C波段宽带正交调制载波泄漏高抑制技术的实现
发布时间：2018-09-03 08:30
【摘要】：I/Q正交调制是通信系统中的主要调制方式之一。单芯片I/Q正交调制器是目前通信系统主要的硬件实现平台。但受工艺以及器件误差的影响,在宽频带正交调制系统中,单芯片调制器的I/Q直流偏置很难实现一致,从而导致调制输出端存在载波泄漏。在正交调制设备中,载波泄漏过大,将会增加系统后级PA的非线性,使得发射EVM性能下降,同时还会降低系统接收端的灵敏度,使误码率增高,从而直接降低系统的性能。本文所研制的设备主要应用于C波段宽带卫星通信系统中心站,频率覆盖范围2.4GHz~4GHz,系统要求正交调制设备的载波泄漏抑制为50dB,本文所研究的技术正是基于实现该指标而开展的。在宽频带正交调制系统中,产生载波泄漏的主要原因是由于输入到调制器的I/Q支路直流偏置的不平衡导致。因此要实现正交调制载波泄漏抑制,需要对调制器I/Q两路信号的直流偏置进行修正。目前修正正交调制I/Q直流偏置的方法主要有平衡技术、载波相移技术、基于功率检测器的矫正技术、数字基带矫正技术等。平衡技术主要用于窄带系统;载波相移技术、基于功率检测校准技术以及数字基带矫正技术虽然可实现较好的载波泄漏的抑制,但是需要增加复杂的硬件路,从而增加设备体积、成本以及功耗。基于上述各方案的特点,本文提出了一种基于LXI频谱仪LAN口自动闭环修正正交调制I/Q直流偏置修正技术。该技术主要是利用LXI仪器厂家提供的LXI接口规范,在PC机安装LXI仪器厂家提供的动态库驱动文件,然后编程通过LAN口读取LXI仪器动态库文件中功率和频率测试参数,再通过配置正交调制设备中DA寄存器参数对其I/Q直流偏置进行修正。该技术的特点是采用自动闭环的方式,在不增加检波、AD、变频等硬件电路的情况下,实现对正交调制载波泄漏的高抑制,极大降低了设备的体积和成本。在-40℃~+70℃全温范围,本文实现了2.4GHz~4GHz频率范围载波泄漏60dB抑制,最终完成了8套设备的研制。本文研究的技术理论上可实用于任何频带的正交调制系统,是一种非常有意义的技术。
[Abstract]:I / Q quadrature modulation is one of the main modulation methods in communication systems. Single chip I / Q quadrature modulator is the main hardware implementation platform of current communication system. However, due to the influence of process and device errors, I / Q DC bias of single chip modulator is difficult to achieve in broadband quadrature modulation system, which leads to carrier leakage in modulation output. In quadrature modulation equipment, if the carrier leakage is too large, it will increase the nonlinearity of the post-stage PA of the system and make the transmitting EVM performance decline. At the same time, it will also reduce the sensitivity of the system receiver and increase the bit error rate, thus directly reducing the performance of the system. The equipment developed in this paper is mainly used in the central station of C-band broadband satellite communication system with a frequency coverage range of 2.4 GHz and 4 GHz, and the carrier leakage suppression of the quadrature modulation equipment is required to be 50 dB. The technology studied in this paper is based on the realization of this index. In a broadband quadrature modulation system, the main cause of carrier leakage is the imbalance of the I / Q branch DC bias input to the modulator. Therefore, in order to suppress the leakage of orthogonal modulation carrier, the DC bias of the modulator I / Q signal needs to be corrected. At present, the methods of correcting I / Q DC bias by orthogonal modulation mainly include balance technique, carrier phase shift technique, power detector based correction technology, digital baseband correction technology and so on. Balance technology is mainly used in narrow band system, carrier phase shift technology, based on power detection and calibration technology and digital baseband correction technology can achieve better carrier leakage suppression, but need to add complex hardware circuit. This increases the volume, cost, and power consumption of the device. Based on the characteristics of the above schemes, an I / Q DC bias correction technique based on LAN port automatic closed-loop correction for LXI spectrometer is presented in this paper. This technology mainly uses the LXI interface specification provided by the LXI instrument manufacturer to install the dynamic library driver file provided by the LXI instrument manufacturer on the PC machine, and then program to read the power and frequency test parameters of the LXI instrument dynamic library file through the LAN port. Then the I / Q DC bias is corrected by configuring the parameters of the DA register in the quadrature modulation equipment. The characteristic of this technique is that it can reduce the leakage of quadrature modulation carrier and greatly reduce the volume and cost of the equipment without adding the hardware circuits such as ADD frequency conversion and so on. In the full temperature range of -40 鈩，
本文编号：2219440
[Abstract]:I / Q quadrature modulation is one of the main modulation methods in communication systems. Single chip I / Q quadrature modulator is the main hardware implementation platform of current communication system. However, due to the influence of process and device errors, I / Q DC bias of single chip modulator is difficult to achieve in broadband quadrature modulation system, which leads to carrier leakage in modulation output. In quadrature modulation equipment, if the carrier leakage is too large, it will increase the nonlinearity of the post-stage PA of the system and make the transmitting EVM performance decline. At the same time, it will also reduce the sensitivity of the system receiver and increase the bit error rate, thus directly reducing the performance of the system. The equipment developed in this paper is mainly used in the central station of C-band broadband satellite communication system with a frequency coverage range of 2.4 GHz and 4 GHz, and the carrier leakage suppression of the quadrature modulation equipment is required to be 50 dB. The technology studied in this paper is based on the realization of this index. In a broadband quadrature modulation system, the main cause of carrier leakage is the imbalance of the I / Q branch DC bias input to the modulator. Therefore, in order to suppress the leakage of orthogonal modulation carrier, the DC bias of the modulator I / Q signal needs to be corrected. At present, the methods of correcting I / Q DC bias by orthogonal modulation mainly include balance technique, carrier phase shift technique, power detector based correction technology, digital baseband correction technology and so on. Balance technology is mainly used in narrow band system, carrier phase shift technology, based on power detection and calibration technology and digital baseband correction technology can achieve better carrier leakage suppression, but need to add complex hardware circuit. This increases the volume, cost, and power consumption of the device. Based on the characteristics of the above schemes, an I / Q DC bias correction technique based on LAN port automatic closed-loop correction for LXI spectrometer is presented in this paper. This technology mainly uses the LXI interface specification provided by the LXI instrument manufacturer to install the dynamic library driver file provided by the LXI instrument manufacturer on the PC machine, and then program to read the power and frequency test parameters of the LXI instrument dynamic library file through the LAN port. Then the I / Q DC bias is corrected by configuring the parameters of the DA register in the quadrature modulation equipment. The characteristic of this technique is that it can reduce the leakage of quadrature modulation carrier and greatly reduce the volume and cost of the equipment without adding the hardware circuits such as ADD frequency conversion and so on. In the full temperature range of -40 鈩，
本文编号：2219440
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