中文摘要：

互联网的广泛应用产生了越来越多与地理空间位置关联的文本信息。现有地理信息系统一般通过外部链接来浏览这些数据．需要频繁的缩放、漫游和点击操作，而其他方法叉难以有效表达出空间位置关系。提出了一种基于标签云的位置关联文本信息可视化方法标签云地图．给出了标签云地图的设计思路和实现流程．并以腾讯微博的真实数据集为例建立了原型，重点研究了点状和面状地理要素的Cartogram生成算法，关键字和词频的提取算法，面向不同尺度和不同时间的标签云显示规则的标签位置生成算法。实验表明．该方法能够帮助用户从大量的位置关联文本信息中快速感知并把握信息的总体特征和发展趋势。

英文摘要：

Based on the characteristics of the digital radio mondiale （DRM）, a new method of array calibration for high-frequency passive radar （HFPBR） by using frequency reference signal of direct wave is proposed. Firstly the signal structure of DRM is introduced, while the feasibility of take fre- quency reference signal as the calibration source is demonstrated. Secondly, taking into account the e- lectromagnetic environment and time-varying non-stationary propagation characteristics, a method of choosing high quality direct wave period by the shift-invariant antenna pairs is proposed. Finally, as- sist by the known DRM transmitter position, we utilized this method deal with measured direct wave data which propagate in surface wave mode and sky wave mode, compared the result of array calibra- tion value with known single frequency signal source. The results showed that the amplitude and phase compensation method in DRM-based HFPBR is effective.