ATSC批准候选移动数字电视标准

美国ATSC近日宣布ATSCM／H（移动／手持）标准为候选状态,这将是该标准最终成为实际移动DTV标准的另一个标志。     

ATSC标准的新发展

1引言20世纪90年代中期,美国发展数制订了ATSC标准。1998年在ATSC标准受到广为此,FCC发出征询对标准改进方案的通知。根据资料ATSC改进方案大体是沿着两个:(1)在多径环境下,改善固定;(2)移动接收的解决方案。年NAB会议上,上述两方面的实现综述如下。2在多径环境下固定接收效果的改进LinxElectronics公司经过两年的开发出ATSC兼容的DTV并在2002年NAB展会上首次产生了很大的震动。NAB会后优2003年3月又在东部华盛顿、巴MSTV(TheAssociationfor,第Linx兼容接收机的性能。测试标准:测试标准是依据在一个3分钟的持视频瞬断(hits)…     

ATSC DTV的移动接收技术

文章从改进ATSC标准、引进自适应阵列天线技术和提出快速均衡算法三方面论述了提高ATSC DTV移动接收性能的方法.通过仿真验证了这些方法的有效性.     

声表面波滤波器中虚假信号的抑制

本文介绍了声表面波滤波器设计中抑制虚假信号的方法，给出了实验结构和结果，结果表明，该方法效果较为明显。     

毫米波谐波抑制滤波器

引言谐波抑制滤波器在现代微波、毫米波接收机和测量系统中有着广泛的应用。例如,在接收机前端系统中,它们可用作为镜像抑制和通路的预选滤波器。此外,把它们和“倍频”式毫米波源结合起来,可以使其谐波成分大为降低,这无疑将会改善测量结果。这类滤波器的关键指标是要求低的通带插入损耗,高的选择性和宽的阻带。为满足这些要求,我们已经设计并试验了多种悬置基片上的平行耦合线滤波器。滤波器由在一块单片的屏蔽盒里集成的印     

TD-LTE基站接收机中镜像抑制滤波器的研究和设计

在TD-LTE基站中,接收机对射频信号中镜像频率的抑制十分重要,在很大程度上是衡量基站接收机性能优越性的重要指标。为了消除TD-LTE基站接收机中的镜像频率,需要在混频器前设计一个抗镜像滤波器。该文提出一种超高频(3GHz~30GHz)LC型镜像抑制滤波器,通过其独特的结构设计来满足TD-LTE基站接收机镜像频率的抑制要求,具有良好的一致性。可以推广到多种通信制式的测试设备、基站等产品中,具有广泛的应用前景。     

有源镜像抑制复数滤波器设计

采用SMIC 0.18μm CMOS工艺设计实现了一款3阶有源RC复数滤波器.该滤波器适用于无线传感网射频接收机.滤波器中心频率为3MHz,带宽为250kHz/500kHz/1MHz/2MHz可配置,仿真结果显示,滤波器通带增益约为10dB,镜像抑制大于35dB,噪声系数小于45dB,三阶交调点(IIP3)优于28.5dBm,消耗电流为0.9mA.经仿真验证,该设计各项性能均满足无线传感网射频接收机要求.     

ATSC标准中8-VSB调制器的算法改进及FPGA设计实现

重点介绍了ATSC标准的8-VSB系统构架以及FPGA系统的具体实现方案.根据具体标准的参数要求,分析了ATSC标准.基于改进的维弗法,提出了频率范围可变的低中频数字信号输出解决方案,给出了系统硬件的设计步骤,并给出实测结果.     

新型高抑制波导滤波器设计

提出了一种新颖的波导带通滤波器设计。该滤波器是一个四阶广义切比雪夫滤波器,中心频率为9.93GHz,带宽为200 MHz,插损小于0.5 dB,带内回波损耗大于20 dB。谐振器为CQ结构,通过一个矩形波导膜片(一个不完全高度的导电杆),实现了交叉耦合,相比传统方法,产生一个额外的传输零点。由于在高端产生了两个零点,使得滤波器在阻带高端10.1 GHz处的带外抑制达到了35 dB以上。仿真实验证明了该设计方法能显著提高滤波器的带外抑制,对滤波器的小型化、高性能化有一定的意义。     

ATSC Terrestrial Digital Television Broadcasting Using Single Frequency Networks

In this paper, we propose an efficient method to broadcast digital television signals using single frequency networks (SFNs) within the Advanced Television Systems Committee (ATSC) transmission systems. In implementing the SFNs of an 8‐vestigial side band (8‐VSB) Digital Television (DTV) system, the ambiguity problem of the trellis coder is unavoidable in a conventional ATSC transmission system. We propose a memory initialization of the trellis coder to resolve this ambiguity problem. Since the proposed scheme to synchronize multiple transmitters minimizes the changes from the conventional ATSC system, the hardware complexity for these changes is very low. Our simulation results show that the proposed scheme makes a less than 0.1 dB degradation at the threshold of visibility with a bit error rate of 3×10^?6 in the additive white Gaussian noise (AWGN) channel. It is possible to reduce the performance degradation by increasing the initialization period of the proposed scheme.     

