431 carrier modulation modes carrier modulation modes

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Unformatted text preview: m the transmitting station to the proper spacecraft hardware. 4.3.1 CARRIER MODULATION MODES Carrier Modulation Modes (CMMs) consist of different states of data modulation upon the RF carrier which creates the physical telecommand channel. The physical methods of modulating the carrier, which may be either spread spectrum (e.g., TDRSS) or subcarrier (e.g., conventional ground station) techniques, are described in Reference [3]. The Carrier Modulation Modes are shown in Table 4-1. Table 4-1: Carrier Modulation Modes Mode CMM-1 Unmodulated CARRIER only CMM-2 CARRIER modulated with ACQUISITION SEQUENCE CMM-3 CARRIER modulated with TC data (e.g., CLTU) CMM-4 4.3.2 State CARRIER modulated with IDLE SEQUENCE TELECOMMAND SESSION During a Telecommand Session, a series of CLTUs is transmitted to a remote spacecraft. The session begins with the initial application of the RF carrier (CMM-1) and ends with the removal of the carrier. The path is further controlled (activated or deactivated) by the selection of appropria...
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