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US5454009A
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Method and apparatus for providing energy dispersal using frequency diversity in a satellite communications system
Assignee: Viasat Inc
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Filing: 1994-01-13
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Granted: 1995-09-26
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Expires: 2014-01-13
Abstract
Abstract A satellite communications system for dispersing energy over a wide bandwidth includes a transmitter, a communication link, and a receiver. The transmitter takes a digital data signal and modulates that signal at a prescribed carrier frequency. The modulated digital data signal is then spread over M adjacent digital channels (M≧2 and being an integer multiple of 2), each channel containing the same information, to disperse the energy over a wide frequency range. The spectral bandwidth of the adjacent digital channels is chosen with compressed spacing to conserve bandwidth. Next, the spread modulated data signal is transmitted via the communication link to the receiver. In particular, a waveform generator at the transmitter generates a phase-aligned multichannel frequency diversity waveform according to a data clock at a predetermined phase relationship to the digital data. At the receiver, the spread modulated data signal received is mixed with a despreading waveform generated in a similar manner to the waveform spectrum generated at the transmitter to recover the modulated data signal. The despreading waveform is generated according to a symbol clock signal recovered from the received modulated data signal. A demodulator recovers the original digital data from the modulated data signal. To achieve higher spreading factors, multichannel frequency diversity may be utilized with known spread spectrum techniques to achieve high data recovery rates during adverse weather (fading) conditions at high radio frequencies in the microwave and higher regions of the radio spectrum.
Inventors
- 👤 Larry J. Fruit
- 👤 John A. Schachte
- 👤 Charles A. Herbst
- 👤 James A. Wilkerson, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:52
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/204; H04B7/208; H04B7/185; H04B7/1853; H04B7/18532; H04B7/18534
Claims Analysis
Total Claims: 85
Claim 1
Independent Claim
109 words
An apparatus for dispersing energy over a wide bandwidth when communicating digital data having a predetermined data rate comprising: means for modulating the digital data by a predetermined carrier frequency; means for generating a plurality of M adjacent channels, M being an integer multiple of two less than or equal to sixteen, wherein each channel has a sinusoidal waveform in a mathematical relationship to each sinusoidal waveform of each other channel and each channel has a predetermined phase relationship to the digital data having the predetermined data rate; and means for dispersing the modulated digital data on the M channels, wherein each channel contains the same modulated digital data.
Claim 2
Independent Claim
109 words
An apparatus for dispersing energy over a wide bandwidth when communicating digital data having a predetermined data rate comprising: means for modulating the digital data by a predetermined carrier frequency; means for generating a plurality of M adjacent channels, M being an integer multiple of two less than or equal to sixteen, wherein each channel has a sinusoidal waveform in a mathematical relationship to each sinusoidal waveform of each other channel and each channel has a predetermined phase relationship to the digital data having the predetermined data rate; and means for dispersing the modulated digital data on the M channels, wherein each channel contains the same modulated digital data.
Claim 3
Dependent Claim
9 words
The apparatus of claim 1 wherein M equals four.
Claim 4
Dependent Claim
35 words
The apparatus of claim 2 wherein said generating means includes means for compressing a spectral bandwidth of the four adjacent digital channels to be approximately equal to a spectral bandwidth of three adjacent digital channels.
Claim 5
Dependent Claim
21 words
The apparatus of claim 1 wherein the mathematical relationship between each sinusoidal waveform is a function of the predetermined data rate.
Claim 6
Dependent Claim
211 words
A communications system for transmitting and receiving digital data at a predetermined data rate comprising: first channel generating means for generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform in a mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; means for modulating the digital data by a carrier frequency; means responsive to said first generating means and said modulating means for forming a composite signal by impressing the modulated digital data onto each channel; means for transmitting the composite signal; means for receiving the composite signal; clock recovery means for recovering a data clock based on the predetermined data rate of the received composite signal; second channel generating means, responsive to the data clock, for generating each channel generated by said first channel generating means, each channel having a sinusoidal waveform in the mathematical relationship to each sinusoidal waveform of each other channel and the phase relationship to the predetermined data rate prescribed by said first channel generating means; means, responsive to said second channel generating means, for coherently combining channels generated by said second channel generating means with the composite signal to recover the modulated digital data; and demodulating means for demodulating the digital data.
