We demonstrate a simple scheme of 6.835 GHz microwave source based on the sub-sampling phase lock loop(PLL). A dielectric resonant oscillator of 6.8 GHz is directly phase locked to an ultra-low phase noise 100 MHz ove...We demonstrate a simple scheme of 6.835 GHz microwave source based on the sub-sampling phase lock loop(PLL). A dielectric resonant oscillator of 6.8 GHz is directly phase locked to an ultra-low phase noise 100 MHz oven controlled crystal oscillator(OCXO) utilizing the sub-sampling PLL. Then the 6.8 GHz is mixed with 35 MHz from an direct digital synthesizer(DDS) which is also referenced to the 100 MHZ OCXO to generate the final6.835 GHz signal. Benefiting from the sub-sampling PLL, the processes of frequency multiplication, which are usually necessary in the development of a microwave source, are greatly simplified. The architecture of the microwave source is pretty simple. Correspondingly, its power consumption and cost are low. The absolute phase noises of the 6.835 GHz output signal are-47 d Bc/Hz,-77 dBc/Hz,-104 dBc/Hz and-121 dBc/Hz at1 Hz, 10 Hz, 100 Hz and 1 kHz offset frequencies, respectively. The frequency stability limited by the phase noise through the Dick effect is theoretically estimated to be better than 5.0 × 10^-14τ^1/2 when it is used as the local oscillator of the Rb atomic clocks. This low phase noise microwave source can also be used in other experiments of precision measurement physics.展开更多
目的探讨简易膀胱容量测定技术与尿流动力学检查在评定脊髓损伤病人膀胱功能方面的一致性。方法 2011年12月~2013年8月,对37例脊髓损伤病人在入院1周内分别接受简易膀胱容量测定和尿流动力学检查。比较两种检查在判断神经源膀胱类型、...目的探讨简易膀胱容量测定技术与尿流动力学检查在评定脊髓损伤病人膀胱功能方面的一致性。方法 2011年12月~2013年8月,对37例脊髓损伤病人在入院1周内分别接受简易膀胱容量测定和尿流动力学检查。比较两种检查在判断神经源膀胱类型、测量残余尿、膀胱容量以及充盈期膀胱内压力变化方面的一致性。结果在残余尿量以及注水50 m L、100 m L、300 m L、400 m L时膀胱压力方面,简易膀胱容量测定与尿流动力学检查比较,均P〉0.05,差异无统计学意义;在膀胱容量和注水200 m L时膀胱压力方面,两者比较,均P〈0.05,差异具有统计学意义。两种检查方法测定结果之间的组间相关系数为0.606~0.919（均P〈0.01）,医生与护士根据两种方法对神经源膀胱类型的判断一致性Kappa系数为0.825（P〈0.001）。结论简易膀胱容量测定技术与尿流动力学在评定脊髓损伤病人膀胱功能方面的一致性良好。由于其操作简单易行、成本较低,因此简易膀胱容量测定可作为尿流动力学检查的补充,用于动态监测脊髓损伤病人的膀胱功能情况。展开更多
基金Supported by the National Key Research and Development Program of China under Grant No 2017YFA0304400the National Natural Science Foundation of China under Grant Nos 91336213,11703031,U1731132 and 11774108
文摘We demonstrate a simple scheme of 6.835 GHz microwave source based on the sub-sampling phase lock loop(PLL). A dielectric resonant oscillator of 6.8 GHz is directly phase locked to an ultra-low phase noise 100 MHz oven controlled crystal oscillator(OCXO) utilizing the sub-sampling PLL. Then the 6.8 GHz is mixed with 35 MHz from an direct digital synthesizer(DDS) which is also referenced to the 100 MHZ OCXO to generate the final6.835 GHz signal. Benefiting from the sub-sampling PLL, the processes of frequency multiplication, which are usually necessary in the development of a microwave source, are greatly simplified. The architecture of the microwave source is pretty simple. Correspondingly, its power consumption and cost are low. The absolute phase noises of the 6.835 GHz output signal are-47 d Bc/Hz,-77 dBc/Hz,-104 dBc/Hz and-121 dBc/Hz at1 Hz, 10 Hz, 100 Hz and 1 kHz offset frequencies, respectively. The frequency stability limited by the phase noise through the Dick effect is theoretically estimated to be better than 5.0 × 10^-14τ^1/2 when it is used as the local oscillator of the Rb atomic clocks. This low phase noise microwave source can also be used in other experiments of precision measurement physics.
文摘目的探讨简易膀胱容量测定技术与尿流动力学检查在评定脊髓损伤病人膀胱功能方面的一致性。方法 2011年12月~2013年8月,对37例脊髓损伤病人在入院1周内分别接受简易膀胱容量测定和尿流动力学检查。比较两种检查在判断神经源膀胱类型、测量残余尿、膀胱容量以及充盈期膀胱内压力变化方面的一致性。结果在残余尿量以及注水50 m L、100 m L、300 m L、400 m L时膀胱压力方面,简易膀胱容量测定与尿流动力学检查比较,均P〉0.05,差异无统计学意义;在膀胱容量和注水200 m L时膀胱压力方面,两者比较,均P〈0.05,差异具有统计学意义。两种检查方法测定结果之间的组间相关系数为0.606~0.919（均P〈0.01）,医生与护士根据两种方法对神经源膀胱类型的判断一致性Kappa系数为0.825（P〈0.001）。结论简易膀胱容量测定技术与尿流动力学在评定脊髓损伤病人膀胱功能方面的一致性良好。由于其操作简单易行、成本较低,因此简易膀胱容量测定可作为尿流动力学检查的补充,用于动态监测脊髓损伤病人的膀胱功能情况。
