發(fā)布時間：2018-01-17 18:04

  本文關鍵詞：非協(xié)作FSK和CPM信號解調方法和實現　出處：《電子科技大學》2014年碩士論文　論文類型：學位論文

  更多相關文章： 連續(xù)相位調制 參數盲估計 復合網格解調

【摘要】：在調制相關信息未知的情況下,接收機對接收信號進行解調,稱之為非協(xié)作信號盲解調。關于非協(xié)作FSK信號的盲解調問題已有大量的研究,調制參數估計和解調算法都很成熟。為了避免了FSK振蕩器突發(fā)式切換產生較大的頻譜旁瓣,由FSK演變出連續(xù)相位鍵控(CPFSK)。它是后續(xù)CPM信號的先驅。連續(xù)相位調制(CPM)顯著特點是包絡恒定,同時相位是連續(xù)變化的,為它帶來了高的頻譜利用率。CPM信號調制方式是非線性的。同時CPM信號隨著設置不同的調制參數,例如調制指數、相關長度,各類CPM信號表現出不同的性質。所以針對這些特點研究相關的解調技術,實現非協(xié)作CPM信號盲解調很有意義。本論文將CPM信號盲解調方法分為調制參數估計算法和解調算法,對它們都進行了深入的分析和研究。主要工作內容有：1、根據循環(huán)平穩(wěn)特性,分析了針對載頻／調制指數／符號周期估計算法的代價函數,研究了針對CPM信號相位展開的方法,為接下來調制指數調整奠定了基礎,仿真驗證了該算法的性能,表明該算法估計性能穩(wěn)定。2、分析推導了多進制CPM信號的二進制表達形式和其與二進制CPM信號的頻域關系。研究了基于信號的循環(huán)譜,根據它的離散譜線結構進行調制階數估計。仿真驗證該算法不受調制指數和頻率成形脈沖限制,具有較高的正確識別率。3、利用CPM信號符號之間有相關性,從而根據信號自相關函數實現相關長度估計。利用先前估計出的調制階數,仿真驗證了適用于任意調制指數的相關長度估計算法性能,表明該算法實現簡單,估計精度高。4、在相關解調算法的基礎上,重點研究了利用復合網格的思想,進行非相下解調的算法。該算法引入旋轉網格圖和狀態(tài)耦合轉移,實現了解調中對多普勒頻移的有效跟蹤。理論分析和仿真表明,該算法可以得到優(yōu)于差分的非相干解調性能,可以很好的接近最佳解調性能,同時它具有抗初相和頻偏跟蹤的優(yōu)點。5、在完成調制參數估計和解調算法分析之后,設計了非協(xié)作CPM信號盲解調器結構,對盲解調器進行模塊劃分,針對DSP實現給出了程序流程和算法代碼優(yōu)化方法。同時分析了復合網格解調算法中關于Viterbi算法和網格之間耦合的算法復雜性,提出了基于多核DSP的復合網格解調方案,利用多個處理器核的并行運算,實現大量數據的并行處理。
[Abstract]:In the case of unknown modulation related information, the receiver demodulates the received signal, which is called non-cooperative signal blind demodulation. There has been a lot of research on the blind demodulation of non-cooperative FSK signal. Modulation parameter estimation and demodulation algorithms are very mature in order to avoid the FSK oscillator burst switching to generate large spectrum sidelobe. The continuous phase keying (FSK) is the precursor of the subsequent CPM signal. The continuous phase modulation (CPM) is characterized by constant envelope and continuous phase variation. It brings high spectral efficiency. CPM signal modulation mode is nonlinear, and CPM signal with different modulation parameters, such as modulation index, correlation length. All kinds of CPM signals show different properties. Therefore, the demodulation technology is studied according to these characteristics. It is very meaningful to realize blind demodulation of non-cooperative CPM signal. In this paper, the blind demodulation method of CPM signal is divided into modulation parameter estimation algorithm and demodulation algorithm. The main work is: 1. According to the characteristics of cyclic stationary, the cost function of carrier frequency / modulation index / symbol period estimation algorithm is analyzed. The method of phase unwrapping for CPM signal is studied, which lays a foundation for the modulation exponent adjustment. The performance of the algorithm is verified by simulation, which shows that the estimation performance of the algorithm is stable. 2. The binary expression of multiary CPM signal and its frequency domain relationship with binary CPM signal are analyzed and deduced. The cyclic spectrum based on the signal is studied. The modulation order is estimated according to its discrete spectral line structure. The simulation results show that the algorithm is not limited by modulation exponent and frequency shaping pulse and has a high recognition rate of 3. 3. The correlation length is estimated according to the autocorrelation function of the signal by using the correlation between the symbols of the CPM signal, and the modulation order is estimated by the previous estimation. The performance of the correlation length estimation algorithm suitable for arbitrary modulation exponents is verified by simulation. It shows that the algorithm is simple in implementation and has high estimation accuracy. 4. The algorithm is based on the correlation demodulation algorithm. The algorithm of non-phase demodulation based on the idea of composite mesh is studied, which introduces the rotating grid graph and the state coupling transfer. The theoretical analysis and simulation show that the proposed algorithm can obtain better performance than the differential non-coherent demodulation and approach the best demodulation performance. At the same time, it has the advantages of anti-initial phase and frequency offset tracking. After completing the modulation parameter estimation and demodulation algorithm analysis, a non-cooperative CPM signal blind demodulator structure is designed, and the blind demodulator is divided into modules. The optimization method of program flow and algorithm code for DSP implementation is given, and the complexity of Viterbi algorithm and grid coupling algorithm in complex mesh demodulation algorithm is analyzed. A multi-core DSP based complex mesh demodulation scheme is proposed. The parallel processing of a large number of data is realized by using the parallel operation of multiple processor cores.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN911.3
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本文編號：1437339