![]() For a stationary target with a RCS of 5 m2 located 8 nmi away from the radar compute the expected radar received power in dBm (dBmilliWatts). Pt =6 kW Gt =36 dB Fc = 5 GHz Noise Figure = 8 dB System Temperature = 290K PRF=1500 Hz Bandwidth = 1 MHz Azimuth Beamwidth = 1.5 deg Scan Rate = 60 RPMĪ. A radar has the following design parameters: A radar has the following design parameters:ġ. For the target described in Problem 1a, compute the corresponding fast (short) time at which the reflected waveform is expected to appear within the received signal, assuming each PRI starts at tfast = 0 and ends at tfast = 1/PRF. Continue to accumulate slow time and PRI count as the antenna rotates through multiple scans.Ĭ. Calculate the number of the relevant PRI as well as the antenna pointing angle and slow time at the start of that PRI. Assume slow (long) time is 0 sec when the radar antenna starts its first clockwise rotational scan beginning at 0 deg. If the target described in Problem 1a is located at a bearing of 36 deg clockwise from true North, find the first PRI in the fourth radar scan to contain a target reflection. Verify that the Pr computed with the multiplicative equation is the same as the Pr computed with the decibel equation.ī. (Read Module 2B again for additional help.) Convert all units as needed and demonstrate that all dimensional units are accounted for. Perform this calculation using both the linear (multiplicative) form of the radar range equation and the decibel (additive) form. For a stationary target with an RCS of 5 m^2 located 8 nmi away from the radar, compute the expected radar received power in dBm (dB milliwatts). A radar has the following design parameters:Ī. Very heavy rain, hail very likely, large hail possible.SOLVED: Radar Range Equation and Timing. For an exponential distribution of reflectors, Z is expressed by: Z = ∫ 0 D m a x N 0 e − Λ D D 6 d D NOAA dBZ scale for weather radar Reflectivity in dBZ and Rainrate Very sensitive radars can also measure the reflectivity of cloud drops and ice. The radar reflectivity factor ( Z) of precipitation is dependent on the number ( N 0) and size ( D) of reflectors ( hydrometeors), which includes rain, snow, graupel, and hail. Values above 20 dBZ usually indicate falling precipitation. In short, the higher the dBZ value, the more likely it is for severe weather to occur in the form of precipitation. Both the radar reflectivity factor and its logarithmic version are commonly referred to as reflectivity when the context is clear. With other variables analyzed from the radar returns it helps to determine the type of precipitation. It is proportional to the number of drops per unit volume and the sixth power of drops' diameter and is thus used to estimate the rain or snow intensity. ![]() The scale of dBZ values can be seen along the bottom of the image.ĭecibel relative to Z, or dBZ, is a logarithmic dimensionless technical unit used in radar, mostly in weather radar, to compare the equivalent reflectivity factor (Z) of a remote object (in mm 6 per m 3) to the return of a droplet of rain with a diameter of 1 mm (1 mm 6 per m 3). JSTOR ( May 2023) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification. ![]()
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