Research On Novel MRI RF Transceiver Based On Software-Radio

RF signal transceiver is an important component of MRI spectrometer. It is responsible for the receive of MR signal and the transmit of RF pulse. This dissertation focused on the research of all-digital RF signal transceiver with high performance, including principles, algorithms and hardware implementation. Firstly, the principles and algorithms of MRI signal transceiver were described and designed. An new algorithm combined all-digital quadrature demodulation and multi-stage decimation was presented in detail. By comparing and analyzing several shaped pulse design methods were compared and analyzed, and a composite method was presented for various MRI pulse sequences. After comparing with the performance of double sideband modulation and single sideband modulation, Single sideband modulation based on phasing was used for RF pulse modulation, which can cut down the peak power of RF pulse transmitter and achieve a precise phase. Secondly, a novel MRI RF transmitter hardware architecture based on software-radio idea was presented, which used DSP and FPGA devices including high speed ADC/DAC chipsets. Advantages of this solution are of high precision and good flexibility. After the system level design and concerns were analyzed, the detailed chart of hardware platform was given. Finally, DSP module simulation based on TMS320C6713 DSK was demonstrated in detail. An optimized filter-decitmation method was established and implemented with a DSP program in ANSI C and inline assembly, and Single-precision floating-point format was used in the whole process so that large dynamic range and high processing precision are achieved. The result of simulation on 6713DSK proved that this algorithm satisfied the real-time requirement.