Satellite communications transmission apparatus and method

• US 4,010,420 A
• Filed: 01/13/1975
• Issued: 03/01/1977
• Est. Priority Date: 01/14/1974
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Reiner, Udo, Zilg, Jochen
• Primary Examiner(s): Richardson, Robert L.
• Assistant Examiner(s): Masinick, Michael A.
• Application Number:
  US05/540,548
• Time in Patent Office: 778 Days
• Field of Search: 325/4, 325/58, 179/15 BS, 343/176, 343/178, 343/179, 178/69.5 R
• US Class Current: 370/324
• CPC Class Codes: H04B 7/2126 using a reference station

Abstract

A satellite communication system wherein transmissions from a plurality of ground stations are transmitted via a satellite in a time-multiplex manner and where each station is assigned a particular time slot wherein for synchronizing a ground station into its time slot there is provided a time synchronizing means which first synchronizes the initial portion of the incoming stations transmission to a time delayed from its desired time after which when the signal has been accurately positioned to such delayed time it is shifted a pre-set time in its time slot such that the transmission from said incoming ground station is accurately positioned at its correct time slot.

Claims

1. A method of satellite communication whereby signal transmission bursts of different ground stations are provided with a preamble and are arranged in a time-multiplex manner and are combined to form a frame at the satellite station and are re-transmitted comprising the steps of transmitting an initial access signal by a ground station, receiving and retransmitting said access signal by said satellite station, receiving said access signal at said ground station and evaluating its position in the frame assigned to said ground station, adjusting the phase position of a preamble transmit burst which is to be transmitted by said accessing ground station and the phase position of the preamble transmit burst controlled with respect to its desired phase position by using burst phase regulation control, and evaluating the initial access signal and controlling the transmission phase to a desired intermediate phase position which is delayed with respect to the desired phase by a known time and shifting the phase with a program control of the preamble transmit burst to the desired phase position from the desired intermediate phase position and then transmittng the entire burst.

2. The method of satellite communication of claim 1 wherein said program control makes a correction of the desired intermediate phase to obtain the desired phase position at a speed which is equal to a phase-correction step per frame of the burst-transmission phase regulation control.

3. The method of satellite communication of claim 1 wherein the phase delay of the desired intermediate phase position relative to the desired phase position is selected to be approximately equal to one half the tolerance width of the phase-measuring precision of the initial access signal.

4. The method of satellite communication of claim 3 wherein the phase delay of the desired intermediate phase position relative to the desired phase is 5 microseconds for a tolerance width of the phase measuring precision of the initial access signal of 8 microseconds in a tolerance range of +1 microsecond through +9 microseconds with respect to the desired phase.

5. In a satellite communications system comprising a number of ground stations having transmitters and receivers and at least one satellite with a receiver and transmitter and wherein communication between the ground stations via the satellite is accomplished with a single carrier by assigning different time slots in an information frame to each station comprising means at each station for controlling its transmission in its assigned time slot including means at each ground station for sending an initial access signal to said satellite and receiving said signal from said satellite comprising, receiving and transmit means in each ground station, an access generator in each ground station connected to said transmit means and supplying an access signal thereto, a phase measuring and adjusting means in each ground station connected to said receiving means to adjust the phase of transmitted signals to an intermediate phase position, a preamble generator connected to said phase measuring and adjusting means and to said transmit means to radiate a preamble signal to said satellite receiver which furnishes it to the satellite transmitter, said receiving means at said ground station receiving said preamble signal from said satellite transmitter, said phase measuring and adjusting means controlling the phase of said received preamble signal to said intermediate phase position, and then shifting said preamble signal to the desired phase position and keying said transmit means so that transmission by said ground station starts at said desired phase position.

6. In a satellite communications system according to claim 5 wherein the time between said desired intermediate phase position and said desired phase position is 5 microseconds.