As microsatellite technology develops, its applications broaden constantly. Distributing the functions of traditional satellites to various microsatellites has become a new operating mode, which is turning into a hotspot of aerospace area rapidly[
Chinese Optics Letters, Volume. 14, Issue 11, 110608(2016)
Inter-satellite range-finding method with high precision and large range based on optoelectronic resonance
As microsatellite technology develops, precise inter-satellite measurement shows its significance in distributed satellite systems. In this Letter, a novel technique is proposed for measuring the inter-satellite distance, which adopts optoelectronic resonance and has a function of self-referencing. Resonance cavities have a high spectral purity and a high oscillation frequency. By utilizing the accumulative amplification principle to convert the measurement of distance to that of the frequency, high accuracy is achieved. In the experiment, this measuring scheme has a large measuring range between 1 and 6 km (can be potentially larger), and the accuracy is better than 1.5 μm. The relative accuracy reaches the level of
As microsatellite technology develops, its applications broaden constantly. Distributing the functions of traditional satellites to various microsatellites has become a new operating mode, which is turning into a hotspot of aerospace area rapidly[
Developed jointly by the National Aeronautics and Space Administration (NASA) and the German Space Agency, the Gravity Recovery and Climate Experiment (GRACE) satellite is composed of two satellites which are 200 km apart. Their orbit altitude is 500 km. The fundamental principle of gravity measurement is inverting the accurate measurement of the distance change and relative velocity between two satellites into the variations of the gravitational field. Therefore, range-finding accuracy in double-satellite systems is a basic premise as well as an important guarantee for the spatial resolution of Earth’s gravitational field[
In order to achieve high-precision observations or measurements on the basis of multi-satellite coordination, the high-precision inter-satellite range-finding method (with high precision and a large range) should be first solved. Inter-satellite range-finding methods include laser radar range finding, infrared tracking range finding, microwave radar range finding, and GPS range finding. Laser radar technology is growing more mature. However, no laser range-finding device developed independently in China has been applied to small-satellite flying formations. The measuring accuracy of infrared tracking ranging would be affected significantly by the device itself. Microwave radar range-finding technology can be conducted an independent search and measurement. However, the measuring accuracy is not high enough to satisfy the demands of moonlets. Meanwhile, the application of GPS is limited since part of the ranging codes is kept secret.
Sign up for Chinese Optics Letters TOC Get the latest issue of Advanced Photonics delivered right to you!Sign up now
In this Letter, a novel technique is proposed for measuring the inter-satellite distance that adopts optoelectronic resonance and has the function of self-reference. Resonance cavities have a high spectral purity and high oscillation frequency. By utilizing the accumulative amplification principle to convert the measurement of distance to the measurement of frequency, record measuring accuracy can be achieved by common measuring instruments. In the experiment, this measuring scheme has a large measuring range between 1 and 6 km (can be potentially longer), and the accuracy is better than 1.5 μm. The relative accuracy reaches the level of
Most methods aiming at measuring the absolute distance with a large range and high precision convert the measurement of distance to the measurement of time (time-of-flight method) or phase (phase measurement method or interference method), making the results more accurate by means of improving the measurement resolution continually. The requirement of resolution brings technical difficulty and sensibility to other factors.
Actually, there is another effective measuring method that magnifies the deviation before it is measured: the accumulative amplification principle. In this way, high-precision measuring results can be obtained by low-resolution measuring instruments, such as the classic test of the pendulum cycle.
Optoelectronic oscillators (OEOs) are one kind of new optoelectronic resonance oscillator that has developed rapidly in recent years[
OEOs are a new microwave signal generator that utilize long fibers to store energy. Their fundamental schematic diagram is shown in Fig.
Figure 1.Fundamental schematic diagram of OEO.
The interval of oscillation modes, which means the basic frequency, is decided by signal delay of the loop
The system’s stability (which decides
In order to ensure the stability of
Figure 2.Realization of self-referencing function.
Based on the above principle analysis, experimental research was carried out to prove the proposed scheme. The experimental scheme is shown in Fig.
Figure 3.Inter-satellite ranging system based on optoelectronic resonance.
