In this paper, a reliable spectrum sensing (SS) scheme using dual detectors for IEEE 802.22 WRAN has been presented. In dual or double detectors, first one detector is energy detector (ED) with fixed threshold (FT), while second one is ED with adapti

A bistatic point target reference spectrum (BPTRS) based on Loffeld's bistatic formula (LBF) is derived in this letter. For LBF, the same contributions of the transmitter and receiver to the total azimuth modulation are assumed. This assumption results in the failure of LBF in the extreme configuration (i.e., spaceborne/airborne configuration). For general bistatic configurations, the azimuth modulations are unequal for the transmitter and receiver due to the different slant ranges and velocities. Therefore, the azimuth time-bandwidth products (TBPs) from the transmitter and receiver are different; in some cases (e.g., spaceborne/airborne case), one of them might be very small, which might even result in a serious error of the principle of stationary phase. This letter uses TBP to weight the azimuth phase modulation contributions of the transmitter and receiver to the common azimuth spectrum to approximately obtain the point of stationary phase of the total azimuth phase history. Simulations show that the proposed BPTRS can work well for spaceborne/airborne configurations.

This paper concentrates on the bistatic SAR (BiSAR) signal processing for the spaceborne/airborne hybrid bistatic configuration. A bistatic SAR experiment based on this hybrid configuration is being planned in cooperation with FGAN/FHR and DLR. Due to the extreme differences of the platform's velocities and altitudes, the spaceborne system works in the sliding spotlight mode, while the airborne system operates in the inverse sliding spotlight mode. In this paper, our previous work (i.e. ISFT) is applied to focus the hybrid bistatic SAR data based on the extended Loffeld's Bistatic Formula (ELBF).

There are two sorts of energy resources: sustainable power resources and non-sustainable power resources. Due to some negative ecological effects including air pollution, climate change, and resource rot, people are concentrating on using sustainable energy resources to produce electricity. Solar energy, usually referred to as sun-oriented energy, is one of the most frequently researched environmentally beneficial power resources. In order to fulfill the growing demand for energy and increase energy efficiency, new developments and advancements in the field of solar energy are required. There are two sorts of energy resources: sustainable power resources and non-sustainable power resources. Due to some negative ecological effects including air pollution, climate change, and resource rot, people are concentrating on using sustainable energy resources to produce electricity. Solar energy, usually referred to as sun-oriented energy, is one of the most frequently researched environmentally beneficial power resources. In order to fulfill the growing demand for energy and increase energy efficiency, new developments and advancements in the field of solar energy are required. The traditional solar energy cell's inability to create power in the evening is a horrible flaw. This investigation focuses mostly on solar-powered energy and discusses its evolution, improvements, and future perspectives.