초록 ▼

The satellite communication system has a ground station and multiple remote terminal units (RTUs). The RTUs are designed to infrequently transmit relatively short duration messages, and to repeatedly transmit the same message, so that it is received by a sweeping high gain satellite antenna. To mini

The satellite communication system has a ground station and multiple remote terminal units (RTUs). The RTUs are designed to infrequently transmit relatively short duration messages, and to repeatedly transmit the same message, so that it is received by a sweeping high gain satellite antenna. To minimize costs, the system is designed to allow the use of RTUs that use a fixed modulation scheme. Because the transmissions are infrequent and short, the loss of messages due to collisions is unlikely. As a further optimization, the RTUs have CDMA transmitters that each use the same CDMA code, and the ground station has multiple CDMA correlators using the same CDMA code. By using the same CDMA code, the loss of messages due to collisions is further reduced. For transmitting to the RTUs, the ground station has multiple CDMA modulators, each using a second CDMA code that is preferrably orthogonal to the first CDMA code.

대표청구항 ▼

1. A communication system comprising: a plurality of remote terminal units, each including a transmitter that transmits a transmission message to a satellite having a service area and a high-gain antenna with a field of view that sweeps the service area during a sweep period, such that the transmi

1. A communication system comprising: a plurality of remote terminal units, each including a transmitter that transmits a transmission message to a satellite having a service area and a high-gain antenna with a field of view that sweeps the service area during a sweep period, such that the transmitter is within the field of view for an illumination period that is substantially less than the sweep period and the transmission message has a message duration that is less than the illumination period; and, a ground station that receives retransmission messages corresponding to the transmission message of at least a first terminal unit of the plurality of remote terminal units when the transmitter of the first terminal unit is within the field of view.