The total range to be explored consists of a succession of range-steps. For each range-step, a transmitter emits upwards at least one laser pulse, which is reflected downward by clouds onto a range gated receiver. The gating interval is progressively shifted, to run through the range-steps. For each range-step, reflected laser pulses received during the gating intervals, if any, are integrated. The power attenuation of the reflected pulses is an approximately quadratic function of height, the relationship between the range-step value and the integrated signal is thus made approximately quadratic. In the lower part of the total range, the conical beam patterns of transmitter and receiver progressively overlap, to create an overlap which increases quadratically with height. At least in the remaining upper part, an integration schedule is established, fixing for each range-step the number of pulses integrations performed before going onto the next range-step. The number of integrations performed per range-step increases approximately quadratically as a function of range-step value or height. IMAGE
展开▼
