Method and apparatus for deriving uplink timing from asynchronous traffic across multiple transport streams
First Claim
1. A control station for two-way satellite communication, comprising:
- an RF section for transmitting a broadcast signal and receiving a return channel uplink;
a plurality of burst channel demodulators for demodulating the return channel uplink;
a timing section including a delay receiver, an echo timing receiver, and a timing processor receiving outputs from the delay receiver and the echo timing receiver;
a frame pulse generator coupled to the plurality of burst channel demodulators and the timing section, wherein the frame pulse generator provides a superframe marker pulse to the timing section at a first fixed time interval and concurrently provides a superframe header which is included in the broadcast signal, wherein the frame pulse generator pulses the plurality of burst channel demodulators at a second fixed time interval different from the first fixed time interval and at a time later than a time of the superframe marker pulse by a space timing offset interval.
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Accused Products
Abstract
A communication apparatus that shares precise return channel uplink timing information includes a common symbol timing reference and one or more control stations that each transmit independent asynchronous DVB data streams which evenly share the common symbol timing. The control stations each include respective delay trackers to determine broadcast transmission delays associated with the particular control station and transmission path. Each broadcast data stream includes the same non real-time frame marker and a transmission delay message particular to the respective control station. A remote receiver receives one of the broadcast streams and timestamps the non real-time frame marker with a local time of receipt. A timing recovery circuit determines an upcoming return channel frame start time by adjusting the local time of receipt by the particular broadcast transmission delay and a unique receiver offset time. A local transmitter subsequently uplinks a TDMA message in a predetermined time-slot after the return channel frame start time. The method for transmitting a frame synchronized message includes receiving a non real-time frame reference marker in a receiver, timestamping the received frame reference marker with a reception time, and subsequently receiving a control node timing differential at the receiver. The local reception time of the non real-time frame marker is corrected to determine the proper return channel frame transmit start time by applying the control node timing differential and the local offset time. Users then uplink a message during an assigned period after the return channel frame transmit start time.
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Citations
33 Claims
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1. A control station for two-way satellite communication, comprising:
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an RF section for transmitting a broadcast signal and receiving a return channel uplink; a plurality of burst channel demodulators for demodulating the return channel uplink; a timing section including a delay receiver, an echo timing receiver, and a timing processor receiving outputs from the delay receiver and the echo timing receiver; a frame pulse generator coupled to the plurality of burst channel demodulators and the timing section, wherein the frame pulse generator provides a superframe marker pulse to the timing section at a first fixed time interval and concurrently provides a superframe header which is included in the broadcast signal, wherein the frame pulse generator pulses the plurality of burst channel demodulators at a second fixed time interval different from the first fixed time interval and at a time later than a time of the superframe marker pulse by a space timing offset interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A transceiver for transmitting a frame synchronized message, comprising:
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a receiver which detects a frame reference marker and a control node timing message in a received broadcast signal; a local clock adapted to tag the detected frame reference marker with a local reception time; a timing recovery section which uses the control node timing message to determine a transmit frame start time; and a transmitter adapted to uplink a message during an assigned period after the transmit frame start time, wherein the timing recovery section uses the local reception time and local offset time to determine the transmit frame start time. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for providing communication timing information from a control station, comprising:
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generating a timing marker; determining a control station timing delay; and providing the timing marker and the control station timing delay in a message received by a remote user; wherein the timing marker is a superframe marker, and wherein the superframe marker is periodically provided in messages to the remote user at a first fixed interval, and further comprising pulsing an inroute receiver at a time later than a time of the superframe marker pulse by a space timing offset interval. - View Dependent Claims (17)
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18. A method for transmitting a frame synchronized message, comprising:
- receiving a frame reference marker in a local receiver of one of a plurality of distributed user nodes;
timestamping the received frame reference marker with a local reception time; receiving a control node timing differential at the local receiver; correcting the local reception time by applying the control node timing differential and a local offset time; determining a start time for a return channel frame using the corrected local reception time; and transmitting a first message from one of the plurality of distributed user nodes during an assigned period within the return channel frame. - View Dependent Claims (19, 20, 21, 22, 23)
- receiving a frame reference marker in a local receiver of one of a plurality of distributed user nodes;
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24. A communication system for sharing return channel uplink timing information, comprising:
- a common symbol timing reference;
a first control station transmitting a first broadcast data stream in accordance with the common symbol timing reference, said first control station including a first delay tracker to determine a first transmission delay associated with the first control station; said first broadcast data stream including a non-real time frame marker and a first transmission delay message; a first receiver to receive the first broadcast data stream, said first receiver receiving the first delay message and timestamping the non-real time frame marker with a first local time of receipt; a first timing recovery circuit to determine an upcoming real-time return channel frame start time by adjusting the first local time of receipt by the first transmission delay and a first receiver offset time; and a first local transmitter to uplink a message in a predetermined time-slot after the real-time return channel frame start time. - View Dependent Claims (25, 26, 27, 28)
- a common symbol timing reference;
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29. A method for sharing a set of TDMA channels between a plurality of uplink channels, comprising:
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providing a non-real time system reference timing message to a remote user; determining a control station timing delay; calculating a message transport delay; offsetting a local time reference from the non-real time system timing by the message transport delay and the control station timing delay; determining a realtime TDMA transmit frame timing from the offset local time reference; and transmitting uplink channel information in accordance with the realtime TDMA transmit frame timing and a TDMA time-sharing arrangement. - View Dependent Claims (30, 31, 32, 33)
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Specification