一、无线电数据广播 近年来世界上出现了一些数据系统广播电台。在欧洲称为RDS(Radio Data System),即无线电数据系统;在美国称为RBDS(Radio Broadcast Data System),即无线电广播数据系统。 无线电数据广播(RDS)与SCA一样,通过调频立...一、无线电数据广播 近年来世界上出现了一些数据系统广播电台。在欧洲称为RDS(Radio Data System),即无线电数据系统;在美国称为RBDS(Radio Broadcast Data System),即无线电广播数据系统。 无线电数据广播(RDS)与SCA一样,通过调频立体声广播的子载波发射出去(子载波频率通常为57、67或76kHz),采用PSK(QPSK等)调制。带宽为7.5kHz,速率为1187.5bps。由于它是数字广播,因此与SCA相比,它具有更多优点,在许多方面获得了广泛的应用。展开更多
A novel technique called the bitmap lattice index(BLI) is proposed, which combines the advantages of a wireless broadcasting environment with a road network. Existing road networks are based on the on-demand method: a...A novel technique called the bitmap lattice index(BLI) is proposed, which combines the advantages of a wireless broadcasting environment with a road network. Existing road networks are based on the on-demand method: a server's workload increases as the query request increases when a server sends a client information. To solve this problem, we propose the BLI. The BLI denotes an object and a node as 0 and 1 in the Hilbert curve(HC) map. The BLI can identify the position of a node and an object through bit information; it can also reduce the broadcasting frequency of a server by reducing the size of the index, thereby decreasing the access latency and query processing times. Moreover, the BLI is highly effective for data filtering, as it can identify the positions of both an object and a node. In a road network, if filtering is done via the Euclidean distance, it may result in an error. To prevent this, we add another validation procedure. The experiment is conducted by applying the BLI to kNN query, and the technique is assessed by a performance evaluation experiment.展开更多
无线数据广播系统(Radio Data System,RDS)能在调频广播发射信号中利用副载波把电台名称、节目类型、节目内容及其它信息以文字形式发送出去。文章介绍了利用RDS传送广播文本的方法,首先分析RDS的原理、消息格式和编码结构,之后详细解...无线数据广播系统(Radio Data System,RDS)能在调频广播发射信号中利用副载波把电台名称、节目类型、节目内容及其它信息以文字形式发送出去。文章介绍了利用RDS传送广播文本的方法,首先分析RDS的原理、消息格式和编码结构,之后详细解说了广播文本这个组型的结构与编码方式,然后用一个具体的例子通过RDS编码生成了广播文本信息。最后,实验结果验证了其传输广播文本的正确性。展开更多
文摘一、无线电数据广播 近年来世界上出现了一些数据系统广播电台。在欧洲称为RDS(Radio Data System),即无线电数据系统;在美国称为RBDS(Radio Broadcast Data System),即无线电广播数据系统。 无线电数据广播(RDS)与SCA一样,通过调频立体声广播的子载波发射出去(子载波频率通常为57、67或76kHz),采用PSK(QPSK等)调制。带宽为7.5kHz,速率为1187.5bps。由于它是数字广播,因此与SCA相比,它具有更多优点,在许多方面获得了广泛的应用。
基金supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF2013R1A1A1004593, 2013R1A1A1A05012348)
文摘A novel technique called the bitmap lattice index(BLI) is proposed, which combines the advantages of a wireless broadcasting environment with a road network. Existing road networks are based on the on-demand method: a server's workload increases as the query request increases when a server sends a client information. To solve this problem, we propose the BLI. The BLI denotes an object and a node as 0 and 1 in the Hilbert curve(HC) map. The BLI can identify the position of a node and an object through bit information; it can also reduce the broadcasting frequency of a server by reducing the size of the index, thereby decreasing the access latency and query processing times. Moreover, the BLI is highly effective for data filtering, as it can identify the positions of both an object and a node. In a road network, if filtering is done via the Euclidean distance, it may result in an error. To prevent this, we add another validation procedure. The experiment is conducted by applying the BLI to kNN query, and the technique is assessed by a performance evaluation experiment.
文摘无线数据广播系统(Radio Data System,RDS)能在调频广播发射信号中利用副载波把电台名称、节目类型、节目内容及其它信息以文字形式发送出去。文章介绍了利用RDS传送广播文本的方法,首先分析RDS的原理、消息格式和编码结构,之后详细解说了广播文本这个组型的结构与编码方式,然后用一个具体的例子通过RDS编码生成了广播文本信息。最后,实验结果验证了其传输广播文本的正确性。
