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许多目前工作的通信卫星系统和事实上已纳入计划的所有这种系统都使用数字传输技术。这种技术使具有不同振幅和频率的模拟音频信号转换成短的码脉冲或比特,这样就可以使用不同的技术来增加信道的信息容量,允许在给定的频带和时间内传输更多信息。许多这样的技术允许同时传送多路会话。为克服环境困难,例如雨致高频信号(10千兆赫以上)衰减,要进行有效的通信,这些技术也是有价值的。
Many of the currently operating communications satellite systems and virtually all such systems that have been factored into the plan use digital transmission technology. This technique converts analog audio signals of different amplitudes and frequencies into short code pulses or bits so that different techniques can be used to increase the channel’s information capacity, allowing more information to be transmitted over a given frequency band and time. Many of these technologies allow multiple sessions to be transmitted at the same time. These techniques are also valuable for overcoming environmental difficulties such as attenuation of rain-induced high-frequency signals (above 10 gigahertz) for effective communications.