The wavelengths of the continuous lights emitted by laser devices LD1 and LD2 are
The phase-locked loop is utilized to precisely control the stability of the cavity length of the stabilized cavity loop built by
Although the above scheme compensates for the vast majority of cavity length drifts of the test OEO, OEO loops with different wavelengths go through different devices and microwave lines when they pass the microwave amplifier and filter. The phase-locked loop can guarantee the stability of the cavity length of the loop built by
In this range-finding system, a long SMF is placed in the loop to emulate long distances in space; it should have been placed on the path of the measured distance. However, the fiber length varies greatly with the temperature (1 μm/°C/m), so there is no way to verify the measuring accuracy of the test system. If the long fiber is placed on the measured path, it is equivalent to continuous variations of the measuring distance. Therefore, the long fiber is placed on the public loop of the test loop and stabilized cavity loop. In this way, long fiber drifts can be compensated by the stabilized cavity loop so as to measure distance variations precisely.
In this experimental system, an ODL-650 optical fiber delay line produced by Ozoptics is used to change the measured distance precisely. Its range is 50 mm, equal to a round trip of a 25 mm light path. The accuracy of the fiber delay line is less than 1 μm. The accuracy of the measuring system can be verified by testing 16 points along the 25 mm optical path.
In order to test the measurement range of the absolute distance test system based on the OEO, we change the length of the ordinary single-mode fiber in the public loop from 1.5 to 8 km to emulate the spatial distance from 1.1 to 6 km. In each test, 16 points are selected at a range of 25 mm and the tests are performed there. At every location, the tests are performed 30 times, and the results are averaged and compared with the distance variation caused by the delay line. Errors in the test results are shown in Fig.
Figure 4.Test results of measuring system.
In this way, a measuring accuracy that is higher than 1.5 μm is obtained from a multipoint test on an emulative spatial distance from 1.2 to 6 km. It is proven that this experimental system is able to get a high measuring accuracy with such a large range. Meanwhile, the relative measuring accuracy reaches
Although optical loss caused by special propagation is high and the inter-satellite environment is complicated, the line of sight between satellites could be made available by applying the appropriate pointing, acquisition, and tracking technique. In practice, propagating through a long distance will cause high optical losses, which would broaden the linewidth of the OEO and decrease the measurement accuracy. In order to imitate a practical measurement environment, another experiment for measuring the OEO linewidth under high optical loss was performed. The experimental setup is shown in Fig.
Figure 5.Experimental setup for measuring the OEO linewidth under high optical loss.
Figure
|
As shown in Table
An inter-satellite range-finding method with a large range and high precision based on optoelectronic resonance is proposed. It utilizes the characteristics of a long resonant cavity, high spectral purity, and high oscillation frequency of an OEO to magnify the measured distance variation
[1] M. Navabi, M. Barati, H. Bonyan. Proceeding of International Conference on Recent Advances in Space Technologies, 277(2013).
[6] D. Schutze, G. Stede, V. Muller, O. Gerberding, C. Mahrdt, B. Sheard, G. Heinzel, K. Danzmann. Proceeding of LISA Symposium, 285(2012).
[7] H. Zhang, W. Meng, Z. Wu, J. Chen, Z. Zhang. Chin. J. Lasers, 40, 0308005(2013).
[8] J. Shen, S. She, K. Wang, D. He, Y. Huang. Chin. J. Space Sci., 27, 342(2007).
[12] X. Yao, L. Maleki, D. Eliyahu. IEEE MTT-S Int. Microw. Symp. Dig., 1, 287(2004).
Get Citation
Copy Citation Text
Bin Chen, Jinlong Yu, Ju Wang, Tianyu Li, Wenrui Wang, Yang Yu, Tianyuan Xie, "Inter-satellite range-finding method with high precision and large range based on optoelectronic resonance," Chin. Opt. Lett. 14, 110608 (2016)
Category: Fiber Optics and Optical Communications
Received: Jun. 22, 2016
Accepted: Sep. 30, 2016
Published Online: Aug. 2, 2018
The Author Email: Ju Wang (wangju@tju.edu.cn)