Methods and apparatus for coupling a satellite to an earth terminal

• US 20040022206A1
• Filed: 08/02/2002
• Published: 02/05/2004
• Est. Priority Date: 08/02/2002
• Status: Active Grant

• Current Assignee: General Dynamics C4 Systems Incorporated (General Dynamics Corporation)
• Original Assignee: General Dynamics C4 Systems Incorporated (General Dynamics Corporation)
• Inventors: Blanchard, Scott D.
• Granted Patent: US 7,280,496 B2
• Time in Patent Office: Days
• US Class Current: 370/320
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]

Abstract

Methods and apparatus are provided for coupling a satellite to an earth terminal. The apparatus inputs of the satellite that is configured to receive digital uplink signals, an autoscaling digital multiplexer of the satellite that is configured to digitally multiplex the digital uplink signals to produce a digital composite signal, and a digital modulator of the satellite that is configured to digitally modulate the digital composite signal to produce a digitally modulated composite signal. In addition, the apparatus comprises an input of the earth terminal that configured to receive the digitally modulated composite signal and a digital demodulator of the earth terminal that is configured to digitally demodulate the digitally modulated composite signal received by the input of the earth terminal to produce a second digital composite signal. Furthermore, the apparatus comprises an autoscaling digital demultiplexer of the earth terminal that is configured to digitally separate the second digital composite signal into digital uplink signals, and a modulator of the earth terminal configured to modulate the digital uplink signals to produce modulated analog signals.

Claims

1. An apparatus for coupling a satellite to an earth terminal, comprising:

a plurality of inputs of the satellite configured to receive a plurality of digital uplink signals;

an autoscaling digital multiplexer of the satellite configured to digitally multiplex said plurality of digital uplink signals to produce a digital composite signal;

a digital modulator of the satellite configured to digitally modulate said digital composite signal to produce a digitally modulated composite signal;

an input of the earth terminal configured to receive said digitally modulated composite signal;

a digital demodulator of the earth terminal configured to digitally demodulate said digitally modulated composite signal received by said input of the earth terminal to produce a second digital composite signal;

an autoscaling digital demultiplexer of the earth terminal configured to digitally separate said second digital composite signal into a second plurality of digital uplink signals; and

a modulator of the earth terminal configured to modulate said second plurality of digital uplink signals to produce a plurality of modulated analog signals.

2. The apparatus for coupling the satellite to the earth terminal of claim 1, wherein said plurality of digital uplink signals are Third Generation Partnership Project (3GPP) Wideband Code Division Multiple Access (WCDMA) Direct Sequence Spread Spectrum (DSSS) signals.

3. The apparatus for coupling the satellite to the earth terminal of claim 1, further comprising a digital filter bank of the satellite that is configured to digitally filter said plurality of digital uplink signals.

4. The apparatus for coupling the satellite to the earth terminal of claim 1, wherein the autoscaling digital multiplexer of the satellite comprises:

a processor configured to generate a scaling vector for said plurality of digital uplink signals;

an operator configured to produce a mantissa for each of said plurality of digital uplink signals with said scaling vector and said plurality of digital uplink signals; and

a multiplexer configured to multiplex said mantissa for each of said plurality of digital uplink signals and said scaling vector to produce said digital composite signal.

5. The apparatus for coupling the satellite to the earth terminal of claim 4, wherein said processor is configured to encode said scaling vector.

6. The apparatus for coupling the satellite to the earth terminal of claim 4, wherein said processor is configured to:

determine a minimum exponent of said scaling vector;

calculate a difference between each of the exponents of said scaling vector and said minimum exponent; and

form an encoded scaling vector from said minimum exponent and said difference between each of the exponents of said scaling vector and said minimum exponent.

7. The apparatus for coupling the satellite to the earth terminal of claim 4, wherein said processor is configured to:

determine a maximum exponent of said scaling vector;

calculate a difference between said maximum exponent of said scaling vector and each of the exponents of said scaling vector; and

form an encoded scaling vector from said maximum exponent and said difference between said maximum exponent and each of the exponents of said scaling vector.

