本文選題：頻率鏈接 + 頻率穩(wěn)定度��； 參考：《西安電子科技大學》2014年碩士論文

【摘要】：原子鐘利用原子的超精細能級間躍遷所輻射的頻率對時間進行度量。由于它計時的準確性和穩(wěn)定性,原子鐘在過去的五十年中已成為航空航天、導航定位、通信以及科學測量等領域中不可或缺的器件之一。原子鐘主要包括物理部分和線路部分,是高穩(wěn)定度晶體振蕩器的物理鎖定系統(tǒng),其性能主要取決于物理部分和線路部分的配合。通常情況下,物理部分由于受到外界溫度變化和自身老化等因素的影響而不能達到理想的效果,同時由于線路部分需要通過多級倍頻、混頻、合成等復雜頻率變換,將物理部分躍遷頻率鎖定到高穩(wěn)定度晶體振蕩器上,在這個過程中,會引入附加噪聲,影響了原子鐘的短期穩(wěn)定度指標。針對物理部分和線路部分的不足,可以分別利用線路部分的補償以及精密頻率鏈接等時頻信號處理技術來解決。本文基于廣泛使用的銣原子鐘,針對以上情況完成了以下幾個方面的工作：1.針對銣原子鐘溫度漂移問題進行了溫度補償技術研究。本文利用原子鐘的輸出隨溫度變化的重現(xiàn)性的穩(wěn)定性,采用直接數(shù)字頻率合成器對銣鐘進行補償,在沒有對被補償頻率源的自身短期穩(wěn)定度產(chǎn)生太大影響的前提下,減小了銣原子鐘的溫度系數(shù)。驗證了該設計方法的可行性和有效性。2.針對銣原子鐘長期漂移造成頻率準確度降低的問題進行了研究。本文利用GPS接收機輸出的1PPS信號的長期平均無漂移的的特性,設計了基于GPS的1PPS的銣原子鐘馴服系統(tǒng)。對比馴服前后的實驗結果,發(fā)現(xiàn)輸出頻率的準確度得到了提高。3.針對傳統(tǒng)銣原子鐘進行了線路簡化研究。在研究傳統(tǒng)線路的基礎上,根據(jù)周期性信號間相位比對過程中的相位群規(guī)律性變化,提出了對線路鏈接部分的簡化處理技術,即將一個特殊頻率值為13.669375MHz的VCOCXO,經(jīng)過500倍頻后可直接得到銣原子能級躍遷的激勵信號,再經(jīng)過鐘伺服對VCOCXO進行鎖定,從而改善了13.669375MHz VCOCXO的輸出頻率信號指標。但13.669375MHz的信號往往不能直接被使用,可進一步通過基于周期性信號間的精密頻率鏈接技術,將擁有銣原子能級躍遷指標的13.669375MHz VCOCXO信號的高準確度傳遞給10MHz VCOCXO的標準頻率輸出。經(jīng)改進后,相噪指標得到了有效改善。
[Abstract]:Atomic clocks measure time using the frequency of transitions between the hyperfine energy levels of an atom. Due to the accuracy and stability of its timing, atomic clock has become one of the indispensable devices in the fields of aerospace, navigation and positioning, communication and scientific measurement in the past 50 years. Atomic clock mainly includes physical part and circuit part. It is a physical locking system of high stability crystal oscillator. Its performance depends on the cooperation of physical part and circuit part. In general, the physical part can not achieve the ideal effect because of the influence of the external temperature change and the aging of itself, and the circuit part needs the complex frequency conversion, such as multistage frequency doubling, mixing, synthesizing and so on. When the physical partial transition frequency is locked on the high stability crystal oscillator, additional noise will be introduced in the process, which will affect the short-term stability index of atomic clock. Aiming at the deficiency of the physical part and the line part, the time-frequency signal processing technology, such as the compensation of the circuit part and the precise frequency link, can be used to solve the problem. In this paper, based on the widely used rubidium atomic clock, we have done the following work: 1. The temperature compensation technique for the temperature drift of rubidium atomic clock is studied. In this paper, using the stability of the reproducibility of atomic clock output with temperature variation, the direct digital frequency synthesizer is used to compensate the rubidium clock without too much influence on the short-term stability of the compensated frequency source. The temperature coefficient of rubidium atomic clock is reduced. The feasibility and effectiveness of the design method are verified. The reduction of frequency accuracy caused by long-term drift of rubidium atomic clock is studied. In this paper, a rubidium atomic clock taming system based on GPS and 1PPS is designed based on the long-term average no drift characteristic of 1PPS signal output by GPS receiver. By comparing the experimental results before and after acclimation, it is found that the accuracy of output frequency is improved by .3. The circuit simplification of rubidium atomic clock is studied. On the basis of studying the traditional circuit, according to the regular change of phase group in the process of phase comparison between periodic signals, the simplified processing technology for link part of the line is put forward. VCOCXO, which has a special frequency value of 13.669375MHz, can directly obtain the excitation signal of rubidium atomic energy level transition after 500 times frequency, and then lock the VCOCXO through clock servo, thus improving the output frequency signal index of 13.669375MHz VCOCXO. However, the signal of 13.669375MHz can not be used directly, and the high accuracy of 13.669375MHz VCOCXO signal with rubidium atomic level transition index can be transferred to the standard frequency output of 10MHz VCOCXO by means of precise frequency link technology based on periodic signal. After improvement, the phase noise index is improved effectively.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM935.115

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