Abstract: A system and method for pointing a non-tracking antenna in a geo-synchronous satellite-based communication system is provided. A satellite terminal antenna is initially pointed towards the target satellite by any desired method. The antenna bore sight is then aligned towards the center of a satellite station-keeping box for operational use. By pointing the antenna bore sight towards the center of the satellite station-keeping box, the largest excursion between the antenna's bore sight and the actual satellite position is no greater than half the diagonal of the satellite station-keeping box despite the fact that satellite will move within the satellite station-keeping box's outer limits after the installation of the non-tracking antenna.

Abstract: A network of personal communications terminals communicating in a CDMA mode includes a reference station for transmitting a pilot tone that is pre-corrected at the reference station and is used at the remaining stations for frequency control, transmit power control and antenna acquisition and tracking. Voice activation is employed to permit the CDMA system to share the satellite transponder power and bandwidth in a fully Demand-Assignment-Multiple-Accessing (DAMA) manner. Burst-mode operation of a voice activated CDMA system is permitted by sending dummy data in the speech pausing period at a reduced (but not zero) power level, and the "near-far" problem inherent in a CDMA system is mitigated by the use of uplink power control.

Abstract: In a secure communications system, a key number which is changed periodically, e.g. monthly, and a random number from a random number generator are combined and used as a seed to reset a PN sequence generator, with the output of the generator being used to control encryption of transmission data in a signal processor. The key is also provided to a first encipherer to encipher the random number for transmission with the encrypted data. At the receiver, the key is provided on common to a decipherer for deciphering the random number and a PN sequence generator which is periodically reset by the combination of the key and random number in the same manner as in the transmitter. The PN sequence is then used to decrypt the information. User identification codes are stored in the transmitter and are used to encipher the key, with each employing its ID code to decipher the key. The user ID codes are known only to the system operator, so that not even a particular user can know the key.

Abstract: In a secure communications system, a key number which is changed periodically, e.g. monthly, and a random number from a random number generator are combined and used as a seed to reset a PN sequence generator, with the output of the generator being used to control encryption of transmission data in a signal processor. The key is also provided to a first encipherer to encipher the random number for transmission with the encrypted data. At the receiver, the key is provided on common to a decipherer for deciphering the random number and a PN sequence generator which is periodically reset by the combination of the key and random number in the same manner as in the transmitter. The PN sequence is then used to decrypt the information. User identification codes are stored in the transmitter and are used to encipher the key, with each employing its ID code to decipher the key. The user ID codes are known only to the system operator, so that not even a particular user can know the key.