Spectrum Sensing Based on Time-frequency Dispersion Analysis

2014 ◽  
Vol 11 (11) ◽  
pp. 3765-3774
Author(s):  
Wenxiu Zheng
Keyword(s):  
Spectrum Sensing ◽  
Frequency Dispersion ◽  
Dispersion Analysis ◽  
Time Frequency

Spectrum Sensing of TETRA Systems through Time-Frequency Analysis

2013 ◽  
Vol 11 (3) ◽  
pp. 913-919 ◽  
Author(s):  
Wilson Diniz Wellisch ◽  
Andre Noll Barreto
Keyword(s):  
Spectrum Sensing ◽  
Frequency Analysis ◽  
Time Frequency Analysis ◽  
Time Frequency

scholarly journals Single Versus Multi-channel Dispersion Analysis of Ultrasonic Guided Waves Propagating in Long Bones

2021 ◽  
pp. 016173462110066
Author(s):  
Tho N. H. T. Tran ◽  
Feng He ◽  
Zhenggang Zhang ◽  
Mauricio D. Sacchi ◽  
Dean Ta ◽  
...  
Keyword(s):  
Guided Waves ◽  
Single Channel ◽  
Dispersion Analysis ◽  
Guided Wave ◽  
Diagnostic Methods ◽  
Bovine Bone ◽  
Time Frequency ◽  
Advantages And Disadvantages ◽  
Frequency Map ◽  
Channel Dispersion

Ultrasonic guided wave techniques have been applied to characterize cortical bone for osteoporosis assessment. Compared with the current gold-standard X-ray-based diagnostic methods, ultrasound-based techniques pose some advantages such as compactness, low cost, lack of ionizing radiation, and their ability to detect the mechanical properties of the cortex. Axial transmission technique with a source-receiver offset is employed to acquire the ultrasound data. The dispersion characteristics of the guided waves in bones are normally analyzed in the transformed domains using the dispersion curves. The transformed domain can be time-frequency map using a single channel or wavenumber-frequency (or phase velocity-frequency) map with multi-channels. In terms of acquisition effort, the first method is more cost- and time-effective than the latter. However, it remains unclear whether single-channel dispersion analysis can provide as much quantitative guided-wave information as the multi-channel analysis. The objective of this study is to compare the two methods using numerically simulated and ex vivo data of a simple bovine bone plate and explore their advantages and disadvantages. Both single- and multi-channel signal processing approaches are implemented using sparsity-constrained optimization algorithms to reinforce the focusing power. While the single-channel data acquisition and processing are much faster than those of the multi-channel, modal identification and analysis of the multi-channel data are straightforward and more convincing.

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