In practice, the NEXRAD measures radial velocity Group of answer choices by measuring the difference in phase of two successive return pulses continuously like a police radar using the cell tracking algorithm.
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NEXRAD (Next Generation Weather Radar) is a network of Doppler weather radars used to measure various atmospheric conditions, including precipitation and wind patterns. Show more…
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This type of technology measures changes in wavelength caused by the relative motion of precipitation, tornadoes, and other severe weather events. Theissen Method Doppler Radar Rain Gauge Method Arithmetic Mean Method
Sri K.
Phased-Array Radar. In one common type of radar installation, a rotating antenna sweeps a radio beam around the sky. But in a phased-array radar system, the antennas remain stationary and the beam is swept electronically. To see how this is done, consider an array of $N$ antennas that are arranged along the horizontal $x$ -axis at $x=0, \pm d, \pm 2 d, \ldots, \pm(N-1) d / 2 .$ (The number $N$ is odd.) Each antenna emits radiation uniformly in all directions in the horizontal $x y$ -plane. The antennas all emit radiation coherently, with the same amplitude $E_{0}$ and the same wavelength $\lambda$ . The relative phase $\delta$ of the emission from adjacent antennas can be varied, however. If the antenna at $x=0$ emits a signal that is given by $E_{0} \cos \omega t,$ as measured at a point next to the antenna, the antenna at $x=d$ emits a signal given by $E_{0} \cos (\omega t+\delta),$ as measured at a point next to that antenna. The corresponding quantity for the antenna at $x=-d$ is $E_{0} \cos (\omega t-\delta) ;$ for the antennas at $x=\pm 2 d,$ it is $E_{0} \cos (\omega t \pm 2 \delta) ;$ and so on. $(a)$ If $\delta=0$ , the interference pattern at a distance from the antennas is large compared to $d$ and has a principal maximum at $\theta=0$ (that is, in the angular range $-90^{\circ}<\theta<90^{\circ} .$ Hence this principal maximum describes a beam emitted in the direction $\theta=0$ . As described in Section $36.4,$ if $N$ is large, the beam will have a large intensity and be quite narrow. (b) If $\delta \neq 0$ , show that the principal intensity maximum described in part (a) is located at $$ \boldsymbol{\theta}=\arcsin \left(\frac{\delta \boldsymbol{\lambda}}{2 \pi d}\right) $$ where $\delta$ is measured in radians. Thus, by varying $\delta$ from positive to negative values and back again, which can easily be done electronically, the bearn can be made to sweep back and forth around $\boldsymbol{\theta}=\mathbf{0} .$ (c) A weather radar unit to be installed on an airplane emits radio waves at 8800 $\mathrm{MHz}$ . The unit uses 15 antennas in an array 28.0 $\mathrm{cm}$ long (from the antenna at one end of the array to the antenna at the other end). What must the maximum and minimum values of $\delta$ be (that is, the most positive and most negative values) if the radar beam is to sweep $45^{\circ}$ to the left or right of the air- plane's direction of flight? Give your answer in radians.
binary integration in radar
Anand J.
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