scholarly journals The Effect of Light Source Line Width on the Spectrum Resolution of Dual-Frequency Coherent Detection Signals

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5264
Author(s):  
Ren ◽  
Sun ◽  
Zhang ◽  
Zhao
Keyword(s):  
Power Spectrum ◽  
Light Source ◽  
Line Width ◽  
Delay Time ◽  
Doppler Frequency ◽  
Frequency Difference ◽  
Coherent Detection ◽  
Necessary Condition ◽  
Dual Frequency ◽  
Source Line

In this paper, the power spectrum resolution problem of dual-frequency coherent mixing signals is analyzed when the Doppler frequency difference is small. The power spectrum function formula of the four optical coherent mixing signals is obtained using statistical theory and the Wiener–Khinchin theorem. The influence of delay time and light source line width on the power spectrum of dual-frequency coherent signals is analyzed using this formula. The results show that delay time only affects the peak of the power spectrum of the coherent signal. An increase in the line width of the light source broadens the signal power spectrum and reduces the peak value. The necessary condition for distinguishing the Doppler frequency difference is that the theoretical Doppler frequency difference is greater than 1/5 times the line width of the light source.

Dual-frequency light source with widely tunable frequency difference based on single-side-band modulator

2019 ◽  
Vol 445 ◽  
pp. 50-55
Author(s):  
Zhenkun Jiang ◽  
Zhaoying Wang ◽  
Taoran Xie ◽  
Quan Yuan ◽  
Chunfeng Ge
Keyword(s):  
Light Source ◽  
Frequency Difference ◽  
Dual Frequency ◽  
Side Band ◽  
Single Side ◽  
Tunable Frequency ◽  
Single Side Band

Low‐complexity GNSS anti‐spoofing technique based on Doppler frequency difference monitoring

2018 ◽  
Vol 12 (9) ◽  
pp. 1058-1065 ◽  
Author(s):  
Jiaxun Tu ◽  
Xingqun Zhan ◽  
Xin Zhang ◽  
Zhenjun Zhang ◽  
Shuai Jing
Keyword(s):  
Doppler Frequency ◽  
Low Complexity ◽  
Frequency Difference

A New Airborne Passive DF Method only Based on Frequency Difference

2011 ◽  
Vol 219-220 ◽  
pp. 846-850
Author(s):  
Tao Yu
Keyword(s):  
Direction Cosine ◽  
Doppler Frequency ◽  
Frequency Measurement ◽  
Frequency Difference ◽  
Baseline Length ◽  
Direct Proportion ◽  
Unknown Parameters ◽  
Flight Direction ◽  
Phase Interference ◽  
Circular Functions

If three antenna units are divided into two set and two baselines are placed at right angles to each other in flight plain, in which the direction of one baseline is parallel to the actual flight direction of air vehicle, the sine and cosine function of target bearing respectively in two baseline directions can be simultaneously obtained according to the analysis principle of the direction cosine change rate. The angulations’ formula only based on Doppler frequency difference can be derived after eliminating the unknown parameters including angular velocity and wavelength by the specific value of two circular functions. The analog calculation shows that the relative error is in direct proportion to the baseline length provided that the incident wave is parallel in derivation. But the error analysis depicts that the measurement accuracy is in direct proportion to the baseline length. Moreover, the measurement error relies on mainly the accuracy of frequency measurement. Furthermore, the derived formula has irregularity in airborne axis direction. However, since the new method is not associated with wavelength, this new DF only based on Doppler frequency difference will be more adapted to passive sounding as compared with phase interference method.

