發(fā)布時間：2018-06-08 04:27

  本文選題：LXI + GPS��； 參考：《哈爾濱工業(yè)大學》2012年碩士論文

【摘要】：網(wǎng)絡技術和總線技術的進步極大的推動了自動化測試系統(tǒng)的發(fā)展。基于網(wǎng)絡的LXI總線技術自2005年發(fā)布第一個版本的規(guī)范后一直成為眾多企業(yè)和研究機構的研究熱門。目前，市場上已經(jīng)有了各種功能的LXI儀器，隨著技術的發(fā)展，LXI儀器的應用范圍必將越來越廣泛。在LXI儀器的三個功能類中，A類和B類儀器需要IEEE1588精密時鐘同步協(xié)議的支持。出于降低成本考慮， LXI系統(tǒng)的主時鐘一般由普通的晶體振蕩器來驅動，由于普通晶振的輸出頻率精度不高，且易受環(huán)境溫度影響、長期穩(wěn)定性差，因此導致主時鐘與物理時間有較大偏差。這個偏差的存在導致主時鐘與從時鐘之間有較大誤差，為了提高IEEE1588同步精度必須研制精度高穩(wěn)定性好的主時鐘模塊。 本文研究和設計了基于GPS的LXI主時鐘模塊，利用GPS發(fā)布的高精度和高穩(wěn)定度時間信息來修正LXI儀器上的實時時鐘模塊，提高了精密時鐘同步協(xié)議的同步精度。 為了獲取GPS面向全球發(fā)布的時間信息，，本文設計了一款低成本的GPS接收機。GPS接收機是一種典型的嵌入式系統(tǒng)，在硬件上主要包括微處理器、相關通道、射頻前端和存儲器，在軟件上包括嵌入式操作系統(tǒng)、設備驅動程序和實現(xiàn)時間解算的應用程序。GPS接收機的核心是偽碼跟蹤環(huán)和載波跟蹤環(huán)，本文設計了一階鎖頻環(huán)輔助的二階鎖相環(huán)來實現(xiàn)載波和偽碼的捕獲與跟蹤。在跟蹤鎖定載波和偽碼后，GPS接收機提取導航電文，算出UTC時間，并輸出與UTC高度同步的秒脈沖。LXI儀器接收GPS輸出的UTC時間信息和秒脈沖，以秒脈沖為觸發(fā)信號對LXI儀器上的實時時鐘模塊進行修正，使被修正的LXI儀器成為LXI系統(tǒng)的主時鐘。 本文最后對GPS接收機的高頻通道進行了測試，并使用本文設計的主時鐘模塊進行了同步實驗，實驗結果表明使用本模塊可以達到較高的同步精度。
[Abstract]:The progress of network technology and bus technology has greatly promoted the development of automated test system. Network-based LXI bus technology has been a hot topic in many enterprises and research institutions since the first version of the specification was released in 2005. At present, there are various kinds of LXI instruments in the market. With the development of technology, the application of LXI instruments will be more and more extensive. Among the three functional classes of LXI instruments, class A and class B require the support of IEEE1588 precision clock synchronization protocol. In order to reduce the cost, the main clock of the LXI system is generally driven by the ordinary crystal oscillator. Because the output frequency accuracy of the ordinary crystal oscillator is not high, and is easy to be affected by the environment temperature, the long-term stability is poor. As a result, the main clock has a large deviation from the physical time. In order to improve the synchronization accuracy of IEEE1588, the master clock module with high precision and stability must be developed. In this paper, the LXI master clock module based on GPS is studied and designed. The high precision and high stability time information issued by GPS is used to correct the real time clock module in the LXI instrument, and the synchronization accuracy of the precision clock synchronization protocol is improved. This paper designs a low cost GPS receiver. GPS receiver is a typical embedded system. In hardware, it mainly includes microprocessor, correlation channel, RF front-end and memory, and includes embedded operating system in software. The core of GPS receiver is pseudo-code tracking loop and carrier tracking loop. In this paper, a first-order frequency-locked loop assisted second-order phase-locked loop is designed to realize carrier and pseudo-code acquisition and tracking. After tracking and locking the carrier and pseudo-code, the GPS receiver extracts the navigation message, calculates the UTC time, and outputs the UTC time information and the second pulse from the GPS output by the second pulse .LXI instrument, which is in high synchronization with the UTC. The real time clock module on LXI instrument is modified by using second pulse as trigger signal, which makes the modified LXI instrument become the main clock of LXI system. In the end, the high frequency channel of GPS receiver is tested. The synchronization experiment is carried out with the main clock module designed in this paper. The experimental results show that the synchronization precision can be achieved by using this module.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TP336

【參考文獻】

相關期刊論文 前2條

1 張艷梅;柴劍平;宋金寶;;下一代測試自動化總線技術—LXI[J];中國傳媒大學學報(自然科學版);2006年02期

2 趙雷;;LXI——新一代基于LAN的模塊化測試平臺標準[J];儀表技術;2007年05期

本文編號：1994456