Abstract: In a TDMA system comprising a plurality of earth stations communicable with one another by the use of a plurality of carrier waves through a transponder of a satellite which has an available electric power level, bursts carried by the carrier waves are individually and flexibly controlled in accordance with a burst time plan so that selected ones of the carrier waves have on the satellite a total electric power level which does not exceed the available electric power level at any time. The bursts therefore may have different power levels in dependency upon scales of the earth stations, traffics carried by the bursts, and receiving conditions at the earth conditions. The selected carrier waves can be transmitted or received by frequency hopping. Such control of the power level is carried out in each earth station by the use of a combination of an attenuator (67) and an attenuation control circuit (71) operated in accordance with the burst time plan.

Abstract: In each terrestrial station (12), a collecting circuit (97) collects those state information signals as a collected signal which represent states of operation of communication devices (94, 95). A state information signal sending device (101) sends the collected signal in a state information time slot which is predetermined in a TDMA frame outwardly of a standard/synchronization burst part and a data burst part for a standard earth station (10) and all terrestrial stations. The state information time slot is selected in different TDMA frames by the terrestrial stations. A central supervise/control apparatus (40) accompanying the standard earth station monitors the terrestrial station in response to the collected signals extracted from the respective TDMA frames. An alarm signal sending device (115) may send an alarm signal representative of an extraordinary state of operation in a synchronization burst of the terrestrial station in question.

Abstract: In a TDMA satellite communication network comprising a plurality of earth stations, a predetermined one of the stations is operable as a primary reference station for producing a first and a second reference burst to define a multiframe and a frame in an up-link signal, respectively. A synchronization burst is placed at every multiframe by each station with reference to the first and the second reference bursts detected from a down-link signal. A subsidiary reference station is selected from the remaining station to produce a specific one (SY2) of the synchronization bursts and a subsidiary reference burst (SR1) which is placed at the same time instant as the first and the second reference bursts. When the first and the second reference bursts disappear from the down-link signal, each station keeps synchronization with reference to the specific synchronization burst. Thereafter, synchronization is kept in each station with reference to the subsidiary reference station.

Abstract: Like a conventional time division multiplex communication device, a device according to this invention comprises first terminals, a switching matrix, transducers or C/E buffers, control circuits, and second terminals. The first and second terminals are for low-speed and high-speed signal sequences. The control circuits are connected to the second terminals. In contrast to the conventional one, the transducers are connected to the respective first terminals, with the switching matrix interposed between the transducers and the control circuits and rendered capable of dealing with the high-speed signal sequences, among others, rather than the low-speed ones as in the conventional device. The devices are particularly useful in earth stations of TDMA satellite communication to which multi-transponder operation is applied, although useful also in carrying out conversion between low-frequency analog signal or PAM signal sequences and PAM signal sequences of a higher rate.

Abstract: A burst synchronization technique employed in a multiple access TDMA communication system in which all member stations communicate through a common repeater apparatus such as a stationary satellite.A member station may gain access by transmitting during its allocated time slot. A time frame is defined as having a time duration equal to at least the time for the burst intervals of all the member stations preferably with at least a small guard time between bursts. A super-frame is defined as containing a plurality of frames which are sufficient in number to provide for a measurement period, a correction period and advance notice period and a propagation period.

Abstract: An initial acquisition technique for a time division multiple access (TDMA) communication system, employing an access signal of a frequency varying periodically in a predetermined relation to the TDMA time frame. Means are provided for detecting when the frequency of the signal as relayed back to the accessing station is at a predetermined value or within a predetermined frequency band to obtain the desired transmission timing information without necessitating use of any automatic frequency control means despite any deviation in the central frequency of the signal occurring during its travel.