弱信號下基于卡爾曼濾波導航接收機載波恢復算法研究
本文選題:導航接收機 + 載波恢復 ; 參考:《國防科學技術大學》2014年碩士論文
【摘要】:隨著衛(wèi)星導航技術的不斷發(fā)展和應用,人們對導航服務性能的需求不斷提升,特別是弱信號條件下的服務性能。由于信號強度較低,在弱信號下載波跟蹤環(huán)路容易失鎖,不能實現(xiàn)穩(wěn)定的跟蹤。針對該問題,本文研究了弱信號下的卡爾曼濾波載波恢復算法。論文的研究工作主要從以下四個方面展開:(1)總結歸納了傳統(tǒng)的載波恢復方法,詳細介紹了載波恢復環(huán)路中影響性能的鑒相器、鑒頻器和環(huán)路濾波器。針對傳統(tǒng)的載波恢復模型在弱信號容易出現(xiàn)失鎖的問題,本文在傳統(tǒng)的鎖相環(huán)載波恢復模型的基礎上,利用卡爾曼濾波器替代了其中的環(huán)路濾波器,建立了卡爾曼濾波載波恢復模型。(2)相位卡爾曼濾波的原始輸入為鑒相器的輸入,鑒別結果的好壞及卡爾曼濾波積分時間直接決定了卡爾曼濾波的性能。目前的研究主要針對給定積分時間的跟蹤性能問題,沒有針對卡爾曼濾波積分時間優(yōu)化選擇的研究。本文建立了鑒相器的噪聲模型,結合鑒相器噪聲模型和卡爾曼濾波載波恢復模型,以穩(wěn)態(tài)卡爾曼濾波相位標準差最小為準則針對積分時間進行優(yōu)化設計。針對相位卡爾曼濾波載波恢復算法在低載噪比下容易發(fā)生載波周跳的問題,本文提出了一種控制新息幅度的周跳抑制方法。(3)在高動態(tài)應用中,傳統(tǒng)的鑒相器無法滿足高動態(tài)跟蹤需求,需要使用鑒頻器對頻率進行鑒別,并作為卡爾曼濾波器的原始觀測量。頻率卡爾曼濾波也需要針對積分時間進行優(yōu)化設計。本文研究了鑒頻器的噪聲模型,結合鑒頻器噪聲模型和卡爾曼濾波頻率估計模型,以穩(wěn)態(tài)卡爾曼濾波頻率標準差最小為準則針對積分時間進行優(yōu)化設計。(4)結合本文中提出的積分時間優(yōu)化,利用穩(wěn)態(tài)卡爾曼濾波器作為環(huán)路濾波器,本文給出了一種應用協(xié)處理器的跟蹤環(huán)路設計方案。設計硬件加速器和相關值預處理的方式增強了協(xié)處理器的性能。該方案簡化了基帶處理芯片設計,可直接應用于導航接收機基帶芯片開發(fā)。
[Abstract]:With the development and application of satellite navigation technology, the demand for navigation service performance is increasing, especially under the condition of weak signal. Because of the low signal intensity, it is easy to lose the lock in the weak signal download wave tracking loop and can not achieve stable tracking. To solve this problem, the Kalman filter carrier recovery algorithm for weak signals is studied in this paper. The main work of this paper is as follows: (1) the traditional carrier recovery methods are summarized, and the phase discriminator, frequency discriminator and loop filter which affect the performance of the carrier recovery loop are introduced in detail. Aiming at the problem that the traditional carrier recovery model is prone to lose lock in weak signal, the Kalman filter is used to replace the loop filter on the basis of the traditional phase-locked loop carrier recovery model. The carrier recovery model of Kalman filter is established. (2) the original input of phase Kalman filter is the input of phase discriminator. The performance of Kalman filter is directly determined by the quality of discriminating result and the integral time of Kalman filter. The current research focuses on the tracking performance of given integral time, and there is no research on the optimal selection of Kalman filter integral time. In this paper, the noise model of the phase discriminator is established. Combining the noise model of the phase discriminator and the Kalman filter carrier recovery model, the integration time is optimized based on the minimum standard deviation of the steady-state Kalman filter phase. Aiming at the problem that phase Kalman filter carrier recovery algorithm is easy to occur carrier cycle slip at low carrier / noise ratio, a cycle slip suppression method to control the amplitude of innovation is proposed in this paper. (3) in high dynamic applications, The traditional phase discriminator can not meet the high dynamic tracking requirement, so it is necessary to use frequency discriminator to identify the frequency and to be the original observation of Kalman filter. The frequency Kalman filter also needs to be optimized for integral time. In this paper, the noise model of the discriminator is studied, which combines the noise model of the discriminator and the Kalman filter frequency estimation model. The minimum standard deviation of steady-state Kalman filter frequency is taken as the criterion to optimize the integration time. (4) combined with the integration time optimization proposed in this paper, the steady-state Kalman filter is used as the loop filter. This paper presents a design scheme of tracking loop with coprocessor. The design of hardware accelerator and correlation value preprocessing enhances the performance of the coprocessor. This scheme simplifies the design of baseband processing chip and can be directly applied to the development of baseband chip of navigation receiver.
【學位授予單位】:國防科學技術大學
【學位級別】:碩士
【學位授予年份】:2014
【分類號】:TN965.5
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