SATELLITE INTERLACE SYNCHRONIZATION SYSTEM

• US 3,593,138 A
• Filed: 07/31/1968
• Issued: 07/13/1971
• Est. Priority Date: 07/31/1968
• Status: Expired due to Term

• Current Assignee: Fletcher Irving Lane, Irving A. Krause, James G. Dunn, John E. Miller, Walter K. Allen
• Original Assignee: Fletcher Irving Lane, Irving A. Krause, James G. Dunn, John E. Miller, Walter K. Allen
• Inventors: Dunn, James G., Krause, Irving A., FLETCHER IRVING LANE, Allen, Walter K., Miller, John E.
• Application Number:
  US04/749,121
• Time in Patent Office: 1,077 Days
• US Class Current: 375/211
• CPC Class Codes: H04B 7/2126 using a reference station

Abstract

A master station and a plurality of slave stations include synchronization equipment to enable each of the stations to have access to a common repeater in a different time slot of a time division multiplex format at the repeater, there being motion between the stations and the repeater. The master station propagates a sync burst through the repeater. Each of the stations receives this sync burst from the repeater and adjusts the frequency of the timing signals therein to compensate for the doppler shift experienced in the propagation path from each of the stations to the repeater so that the desired frequency of the timing signals is present in the repeater. Each of the slave stations also propagates different low power level, psuedo noise code ranging signal through the repeater back to itself which is used to adjust the phase of the timing signals digitally and in an analog manner by means of a motor-driven phase shifter to account for the changing range between the repeater and each of the slave stations so that a data burst of each of the slave stations appears in the proper time slot of the time division multiplex format at the repeater.

Claims

1. A synchronization system to control signals transmitted from each of a master station and a plurality of slave stations to be propagated through a common repeater in a different one of a plurality of time slots of time division multiplex format as said repeater, said stations and said repeater having relative motion therebetween, comprising:

first means disposed in said master station to transmit a sync burst through said repeater in one of said time slots;

second means disposed in each of said slave stations responsive to said sync burst from said repeater to control the production of timing signals employed to control the time of transmission of said transmitted signals from the associated one of said slave stations;

third means disposed in each of said slave stations to transmit a ranging signal through said repeater in its associated one of said time slots;

means disposed in each of the slave stations for receiving the ranging signal transmitted by the associated slave station through the repeater; and

means, including digital and analog signal processing means, disposed in each of said slave stations coupled to said second means responsive to said ranging signal received from said repeater to adjust the time position of said timing signals so that the time of transmission of said transmitted signals from the associated one of said slave stations is such that said transmitted signals occurs in the proper one of said time slots at said repeater.

2. A system according to claim 1, further including a source of said ranging signal in each of said slave stations, said ranging signal source including a lower power level psuedo noise code signal.

3. A system according to claim 1, wherein said first means includes fourth means to adjust the carrier frequency of said sync burst to compensate for the doppler effect in the transmission path from said master station to said repeater to provide said sync burst received at said repeater with the desired carrier frequency.

4. A system according to claim 3, wherein said fourth means includes fifth means to receive said sync burst from said repeater, and sixth means coupled to said fifth means to maintain the sum of the carrier frequencies said received and transmitted sync burst constant.

5. A system according to claim 4, wherein said sixth means includes a first source of reference frequency signal, a second source of offset frequency signal, a voltage-controlled oscillator, mixer means coupled to said fifth means, said oscillator and said second source, and a phase detector coupled to said first source, said mixer means and said oscillator compensating the output signal of said oscillator for said doppler effect.

6. A system according to claim 1, wherein said second means includes a voltage-controlled oscillator, a phase shifter responsive to said oscillator, and binary counter means responsive to said phase shifter to produce said timing signals;

and said signal-processing digital and analog means includes fourth means to receive said ranging signal from said repeater, a source of reference ranging signal, fifth means responsive to said source of reference ranging signal and said fourth meanS to produce at least first and second control signals, sixth means to couple one of said control signals to said counter means to digitally control the count thereof, and seventh means to couple the other of said control signals to said phase shifter to phase shift in analog manner the output signal of said oscillator.

