Читать книгу Position, Navigation, and Timing Technologies in the 21st Century - Группа авторов - Страница 129

The MBS signal structure is designed to be similar to GPS so that significant reuse of the GNSS chipsets is possible. Potentially, the entire GPS baseband processing can be reused for MBS processing. One of the key differences between MBS and GPS/GNSS is the dynamic range of the terrestrial MBS signals as compared with satellite signals. In addition, MBS is a slotted system, and the receiver signal strengths can be above the receiver noise floor, necessitating an automatic gain control (AGC) with a fast response. On the other hand, GNSS signals are generally CDMA/FDMA with no slotting, and, moreover, the signals are always well below the receiver noise floor. Section 39.1.4.1 discusses the signal dynamic range, and gain control requirements for MBS, followed by Section 39.1.4.2, which discusses acquisition, tracking, and ranging of the MBS signal, and Section 39.1.4.3, which discusses position calculation using MBS ranges.