| 主权项 |
1. A method for measuring distance, the method comprising:
transmitting a first pair of RF pulses from an airborne interrogator, wherein the RF pulses in the first pair of RF pulses are temporally separated from each other by a first time interval, and each of RF pulses in the first pair of RF pulses has a first pulse waveform; receiving, at the airborne interrogator, a second pair of RF pulses transmitted by a ground transponder after the ground transponder has received the first pair of RF pulses transmitted by the airborne interrogator, wherein the RF pulses in the second pair of RF pulses are temporally separated from each other by a second time interval, and each of the RF pulses in the second pair of RF pulses has a second pulse waveform characterized by a smoothed concave hexagonal function, wherein the hexagonal function is characterized by a first segment having a first positive slope, a second flat segment, a third segment having a second negative slope, a fourth segment having a third negative slope, and a fifth segment having a fourth negative slope, an absolute value of the third negative slope being less than an absolute value of the second negative slope; determining an elapsed time between transmitting the first pair of RF pulses and receiving the second pair of RF pulses; and determining a distance between the airborne interrogator and the ground transponder based on at least the elapsed time. |
