Space diversity system in PCM-TDMA telecommunication system using stationary communication satellite

In a space diversity satellite PCM-TDMA telecommunication system of the type including at least a pair of ground antennas located at separate sites and a satellite generally stationary with respect to the ground antennas, each of the ground antennas and the satellite defining therebetween a respective space signal channel through which signals are transmitted between the satellite and the ground antennas, the satellite including a transmitter for transmitting PCM signals in a burst mode to the ground antennas, and at least two receivers each connected to a respective one of the ground antennas for receiving signals transmitted from the satellite, the improvement which comprises:

• a respective signal conversion means connected to each of the receivers for converting received PCM burst mode signals, transmitted from the satellite through the respective space channels, into synchronized PCM signals synchronized with respective clock pulse trains;
• phase difference detecting means connected to receive the respective synchronized PCM signals from the respective signal conversion means for developing phase difference signals representative of phase differences between the respective synchronized PCM signals and which phase differences are representative of the difference between the arrival times of PCM signals transmitted from the satellite and received at respective ones of the ground receiving antennas;
• first delay means connected to receive the respective synchronized PCM signals from one of said signal conversion means for delaying the respective synchronized PCM signals by a fixed delay equal to a fixed delay in arrival time of the PCM burst mode signals, transmitted from the satellite through the space transmission channel corresponding to said one of said signal conversion means, after the arrival time of the PCM burst mode signals transmitted from the satellite through the space transmission channel corresponding to the other of said signal conversion means, thereby to correct the fixed delay;
• second delay means connected to receive the respective synchronized PCM signals from the other one of said signal conversion means, and responsive to the output of said phase difference detecting means for delaying the synchronized PCM signals in dependence on the phase difference signals for correcting a variation of the arrival time difference between the arrival times of the PCM burst mode signals received at the ground station antennas which occurs in response to motion of the satellite relative to the ground antennas;
• and
• signal selecting means, connected to receive the delayed synchronized PCM signals developed by said first delay means corresponding to one of the space channels and connected to receive the delayed synchronized PCM signals developed by said second delay means corresponding to the other of the space channels, and operable for selecting one of the delayed synchronized PCM signals in accordance with the signal quality of the PCM signals transmitted through the respective space signal channels.