Claim 7
Dependent Claim
211 words
A communications system for transmitting and receiving digital data at a predetermined data rate comprising: first channel generating means for generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform in a mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; means for modulating the digital data by a carrier frequency; means responsive to said first generating means and said modulating means for forming a composite signal by impressing the modulated digital data onto each channel; means for transmitting the composite signal; means for receiving the composite signal; clock recovery means for recovering a data clock based on the predetermined data rate of the received composite signal; second channel generating means, responsive to the data clock, for generating each channel generated by said first channel generating means, each channel having a sinusoidal waveform in the mathematical relationship to each sinusoidal waveform of each other channel and the phase relationship to the predetermined data rate prescribed by said first channel generating means; means, responsive to said second channel generating means, for coherently combining channels generated by said second channel generating means with the composite signal to recover the modulated digital data; and demodulating means for demodulating the digital data.
Claim 8
Dependent Claim
21 words
The communications system of claim 5 further comprising a satellite communication link for coupling said transmitting means and said receiving means.
Claim 9
Dependent Claim
39 words
The communications system of claim 5 wherein said first channel generating means includes a programmable read only memory which receives phases of a clock signal based on the predetermined data rate and generates digital word samples of digital waveforms.
Claim 10
Dependent Claim
39 words
The communications system of claim 7 wherein said first channel generating means further includes a digital to analog converter responsive to said programmable read only memory for converting the digital word samples to at least one analog waveform signal.
Claim 11
Dependent Claim
20 words
The communications system of claim 8 wherein the mathematical relationship between each sinusoidal waveform includes an odd integer multiplication factor,
Claim 12
Dependent Claim
39 words
The communications system of claim 9 wherein a first sinusoidal waveform is represented by sin(2π*f 1 t+φ) and a second sinusoidal waveform is represented by sin(2π*3f 1 t+3φ) wherein f 1 is a function of the predetermined symbol rate.
Claim 13
Dependent Claim
24 words
The communications system of claim 10 wherein the mathematical relationship further includes a sum of the first sinusoidal waveform and the second sinusoidal waveform.
Claim 14
Dependent Claim
33 words
The communications system of claim 5 wherein said second channel generating means includes a programmable read only memory which receives phases of the data clock and generates digital word samples of digital waveforms.
Claim 15
Dependent Claim
39 words
The communications system of claim 12 wherein said second channel generating means further includes a digital to analog converter responsive to said programmable read only memory for converting the digital word samples to at least one analog waveform signal.
Claim 16
Dependent Claim
18 words
The communications system of claim 5 wherein the phase relationship is within a range from 0° to 90°.
Claim 17
Dependent Claim
40 words
The communications system of claim 5 further including: means for encoding the digital data with forward error correction information; and error decoding means for detecting and correcting errors in the demodulated digital data based on the forward error correction information.
Claim 18
Dependent Claim
17 words
The communications system of claim 5 wherein said first channel generating means generates four adjacent digital channels.
Claim 19
Dependent Claim
35 words
The communications system of claim 16 wherein said first channel generating means compresses a spectral bandwidth of the four adjacent digital channels to be approximately equal to a spectral bandwidth of three adjacent digital channels.
Claim 20
Dependent Claim
13 words
The communications system of claim 17 wherein the phase relationship is approximately 45°.
Claim 21
Dependent Claim
24 words
The communications system of claim 5 wherein said first channel generating means compress a spectral bandwidth of the adjacent digital channels by approximately 25%.
Claim 22
Dependent Claim
119 words
In a system for receiving a modulated data signal transmitted at a predetermined data rate via a communication link, a receiving apparatus comprising: clock recovery means for recovering a data clock based on the predetermined data rate from the modulated data signal; periodic waveform generating means, responsive to the data clock, for generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform having a first mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; means, responsive to said waveform generating means, for recovering digital data from the modulated data signal based on each sinusoidal waveform of each channel; and demodulating means for demodulating the digital data.
Claim 23
Dependent Claim
119 words
In a system for receiving a modulated data signal transmitted at a predetermined data rate via a communication link, a receiving apparatus comprising: clock recovery means for recovering a data clock based on the predetermined data rate from the modulated data signal; periodic waveform generating means, responsive to the data clock, for generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform having a first mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; means, responsive to said waveform generating means, for recovering digital data from the modulated data signal based on each sinusoidal waveform of each channel; and demodulating means for demodulating the digital data.
Claim 24
Dependent Claim
22 words
The receiving apparatus of claim 20 wherein the communication link includes a satellite link for coupling a transmitter and said receiving apparatus.
Claim 25
Dependent Claim
32 words
The receiving apparatus of claim 20 wherein said waveform generating means includes a programmable read only memory which receives phases of the data clock and generates digital word samples of digital waveforms.
