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FM-CDR在广州地区的传输覆盖情况
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作者 叶伟明 李建威 连秀东 《广播与电视技术》 2020年第7期114-117,共4页
结合市区及周边不同区域地形情况,采用定点接收和移动接收等不同的收测方式,获取调频段数字广播(简称FM-CDR)在广州地区的地面无线覆盖和主观收听情况的第一手材料,包括所有点的信号接收场强、地理坐标和主观收听等数据,初步验证了FM-CD... 结合市区及周边不同区域地形情况,采用定点接收和移动接收等不同的收测方式,获取调频段数字广播(简称FM-CDR)在广州地区的地面无线覆盖和主观收听情况的第一手材料,包括所有点的信号接收场强、地理坐标和主观收听等数据,初步验证了FM-CDR作为一种新型的调频广播无线覆盖和接收模式替代传统调频模拟广播的可行性,以及在实际运用中存在的一些瑕疵。广州越秀山发射点采用数模同播模式中的模式9,同时传输3套广播立体声节目的模式,节目收听质量略逊于传统的模拟调频广播,通过改变FM-CDR的工作模式,增加数字广播数据传输率,提升节目收听质量。 展开更多
关键词 FM-CDR 数模同播 定点收测 移动 频谱模式
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Application of High-Density Seismic Image in Nondestructive Exploration of Cut-off Cement-Soil Wall in Earth Dam
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作者 蔡靖 王建华 张献民 《Transactions of Tianjin University》 EI CAS 2005年第2期141-145,共5页
In order to quickly explore the quality of cut-off wall in dams, a new method of high-density seismic image was adopted and estimated by model and in-situ wall tests.The vibration exciter was employed and several para... In order to quickly explore the quality of cut-off wall in dams, a new method of high-density seismic image was adopted and estimated by model and in-situ wall tests.The vibration exciter was employed and several parameters such as hypocentral distance, length of signal record and sampling space in signal collection were determined, which are 8 m, 0.25 ms and 128 ms respectively. Through time and frequency field signal analyses, it is concluded that, the smaller arrival times of reflected longitudinal and surface waves, and the higher their main frequencies, the higher the strength of the wall, vice versa. Accordingly the construction quality of the wall can be evaluated quickly by high-density seismic image. 展开更多
关键词 high-density seismic image cut-off wall nondestructive exploration signal collection
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