GPS接收机软件调度方法与性能分析及测试

基于Altera公司的现场可编程门陈列（FPGA）实现了GPS的L1频点基带相关处理,多任务操作系统（eCos）实现了软件各个功能模块的调度。本文设计了两种线程执行时间开销测试方法,并进行了相互验证。分析了基于多任务与单任务操作系统情况下各自的软件调度模型及不同调度模型对CPU利用效率以及输出更新率的影响。实测数据表明：当伪距输出频率为10Hz,定位解算输出频率为5HZ,可见卫星为5颗的情况下,相对于单任务操作系统的接收机,设计实现的基于多任务操作系统的接收机处理效率提高了约1．2倍。     

Antiviral active peptide from oyster

An active peptide against herpes virus was isolated from the enzymic hydrolysate of oyster （Crassostrea gigas） and purified with the definite direction hydrolysis technique in the order of alcalase and bromelin. The hydrolysate was fractioned into four ranges of molecular weight （〉10 kDa, 10-5 kDa, 5-1 kDa and 〈1 kDa） using ultrafiltration membranes and dialysis. The fraction of 10-5 kDa was purified using consecutive chromatographic methods including DEAE Sephadex A-25 column, Sephadex G-25 column, and high performance liquid chromatogram （HPLC） by activity-guided isolation. The antiviral effect of the obtained peptide on herpetic virus was investigated in Vero cells by observing cytopathic effect （CPE）. The result shows that the peptide has high inhibitory activity on herpetic virus.