Claim 26
Dependent Claim
38 words
The receiving apparatus of claim 22 wherein said waveform generating means further includes a digital to analog converter responsive to said programmable read only memory for converting the digital word samples to at least one analog waveform signal.
Claim 27
Dependent Claim
20 words
The receiving apparatus of claim 23 wherein the mathematical relationship between each sinusoidal waveform includes an odd integer multiplication factor.
Claim 28
Dependent Claim
47 words
The receiving apparatus of claim 24 wherein a first sinusoidal waveform is represented by sin(2π*f 1 t+φ) and a second sinusoidal waveform is represented by sin(2π*3f 1 t+3φ) wherein f 1 is a function of the symbol clock and φ is a function of the phase relationship.
Claim 29
Dependent Claim
24 words
The receiving apparatus of claim 25 wherein the mathematical relationship further includes a sum of the first sinusoidal waveform and the second sinusoidal waveform.
Claim 30
Dependent Claim
18 words
The receiving apparatus of claim 20 wherein the phase relationship is within a range from 0° to 90°.
Claim 31
Dependent Claim
16 words
The receiving apparatus of claim 20 wherein said waveform generating means generates four adjacent digital channels.
Claim 32
Dependent Claim
34 words
The receiving apparatus of claim 28 wherein said waveform generating means compresses a spectral bandwidth of the four adjacent digital channels to be approximately equal to a spectral bandwidth of three adjacent digital channels.
Claim 33
Dependent Claim
13 words
The receiving apparatus of claim 29 wherein the phase relationship is approximately 45°.
Claim 34
Dependent Claim
23 words
The receiving apparatus of claim 20 wherein said waveform generating means compresses a spectral bandwidth of the adjacent digital channels by approximately 25%.
Claim 35
Dependent Claim
98 words
In a system for transmitting digital data having a predetermined data rate via a communication link to a receiver, a transmitting apparatus comprising: periodic waveform generating means for generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform having a mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; means for modulating the digital data by a carrier frequency; and means responsive to said waveform generating means and said modulating means for forming a composite signal by impressing the modulated digital data onto each channel.
Claim 36
Dependent Claim
98 words
In a system for transmitting digital data having a predetermined data rate via a communication link to a receiver, a transmitting apparatus comprising: periodic waveform generating means for generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform having a mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; means for modulating the digital data by a carrier frequency; and means responsive to said waveform generating means and said modulating means for forming a composite signal by impressing the modulated digital data onto each channel.
Claim 37
Dependent Claim
20 words
The transmitting apparatus of claim 32 further comprising a satellite communications link for coupling said transmitting apparatus and said receiver.
Claim 38
Dependent Claim
39 words
The transmitting apparatus of claim 32 wherein said waveform generating means includes a programmable read only memory which receives phases of a clock signal based on the predetermined data rate and generates digital word samples of a digital waveform.
Claim 39
Dependent Claim
38 words
The transmitting apparatus of claim 34 wherein said waveform generating means further includes a digital to analog converter responsive to said programmable read only memory for converting the digital word samples to at least one analog waveform signal.
Claim 40
Dependent Claim
20 words
The transmitting apparatus of claim 35 wherein the mathematical relationship between each sinusoidal waveform includes an odd integer multiplication factor.
Claim 41
Dependent Claim
48 words
The transmitting apparatus of claim 36 wherein a first sinusoidal waveform is represented by sin(2π*f 1 t+φ) and a second sinusoidal waveform is represented by sin(2π*3f 1 t+3φ) wherein f 1 is a function of the predetermined symbol rate and φ is a function of the phase relationship.
Claim 42
Dependent Claim
24 words
The transmitting apparatus of claim 37 wherein the mathematical relationship further includes a sum of the first sinusoidal waveform and the second sinusoidal waveform.
Claim 43
Dependent Claim
18 words
The transmitting apparatus of claim 32 wherein the phase relationship is within a range from 0° to 90°.
Claim 44
Dependent Claim
16 words
The transmitting apparatus of claim 32 wherein said waveform generating means generates four adjacent digital channels.
Claim 45
Dependent Claim
34 words
The transmitting apparatus of claim 40 wherein said waveform generating means compresses a spectral bandwidth of the four adjacent digital channels to be approximately equal to a spectral bandwidth of three adjacent digital channels.
Claim 46
Dependent Claim
23 words
The transmitting apparatus of claim 32 wherein said waveform generating means compresses a spectral bandwidth of the adjacent digital channels by approximately 25%.
