scholarly journals Theory and Measurement of Signal-to-Noise Ratio in Continuous-Wave Noise Radar

Sensors ◽  
2018 ◽  
Vol 18 (5) ◽  
pp. 1445 ◽  
Author(s):  
Bronisław Stec ◽  
Waldemar Susek
Keyword(s):  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Noise Radar ◽  
Noise Ratio

Telecom technology based continuous wave terahertz photomixing system with 105 decibel signal-to-noise ratio and 35 terahertz bandwidth

2013 ◽  
Vol 38 (20) ◽  
pp. 4197 ◽  
Author(s):  
Thorsten Göbel ◽  
Dennis Stanze ◽  
Björn Globisch ◽  
Roman J. B. Dietz ◽  
Helmut Roehle ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Noise Ratio

scholarly journals Silicon Photomultipliers Signal-to-Noise Ratio in the Continuous Wave Regime

2014 ◽  
Vol 20 (6) ◽  
pp. 284-290 ◽  
Author(s):  
Gabriele Adamo ◽  
Antonino Parisi ◽  
Salvatore Stivala ◽  
Alessandro Tomasino ◽  
Diego Agro ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Silicon Photomultipliers ◽  
Wave Regime ◽  
Noise Ratio

scholarly journals Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

2019 ◽  
Vol 9 (7) ◽  
pp. 1312 ◽  
Author(s):  
Tiago Bueno Moraes ◽  
Tatiana Monaretto ◽  
Luiz Colnago
Keyword(s):  
Time Domain ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Flip Angle ◽  
Time Interval ◽  
Single Shot ◽  
Free Precession ◽  
Signal To Noise ◽  
Low Field ◽  
Noise Ratio

This review discusses the theory and applications of the Continuous Wave Free Precession (CWFP) sequence in low-field, time-domain nuclear magnetic resonance (TD-NMR). CWFP is a special case of the Steady State Free Precession (SSFP) regime that is obtained when a train of radiofrequency pulses, separated by a time interval Tp shorter than the effective transverse relaxation time (T2*), is applied to a sample. Unlike regular pulsed experiments, in the CWFP regime, the amplitude is not dependent on T1. Therefore, Tp should be as short as possible (limited by hardware). For Tp < 0.5 ms, thousands of scans can be performed per second, and the signal to noise ratio can be enhanced by more than one order of magnitude. The amplitude of the CWFP signal is dependent on T1/T2; therefore, it can be used in quantitative analyses for samples with a similar relaxation ratio. The time constant to reach the CWFP regime (T*) is also dependent on relaxation times and flip angle (θ). Therefore, T* has been used as a single shot experiment to measure T1 using a low flip angle (5°) or T2, using θ = 180°. For measuring T1 and T2 simultaneously in a single experiment, it is necessary to use θ = 90°, the values of T* and M0, and the magnitude of CWFP signal |Mss|. Therefore, CWFP is an important sequence for TD-NMR, being an alternative to the Carr-Purcell-Meiboom-Gill sequence, which depends only on T2. The use of CWFP for the improvement of the signal to noise ratio in quantitative and qualitative analyses and in relaxation measurements are presented and discussed.

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