本文選題：遙測 + 軟件無線電　； 參考：《西南科技大學》2017年碩士論文

【摘要】：遙測是將測量信息通過無線通信傳輸給遠距離終端的一種技術,該技術被廣泛應用于導彈衛(wèi)星等飛行器的飛行測試任務中。隨著遙測技術的高速發(fā)展,未來遙測系統(tǒng)的技術特點主要向多調制體制、高速率等方向發(fā)展,而目前國內遙測系統(tǒng)整體表現為功能單一、設備兼容性差,不能夠適應未來遙測任務的發(fā)展。針對以上現狀,軟件無線電(Software Defined Radio,SDR)技術提供了一種有效的解決方法,其核心思想是利用統(tǒng)一硬件平臺,采用軟件方式實現各通信功能。本研究基于SDR設計思想,利用全數字化方法設計了一種多調制模式中頻數字遙測發(fā)射機,以適應目前及未來遙測任務的需求。本文首先對遙測信道的非線性特性和帶限特性進行了研究分析,結合信道特性和國際遙測標準IRIG 106,選取了PCM/FM、QPSK及SOQPSK調制體制作為研究對象,并對PCM/FM、QPSK和SOQPSK的調制解調算法進行了分析研究,仿真分析了各調制解調技術的相位特性、誤碼率和頻譜效率。針對傳統(tǒng)的PCM/FM相干解調算法載波恢復較難的缺陷,給出了一種不需要恢復載波的解調方法,可降低系統(tǒng)實現復雜度;同時,由于現有SOQPSK調制信號的帶外頻譜衰減較慢,本文通過優(yōu)化其頻率脈沖函數,給出了一種改進的SOQPSK調制方法,通過仿真結果,證明了改進后的SOQPSK調制信號具有更快的帶外衰減特性。此外,本文在加性高斯白噪聲信道環(huán)境下,對自適應調制中的關鍵參數—信噪比,進行了估計分析。針對幾種現有典型的非數據輔助信噪比估計算法存在估計精度差和估計范圍窄的缺點,提出了一種改進的信噪比估計算法。通過仿真說明了改進算法的信噪比估計性能優(yōu)于原有算法,為多調制遙測系統(tǒng)的自適應調制提供了依據。最后,本研究利用Verilog硬件描述語言編寫了各調制算法的FPGA實現代碼,完成了Modelsim功能仿真驗證與實際測試,測試結果驗證了本設計的有效性。
[Abstract]:Telemetry is a technology that transmits measurement information to remote terminals through wireless communication. It is widely used in flight test missions of missile satellites and other aircraft. With the rapid development of telemetry technology, the technical characteristics of the future telemetry system mainly develop in the direction of multi-modulation system and high speed. At present, the whole domestic telemetry system is characterized by a single function and poor equipment compatibility. Unable to adapt to the development of future telemetry missions. In view of the above situation, the software radio Defined radio SDR (Software Radio Defined) technology provides an effective solution. Its core idea is to use the unified hardware platform and software to realize the communication functions. Based on the design idea of SDR, a multi-modulation mode intermediate frequency digital telemetry transmitter is designed by using all-digital method to meet the needs of current and future telemetry tasks. In this paper, the nonlinear characteristics and band limit characteristics of telemetry channel are studied and analyzed. Combining the channel characteristics and the international telemetry standard IRIG 106, PCM / FM QPSK and SOQPSK modulation system are selected as the research objects. The modulation and demodulation algorithms of PCM / FM QPSK and SOQPSK are analyzed, and the phase characteristics, bit error rate and spectrum efficiency of each modulation and demodulation technology are simulated and analyzed. Aiming at the disadvantage of the traditional PCM/FM coherent demodulation algorithm, a demodulation method without carrier recovery is proposed, which can reduce the complexity of the system. At the same time, the out-of-band spectrum attenuation of the existing SOQPSK modulation signal is slow. This paper presents an improved SOQPSK modulation method by optimizing its frequency pulse function. The simulation results show that the modified SOQPSK modulation signal has faster out-of-band attenuation. In addition, the signal to noise ratio (SNR), a key parameter in adaptive modulation, is estimated and analyzed in additive Gao Si white noise channel. A modified SNR estimation algorithm is proposed to overcome the disadvantages of poor estimation accuracy and narrow estimation range in several typical non-data-aided SNR estimation algorithms. The simulation results show that the performance of the improved algorithm is better than that of the original algorithm, which provides a basis for adaptive modulation of multi-modulation telemetry systems. Finally, the FPGA implementation code of each modulation algorithm is compiled by using Verilog hardware description language, and the Modelsim function simulation and actual test are completed. The test results verify the validity of the design.
【學位授予單位】：西南科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN911.3

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