7. A system according to claim 1, wherein said second means includes fourth means to adjust the carrier frequency of said transmitted signals to compensate for the doppler effect in the transmission path from the associated one of said slave stations to said repeater to provide said transmitted signal received at said repeater with the desired carrier frequency.

8. A system according to claim 7, wherein said fourth means includes fifth means to receive said sync burst from said repeater, and sixth means coupled to said fifth means to maintain the sum of the carrier frequencies of said received sync burst and said transmitted signal constant.

9. A system according to claim 8, wherein said sixth means includes a first source of reference frequency signal, a second source of offset frequency signal, a voltage-controlled oscillator, mixer means responsive to said fifth means, said oscillator and said second source, and a phase detector coupled to said first source, said mixer means and said oscillator to compensate the output signal of said oscillator for said doppler effect.

10. A system according to claim 9, wherein said second means further includes a phase shifter responsive to said oscillator, and binary counter means responsive to said phase shifter to produce said timing signals;

and said digital and analog signal-processing means includes seventh means to receive said ranging signal from said repeater, a source of reference ranging signal, eighth means responsive to said source of reference ranging signal and said seventh means to produce at least first and second control signals, ninth means to couple one of said control signals to said counter means to digitally control the count thereof, and tenth means to couple the other of said control signals to said phase shifter to phase shift in an analog manner the output signal of said oscillator.

11. The synchronization system of claim 1 wherein the time position adjusting means includes:

counter means, a variable phase source of oscillations driving the counter means, means for slew adjusting the count of the counter means in response to the ranging signal and independently of the oscillations, and means for controlling the phase of the oscillations in response to the ranging signal, the slew adjustment of the counter means and the phase adjustment of the oscillations respectively being relatively coarse and fine controls for the time of transmissions of the transmitted signals.

12. The system of claim 11 wherein the slew-adjusting means includes:

first means for adjusting the count of the counter means by a first predetermined number of steps in response to a first condition of the range signal received at the slave station, and second means for adjusting the count of the counter means by a second predetermined number of steps in response to a second condition of the received signal at the slave station.

13. A system according to claim 12 further including a source of said ranging signal in each of said slave stations, said ranging signal source including pseudo noise code signal, means for detecting the pseudo noise code signal in the ranging signal received a t the slave station, means for comparing the transmitted and detected pseudo noise code signals for deriving first and second signals respectively indicative of lock between the detected and transmitted pseudo noise signal and the relative time positions of the detected and transmitted pseudo noise signal, and means for controlling said first and second means in response to the first and second signals respectively.

14. A sYnchronization system to control signals transmitted from each of a master station and a plurality of slave stations to be propagated through a common repeater in a different one of a plurality of time slots of a time division multiplex format at said repeater, said stations and said repeater having relative motion therebetween comprising:

first means disposed in said master station to transmit a sync burst through said repeater in one of said time slots;

second means disposed in each of said slave stations responsive to said sync burst from said repeater to control the production of timing signals employed to control the time of transmission of said transmitted signals from the associated one of said slave stations;

third means disposed in each of said slave stations to transmit a ranging signal through said repeater in its associated one of said time slots;

means disposed in each of the slave stations for receiving the ranging signal transmitted by the associated slave station through the repeater; and

means disposed in each of said slave stations coupled to said second means responsive to said ranging signal received from said repeater to adjust the time position of said timing signals so that the time of transmission of said transmitted signals from the associated one of said slave stations is such that said transmitted signal occurs in the proper one of said time slots at said repeater and said time position-adjusting means including;

counter means, a variable phase source of oscillations driving the counter means, means in response to the ranging signal and independently of the oscillations, and means for controlling the phase of the oscillations in response to the ranging signal, the slew-adjustment of the counter means and the phase adjustment of the oscillations respectively being relatively coarse and fine controls for time of transmission of the transmitted signals.