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In a satellite system, a time frame to be used for establishing a time correlation between the satellite system and a ground station is inserted between the transmission frames at an arbitrary timing. The ground station computes the time at which the data was generated in the satellite system from t

In a satellite system, a time frame to be used for establishing a time correlation between the satellite system and a ground station is inserted between the transmission frames at an arbitrary timing. The ground station computes the time at which the data was generated in the satellite system from this time frame and establishes a time correlation with the satellite time by using only this time frame.

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What is claimed is: 1. A time synchronization system comprising: a satellite system transmitting a time frame by inserting the time frame between transmission frames at a specified timing, wherein the time frame comprises a frame containing information that indicates a time in the satellite for tim

What is claimed is: 1. A time synchronization system comprising: a satellite system transmitting a time frame by inserting the time frame between transmission frames at a specified timing, wherein the time frame comprises a frame containing information that indicates a time in the satellite for time synchronization; and a ground system acquiring a ground time at which data is generated in the satellite system based on the information indicating a time in the satellite in the time frame inserted between the transmission frames, wherein the satellite system appends a satellite time to data in the transmission frames when the data is generated in the satellite system, wherein the time in the satellite for time synchronization of the time frame can be matched to a time in the ground system with substantially higher accuracy than the satellite time appended to the data in the transmission frames, and where the acquiring of the ground time at which the data is generated in the satellite system, is also based on the satellite time appended to the data. 2. A time synchronization system according to claim 1, wherein the satellite system generates the transmission frames by packetizing the data generated in the satellite system. 3. A time synchronization system according to claim 1, wherein the satellite system comprises a plurality of equipments each generating a set of observation data and the data generated in the satellite system comprises the observation data. 4. A time synchronization system according to claim 3, wherein each of the equipments has an internal time, and the satellite system distributes a time clock to each of the equipments and synchronizes the internal time of each of the equipment with the internal satellite time. 5. A time synchronization system according to claim 1, wherein there are differing times between generation of the generated data and transmission of frames containing the generated data. 6. A time synchronization system comprising: a satellite system transmitting a time frame by inserting the time frame between transmission frames at a specified timing, wherein the time frame comprises a frame containing information that indicates a time in the satellite for time synchronization; and a ground system acquiring a ground time at which data is generated in the satellite system based on the information indicating a time in the satellite in the time frame inserted between the transmission frames, wherein the satellite system appends a satellite time to data in the transmission frames when the data is generated in the satellite system, wherein the satellite system comprises a plurality of equipments each generating a set of observation data and the data generated in the satellite system comprises the observation data and the data generated in the satellite system comprises the observation data, each of the equipments, the satellite system distributes a time clock to each of the equipments and synchronizes the internal time of each of the equipment with the internal satellite time, and the satellite system corrects the satellite time depending upon a change in temperature. 7. A time synchronization system comprising: a satellite system transmitting a time frame by inserting the time frame between transmission frames at a specified timing, wherein the time frame comprises a frame containing information that indicates a time in the satellite for time synchronization; and a ground system acquiring a ground time at which data is generated in the satellite system based on the information indicating a time in the satellite in the time frame inserted between the transmission frames, wherein the satellite system appends a satellite time to data in the transmission frames when the data is generated in the satellite system, wherein there are differing times between generation of the generated data and transmission of frames containing the generated data, and the satellite system estimates an amount of change in the frequency to be used for acquiring satellite time depending upon a change in the internal temperature, and transmits the estimated amount of change in the frequency by inserting the estimated amount of change into the transmission frame, while the ground system corrects the ground time at which the data is generated in the satellite system by taking into account the estimated amount of change in the frequency. 8. A time synchronization system comprising: a ground system receiving from a satellite system a stream of frames comprising data frames and time frames, where the data frames carry data, where the time frames are between the data frames, where the time frames each contain a satellite time, where the satellite times each are generated at a substantially consistent length of time before transmission, and where the times in the time frames are capable of being used by the ground system to determine corresponding ground times at which data in the data frames were generated or acquired in the satellite system, wherein some of the data frames include a data time of their respective data, wherein some data frames have a preceding time frame or a following time frame, respectively preceding or following the data frame, and where, a difference in time between the data time of a data frame and the satellite time of its preceding or following time frame can substantially vary between successive data frames, and where the ground time of the generation or acquisition of data in a data frame is determined based on the satellite time of its preceding or following time frame, the data time of the data frame, and a ground time of receiving the preceding or following time frame.