Cancellation ratio: Difference between revisions
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#<div class="definition"><div class="short_definition">Broadly, a [[power]] ratio used in certain applications of [[radar]] that describes the degree to which the backscattered power from unwanted targets ([[clutter]]) is suppressed or canceled in one mode of measurement relative to another mode of measurement.</div><br/> <div class="paragraph">It is defined to yield a value greater than unity or, equivalently, a positive [[decibel]] quantity. For example, in some applications it is defined as the ratio of [[signal intensity]] backscattered from [[rain]] observed with [[linear]] polarization to the signal intensity backscattered from rain observed with [[circular polarization]]. Values of 25–30 dB are typical of light rain observed at wavelengths of 3– 10 cm.</div><br/> </div> | #<div class="definition"><div class="short_definition">Broadly, a [[power]] ratio used in certain applications of [[radar]] that describes the degree to which the backscattered power from unwanted targets ([[clutter]]) is suppressed or canceled in one mode of measurement relative to another mode of measurement.</div><br/> <div class="paragraph">It is defined to yield a value greater than unity or, equivalently, a positive [[decibel]] quantity. For example, in some applications it is defined as the ratio of [[signal intensity]] backscattered from [[rain]] observed with [[linear]] polarization to the signal intensity backscattered from rain observed with [[circular polarization]]. Values of 25–30 dB are typical of light rain observed at wavelengths of 3– 10 cm.</div><br/> </div> | ||
#<div class="definition"><div class="short_definition"> For a [[dual-channel radar]], the ratio of the [[power]] received in the [[orthogonal]] channel to that received in the transmission channel for transmitted [[circular polarization]]. The stronger component of the [[target signal]] from [[precipitation]] is the component in the orthogonal channel because the sense of the circular polarization is reversed as its direction of propagation changes when it is [[scattered]] back toward the [[radar]].</div><br/> </div> | #<div class="definition"><div class="short_definition"> For a [[dual-channel radar]], the ratio of the [[power]] received in the [[orthogonal]] channel to that received in the transmission channel for transmitted [[circular polarization]]. The stronger component of the [[target signal]] from [[precipitation]] is the component in the orthogonal channel because the sense of the circular polarization is reversed as its direction of propagation changes when it is [[scattered]] back toward the [[radar]].</div><br/> </div> | ||
#<div class="definition"><div class="short_definition">A ratio that describes the degree to which [[radar]] clutter is suppressed by a [[clutter]] filter. This usage applies particularly to [[moving-target indication]] (MTI) radars. Shrader and Gregers-Hansen recommend that the term | #<div class="definition"><div class="short_definition">A ratio that describes the degree to which [[radar]] clutter is suppressed by a [[clutter]] filter. This usage applies particularly to [[moving-target indication]] (MTI) radars. Shrader and Gregers-Hansen recommend that the term "improvement factor" be used in place of "cancellation ratio" because the latter term has been used inconsistently. </div><br/> <div class="paragraph"><br/>''Compare'' [[circular depolarization ratio]].</div><br/> </div><div class="reference">Shrader, W. W., and V. Gregers-Hansen 1990. Radar Handbook. 2d ed., M. I. Skolnik, ed., McGraw-Hill, . MTI Radar, chapter 15, . 15.1–15.72. </div><br/> | ||
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Latest revision as of 13:47, 20 February 2012
cancellation ratio
- Broadly, a power ratio used in certain applications of radar that describes the degree to which the backscattered power from unwanted targets (clutter) is suppressed or canceled in one mode of measurement relative to another mode of measurement.
It is defined to yield a value greater than unity or, equivalently, a positive decibel quantity. For example, in some applications it is defined as the ratio of signal intensity backscattered from rain observed with linear polarization to the signal intensity backscattered from rain observed with circular polarization. Values of 25–30 dB are typical of light rain observed at wavelengths of 3– 10 cm.
- For a dual-channel radar, the ratio of the power received in the orthogonal channel to that received in the transmission channel for transmitted circular polarization. The stronger component of the target signal from precipitation is the component in the orthogonal channel because the sense of the circular polarization is reversed as its direction of propagation changes when it is scattered back toward the radar.
- A ratio that describes the degree to which radar clutter is suppressed by a clutter filter. This usage applies particularly to moving-target indication (MTI) radars. Shrader and Gregers-Hansen recommend that the term "improvement factor" be used in place of "cancellation ratio" because the latter term has been used inconsistently.
Compare circular depolarization ratio.
Shrader, W. W., and V. Gregers-Hansen 1990. Radar Handbook. 2d ed., M. I. Skolnik, ed., McGraw-Hill, . MTI Radar, chapter 15, . 15.1–15.72.
