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Design and Optimization of Magnetic Resonance Signal Detector to Enhancement of Sensitivity and SNR in Proton Precession Sensor

Mazaheri Karvani, Jamal | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47223 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Fardmanesh, Mahdi
  7. Abstract:
  8. Proton precession is used in measurement of scalar magnetic field intensity. In this sensor, the magnetic field intensity is calculated through Larmor frequency using the proton precession frequency around the magnetic field. The accuracy of this sensor is in the range of picoTesla which is used for magnetic field measurement as well as the calibration of vector magnetic sensors. The signal to noise ratio in this sensor is due to the dimension and resistances of the wires and is a kind of RMS random noise. Although, changing the dimension of the wires for noise reduction and increasing the signal amplitude requires the fabrication of a bulky sensor with low power consumption. Therefore, it is required to consider different parameters in optimal design of the sensor. Also, it is necessary to eliminate the effect of different parameters in precession signal reduction in order to increase the signal to noise ratio. The magnitude of signal to noise ratio as well as the accuracy of frequency meter electronic circuit results in accurate measurement of magnetic field which depends on the accurate measurement of precession signal frequency. The magnitude of noise power has impact on frequency measurement accuracy. Therefore, we should consider the noise effect in all the design process. In order to have picoTesla accuracy in electronic circuit, it is necessary to have 20 MHz clock. At first, the time domain frequency measurement was done that in the case of fourier analysis of the precession signal, it is possible to accurately measure the precession frequency as well as diagnosing different concurrent precession and differentiation of them. Diagnosing different kinds of concurrent precession is the basis of NMR system based on magnetic resonance in finding the kind of the material. The main application of this sensor is in the measurement of the earth magnetic field and the creation of a magnetic map. Also, it is applied in earth gradiometry in which the measurement of earth magnetic field intensity to diagnose the magnetic storms
  9. Keywords:
  10. Magnetic Resonance ; Signal to Noise Ratio ; Proton Precession Magnetometer

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