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A Novel Modified Omega-K Algorithm for Synthetic Aperture Imaging Lidar through the Atmosphere

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ABSTRACT

The spatial resolution of a conventional imaging lidar system is constrained by the diffraction limit of the telescope's aperture. The combination of the lidar and synthetic aperture (SA) processing techniques may overcome the diffraction limit and pave the way for a higher resolution air borne or space borne remote sensor. Regarding the lidar transmitting frequency modulation continuous-wave (FMCW) signal, the motion during the transmission of a sweep and the reception of the corresponding echo were expected to be one of the major problems. The given modified Omega-K algorithm takes the continuous motion into account, which can compensate for the Doppler shift induced by the continuous motion efficiently and azimuth ambiguity for the low pulse recurrence frequency limited by the tunable laser. And then, simulation of Phase Screen (PS) distorted by atmospheric turbulence following the von Karman spectrum by using Fourier Transform is implemented in order to simulate turbulence. Finally, the computer simulation shows the validity of the modified algorithm and if in the turbulence the synthetic aperture length does not exceed the similar coherence length of the atmosphere for SAIL, we can ignore the effect of the turbulence.

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Sketch of azimuth preprocessing.The data processing using the modified Omega-K algorithm.
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f3-sensors-08-03056: Sketch of azimuth preprocessing.The data processing using the modified Omega-K algorithm.

Mentions: We finally rewrite eq. (13) as follows:(15)sconv(nΔt″,RB)=exp(jka,ref(nΔt″)2)DFT[sa(iΔt′,RB)exp(jka,ref(iΔt′)2)]n=−P/2,…,P/2−1where the symbol DFT [·] represents the discrete Fourier transform operator. In a word, this operation can be carried out by the simple multiplication and a discrete Fourier transform, and the block diagram showing the azimuth preprocessing implemented in Equation (10) is presented in Figure 3.


A Novel Modified Omega-K Algorithm for Synthetic Aperture Imaging Lidar through the Atmosphere
Sketch of azimuth preprocessing.The data processing using the modified Omega-K algorithm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3675531&req=5

f3-sensors-08-03056: Sketch of azimuth preprocessing.The data processing using the modified Omega-K algorithm.
Mentions: We finally rewrite eq. (13) as follows:(15)sconv(nΔt″,RB)=exp(jka,ref(nΔt″)2)DFT[sa(iΔt′,RB)exp(jka,ref(iΔt′)2)]n=−P/2,…,P/2−1where the symbol DFT [·] represents the discrete Fourier transform operator. In a word, this operation can be carried out by the simple multiplication and a discrete Fourier transform, and the block diagram showing the azimuth preprocessing implemented in Equation (10) is presented in Figure 3.

View Article: PubMed Central

ABSTRACT

The spatial resolution of a conventional imaging lidar system is constrained by the diffraction limit of the telescope's aperture. The combination of the lidar and synthetic aperture (SA) processing techniques may overcome the diffraction limit and pave the way for a higher resolution air borne or space borne remote sensor. Regarding the lidar transmitting frequency modulation continuous-wave (FMCW) signal, the motion during the transmission of a sweep and the reception of the corresponding echo were expected to be one of the major problems. The given modified Omega-K algorithm takes the continuous motion into account, which can compensate for the Doppler shift induced by the continuous motion efficiently and azimuth ambiguity for the low pulse recurrence frequency limited by the tunable laser. And then, simulation of Phase Screen (PS) distorted by atmospheric turbulence following the von Karman spectrum by using Fourier Transform is implemented in order to simulate turbulence. Finally, the computer simulation shows the validity of the modified algorithm and if in the turbulence the synthetic aperture length does not exceed the similar coherence length of the atmosphere for SAIL, we can ignore the effect of the turbulence.

No MeSH data available.