System and method for combining multiple satellite channels into a virtual composite channel

• US 6,452,989 B1
• Filed: 11/12/1999
• Issued: 09/17/2002
• Est. Priority Date: 02/03/1999
• Status: Expired due to Term

• Current Assignee: F Poszat Hu LLC (Intellectual Ventures LLC)
• Original Assignee: Virtual Satellite Corporation
• Inventors: Friedman, Robert F.
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US09/438,865
• Time in Patent Office: 1,040 Days
• Field of Search: 375/260, 375/371, 375/267, 375/316, 375/211, 375/347, 375/130, 375/34.4, 455/132, 455/137, 455/138, 455/13.1, 455/13.2, 455/13.3, 455/11.1, 455/12.1, 455/139, 370/315, 370/316, 370/326, 370/274, 370/480
• US Class Current: 375/347
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays

Abstract

A satellite communications system provides an information channel between remotely located transmitters and receivers. A virtual satellite system provides the same service, but divides the signal either in power or in data content into subchannels such that any particular signal is conducted to the intended receiver via a plurality of traditional satellite channels. The receiving terminal accepts the plurality of signals simultaneously from a possible plurality of satellites, combining the subchannels comprising the virtual channel into the original signal content as if conducted via a single channel. The receiving antenna system receives satellite subchannel signals from a plurality of directions using multiple antennas or a single antenna with multi-direction capability. Prior to signal combining, the receiver necessarily time-synchronizes the plurality of subchannels by introducing time delay in some channels before combining the subsignals into the original composite. A timing signal present in the virtual satellite system assists the receiver in determining the amount of delay to apply to each incoming signal. The timing signal is either a separate carrier or an additional modulation on the existing information-bearing carrier.

Claims

1. A receiving terminal system collecting signals from a plurality of satellite transponders and creating a delayed reconstruction of an original digital signal, the receiving terminal system comprising:

an antenna subsystem, the antenna subsystem comprising one of

a multiple beam antenna simultaneously receiving the signals from the plurality of transponders and presenting each of said signals on a corresponding one of a plurality of separate output ports; and

a plurality of independent single beam antennas simultaneously receiving the signals from the plurality of transponders and presenting each of said signals on said corresponding one of said plurality of separate output ports;

a plurality of tuners, each coupled to each separate output port, for translating a frequency of each received signal to a fixed intermediate frequency;

a plurality of demodulators, each coupled to each tuner, demodulating for each tuner output and creating a plurality of bit streams each corresponding to information content of an associated subchannel;

a plurality of delay means, each coupled to a demodulator output, for delaying one or more first-arriving of the plurality of bit streams such that outputs of the plurality of delay means are synchronized in time;

a digital combiner, coupled to the outputs of the plurality of delay means, for combining information in each of the outputs of the plurality of delay means into the delayed reconstruction of the original digital signal;

a timing signal correlator, coupled to each tuner output, for measuring a relative delay between each received signal and in accordance therewith generating a timing signal correlation signal;

a nonvolatile memory for storing information about a frequency property and a propagation delay property of each of a plurality of virtual channels to be selected, and in accordance with there generating a plurality memory of nonvolatile signals; and

a controller, coupled to the antenna subsystem, the plurality of tuners, the plurality of delay means, the timing signal correlator, and the nonvolatile memory, for receiving the timing signal correlation signal and the nonvolatile memory signals and issuing a plurality of control signals to the antenna subsystem setting a beam direction and a polarization, a plurality of tuner control signals to the plurality of tuners to set a plurality of subchannel receive frequencies, and a plurality of delay control signals to the plurality of delay means to synchronize the outputs of the delay means.

2. The receiving terminal system of claim 1 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.

3. The receiving terminal system of claim 1 wherein a timing signal associated with a particular subchannel is transmitted on one satellite in a separate frequency allocation as an information-bearing carrier, and the controller operates firstly to direct the tuners to receive the timing signal to measure a relative propagation delay of the subchannels, secondly to set an amount of delay in the plurality of delay means in accordance with the relative propagation delays measured in the first step, and thirdly to redirect the tuners to receive the associated information-bearing subchannels.

4. The receiving terminal system of claim 3 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.

5. A receiving terminal system collecting signals from a plurality of satellite transponders and creating a delayed reconstruction of an original digital signal, the receiving terminal system comprising:

an antenna subsystem, the antenna subsystem comprising one of;

a multiple beam antenna simultaneously receiving the signals from the plurality of satellite transponders and presenting each of said signals on a corresponding one of a plurality of separate output ports; and

a plurality of independent single beam antennas simultaneously receiving the signals from the plurality of transponders and presenting each of said signals on said corresponding one of said plurality of separate output ports;

a plurality of tuners, each coupled to each separate output port, for translating a frequency of each received signal to a fixed intermediate frequency;

a plurality of demodulators, each coupled to each tuner, for demodulating each tuner output and each creating one of a plurality of streams of soft decisions in the form of digitized decision-confidence-values corresponding to an associated subchannel;

a plurality of delay means, each coupled to a demodulator output, for delaying one or more first-arriving of the streams of soft decisions such that the streams of soft decisions output from the plurality of delay means are synchronized in time;

a digital combiner, coupled to the outputs of the plurality of delay means, for combining soft decisions from all subchannels received into a delayed reconstruction of the original digital signal;

a timing signal correlator, coupled to each tuner output, measuring for a relative delay between arriving subchannel signals, and in accordance therewith generating a timing signal correlation signal;

a nonvolatile memory for storing information about a frequency property and a propagation delay property of a plurality of virtual channels to be selected, and in accordance therewith generating a plurality memory of nonvolatile signals; and

a controller, coupled to the antenna subsystem, the plurality of tuners, the plurality of delay means, the timing signal correlator, and the nonvolatile memory, for receiving the timing signal correlation signal and the nonvolatile memory signals and issuing control signals to the antenna subsystem setting a beam direction and a polarization, a plurality of tuner control signals to the tuners to set a plurality of subchannel receive frequencies, and a plurality of delay control signals to the plurality of delay means to synchronize the outputs of the delay means.

