Patent ID: 8229679
Filing Date: 2012-07-24
Classification: G01N,G01S,Y02A

Abstract:
1. A system for assessing a column of gas in an atmosphere comprising: an optical transmitter for transmitting (a) an online signal tuned to an online wavelength of gas, (b) an offline signal tuned to an offline wavelength of the gas, and (c) an optical signal for providing altimetry data, a modulator for modulating the online signal with a first stepped chirp waveform and modulating the offline signal with a second stepped chirp waveform, and a processor for assessing the column of gas, after receiving a returned online signal, a returned offline signal and a returned optical signal, wherein the first and second stepped chirp waveforms each includes finite steps, each step having a time period sufficiently long to allow for travel time to a ground surface and sampling time of return signals at a substantially fixed frequency, and each step having a different frequency.