| 摘要 |
<p>The speed of a moving object (1) relative to the ground (2) may be measured with a wide beam Doppler radar (3) on board the moving object by transmitting two closely spaced incident radar waves at the ground and collecting the corresponding reflected waves, at least the first incident wave having a frequency that is variable over time, multiplying signals representing the first incident and reflected waves, determining a spectrum of the low frequency component of the product of the two signals, processing the second incident and reflected waves in the same way, then finding two peaks on said spectra that match with a certain frequency shift, and determining the speed of the moving object from the frequencies of these two significant points and the height of the radar above the ground.</p> |
