A simple inertial or Dopplernavigation has a common defect that position errors are always increasing with flight time or distance, therefore an external reference system is necessary.
There is great Doppler frequency shift under high dynamic circumstances, thus the common GPS receiver cannot work reliably without the help of inertialnavigation devices.
高动态环境存在较大的多普勒频移，这使得普通的GPS接收机在没有惯导辅助的情况下很难可靠工作。
3
It is an effective way in integrated navigation by using Strapdown Inertialnavigation System (SINS), GPS and Doppler Velocity Log (DVL).