共查询到19条相似文献,搜索用时 171 毫秒
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李永红 《环球市场信息导报》2014,(1):119-119
该文以湖南广播电视台播控中心娱乐,卡通等四频道播控系统的设计建设为例,通过切换矩阵在多频道播控系统中的应用,分析了建成后系统的功能特点。 相似文献
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为适应多频道通信的需要,在采用的频率综合技术中,锁相多环式频率综合可同时满足信号频谱纯、频道多且间隔小、换频速度快等要求。本文利用典型的带电流源鉴频鉴相器的锁相环,推导了其环路数学模型,并对其稳定性进行了讨论。最后,结合大规模集成销相环,给出一个三环式多频道频率综合器的原理框图及主要性能指标,并讨论了低噪声压控振荡器等具体电路的设计。 相似文献
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为创造宁夏广播电视总台事业发展、产业壮大的良好外围环境,在宁夏广播电视总台大力实施频道、频率“品牌化”战略,四大频道全新改版之际,由宁夏广播电视总台主办,宁夏广播电视总台广告中心承办,宁夏广播电视总台各频道频率及宁夏广播电视报等相关部门积极参与的2006宁夏广播电视总台媒介推广会于8月18日-8月21日在银川举行,来自全国的300多名专家媒体、知名企业、4A广告公司代表参加了推广会。 相似文献
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变频调速技术极大地改善了供水环境和质量,但由于恒压供水系统采用多台水泵并联运行,当水泵由变频电源向工频电源直接切换时,容易产生很大的电流冲击,对电网和电动机的寿命均不利。采用锁相环同步切换技术可实现两个电源同频率同相位的平稳切换,可大大减小电流冲击,切换过程设备运行平稳。 相似文献
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为创造宁夏广播电视总台事业发展、产业壮大的良好外围环境,在宁夏广播电视总台大力实施频道、频率“品牌化”战略,四大频道全新改版之际,由宁夏广播电视总台主办,宁夏广播电视总台广告中心承办,宁夏广播电视总台各频道频率及宁夏广播电视报等相关部门积极参与的2006宁夏广播电视总台媒介推广会于8月18日—8月21日在银川举行,来自全国的300多名专家媒体、知名企业、4A广告公司代表参加了推广会。这次媒介推广会是宁夏广播电视总台成立一年多来,第一次在自家门口举办的自我推介活动。在主题为“真情相约,体验宁夏——我们一起成长”的推广会… 相似文献
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十多年来,整个中国的发展和变化是惊人的,在电视媒体行业,情况也是这样。曾几何时,中国的电视观众只能收看到四五个电视频道,而如今,观众切换遥控器的手指都会感到酸痛,大部分城市的电视机都可以收到30-60个不同的电视频道,中国也因为拥有大小三千多家电视台,而几乎成为世界上拥有电视媒体最多的国家。对于某个城市的电视观众来说,这些媒体包含:央视十多个频道(覆盖全国)、几十个省级卫视(基本覆盖全国)、十个左右本省台的频道(覆盖全省)、几个本市、地频 相似文献
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早在1878年就出现了人工交换机,经历了人工交换、机电交换、和电子交换的发展历程,数字程控交换机已经是当今通信舞台的主演。数字程控交换机具有接续速度快、业务功能多、声音清晰、质量可靠等优点。本文主要针对交换机的发展史以及现代程控交换机的维护进行了阐述。 相似文献
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Niels Peter Mols 《International Review of Retail, Distribution & Consumer Research》2013,23(3):227-246
The existence of dual or multiple channels of distribution consisting of independent distributors in combination with producer-owned distribution channels has been documented by several researchers, and some of them find indications that dual or multiple channels of distribution are likely to become more widespread in the future. This article briefly reviews the empirical studies on and theorizing about dual channels of distribution. Then mainstream transaction cost theory is explained and used to advance eleven propositions delimiting when dual channels of distribution are efficient. Most of the propositions are explained by differences in transaction-specific investments, uncertainty, transaction frequency and the institutional environment. The rest of the propositions are based on synergistic explanations such as dual systems induce competition, they result in higher powered incentives, and they provide better information. 相似文献
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This research examines the influence of service recovery transparency on customer forgiveness to retain customers in the context of service recovery via social media. We propose that customer forgiveness mediates the effect of service recovery transparency on switchover intentions. We further posit that the effect of service recovery transparency on customer forgiveness is moderated by two additional recovery strategies, i.e., apology and explanation. The results of two studies, i.e., a survey and a scenario-based experiment, show that service recovery transparency acts to elicit customer forgiveness, which subsequently negatively affects switchover intentions. Furthermore, both apology and explanation moderate the effect of service recovery transparency on customer forgiveness. The positive effect of service recovery transparency on customer forgiveness is attenuated when an apology/explanation is absent. 相似文献
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In this research note the pricing behaviour of UK depository institutions is examined. The study uses daily interest rate data for 186 UK deposit saving accounts over the sample period, 1997-2001, which are distributed through branches and across postal and telephone networks. The relative level and dispersion of interest rates and the frequency and responsiveness of interest rate change are examined for deposit products that are distributed through different distribution channels. Slight and mostly insignificant interest rate differentials are recorded between deposit accounts distributed through branch, postal and telephone channels. Similarly, only small differences are recorded for the dispersion, frequency and responsiveness of interest rate change of deposit products distributed through different distribution channels. 相似文献
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本文提出了一种快速提取位同步的全数字锁相环方案。该方案通过对同步区、反相区以及快慢区的切换,有效地克服了同步时间与量化相位误差的矛盾。具有同步建立时间短、保持时间长、且同步精度高、抗干扰能力强等优点。 相似文献
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讨论了信道非线性特性引起的各种失真特性,利用仿真软件比较了信道非线性对单载
波和多载波数字通信的影响,总结并分析了目前常用的信道线性化技术,对于高频段多
载波数字通信系统射频信道的线性化设计具有一定的指导意义。 相似文献
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可用卫星数量的大幅增加使得传统的并行通道结构很难满足多星座卫星导航接收机的设计需求。为了减少电路规模和功耗,提出了一种通用的相关器跟踪结构,其可以跟踪GPS(Global Positioning System)/BDS(BeiDou Navigation Satellite System)/GLONASS(Global Navigation Satellite System) 3种卫星信号。该电路通过预先存储中频数据、提高相关器工作频率的方法,充分利用了每个通道的效能。这种时分复用的电路改进方法可以实现大量等效并行通道。65 nm工艺下的实验结果表明,该结构在电路资源和功耗方面优于传统结构。FPGA(Field Programmable Gate Array)的验证结果进一步证明了该电路结构的有效性和正确性。 相似文献