Agilent 5990-7527EN Improving Radar Performance by Optimizing Overall Signal-to-Noise Ratio c20140725 [6] free download

File name 5990-7527EN Improving Radar Performance by Optimizing Overall Signal-to-Noise Ratio c20140725 [6].pd

Keysight Technologies Improving Radar Performance by Optimizing Overall Signal-to-Noise Ratio Application Note Radar Measurement Series Better noise-figure measurements enhance characterization of excess noise in receivers Overview Problem In radar system design, optimizing the overall signal-to-noise ratio Radars need to extract very small signals--those coming from tar- (SNR) of the system will improve the overall performance of the gets of interest--in an environment that may include artifacts such system. This is typically done in one of two ways: by increasing as clutter, jamming signals and spurious noise (e.g., signals from the signal or by reducing noise. Because a radar is a transmit/ other radars). Any internally generated noise in the radar receiver receive system, improved SNR can be achieved by increasing the circuit reduces the ability of the radar to discern the targets of transmitted power by using bigger, more-powerful amplifiers, by interest. Noise generated within a receiver component is indistin- using larger or higher gain antennas, or a combination of these guishable from any legitimate signal within the signal frequency changes. band and will be amplified equally along with expected signals in any subsequent gain stages. SNR can also be increased by decreasing receiver-contributed noise, which is usually determined by the quality of the low-noise amplifier (LNA) at the front end of the receiver. In general, it is easier and less Measuring noise properties is an essential step in the process of expensive to decrease receiver noise--and achieve a better noise minimizing the noise generated within a receiving system. The fol- figure (NF)--than to increase transmitter power. lowing equation determines the minimum signal level required to overcome system noise at the maximum range of the radar: In the pursuit of a better SNR, NF is a figure-of-merit that describes the amount of excess noise present in a system. The definition of Smin = kToBnFn(So/No)min noise figure is very straightforward. The noise factor (F) of a network Where: is defined as the input SNR divided by the output SNR: S