Quadrature amplitude modulation ( QAM ) can get a higher channel band efficiency, has been widely used in high-speed underwater acoustic communication. 正交幅度调制(QAM)可以获得更高的信道频带(CB)效率,在高速水声通信中得到了广泛使用。
Narrow channel band, severe multipaths and frequency dispersion are the main obstacles in reliable high data rate underwater acoustic communications. 信道带宽有限、多径干扰强、频率扩散严重是实现高速和可靠的水声通信的主要障碍。
A seven channel band pass filter was made by the technique through a 1 cm chirped phase mask with chirping amount of 10 nm / cm. 利用啁啾量为10nm/cm,长度为1cm的啁啾相位掩模板制作了7信道的带通滤波器。
Because no separate pilot is used for channel estimation, channel band is saved. As the simulation shows, hidden pilot can save 9 % 11 % of the channel band. 由于节省了信道估计用的导频,因此节省系统带宽,仿真显示,隐藏导频的信道估计方法可以节省9%11%左右的系统带宽。
Application of An Multi Channel Wide Band Digital Strain Monitoring System on a Construction Site 多点、宽频带、数字化系统在建筑工程中的应用