Flywheel timing generation method and apparatus for TDMA satellite communications system
OwnerJunghoon Lee, Tzeta Tsao +2inventors
InventorsJunghoon Lee, Tzeta Tsao, Lan Ngoc Nguyen, John Albert Lunsford
Life of this patent
Estimating the term…
Abstract
In a satellite communications system, a flywheel timing value generating method includes generating flywheel timing values based on a satellite drift over a predetermined time. This drift can be a satellite drift in the north/south direction, measured over a sidereal day. By measuring and recording prior drift history in a normal operation, predicted receive and transmit delay times are calculated in order to generate a start of receive control frame and a start of transmit control frame used in a flywheel operation.
Claims25
A method for satellite communications, comprising:
- measuring a satellite drift in the north/south direction at an earth station;
- generating a history of the measured drift over a period of time;
- and
- generating flywheel timing values based on delay values predicted according to the measured satellite drift history over a predetermined time.
A flywheel timing generation method, comprising:
- generating a reference pulse stream with a period of one control frame;
- measuring and recording a plurality of receive time delay and transmit time delay values for a satellite communication signal over a predetermined period of time;
- designating, for every control frame interval, start of receive frame delay and start of transmit frame delay values based on the control frame period and based on the recorded time delay values, referenced to a designated time;
- from a designated value for receive frame delay, generating a flywheel receive start timing by counting a calculated number of symbols from a corresponding designated reference pulse;
- from a designated value for start of transmit frame delay, generating a flywheel transmit start timing by counting a calculated number of symbols from a corresponding designated reference pulse.
A method for satellite communications, comprising:
- measuring and recording a plurality of timing delay values at an earth station for a period of time;
- and
- generating flywheel timing values by calculating a satellite range change based on the recorded delay values, the range change predicted to compensate a satellite drift in the north/south direction over a predetermined time.
A computer system used for satellite communications, comprising:
- a processor;
- and
- a memory including software instructions adapted to enable the computer system to perform the steps of:
- generating a reference pulse stream with a period of one control frame;
- measuring and recording a plurality of receive time delay and transmit time delay values for a satellite communication signal over a predetermined period of time;
- designating, for every control frame interval, start of receive frame delay and start of transmit frame delay values based on the control frame period and based on the recorded time delay values, referenced to a designated time;
- from a designated value for receive frame delay, generating a flywheel receive start timing by counting a calculated number of symbols from a corresponding designated reference pulse;
- from a designated value for start of transmit frame delay, generating a flywheel transmit start timing by counting a calculated number of symbols from a corresponding designated reference pulse.
A computer system used for satellite communications, comprising:
- a processor;
- and
- means for generating flywheel timing values considering the daily inclination change due to a satellite drift in the north/south direction.
A computer system used for satellite communications, comprising:
- a processor;
- and
- means for generating flywheel timing values considering a daily delay value change for received and transmitted signals due to satellite drift in the north/south direction.
A circuit for flywheel operation in a satellite communications system, comprising:
- a first counter operative to measure a receive delay time during a normal operation, the first counter operative to receive a predicted receive delay value and generate a flywheel receive control timing during flywheeling operation;
- a second counter operative to measure a transmit delay time during a normal operation, the second counter operative to receive a predicted transmit delay value and generate a flywheel transmit control timing during flywheeling operation;
- a first latch operative to record the measured receive delay time;
- and
- a second latch operative to record the measured transmit delay time.
A satellite communications system having a satellite, at least one reference terminal, and a plurality of traffic terminals in communication with the reference terminal for transferring timing correction information between the terminals, the system comprising:
- a timing correction signal generator in the satellite for transmitting the timing correction information to the reference terminal;
- and
- a flywheel timing generator operative to generate flywheel timing signals when the timing correction information transmitted by the satellite is not available to the reference terminal,
- wherein the flywheel timing generator generates the flywheel timing signals based on at least one of a daily inclination change due to a satellite drift in the north/south direction and a daily delay value change for received and transmitted signals due to satellite drift in the north/south direction.
Dependencies are inferred from the claim text.