针对传统微波辐射计集成度低、射频前端功能固化、可编程性局限在数字后端的问题,基于软件定义无线电(Software Defined Radio,SDR)技术设计并实现一款射频前端及数字处理后端均可编程的软件定义辐射计。可编程射频前端核心采用零中频...针对传统微波辐射计集成度低、射频前端功能固化、可编程性局限在数字后端的问题,基于软件定义无线电(Software Defined Radio,SDR)技术设计并实现一款射频前端及数字处理后端均可编程的软件定义辐射计。可编程射频前端核心采用零中频架构的SDR平台,实现频段、带宽、增益等可配置。数字处理后端采用嵌入ARM的FPGA,对微波辐射信号进行实时FFT频谱处理和功率谱积分,支持对射频干扰的识别和剔除。该型辐射计覆盖L、S、C波段,积分时间500~1 000 ms内可调,在L波段经实验测试得到系统灵敏度为0.13 K。就国内而言,该软件定义辐射计率先实现了射频前端可编程,支持动态调节工作波段和参数,达成了突破。展开更多
The problem of designing a digital frontend (DFE) was considered which can dynamically access or sense dual bands in any radio frequency (RF) regions without requiring hardware changes. In particular, second-order ban...The problem of designing a digital frontend (DFE) was considered which can dynamically access or sense dual bands in any radio frequency (RF) regions without requiring hardware changes. In particular, second-order bandpass sampling (BPS) as a technique that enables to realize the multiband reception function was discussed. In a second-order BPS system, digital reconstruction filters were utilized to eliminate the interferences generated while down converting arbitrarily positioned RF-band signals by using the direct digitization method. However, the inaccuracy in the phase shift or the amplitude mismatch between the two sample streams may cause insufficient rejection of interference. Practical problems were studied, such as performance degradation in signal-to-interference ratio (SIR) and compensation methods to overcome them. In order to demonstrate the second- order BPS as a flexible DFE suitable for software-defined radio (SDR) or cognitive radio (CR), a DFE testbed with a reconfigurable structure was implemented. Moreover, with a view to further demonstrate the proposed compensation algorithms, experimental results show that dual bands are received simultaneously.展开更多
基金Research financially supported by Changwon National University in 2009-2010the Second Stage of Brain Korea 21 Projects
文摘The problem of designing a digital frontend (DFE) was considered which can dynamically access or sense dual bands in any radio frequency (RF) regions without requiring hardware changes. In particular, second-order bandpass sampling (BPS) as a technique that enables to realize the multiband reception function was discussed. In a second-order BPS system, digital reconstruction filters were utilized to eliminate the interferences generated while down converting arbitrarily positioned RF-band signals by using the direct digitization method. However, the inaccuracy in the phase shift or the amplitude mismatch between the two sample streams may cause insufficient rejection of interference. Practical problems were studied, such as performance degradation in signal-to-interference ratio (SIR) and compensation methods to overcome them. In order to demonstrate the second- order BPS as a flexible DFE suitable for software-defined radio (SDR) or cognitive radio (CR), a DFE testbed with a reconfigurable structure was implemented. Moreover, with a view to further demonstrate the proposed compensation algorithms, experimental results show that dual bands are received simultaneously.
