| Magnetic Resonance Imaging (MRI) technology is one of the commonly applied fields based on the phenomenon of MRI. Recently Magnetic Resonance imaging instrument has become one of the most primarily used tool for both clinic and scientific research. As the development of relevant technologies, including those of superconductivity, electricity, image processing, and computing, gigantic progress has been achieved for the methodology and technology of imaging, with its applicable field is enlarged as well, which incurs more stringent requirement for magnetic resonance imaging instrument. This study focuses on designing and implementing a digital multichannel receiver that based on one frequency conversion technology.This thesis mainly do a research on a major part of the MRI spectrometer and transceiver system, which is the digital receiver. The receiver, which is a multi-channel magnetic resonance, is designed to use digital direct down-conversion technology, and implements fully digital one down-conversion with one piece of LTC1750 and one piece of AD6624. It avoids complex processing of phase correction of two orthogonal signals in analogue technique, and solves the error of analog mixing in two down-conversion. The digital receiver use four pieces of LTC1750, two pieces of AD6624, and a 32 bit single chip microcomputer to implement the function of spectrometer receiver of four channels, it can drop noise, improve the sampling rate of the signal and the overall performance of the receiver. The digital receiver can receive multipath signals simultaneously by using a 32 bit single chip microcomputer, the STM32 is cost reduction compared with multifunctional data acquisition card.The 32 bit single chip microcomputer enforce data acquisition, transmission of digital receiver system and the control system and AD6624 initialization, and the program can directly control and change the system through computer. This makes it more flexible, simple and accurate to control the whole system. |
PDF Full Text Request