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Mathematical Analysis Power Spectrum of M-ary MSK and Detection with Optimum Maximum Likelihood
( Zheng Niu ),( Yuzhong Jiang ),( Shuyan G Jia ),( Zhi Huang ),( Wenliang Zou ),( Gang Liu ),( Yu Li ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.8
In this paper, the power spectral density(PSD) for Multilevel Minimum Shift Keyed signal with modulation index h=1/2 (M-ary MSK) are derived using the mathematical method of the Markov Chain model. At first, according to an essential requirement of the phase continuity characteristics of MSK signals, a complete model of the whole process of signal generation is built. Then, the derivations for autocorrelation functions are carried out precisely. After that, we verified the correctness and accuracy of the theoretical derivation by comparing the derived results with numerical simulations using MATLAB. We also divided the spectrum into four components according to the derivation. By analyzing these figures in the graphic, each component determines the characteristics of the spectrum. It is vital for enhanced spectral characteristics. To more visually represent the energy concentration of the main flap and the roll-down speed of the side flap, the specific out-of-band power of M-ary MSK is given. OMLCD(Optimum Maximum Likelihood Coherent Detection) of M-ary MSK is adopted to compare the signal received with prepared in advance in a code element T to go for the best. And M-ary MSK BER(Bit Error Rate) is compared with the same ary PSK (Phase Shift Keying) with M=2,4,6,8. The results show the detection method could improve performance by increasing the length of L(memory inherent) in the phase continuity.
Chunteng Li,Yuzhong Jiang,Guanghui Yang,Fangjun Liu 한국자기학회 2018 Journal of Magnetics Vol.23 No.2
In order to design a kind of high-sensitive, narrow-band and portable search coil magnetometer, based on the principle of magnetic measuring, an equivalent model of search coil magnetometer with parallel matched capacitor is established. The formula of the induced coil is derived, low-noise integrated operational amplifier is designed and made as the preamplifier circuit of search coil magnetometer. The parameters of the inductive coil based on multi-parameter joint optimization are obtained under consideration of the sensitivity, bandwidth, weight and volume of the inductive coil simultaneously. The search coil magnetometer test is completed in the electromagnetic shielding room. And the result shows that the sensitivity of the designed search coil magnetometer is 40 fT√Hz @80 Hz, under the precondition of guaranteeing the weight, volume and bandwidth, which is basically the same as that of the simulation.