6. The receiving terminal system of claim 5 further comprising:

a digital correlator, coupled to the delay means outputs, for providing an additional measure of the relative delay between channels.

7. The receiving terminal system of claim 5 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.

8. The receiving terminal system of claim 5 wherein a timing signal associated with a particular subchannel is transmitted on one satellite in a separate frequency allocation as an information-bearing carrier, and the controller operates firstly to direct the tuners to receive the frequency-separated periodic signal to measure a relative propagation delay of the subchannels, secondly to set an amount of delay in the plurality of delay means in accordance with the relative propagation delays measured in the first step, and thirdly to redirect the tuners to receive the associated information-bearing subchannels.

9. The receiving terminal system of claim 8 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.

10. A receiving terminal system collecting analog signals from a plurality of satellite transponders and creating a delayed reconstruction of an original analog signal, the receiving terminal system comprising:

an antenna subsystem, the antenna subsystem comprising one of;

a multiple beam antenna simultaneously receiving the analog signals from the plurality of satellite transponders and presenting each of said analog signals on a corresponding one of a plurality of separate output ports; and

a plurality of independent single beam antennas simultaneously receiving the analog signals from the plurality of satellite transponders and presenting each of said analog signals on the corresponding one of the plurality of separate output ports;

a plurality of tuners, each coupled to each separate output port, for translating a frequency of each received analog signal to a fixed intermediate frequency;

a plurality of demodulators, each coupled to each tuner, for demodulating each tuner output and each creating one of the analog signals corresponding to an information content of an associated subchannel;

a plurality of delay means, each coupled to a demodulator output, for delaying one or more first-arriving of the subchannel signals such that outputs of the plurality of delay means are synchronized in time;

an analog combiner, coupled to the outputs of the plurality of delay means, for combining information in each of the subchannels into the delayed reconstruction of the original analog signal;

a timing signal correlator, coupled to each of the plurality of tuners, for measuring a relative delay between arriving subchannel signals, and in accordance therewith generating a timing signal correlation signal;

a nonvolatile memory for storing information about a frequency property and a propagation delay property of a plurality of virtual channels to be selected, and in accordance therewith generating a plurality of nonvolatile memory signals; and

a controller, coupled to the antenna subsystem, the plurality of tuners, the plurality of delay means, the timing signal correlator, and the nonvolatile memory, for receiving the timing signal correlation signal and the nonvolatile memory signals and issuing control signals to the antenna subsystem setting a beam direction and a polarization, a plurality of tuner control signals to the tuners to set a plurality of subchannel receive frequencies, and a plurality of delay control signals to the plurality of delay means to synchronize the outputs of the delay means.

11. The receiving terminal system of claim 10 wherein the analog combiner provides additional relative subchannel delay information to the controller.

12. The receiving terminal system of claim 10 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.

13. The receiving terminal system of claim 10 wherein a timing signal associated with a particular subchannel is transmitted on one satellite in a separate frequency allocation as an information-bearing carrier, and the controller operates firstly to direct the tuners to receive the frequency separated timing signal to measure a relative propagation delay of the subchannels, secondly to set an amount of delay in the plurality of delay means in accordance with the relative propagation delays measured in the first step;

and thirdly to redirect the tuners to receive the associated information-bearing subchannels.

14. The receiving terminal system of claim 13 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.

15. The receiving terminal system of claim 10 wherein the plurality of subchannels contain identical information, and associated carriers are modulated identically.

16. The receiving terminal system of claim 15 wherein the analog combiner provides additional relative subchannel delay information to the controller.

17. The receiving terminal system of claim 15 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.

18. The receiving terminal system of claim 15 wherein a timing signal associated with a particular subchannel is transmitted on one satellite in a separate frequency allocation as an information-bearing carrier, and the controller operates firstly to direct the tuners to receive the frequency separated timing signal to measure a relative propagation delay of the subchannels, secondly to set an amount of delay in the plurality of delay means in accordance with the relative propagation delays measured in the first step, and thirdly to redirect the tuners to receive the associated information-bearing subchannels.

19. The receiving terminal system of claim 18 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.

20. A receiving terminal system collecting signals from a plurality of satellite transponders and selecting a subchannel signal containing a desired independent component of an original multiplex signal, the receiving terminal system comprising:

an antenna subsystem, the antenna subsystem comprising one of;

a multiple beam antenna receiving the signals from the plurality of satellite transponders and presenting the selected subchannel signal on an output port; and

a plurality of independent single beam antennas receiving the signals from the plurality of satellite transponders and presenting the selected subchannel signal on the output port;

a tuner, coupled to each output port, for translating a frequency of the received selected subchannel signal to a fixed intermediate frequency;

a demodulator, coupled to the tuner, for demodulating each tuned selected subchannel signal and creating a bit stream corresponding to an information content of each corresponding tuned selected subchannel signal;

a nonvolatile memory for storing information about a frequency property of a plurality of virtual channels to be selected, and in accordance therewith generating a plurality of nonvolatile memory signals; and

a controller, coupled to the antenna subsystem, the tuner, and the nonvolatile memory, for receiving the plurality of nonvolatile memory signals and issuing antenna control signals to the antenna subsystem setting a beam direction and a polarization, and issuing tuner control signals to the tuner to set a subchannel receive frequency.

21. The receiving terminal system of claim 20 wherein at least some of the transponders associated with the plurality of subchannels are located on one satellite.