An optical flequency comb phase-locked on an iodine frequency stabilized diode laser at 634 nm is constructed to transfer the accuracy and stability from the optical domain to the radio frequency domain. An external-c...An optical flequency comb phase-locked on an iodine frequency stabilized diode laser at 634 nm is constructed to transfer the accuracy and stability from the optical domain to the radio frequency domain. An external-cavity diode laser is frequency-stabilized on the Doppler-free absorption signals of the hyperfine transition R（80）8-4 using the third-harmonic detection technique. The instability of the ultra-stable optical oscillator is determined to be 7 ×10^-12 by a cesium atomic clock via the optical frequency comb＇s mass frequencv dividing technique.展开更多
地形遮挡是雷达探测难以克服的困难,其对雷达波束的阻挡会产生探测盲区,严重影响雷达的使用。对于一个雷达站点,搞清雷达盲区的具体分布十分必要,但现实中却很难找到定量计算雷达盲区的实用方法。文中提出了一种快速计算方法,具体方法...地形遮挡是雷达探测难以克服的困难,其对雷达波束的阻挡会产生探测盲区,严重影响雷达的使用。对于一个雷达站点,搞清雷达盲区的具体分布十分必要,但现实中却很难找到定量计算雷达盲区的实用方法。文中提出了一种快速计算方法,具体方法是通过地理信息系统(Geographiic Information System, GIS)软件快速定位遮挡山体,并获取遮挡山体与雷达的地表投影距离,进而快速精确求解盲区高度,以及修正大气折射对盲区高度造成的影响。通过视距公式对新方法的准确性进行了验证,结果表明,新方法可以实现雷达地形遮挡盲区的快速和准确计算。展开更多
基金supported by the National"973"Program of China(No.2006CB921401 and 2006CB921402)the Major Program of National Natural Science Foundation of China(No.60490280)the National Natural Science Foundation of China(No.10574005)
文摘An optical flequency comb phase-locked on an iodine frequency stabilized diode laser at 634 nm is constructed to transfer the accuracy and stability from the optical domain to the radio frequency domain. An external-cavity diode laser is frequency-stabilized on the Doppler-free absorption signals of the hyperfine transition R（80）8-4 using the third-harmonic detection technique. The instability of the ultra-stable optical oscillator is determined to be 7 ×10^-12 by a cesium atomic clock via the optical frequency comb＇s mass frequencv dividing technique.
文摘地形遮挡是雷达探测难以克服的困难,其对雷达波束的阻挡会产生探测盲区,严重影响雷达的使用。对于一个雷达站点,搞清雷达盲区的具体分布十分必要,但现实中却很难找到定量计算雷达盲区的实用方法。文中提出了一种快速计算方法,具体方法是通过地理信息系统(Geographiic Information System, GIS)软件快速定位遮挡山体,并获取遮挡山体与雷达的地表投影距离,进而快速精确求解盲区高度,以及修正大气折射对盲区高度造成的影响。通过视距公式对新方法的准确性进行了验证,结果表明,新方法可以实现雷达地形遮挡盲区的快速和准确计算。
