Patent ID: 9678197
Date: 2017-06-13
CPC Classifications: G01S

Claim:
1. A method for operating a radar altimeter, the method comprising: generating a linear frequency ramp of a radar signal from a first frequency to a second frequency for one modulation period; receiving reflection of the frequency ramp of the radar signal; processing the reflection by determining an approximate distance to a target from which the reflections are received based on an amount of time between transmission of the radar signal having the frequency ramp and reception of the reflection of the radar signal having the frequency ramp, wherein the approximate distance is proportional to frequency difference between received reflections of the frequency ramp and generated linear frequency ramp, and wherein the approximate distance to a target is determined with a resolution based on a distance separating center points of neighboring fast fourier transform (FFT) bins in the radar altimeter; and when the approximate distance is less than or equal to a maximum unambiguous distance: transmitting a first radar signal having a first frequency for a first length of time; receiving a reflection of the first radar signal at the first frequency; transmitting a second radar signal having a second frequency for a second length of time; receiving a reflection of the second radar signal at the second frequency; and processing the reflections of the first radar signal and the second radar signal at the first and second frequency by: