backscatter

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backscatter

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Backscatter allows communication within the skip zone. Normally, station within skip zone cannot hear transmitting station. In this case Y cannot hear station X. Station, however, Z can hear station X by normal ionospheric propagation. On the other hand, when backscatter is strong enough station Y can hear station X, even though Y is within the skip zone.
i. A form of ionospheric propagation of electromagnetic waves via the E and F layers. These layers are highly ionized and have properties of reflecting electromagnetic waves back to the earth. Normally, almost all electromagnetic signals are returned to the earth at roughly equivalent angles of incidence. However, some amount of electromagnetic energy is scattered in all directions. Some energy may be reflected back toward the transmitting station into the skip zone. A receiving station within this skip zone is thus able to receive the transmission. Also called echo.
ii. In radar, the portion of the microwave energy scattered by the terrain surface directly back toward the antenna.
References in periodicals archive ?
Comparison of Corneal Backscatter between FECD and Normal Subjects.
Comparison of Corneal Backscatter between FECD without Edema and Normal Subjects.
Comparison of Corneal Backscatter between FECD Eyes with/without Corneal Edema.
In this study, we developed an integrated algorithm for determining the daytime PBLH from the attenuated backscatter at 532 nm.
If we introduce into the backscatter profile S(z), the convolution of Haar function h with S(z) is given by the following equation:
Because a strong negative gradient of backscatter is presented between the PBL and the free troposphere, the top of the PBL can be identified by searching for the local maximum in [W.sub.f](a,b).
Secondly, we chose all local maxima of the wavelet covariance coefficients that correspond to a maximum in the attenuated backscatter at 532 nm itself in the meantime.
Due to the sharp decrease in the vertical profile of backscattered signals between PBL top and free troposphere above, there is a local maximum in the vertical gradient of backscattered signals.
Due to the sharp gradient caused by the sharp increase in backscatter signal mentioned in Section 1, an improved maximum variance method was developed based on the technique by Jordan et al.
where [beta]' is the total attenuated backscatter at 532 nm and i is the position of the backscatter signal in vertical profiles of backscatter, which is corresponding to the currently local maximum of standard deviation that needed to be judged.
Figures 3(a) and 3(b) show the vertical profiles of total attenuated backscatter at 532 nm acquired, respectively, from CALIOP and CE370 on Lille site at 12:51 UTC (13:51 local time) on December 31, 2015.
Because CALIOP observes the atmosphere by looking downward from space, the clouds (especially the thick clouds) involve significant attenuation of the backscatter signal in underlying layers.