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However, in most fielded systems, unwanted clutter and interference sources mean that the noise level changes both spatially and temporally. In this case, a changing threshold can be used, where the threshold level is raised and lowered to maintain a constant probability of false alarm. This is known as constant false alarm rate (CFAR) detection.
A good PSR should have a designed false alarm rate of two or less false alarms per day. (A false alarm should not be confused with a nuisance alarm caused by, for example, an animal). Characteristics of some perimeter surveillance radar systems: Carrier frequencies range from C-band (about 5 GHz) to W band (about 77 GHz).
In addition, noise in the radar receiver will occasionally exceed the detection threshold of the radar's Constant false alarm rate detector and be incorrectly reported as targets (known as false alarms). The role of the radar tracker is to monitor consecutive updates from the radar system (which typically occur once every few seconds, as the ...
It was discovered that the false alarm rate was high because the radar would pick up swarms of insects and clutter from mountainous terrain. The solution was to allow the operator to change the sensitivity profile of radar by periodically reducing attenuation, and setting threat and non-threat sectors according to changing environment.
At the time, the railSAR fell into the highest category of UWB radar systems, operating across a 950 MHz-wide band from 40 MHz to 1 GHz on a pulse strength of 2.5 megawatts. [1] [3] [4] It provided fully polarimetric, high resolution radar data and possessed 185% bandwidth compared to other radar systems that had less than 25% bandwidth. [1] [5]
CETC YLC-18 3D Radar – Sri Lanka Air Force. The YLC-2 radar (domestic designation: LLQ303, formerly known as 385) is a three-dimensional main guidance and surveillance radar developed by the Nanjing Research Institute of Electronics Technology. In the mid-2000s, an improved version labeled YLC-2A was deployed to the PLA.
An MTI antenna beam is aimed above the horizon to avoid an excessive false alarm rate, which renders systems vulnerable. Aircraft and some missiles exploit this weakness using a technique called flying below the radar to avoid detection (nap-of-the-earth). This flying technique is ineffective against pulse-Doppler radar.
Side-lobes are produced during signal processing and a side-lobe suppression strategy, such as Dolph–Chebyshev window function, is required to reduce false alarms . [1] All of the samples taken from the Sample 1 sample period form the input to the first set of filters. This is the first ambiguous range interval.