Highly reliable distribution control unit with improved control capability

Claim 1

In a communications satellite system of the space division-type, including spot beam antennas receiving uplink communications signal from a plurality of earth stations and transmitting said uplink signals over downlinks to said earth stations, said uplinks being communicated to said downlinks through a switching matrix forming an array of inputs and outputs interconnected in a row and column fashion through electrically controllable crosspoint switching elements, each uplink being designated to a different matrix input and each downlink to a different matrix, output, and a distribution control unit for controlling the conductive states of said crosspoint switching elements, said satellite system operable in a time division mode with uplinks communicating with downlinks in a cyclical fashion, a complete cycle occurring over a frame time, each frame being subdivided into frame units, said distribution control unit including means for dynamically varying the conductive states of said crosspoint switching elements such that a different connection pattern can occur in each frame unit, wherein the improvement comprises: (a) means for generating digital control words, each bit position of said words functioning to control the conductive state of a different crosspoint switching element; (b) a plurality of memory means, at least one such memory means being associated with each input row of said matrix, each of said memory means storing a plurality of digital control words equal in number to at least the number of frame units in the frame time, each control word containing a number of bit positions equal at least to the number of crosspoint switching elements in the input row, with which the memory is associated; and (c) means corresponding to each bit position of a digital control word for controlling the conductive states of the crosspoint switching elements in accordance with the value of the bit in the corresponding bit position, whereby any number of switching elements in each input row can be rendered simultaneously conductive to effect point-to-multipoint interconnection between matrix inputs and outputs during dynamic operation of the satellite system in the time division mode.