With the rapid development of wireless technology, spectrum resources become more and more scare. In order to solve the shortage of spectrum resources, cognitive radio technology is proposed and spectrum sensing is the key technology of it. At present, wide bandwidth signals have been widely used for data transmission and wideband spectrum sensing has become the research focus. Aiming at this problem, this paper proposes a non-cooperative wideband spectrum sensing algorithm based on multi-resolution singular spectrum entropy. Wavelet packet decomposition technology is used to decompose the wideband signalsinto multiple wavelet packet coefficients and each wavelet packet coefficient represents the signal’s characteristics of different frequency bands. On the basis of that, the singular spectrum entropy analysis is performed on the wavelet packet coefficients in the same channel. After that, the spectrum state information of different channels is obtained. Simulations show that the proposed algorithm has better performance than traditional spectrum sensing algorithm and it improves the detection probability of the signals effectively even at low SNR.
KEYWORDS: Magnetism, Data modeling, Submerged target modeling, Signal detection, Magnetic sensors, Target detection, Superposition, Submerged target detection, Signal processing, Signal to noise ratio
For the high cost of practicality experiments and the low precision of available model data cause the deficiently of the effectiveness of the aeromagnetic detection result, a magnetic field simulation method of submarine aircraft model is proposed based on COMSOL Multiphysics finite element software. First, the submarine is equivalent to the hollow cylinder model, and the magnetic field distribution of the distance of 5 times the length of the submarine is received through the simulation. Then the aircraft geometrical model is established to analyze the mechanism of aircraft jamming magnetic field, and the four-way flight scheme of compensation flight state is proposed to get magnetic field simulation data. For the simulation difficulties of large-scale model in the detection flight state, a simulation method of model separation and data superposition is proposed to get the component and the total data of magnetic field. Finally, the aircraft interference magnetic field modeling and the use of ridge estimation method to compensate for compensation flight and detection flight magnetic field data. Four-course flight data compensation accuracy within 0.5nT and detection flight data after compensation can be distinguished the submarine signal. The correctness of the finite element simulation method and the magnetic field data is verified, which is of great significance to the study of aeromagnetic deection simulation.
With the improvement of people’s living standard, the requirement of network is higher and higher. The rate and capacity of network communication are rising all the time, it ’s outstanding on the backbone networks. The rate of backbone network had improved from 10G to 100G in recent years. This change also put forward new requirement for optical network equipment . The key technologies of lower order cross-connect equipment is discussing in this passage. This passage mainly discusses the following aspects: time division multiplexing of STM-1 lower-order pointer interpretation and lower -order pointer generation. By using the technologies discussed in this passage, the lower -order cross-connect devices has the higher cross-connect capacity under consuming the same logic resource, and the equipment will meet the requirement of the backbone network transmission capacity.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.