Claim 47
Independent Claim
106 words
A method of dispersing energy over a wide bandwidth when communicating digital data having a predetermined data rate, said method comprising the steps of: modulating the digital data by a predetermined carrier frequency; generating a plurality of M adjacent channels, M being an integer multiple of two less than or equal to sixteen, wherein each channel has a sinusoidal waveform mathematically related to each sinusoidal waveform of each other channel and each channel has a predetermined phase relationship to the digital data having the predetermined data rate; and dispersing the modulated digital data on the M channels, wherein each channel contains the same modulated digital data.
Claim 48
Independent Claim
106 words
A method of dispersing energy over a wide bandwidth when communicating digital data having a predetermined data rate, said method comprising the steps of: modulating the digital data by a predetermined carrier frequency; generating a plurality of M adjacent channels, M being an integer multiple of two less than or equal to sixteen, wherein each channel has a sinusoidal waveform mathematically related to each sinusoidal waveform of each other channel and each channel has a predetermined phase relationship to the digital data having the predetermined data rate; and dispersing the modulated digital data on the M channels, wherein each channel contains the same modulated digital data.
Claim 49
Dependent Claim
9 words
The method of claim 43 wherein M equals four.
Claim 50
Dependent Claim
35 words
The method of claim 44 wherein said step of generating further includes compressing a spectral bandwidth of the four adjacent digital channels to be approximately equal to a spectral bandwidth of three adjacent digital channels.
Claim 51
Dependent Claim
182 words
In a communications system for transmitting and receiving digital data at a predetermined data rate a method comprising the steps of: a) generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform having a mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; b) modulating the digital data by a carrier frequency; c) impressing the modulated digital data onto each channel to form a composite signal; d) transmitting the composite signal from a first station; e) receiving the composite signal at a second station; f) recovering a data clock based on the predetermined data rate of the received composite signal; g) generating sinusoidal waveforms based on the recovered data clock, the sinusoidal waveforms corresponding to each channel generated at said step a), each sinusoidal waveform having the mathematical relationship to each other sinusoidal waveform and the phase relationship prescribed at said step a); h) recovering the modulated digital data from the composite signal based on the sinusoidal waveforms generated at said step g); and i) demodulating the digital data.
Claim 52
Dependent Claim
182 words
In a communications system for transmitting and receiving digital data at a predetermined data rate a method comprising the steps of: a) generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform having a mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; b) modulating the digital data by a carrier frequency; c) impressing the modulated digital data onto each channel to form a composite signal; d) transmitting the composite signal from a first station; e) receiving the composite signal at a second station; f) recovering a data clock based on the predetermined data rate of the received composite signal; g) generating sinusoidal waveforms based on the recovered data clock, the sinusoidal waveforms corresponding to each channel generated at said step a), each sinusoidal waveform having the mathematical relationship to each other sinusoidal waveform and the phase relationship prescribed at said step a); h) recovering the modulated digital data from the composite signal based on the sinusoidal waveforms generated at said step g); and i) demodulating the digital data.
Claim 53
Dependent Claim
23 words
The method of claim 46 further including the step of coupling the first station and the second station via a satellite communication link.
Claim 54
Dependent Claim
46 words
The method of claim 46 wherein said step a) includes the steps of: receiving phases of a clock signal based on the predetermined data rate; generating digital word samples of a digital waveform; and converting the digital word samples to at least one analog waveform signal.
Claim 55
Dependent Claim
40 words
The method of claim 46 wherein said step g) includes the steps of: receiving phases of the data clock; generating digital word samples of a digital waveform; and converting the digital word samples to at least one analog waveform signal.
Claim 56
Dependent Claim
19 words
The method of claim 49 wherein the mathematical relationship between each sinusoidal waveform includes an odd integer multiplication factor.
Claim 57
Dependent Claim
47 words
The method of claim 50 wherein a first sinusoidal waveform is represented by sin(2π*f 1 t+φ) and a second sinusoidal waveform is represented by sin(2π*3f 1 t+3φ) wherein f 1 is a function of the predetermined data rate and φ is a function of the phase relationship.
Claim 58
Dependent Claim
23 words
The method of claim 51 wherein the mathematical relationship further includes a sum of the first sinusoidal waveform and the second sinusoidal waveform.
Claim 59
Dependent Claim
17 words
The method of claim 46 wherein the phase relationship is within a range from 0° to 90°.
Claim 60
Dependent Claim
41 words
The method of claim 46 further including the steps of: encoding the digital data with forward error correction information before said step d) ; and detecting and correcting errors in the demodulated digital data based on the forward error correction information.
Claim 61
Dependent Claim
18 words
The method of claim 46 wherein said step a) includes the step of generating four adjacent digital channels.
