摘要:
A message communication system employing one or more centralized communication stations transmitting messages through Earth orbit relay satellites to mobile receivers utilizing Time Division Multiplexed (TDM) communication signals having signal time frames divided into a series of transmission channels. A predetermined number of the channels are designated as address channels with the remainder being used for data transfer. Information transmitted on the address channels is used by receivers to determine both the presence of a message and its corresponding data transmission channel. Each system receiver scans, and tracks only the communication signal address channels until a message addressed to that receiver is detected, at which time the selected receiver changes channels to the designated data channel for reception of the message. Thus, demodulation of the entire communication signal is not required and processing time and power is reduced for the typical waiting condition when messages are not being received. While a message is being received only a portion of the communication signal need to be received, demodulated and decoded. The decoded message is then displayed on a display screen or similar device for the recipient.
摘要:
A message communication system employing one or more centralized communication stations (22) transferring messages through Earth orbit repeater satellites (20) to or from mobile terminals (10) with at least one central communication station having a first transceiver for transmitting a first communication signal to one or more mobile terminals and at least one mobile terminal having a second transceiver for receiving the first communication signal and demodulating it, and for transmitting at a predetermined duty cycle of the second transceiver, a second communication signal to at least one of the central communication stations. The preferred duty cycle over which the second communication signal is transmitted is about fifty percent of the second transceiver duty cycle. The communication system uses Time Division Multiplexed (TDM) communication signals using a number of channels as designated address channels (56) with the remainder (58) being used for data transfer.
摘要:
A message communication system employing one or more centralized communication stations transmitting messages through Earth orbit relay satellites to mobile receivers utilizing Time Division Multiplexed (TDM) communication signals having signal time frames divided into a series of transmission channels. A predetermined number of the channels are designated as address channels with the remainder being used for data transfer. Information transmitted on the address channels is used by receivers to determine both the presence of a message and its corresponding data transmission channel. Each system receiver scans, and tracks only the communication signal address channels until a message addressed to that receiver is detected, at which time the selected receiver changes channels to the designated data channel for reception of the message. Thus, demodulation of the entire communication signal is not required and processing time and power is reduced for the typical waiting condition when messages are not being received. While a message is being received only a portion of the communication signal need to be received, demodulated and decoded. The decoded message is then displayed on a display screen or similar device for the recipient.
摘要:
Système de communication de messages utilisant une ou plusieurs stations de communication centralisées (22) qui transfèrent des messages par l'intermédiaire de satellites répéteurs sur orbite terrestre (20) vers ou à partir de terminaux mobiles (10), au moins une station de communication centrale ayant un premier émetteur-récepteur pour transmettre un premier signal de communication vers un ou plusieurs terminaux mobiles, et au moins un terminal mobile ayant un second émetteur-récepteur pour recevoir le premier signal de communication et le démoduler, et pour transmettre à un cycle de travail prédéterminé du second émetteur-récepteur un second signal de communication vers au moins l'une des stations de comunication centrale. Le cycle de travail préféré pendant lequel le second signal de communication est transmis correspond à 50 % environ du cycle de travail du second émetteur-récepteur. Le système de communication utilise des signaux de communication à multiplexage temporel, sur un certain nombre de canaux apellés canaux d'adresse (56), les autres canaux (58) étant utilisés pour le transfert de données.