Abstract: A transmission system that can continue communication even if a tracking error exists and to reduce interference on other transponders when transmitting a video and audio between an endstation facility and another endstation facility via a transponder mounted on communications satellite. This transmission system includes a tracking antenna that tracks a transponder, a tracking error calculation circuit that obtains a tracking error in a tracking operation of the tracking antenna, a transmission level control circuit that obtains a transmission level of a signal in response to the tracking error, and a transmitter that transmits the signal at the obtained signal level via the tracking antenna to the transponder of the communication target.

Abstract: A transmission system that can continue communication even if a tracking error exists and to reduce interference on other transponders when transmitting a video and audio between an endstation facility and another endstation facility via a transponder mounted on communications satellite. This transmission system includes a tracking antenna that tracks a transponder, a tracking error calculation circuit that obtains a tracking error in a tracking operation of the tracking antenna, a transmission level control circuit that obtains a transmission level of a signal in response to the tracking error, and a transmitter that transmits the signal at the obtained signal level via the tracking antenna to the transponder of the communication target.

Abstract: Communication is performed without paying attention to the fact that the communication is executed between multimedia terminals having communication procedures differing from each other. A terminal 2 starts a communication procedure that is necessary to establish a communication path to a communication service unit 1, in order to execute communication with a multimedia terminal 3; when a communication protocol conversion unit 7 receives communication start request from the terminal 2, the communication service unit executes identification process of a calling terminal based on the identification number, which exists in communication start request, for determining the multimedia terminal 2, and inquires a terminal information managing unit 9 of the calling terminal. The terminal information managing unit 9 retrieves terminal information related to the calling terminal based on a terminal information request, and informs of the retrieved terminal information to the communication protocol conversion unit 7.

Abstract: Communication is performed without paying attention to the fact that the communication is executed between multimedia terminals having communication procedures differing from each other. A terminal 2 starts a communication procedure that is necessary to establish a communication path to a communication service unit 1, in order to execute communication with a multimedia terminal 3; when a communication protocol conversion unit 7 receives communication start request from the terminal 2, the communication service unit executes identification process of a calling terminal based on the identification number, which exists in communication start request, for determining the multimedia terminal 2, and inquires a terminal information managing unit 9 of the calling terminal. The terminal information managing unit 9 retrieves terminal information related to the calling terminal based on a terminal information request, and informs of the retrieved terminal information to the communication protocol conversion unit 7.

Abstract: Encoding and decoding devices which are capable of increasing the encoding and decoding speed. In arithmetic encoding, there is a possibility of encoding with high efficiency which is very close to the entropy of the information source, but the encoding and decoding time is generally longer than that in another encoding systems such as an MMR encoding system. For example, in a standard facsimile equipment, about 1.3 sec is required for encoding the picture information in an A4-size copy. In prediction encoding, a memory for storing the past reference symbols and the predicted values therefor is necessary for prediction. Since the memory capacity is generally large, a large-capacity RAM is used. The encoding time is therefore greatly dependent on the access speed of the RAM.