Design and Experimental Study of Two-Cavity Dual-Frequency All-Solid-State Laser with Large Frequency Difference

2010 ◽  
Vol 37 (11) ◽  
pp. 2784-2789
Author(s):  
焦明星 Jiao Mingxing ◽  
邢俊红 Xing Junhong ◽  
刘芸 Liu Yun ◽  
杨云 Yang Yun ◽  
马少华 Ma Shaohua
Keyword(s):  
Experimental Study ◽  
Solid State ◽  
Solid State Laser ◽  
Frequency Difference ◽  
Dual Frequency ◽  
State Laser ◽  
Large Frequency

Dual-frequency Yb3+-doped DBR fiber laser with 32 GHz frequency difference

2018 ◽  
Vol 47 (10) ◽  
pp. 1005005
Author(s):  
侯玉斌 Hou Yubin ◽  
张 倩 Zhang Qian ◽  
齐恕贤 Qi Shuxian ◽  
冯 宪 Feng Xian ◽  
王 璞 Wang Pu
Keyword(s):  
Fiber Laser ◽  
Frequency Difference ◽  
Dual Frequency

Effect of Time-Frequency Disturbance on Performance of Dual-Frequency Laser Coherent Detection System

2016 ◽  
Vol 53 (6) ◽  
pp. 061403 ◽  
Author(s):  
张建华 Zhang Jianhua ◽  
杨德钊 Yang Dezhao ◽  
高洁 Gao Jie ◽  
刘锡民 Liu Ximin
Keyword(s):  
Detection System ◽  
Coherent Detection ◽  
Dual Frequency ◽  
Time Frequency ◽  
Frequency Laser

Dual-frequency solid-state microchip laser and its frequency difference control

2019 ◽  
Vol 58 (11) ◽  
pp. 1
Author(s):  
Jiyang Li ◽  
Yidong Tan ◽  
Kaiyi Zhu ◽  
Yueyue Lu ◽  
Shulian Zhang
Keyword(s):  
Solid State ◽  
Microchip Laser ◽  
Frequency Difference ◽  
Dual Frequency

scholarly journals In Situ Image Acquisition and Measurement of Microdroplets Based on Delay Triggering

Micromachines ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 148
Author(s):  
Xuefeng Chang ◽  
Kang Zheng ◽  
Dan Xie ◽  
Xiayun Shu ◽  
Keyu Xu ◽  
...  
Keyword(s):  
Light Source ◽  
Delay Time ◽  
Imaging System ◽  
Image Acquisition ◽  
Ccd Camera ◽  
Time Interval ◽  
Charge Coupled Device ◽  
Drop On Demand ◽  
Relative Standard

An in situ image acquisition apparatus based on delay triggering for visualizing microdroplets formation is described. The imaging system includes a charge-coupled device camera, a motion control card, a driving circuit, a time delay triggering circuit, and a light source. By adjusting the varying trigger delay time which is synchronized with respect to the signal for jetting, the steady sequential images of the droplet flying in free space can be captured real-time by the system. Several image processing steps are taken to measure the diameters and coordinates of the droplets. Also, the jetting speeds can be calculated according to the delay time interval. For glycerin/water (60:40, mass ratio), under the given conditions of the self-made pneumatically diaphragm-driven drop-on-demand inkjet apparatus, the average of diameter and volume are measured as 266.8 μm and 9944 pL, respectively, and the maximum average velocity of the microdroplets is 0.689 m/s. Finally, the imaging system is applied to measure the volume of 200 microsolder balls generated from the inkjet apparatus. The average diameter is 87.96 μm, and the relative standard deviation is 0.83%. The results show good reproducibility. Unlike previous stroboscopic techniques, the present in situ imaging system which is absence of instantaneous high intensity light employs two control signals to stimulate the microdroplet generator and the charge-coupled device (CCD) camera. Hence, the system can avoid the desynchronization problem of signals which control the strobe light-emitting diode (LED) light source and the camera in previous equipment. This technology is a reliable and cost-effective approach for capturing and measuring microdroplets.

Dual-frequency HeNe lasers of 3MHz - 40MHz frequency-difference

2002 ◽  
Author(s):  
Yan Li ◽  
Zhijun Fan ◽  
Shulian Zhang
Keyword(s):  
Frequency Difference ◽  
Dual Frequency
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