We experimentally study the controllable generation of a beating signal using stored light pulses based on electromagnetically induced transparency(EIT) in a solid medium. The beating signal relies on an asymmetric pr...We experimentally study the controllable generation of a beating signal using stored light pulses based on electromagnetically induced transparency(EIT) in a solid medium. The beating signal relies on an asymmetric procedure of light storage and retrieval. After storing the probe pulse into the spin coherence under the EIT condition, two-color control fields with opposite detunings instead of the initial control field are used to scatter the stored spin coherence. The controllable beating signal is generated due to alternative constructive and destructive interferences in the retrieved signal intensities. The beating of the two-color control fields is mapped into the beating of weak probe fields by using atomic spin coherence. This beating signal will be important in precise atomic spectroscopy and fast quantum limited measurements.展开更多
Dual-frequency satellite positioning receivers are widely used because they can eliminate ionospheric delay and solve the full-circumference ambiguity quickly.However,in traditional dual-frequency receivers,the releva...Dual-frequency satellite positioning receivers are widely used because they can eliminate ionospheric delay and solve the full-circumference ambiguity quickly.However,in traditional dual-frequency receivers,the relevance of dual-frequency signals are not considered,and,with no improvement imposed to the tracking loop,two independent tracking loops are used to achieve the tracking of dual-frequency signals.In this paper,the Bei Dou dual-frequency signals joint tracking algorithm based on Kalman filter is proposed for the tracking of Bei Dou B1I and B3I dual-frequency signals.Taking the relevance of B1I and B3I signals into consideration,the algorithm adds a Kalman filter between the phase detector and carrier loop filter of the traditional dual-frequency independent tracking loop.The output results of the phase detectors of the B1I and B3I branches are then combined and filtered by the Kalman filter,and the results are input to the carrier loop filters of the corresponding branches.Proved by experiments,the algorithm not only enables the loop to enter a stable tracking state quickly,but also reduces the noise bandwidth of the two loop filters by about 10 Hz with the same tracking performance obtained.展开更多
信号在毫米波段的快速衰减是影响毫米波雷达测距范围的重要因素之一。为了增加基于线性调频连续波(linear frequency modulation continuous wave,LFMCW)技术的毫米波雷达的有效作用距离,采用小波包分析与快速傅里叶变换相结合的方法对...信号在毫米波段的快速衰减是影响毫米波雷达测距范围的重要因素之一。为了增加基于线性调频连续波(linear frequency modulation continuous wave,LFMCW)技术的毫米波雷达的有效作用距离,采用小波包分析与快速傅里叶变换相结合的方法对雷达目标进行测距。给出了该方法的实现步骤,并在1GHz带宽的24GHz LFMCW雷达实验平台上验证了该方法的有效性。实验结果表明,与经典的差拍-傅里叶测距方法相比,本文方法可以将实验雷达的有效作用范围从1～30m扩大至1～60m。展开更多
基金Project supported by the National Basic Research Program of China （Grant No. 201 ICB921603）, the National Natural Science Foundation of China （Grant Nos. 11374126, 10904048, 11074097, 11004079, 11004080, and 11247201）, the China Postdoctoral Science Foundation （Grant Nos. 2011M500924 and 2013T60317）. and the National Fund for Fosterin~ Talents of Basic Science （Grant No. J I 103202）.
文摘We experimentally study the controllable generation of a beating signal using stored light pulses based on electromagnetically induced transparency(EIT) in a solid medium. The beating signal relies on an asymmetric procedure of light storage and retrieval. After storing the probe pulse into the spin coherence under the EIT condition, two-color control fields with opposite detunings instead of the initial control field are used to scatter the stored spin coherence. The controllable beating signal is generated due to alternative constructive and destructive interferences in the retrieved signal intensities. The beating of the two-color control fields is mapped into the beating of weak probe fields by using atomic spin coherence. This beating signal will be important in precise atomic spectroscopy and fast quantum limited measurements.
基金supported by the National Natural Science Foundation of China (No.51505221)the Nanjing University of Aeronautics and Astronautics Graduate Innovation Base (Lab) Open Fund (No.kfjj20190312)
文摘Dual-frequency satellite positioning receivers are widely used because they can eliminate ionospheric delay and solve the full-circumference ambiguity quickly.However,in traditional dual-frequency receivers,the relevance of dual-frequency signals are not considered,and,with no improvement imposed to the tracking loop,two independent tracking loops are used to achieve the tracking of dual-frequency signals.In this paper,the Bei Dou dual-frequency signals joint tracking algorithm based on Kalman filter is proposed for the tracking of Bei Dou B1I and B3I dual-frequency signals.Taking the relevance of B1I and B3I signals into consideration,the algorithm adds a Kalman filter between the phase detector and carrier loop filter of the traditional dual-frequency independent tracking loop.The output results of the phase detectors of the B1I and B3I branches are then combined and filtered by the Kalman filter,and the results are input to the carrier loop filters of the corresponding branches.Proved by experiments,the algorithm not only enables the loop to enter a stable tracking state quickly,but also reduces the noise bandwidth of the two loop filters by about 10 Hz with the same tracking performance obtained.
