1、.關于 GPS 冷啟動、暖啟動和熱啟動的一種解釋GPS*器的啟動時間是一個目前比較混亂，同時如果不具備一定的GPS 知識比較難以理解的一個概念。本文借助于外文的一些解釋，希望能夠用比較簡單的語言讓GPS 愛好者們加深認識。關于幾個啟動時間的解釋也只是一家之言，大家還可以進一步探討。GPS 的啟動是一個比較有趣的話題，因為通過這個話題，可以作為深入了解GPS 專業知識的一個門徑。Hot Start - The GPS receiver remembers its last calculated position and which satellites werein view, the alma

2、nac used, and the UTC Time. It then performs a reset and attempts toacquire satellites and calculate a new position based upon the previous information. This isthe quickest re-acquisition of a GPS lock.熱啟動 -GPS*器保存有其最后計算的可視衛星的位置、almanac(歷書 ) 和 UTC 時間，在重啟以后，GPS*器以保存的上述內容為基礎獲取和計算當前衛星的最新位置。Warm Start -

3、 The GPS receiver remembers its last calculated position, almanac used, andknows the UTC Time, but not which satellites were in view. It then performs a reset andattempts to obtain the satellite signals and calculate a new position. The receiver has ageneral idea of which satellites to look for beca

4、use it knows its last position and the almanachelps identify which satellites are visible in the sky. This takes longer than a Hot Start but notas long as a Cold Start.暖啟動 -GPS*器保存有最后計算的衛星的位置、歷書和UTC 時間，但保存的內容不是當前可視衛星的數據。GPS*器重啟以后嘗試去獲得當前衛星和信號并計算其新位置。* 器基于其最后的位置和歷書得以大概知道當前天空中的可視衛星。;.Cold Start - The G

5、PS receiver dumps all information and resets. It then attempts to locatesatellites and then calculate a GPS lock. This takes the longest because there is no knowninformation. The GPS receiver has to attempt to lock a satellite signal from all of the satellites,basically like polling, which takes a l

6、ot longer than knowing which satellites to look for. Thisre-acquisition of a GPS lock takes the longest.冷啟動： GPS*器清空了所有歷史信息并重啟，然后它嘗試定位并鎖定衛星，由于沒有先前信息，這將花去很長的時間。 GPS*器采用類似于輪詢的方法，從所有的衛星中鎖定信號，這將比事前知道該搜索哪些衛星要慢不少。這一類重新獲取鎖定要花最長的時間。比較和小結熱啟動就是啟動時可視的衛星信息和之前保存的信息是基本一致的。暖啟動和熱啟動的區別在于經管也保存了之前的衛星信息，可視搜星的時候可視衛星（當前衛

7、星）并不是以前記憶的信息的衛星，但是保存的歷史信息仍然有利于快速定位當前衛星。冷啟動，最好理解，就是在沒有歷史信息的情況下一個一個輪詢的方式搜星定位，所需時間最長。關鍵名詞解釋：Almanac和 EphemerisThe satellites broadcast two types of data, Almanac and Ephemeris.Almanac data is course orbital parameters for all SVs. Each SV broadcasts Almanac data forALL SVs. This Almanac data is not ver

8、y precise and is considered valid for up to severalmonths.Almanac數據是反映所有衛星狀況的比較粗略的軌道參數，每一個衛星都會廣播所有衛星的Almanac數據，這類數據不是十分精確，有效期長達幾個月。Ephemeris data by comparison is very precise orbital and clock correction for each SV and isnecessary for precise positioning. EACH SV broadcasts ONLY its own Ephemeris

9、data. This;.data is valid for a period of time (maybe several hours) as determined by informationcontained in the broadcast. The Ephemeris data is broadcast by each SV every 30 seconds.Ephemeris數據相比之下是十分精確的軌道和時鐘糾正信息，每一顆衛星只會廣播自己的Ephemeris數據，這類數據的有效期或許有幾個小時（取決于廣播信息的包含的內容）。Ephemeris數據每隔30 秒廣播一次。GPS 開機定位分為冷啟動、溫啟動和熱啟動三種：冷啟動：以下幾種