| 摘要 |
A velocity reference system uses a Doppler shift between transmitted and received wave energy to determine the relative speed between the system and a surface or element. Other systems employing Doppler shifts for detecting velocity suffer from poor measurement accuracy. Cross talk between channels of systems having multiple transmitters and receivers produces measurement errors. Additionally, errant movement generates measurement errors since the sensors cannot distinguish such errant movement from forward velocity. Two sensing units directed towards one another, and preferably towards the same location on the surface, effectively eliminates random vehicle movement. Furthermore, transmitting different frequencies from the two sensing units reduces cross talk between the two channels. Vehicle applications require a system capable of minimizing errant movement and environmental noise. |