8. The apparatus for coupling the satellite to the earth terminal of claim 4, wherein said processor is configure to perform a Huffman encoding to encode said scaling vector.

9. The apparatus for coupling the satellite to the earth terminal of claim 4, wherein said multiplexer is configured to Time Division Multiplexing (TDM) said mantissa for each of said plurality of digital uplink signals and said scaling vector.

10. The apparatus for coupling the satellite to the earth terminal of claim 1, further comprising an encrytor configured to encrypt the digital composite signal.

11. The apparatus for coupling the satellite to the earth terminal of claim 1, wherein said autoscaling digital demultiplexer of the earth terminal comprises:

a demultiplexer configured to separate a plurality of mantissas and an encoded scaling vector from said second digital composite signal;

a processor configured to decode the encoded scaling vector to produce a scaling vector for each of said plurality of mantissas; and

an operator configured to produce said second plurality of digital uplink signals with said plurality of mantissas and said scaling vector.

12. The apparatus for coupling the satellite to the earth terminal of claim 1, further comprising an analog transform matrix of said earth terminal that is configured to transform said plurality of modulated analog signals into a plurality of transformed analog signals.

13. An method for coupling a satellite to an earth terminal, comprising:

receiving a plurality of digital uplink signals with a plurality of inputs of the satellite;

digitally multiplexing said plurality of digital uplink signals with an autoscaling digital multiplexer of the satellite to produce a digital composite signal;

digitally modulating said digital composite signal with a digital modulator of the satellite to produce a digitally modulated composite signal;

receiving said digitally modulated composite signal with an input of the earth terminal;

digitally demodulating said digitally modulated composite signal with a digital demodulator of the earth terminal to produce a second digital composite signal;

digitally separating said second digital composite signal into a second plurality of digital uplink signals with an autoscaling digital demultiplexer of said earth terminal; and

modulating said second plurality of digital uplink signals with a modulator of the earth terminal to produce a plurality of modulated analog signals.

14. The method for coupling the satellite to the earth terminal of claim 13, wherein said plurality of digital uplink signals are Third Generation Partnership Project (3GPP) Wideband Code Division Multiple Access (WCDMA) Direct Sequence Spread Spectrum (DSSS) signals.

15. The method for coupling the satellite to the earth terminal of claim 13, further comprising digitally filtering said plurality of digital uplink signals with a digital filter of the satellite.

16. The method for coupling the satellite to the earth terminal of claim 13, wherein said digitally multiplexing said plurality of digital uplink signals with said autoscaling digital multiplexer of the satellite to produce said digital composite signal, comprises:

generating a scaling vector for said plurality of digital uplink signals;

producing a mantissa for each of said plurality of digital uplink signals with said scaling vector and said plurality of digital uplink signals; and

multiplexing said mantissa for each of said plurality of digital uplink signals and said scaling vector.

17. The method for coupling the satellite to the earth terminal of claim 16, further comprising encoding said scaling vector.

18. The method for coupling the satellite to the earth terminal of claim 16, further comprising:

determining a minimum exponent of said scaling vector;

calculating a difference between each of the exponents of said scaling vector and said minimum exponent; and

forming an encoded scaling vector from said minimum exponent and said difference between each of the exponents of said scaling vector and said minimum exponent.

19. The method for coupling the satellite to the earth terminal of claim 16, further comprising:

determining a maximum exponent of said scaling vector;

calculating a difference between said maximum exponent of said scaling vector and each of the exponents of said scaling vector; and

forming an encoded scaling vector from said maximum exponent and said difference between said maximum exponent and each of the exponents of said scaling vector.

20. The method for coupling the satellite to the earth terminal of claim 13, further comprising performing a Huffman encoding to encode said scaling vector.

