| 摘要 |
A mobile satellite communications terminal (2) comprises a portable computer (68), an interface card (8) containing intermediate frequency (IF) conversion circuitry (28, 52), and an antenna assembly (10) including RF conversion circuitry (34, 50) and an antenna (44). The interface card (8) is connected to the antenna assembly (10) by a detachable cable (32), which carries IF signals. This arrangement reduces RF power losses and interference. The antenna (44) is manually steerable towards a geostationary or quasigeostationary satellite (12). A navigation signal antenna (56) is mounted on the antenna assembly (10) and is steerable independently of the antenna (44) so as to be vertically aligned, which is the optimum position for receiving navigation signals. The antenna assembly (10) includes orientation sensors (70, 75) which allow the difference between the current and the correct orientation of the antenna (44) to be calculated. This difference is indicated to the user to assist manual steering of the antenna (44). |
