(A) new scan conversion algorithm for compound scanning

Abstract

In this dissertation work, scan conversion algorithm for compound scanning, variable rate sampling clock generator and multi-gate Doppler system has been studied. This dissertation work may be divided into three parts. First, scanconversion algorithm for compount scanner has been studied. Input data in spatial domain are sampled by concentric square raster sampling(CSRS) method, and the diplay pixel data is interpolated by one-directional interpolation. The reconstruction error of the proposed algorithm is much smaller than the existed algorithms, because only one-dimensional interpolation rather than the complex two-dimensional interpolation is involved. The proposed algorithm can be applied to the spatial compound scanner where two or more transducers are arranged in linear or circular fashion. The implemention of this algorithm seems to be quite easy compare to the previous algorithms. Second, variable rate sampling clock generator is studied. A new clock generator satisfy the general requirements of sampling clock generators; fast transition time, precise frequency resolution, and phase coherency. The proposed method reduces the accumulated error below the half period of the master clock by accumulated error correction. The clock is generated by dividing a high frequency master clock with proper division value stored in look-up table ROM. The look-up table is divided into base value and bitencoded correction value to reduce the storage size and the required access time of table ROM. access time of table ROM. Finally, multi-gate pulsed Doppler system is investigated. Pulsed ultrasonic Doppler system is a useful diagnostic instrument to measure blood velocity and volume blood flow. This system is more powerful compare with 2-dimensional image. A system has been developed and is being evaluted using TMS32010 DSP. We use this DSP for the purpose of spectrum analyzer in singlegate pulsed Doppler system and for the serial comb filter and zero crossing counter i...