收机保存有其最后计算的可视卫星的位置、almanac(历书)和UTC时间，在重启以后，GPS接收机以保存的上述内容为基础获取和计算当前卫星的最新位置。 

 
Warm Start - The GPS receiver remembers its last calculated position, almanac used, and knows the UTC Time, but not which satellites were in view. It then performs a reset and attempts to obtain the satellite signals and calculate a new position. The receiver has a general idea of which satellites to look for because it knows its last position and the almanac helps identify which satellites are visible in the sky. This takes longer than a Hot Start but not as long as a Cold Start.
暖启动--GPS接收机保存有最后计算的卫星的位置、历书和UTC时间，但保存的内容不是当前可视卫星的数据。GPS接收机重启以后尝试去获得当前卫星和信号并计算其新位置。接收机基于其最后的位置和历书得以大概知道当前天空中的可视卫星。 

 
Cold Start - The GPS receiver dumps all information and resets. It then attempts to locate satellites and then calculate a GPS lock. This takes the longest because there is no known information. The GPS receiver has to attempt to lock a satellite signal from all of the satellites, basically like polling, which takes a lot longer than knowing which satellites to look for. This re-acquisition of a GPS lock takes the longest.
冷启动：GPS接收机清空了所有历史信息并重启，然后它尝试定位并锁定卫星，由于没有先前信息，这将花去很长的时间。GPS接收机采用类似于轮询的方法，从所有的卫星中锁定信号，这将比事前知道该搜索哪些卫星要慢不少。这一类重新获取锁定要花最长的时间。

注：

冷启动：以下几种情况开机均属冷启动。初次使用时； 电池 耗尽导致星历信息丢失时；关机状态下将接收机移动1000公里以上距离。

温启动：距离上次定位的时间超过两个小时的启动。

热启动：距离上次定位的时间小于两个小时的启动。