微波快速载波同步技术的研究
发布时间：2018-11-17 11:15
【摘要】：在过去的几十年里,无线通信系统所传输的数据率按照摩尔定律的速度增长。特别是近些年来多媒体信息的爆炸式增长给移动回传网络的速度和容量带来了巨大的挑战。采用点对点的微波无线回传技术是一种比传统的光纤或者同轴电缆回传技术更经济有效的方法,尤其是在人烟稀少的农村或是地形复杂的区域更具优越性。然而微波回传通信面临着很多技术上的挑战,特别是我国所主导的TDD通信模式下,高速的收发切换导致了对载波同步时间的要求非常高。本文研究了一种减少同步时间的技术。为了减少同步时间,载波同步不能用数字电路实现,所以本文提出了一种模拟电路解决方案。模拟方案中必须让QPSK信号先同通过四倍频来移除调制得到载波的四倍频,引入了距离载波很近的杂散,这需要非常窄带的滤波器才能滤除。SIR滤波器和开口环滤波器都可以实现窄带的功能,但是为了实际应用的考虑,选择了开口环滤波器作为载波恢复中的一个部件。最终设计出的滤波器的中心频率在1.2GHz,相对带宽达到了3%,插入损耗也在3dB以下,实际应用中的效果良好。为了保证载波恢复的质量,使用PLL设计了一个自同步电路。PLL用的是取样锁相鉴相器,解决了对高码速率信号的载波恢复。自同步技术使两路鉴相信号通过相同路径产生了相位对消,从而免除了移相器的使用。然后用信号源分别产生了不同符号率的QPSK信号来测试电路的同步性能。测试结果表明恢复出的载波相位噪声优于-80 dBc/Hz@1kHz,VCO的调谐电压达到稳定的时间也小于22毫秒。接下来是外同步方案的分析。相比于传统的同步方案,它的锁定阈值要更低,在比较低的信噪比情况下也可以保持良好的环路稳定性。TDD通信模式的上下行的数据量并不固定,随时间会有很大的变化,在这种情况下外同步方案可以很到地追踪到载波的变化情况。
[Abstract]:Over the past few decades, wireless communication systems have been transmitting data at the rate of Moore's law. Especially in recent years, the explosive growth of multimedia information has brought great challenges to the speed and capacity of mobile return network. The point to point microwave wireless transmission technology is a more economical and effective method than the traditional optical fiber or coaxial cable technology, especially in the rural areas where people are sparsely populated or in areas with complex terrain. However, microwave return communication faces many technical challenges, especially in the TDD communication mode, which is dominated by our country. The high speed transceiver switching results in a very high requirement of carrier synchronization time. In this paper, a technique to reduce synchronization time is studied. In order to reduce synchronization time, carrier synchronization can not be realized by digital circuit, so this paper proposes an analog circuit solution. In the simulation scheme, the QPSK signal must be removed from the modulation to get the quadruple frequency of the carrier by four times frequency first, and the spurious signal is introduced very close to the carrier. It takes very narrow band filter to filter out. SIR filter and open loop filter can realize narrow band function, but for practical application, open loop filter is chosen as a component of carrier recovery. Finally, the center frequency of the filter is 1.2 GHz, the relative bandwidth is 3 and the insertion loss is below 3dB. The effect of practical application is good. In order to guarantee the quality of carrier recovery, a self-synchronization circuit is designed by using PLL. The PLL uses a sampling phase-locked detector to solve the problem of carrier recovery for high code rate signals. The self-synchronization technique enables the phase cancellation of the two signals through the same path, thus eliminating the use of the phase shifter. Then the synchronization performance of the circuit is tested by using the signal source to generate QPSK signals with different symbol rates. The test results show that the recovered carrier phase noise is less than 22 milliseconds when the tuning voltage of the recovered carrier phase noise is better than -80 dBc/Hz@1kHz,VCO. Next is the analysis of the external synchronization scheme. Compared with the traditional synchronization scheme, the locking threshold is lower, and the loop stability can be maintained under the condition of low SNR. The data volume of TDD communication mode is not fixed, and will vary greatly with time. In this case, the external synchronization scheme can track the carrier changes very well.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN919.34
本文编号：2337588
[Abstract]:Over the past few decades, wireless communication systems have been transmitting data at the rate of Moore's law. Especially in recent years, the explosive growth of multimedia information has brought great challenges to the speed and capacity of mobile return network. The point to point microwave wireless transmission technology is a more economical and effective method than the traditional optical fiber or coaxial cable technology, especially in the rural areas where people are sparsely populated or in areas with complex terrain. However, microwave return communication faces many technical challenges, especially in the TDD communication mode, which is dominated by our country. The high speed transceiver switching results in a very high requirement of carrier synchronization time. In this paper, a technique to reduce synchronization time is studied. In order to reduce synchronization time, carrier synchronization can not be realized by digital circuit, so this paper proposes an analog circuit solution. In the simulation scheme, the QPSK signal must be removed from the modulation to get the quadruple frequency of the carrier by four times frequency first, and the spurious signal is introduced very close to the carrier. It takes very narrow band filter to filter out. SIR filter and open loop filter can realize narrow band function, but for practical application, open loop filter is chosen as a component of carrier recovery. Finally, the center frequency of the filter is 1.2 GHz, the relative bandwidth is 3 and the insertion loss is below 3dB. The effect of practical application is good. In order to guarantee the quality of carrier recovery, a self-synchronization circuit is designed by using PLL. The PLL uses a sampling phase-locked detector to solve the problem of carrier recovery for high code rate signals. The self-synchronization technique enables the phase cancellation of the two signals through the same path, thus eliminating the use of the phase shifter. Then the synchronization performance of the circuit is tested by using the signal source to generate QPSK signals with different symbol rates. The test results show that the recovered carrier phase noise is less than 22 milliseconds when the tuning voltage of the recovered carrier phase noise is better than -80 dBc/Hz@1kHz,VCO. Next is the analysis of the external synchronization scheme. Compared with the traditional synchronization scheme, the locking threshold is lower, and the loop stability can be maintained under the condition of low SNR. The data volume of TDD communication mode is not fixed, and will vary greatly with time. In this case, the external synchronization scheme can track the carrier changes very well.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN919.34
【参考文献】
相关硕士学位论文 前1条
1 谢睦宽;小型腔体滤波器设计技术研究[D];电子科技大学;2011年
，本文编号：2337588
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