21. The method for coupling the satellite to the earth terminal of claim 16, wherein said multiplexing is a Time Division Multiplexing (TDM) of said mantissa for each of said plurality of digital uplink signals and said scaling vector.

22. The method for coupling the satellite to the earth terminal of claim 13, further comprising encrypting said digital composite signal.

23. The method for coupling the satellite to the earth terminal of claim 13, wherein said digitally separating said second digital composite signal into a second plurality of digital uplink signals comprises:

separating a plurality of mantissas and an encoded scaling vector from said second digital composite signal;

decoding the encoded scaling vector to produce a scaling vector for each of said plurality of scaling vectors;

producing said second plurality of digital uplink signals with said plurality of mantissa and said scaling vector.

24. A communication system, comprising:

a satellite comprising;

a plurality of inputs configured to receive a plurality of digital uplink signals;

an autoscaling digital multiplexer configured to digitally multiplex said plurality of digital uplink signals to produce a digital composite signal; and

a digital modulator configured to digitally modulate said digital composite signal to produce a digitally modulated composite signal; and

an earth terminal coupled to said satellite with said digitally modulated composite signal, said earth terminal comprising;

an input configured to receive said digitally modulated composite signal;

a digital demodulator configured to digitally demodulate said digitally modulated composite signal received by said input to produce a second digital composite signal;

a autoscaling digital demultiplexer configured to digitally separate said second digital composite signal into a second plurality of digital uplink signals; and

a modulator configured to modulate said second plurality of digital uplink signals to produce a plurality of modulated analog signals.

25. The communication system of claim 24, wherein said plurality of digital uplink signals are Third Generation Partnership Project (3GPP) Wideband Code Division Multiple Access (WCDMA) Direct Sequence Spread Spectrum (DSSS) signals.

26. The communication system of claim 24, said satellite further comprising a digital filter that is configured to digitally filter said plurality of digital uplink signals.

27. The communication system of claim 24, wherein said autoscaling digital multiplexer comprises:

a processor configured to generate a scaling vector for said plurality of digital uplink signals;

an operator configured to produce a mantissa for each of said plurality of digital uplink signals with said scaling vector and said plurality of digital uplink signals; and

a multiplexer configured to multiplex said mantissa for each of said plurality of digital uplink signals and said scaling vector to produce said digital composite signal.

28. The communication system of claim 27, wherein said processor is configured to encode said scaling vector.

29. The communication system of claim 27, wherein said processor is configured to:

determine a minimum exponent of said scaling vector;

calculate a difference between each of the exponents of said scaling vector and said minimum exponent; and

form an encoded scaling vector from said minimum exponent and said difference between each of the exponents of said scaling vector and said minimum exponent.

30. The communication system of claim 27, wherein said processor is configured to:

determine a maximum exponent of said scaling vector;

calculate a difference between said maximum exponent of said scaling vector and each of the exponents of said scaling vector; and

form an encoded scaling vector from said maximum exponent and said difference between said maximum exponent and each of the exponents of said scaling vector.

31. The communication system of claim 27, wherein said processor is configure to perform a Huffman encoding to encode said scaling vector.

32. The communication system of claim 27, wherein said multiplexer is configured to Time Division Multiplexing (TDM) said mantissa for each of said plurality of digital uplink signals and said scaling vector.

33. The communication system of claim 24, further comprising an encrytor configured to encrypt the digital composite signal.

34. The communication system of claim 24, wherein said autoscaling digital demultiplexer comprises:

a demultiplexer configured to separate a plurality of mantissas and an encoded scaling vector from said second digital composite signal;

a processor configured to decode the encoded scaling vector to produce a scaling vector for each of said plurality of mantissas; and

an operator configured to produce said second plurality of digital uplink signals with said plurality of mantissas and said scaling vector.

35. The communication system of claim 24, further comprising an analog transform matrix configured to transform said plurality of modulated analog signals into a plurality of transformed analog signals.