A Novel Data Transmission Scheme for ATSC Terrestrial DTV Systems

In Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) systems, additional very low‐rate data can be transmitted by modulating the amplitude and polarity of the transmitter identification (TxID) signal. Although the additional data transmission scheme offers reliable transmission and has a very large coverage area, it has a limitation on the data rate. In this paper, we propose a novel additional data transmission scheme based on the TxID sequences of the ATSC DTV system and Walsh modulation. The proposed scheme not only increases the data rate significantly, but also offers a virtually identical coverage area compared to a conventional scheme.     

Near‐Optimum Blind Decision Feedback Equalization for ATSC Digital Television Receivers

This paper presents a near‐optimum blind decision feedback equalizer (DFE) for the receivers of Advanced Television Systems Committee (ATSC) digital television. By adopting a modified trellis decoder (MTD) with a trace‐ back depth of 1 for the decision device in the DFE, we obtain a hardware‐efficient, blind DFE approaching the performance of an optimum DFE which has no error propagation. In the MTD, the absolute distance is used rather than the squared Euclidean distance for the computation of the branch metrics. This results in a reduction of the computational complexity over the original trellis decoding scheme. Compared to the conventional slicer, the MTD shows an outstanding performance improvement in decision error probability and is comparable to the original trellis decoder using the Euclidean distance. Reducing error propagation by use of the MTD in the DFE leads to the improvement of convergence performance in terms of convergence speed and residual error. Simulation results show that the proposed blind DFE performs much better than the blind DFE with the slicer, and the difference is prominent at the trellis decoder following the blind DFE.     

An efficient decision feedback equalizer for the ATSC DTV receiver

In this paper an efficient decision feedback equalizer is presented for the equalization of the received signal in the eight level vestigial sideband, Advanced Television Systems Committee, digital television system, adopting a novel detection rule for symbol detection at the output of the equalizer. The conventional hard limiter is replaced by an efficient symbol detection algorithm, based on the underlying trellis coded modulated coding of the transmitted symbols. The proposed decision device has a marginal computational cost and it can be implemented using simple combinatorial and sequential logic circuitry. When the equalizer operates in the decision directed mode, the normalized least mean squared algorithm is utilized for the adaptation of the equalizer coefficients, in a “stop-and-go” like mode, triggered by a reliability signal associated to the detected symbols. The performance of the proposed method is illustrated by typical computer simulation.     

对ATSC 3.1版物理层的个人建议

ATSC正在积极制定ATSC 3.0版;预计2015年底将完成标准草案。提出其中可补充的3方面技术,作为对ATSC 3.1版物理层的个人建议:1)增加单载波调制的可选项(n-VSB和n-QAM等);2)增加"单频道方案"(仅使用指派频道)实现"回传信道"的可选项,作为"空白频道方案"的补充;3)增加由中国工程师们自主创新的"宽带数字电视(DTV)发射机+M-SFN(多频道单频网)技术"组建DTTB网络,而当它使用于单载波系统的高比特率传输固定接收服务时(如4K/8K-UHDTV),具有一定技术优势。     

高带外抑制声表面波扇形滤波器的研制

根据混合场等效电路模型,详细分析了抽指加权结构对扇形又指换能滤波器频响的影响。在考虑了指间反射、三次行程以及指条寄生阻抗等情况下,根据扇形换能器的导纳矩阵及其外围电路参数得到器件总的频率响应,并通过改变发射和接收换能器指对数来改善扇形又指换能滤波器带外抑制。     

一种实现高带外抑制声表面波滤波器结构

为了获得高的带外抑制，我们设计了一种单相单向换能器与镜像阻抗连结换能器结合的滤波器结构。该结构由双通道组成，每通道上由一个电级宽度控制单相单向端变迹加权换能器和一个抽指加权换能器组成，它具有带外抑制高、插损小、体积小和制作容易等优点，克服了常规滤波器级联带来的插损大，难匹配的问题。最后给出了我们制作在１２７．８６°Ｙ－ＸＬｉＮｂＯ＿３基片上的高带外抑制声表面波滤波器结果，其中心频率为７０ＭＨｚ，带宽为１．５ＭＨｚ，带外抑制大于７０ｄＢ，插损小于１３ｄＢ，芯片尺寸小于５ｍｍ×１０ｍｍ。     

高阻带抑制有源声表面波滤波组件

介绍有源声表面波滤波组件的设计思路。报道最新研制的高性能滤波组件，其中心频率４０ＭＨｚ，３ｄＢ相对带宽０．８％，阻带抑制优于１００ｄＢ，矩形系数（Δｆ１００ｄＢ／Δｆ３ｄＢ）小于３，输入输出端口电压驻波比接近１。组件体积８５ｍｍ×３５ｍｍ×２４ｍｍ，重量小于１１５ｇ     

ATSC DTV系统中TCM编译码器的实现和简化

对ATSC DTV 8 VSB系统调制器中数据处理部分进行分析,给出一种硬件实现方案。采用一个2/3码率的TCM编码器代替ATSC标准中12支路并行的编码器,并自然地插入了同步数据,从而降低了系统复杂度。针对系统中TCM译码器,提出一种可变译码深度的译码方法,简化了系统的控制。结合联合均衡和TCM译码技术,提出多重深度译码的方法,降低了错误传播对判决反馈均衡器的影响,从而提高均衡器的性能。