Claim 62
Dependent Claim
37 words
The method of claim 55 wherein said step a) further includes the step of compressing a spectral bandwidth of the four adjacent digital channels to be approximately equal to a spectral bandwidth of three adjacent digital channels.
Claim 63
Dependent Claim
12 words
The method of claim 56 wherein the phase relationship is approximately 45°.
Claim 64
Dependent Claim
25 words
The method of claim 46 wherein said step a) includes the step of compressing a spectral bandwidth of the adjacent digital channels by approximately 25%.
Claim 65
Independent Claim
102 words
A method of receiving a modulated data signal transmitted at a predetermined data rate via a communication link, comprising the steps of: recovering a data clock from the modulated data signal based on the predetermined data rate; in response to the data clock, generating sinusoidal waveforms, each sinusoidal waveform corresponding to at least one of a plurality of adjacent digital channels, each sinusoidal waveform having a mathematical relationship to each other sinusoidal waveform and a phase relationship to the predetermined data rate; recovering modulated digital data from the modulated data signal based on the generated sinusoidal waveforms; and demodulating the digital data.
Claim 66
Independent Claim
102 words
A method of receiving a modulated data signal transmitted at a predetermined data rate via a communication link, comprising the steps of: recovering a data clock from the modulated data signal based on the predetermined data rate; in response to the data clock, generating sinusoidal waveforms, each sinusoidal waveform corresponding to at least one of a plurality of adjacent digital channels, each sinusoidal waveform having a mathematical relationship to each other sinusoidal waveform and a phase relationship to the predetermined data rate; recovering modulated digital data from the modulated data signal based on the generated sinusoidal waveforms; and demodulating the digital data.
Claim 67
Dependent Claim
41 words
The method of claim 59 wherein said step of generating includes the steps of receiving phases of the data clock; generating digital word samples of a digital waveform; and converting the digital word samples to at least one analog waveform signal.
Claim 68
Dependent Claim
19 words
The method of claim 60 wherein the mathematical relationship between each sinusoidal waveform includes an odd integer multiplication factor.
Claim 69
Dependent Claim
50 words
The method of claim 61 wherein said step of generating includes generating a first sinusoidal waveform represented by sin(2π*f 1 t+φ) and a second sinusoidal waveform represented by sin(2π*3f 1 t+3φ), wherein f 1 is a function of the symbol clock and φ is a function of the phase relationship.
Claim 70
Dependent Claim
23 words
The method of claim 62 wherein the mathematical relationship further includes a sum of the first sinusoidal waveform and the second sinusoidal waveform.
Claim 71
Dependent Claim
17 words
The method of claim 59 wherein the phase relationship is within a range from 0° to 90°.
Claim 72
Dependent Claim
16 words
The method of claim 59 wherein said step of generating includes generating four adjacent digital channels.
Claim 73
Dependent Claim
35 words
The method of claim 65 wherein said step of generating further includes compressing a spectral bandwidth of the four adjacent digital channels to be approximately equal to a spectral bandwidth of three adjacent digital channels.
Claim 74
Dependent Claim
12 words
The method of claim 66 wherein the phase relationship is approximately 45°.
Claim 75
Dependent Claim
23 words
The method of claim 59 wherein said step of generating includes compressing a spectral bandwidth of the adjacent digital channels by approximately 25%.
Claim 76
Independent Claim
78 words
A method of transmitting digital data having a predetermined data rate via a communication link to a receiver comprising the steps of: generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform having a mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; modulating the digital data by a carrier frequency; and impressing the modulated digital data onto each channel to form a composite signal.
Claim 77
Independent Claim
78 words
A method of transmitting digital data having a predetermined data rate via a communication link to a receiver comprising the steps of: generating a plurality of adjacent digital channels, each channel having a sinusoidal waveform having a mathematical relationship to each sinusoidal waveform of each other channel and a phase relationship to the predetermined data rate; modulating the digital data by a carrier frequency; and impressing the modulated digital data onto each channel to form a composite signal.
Claim 78
Dependent Claim
47 words
The method of claim 69 wherein said step of generating includes the steps of: receiving phases of a clock signal based on the predetermined data rate; generating digital word samples of a digital waveform; and converting the digital word samples to at least one analog waveform signal.
Claim 79
Dependent Claim
19 words
The method of claim 70 wherein the mathematical relationship between each sinusoidal waveform includes an odd integer multiplication factor.
Claim 80
Dependent Claim
54 words
The method of claim 71 wherein said step of generating includes the step of generating a first sinusoidal waveform represented by sin(2π*f 1 t+φ) and a second sinusoidal waveform represented by sin(2π*3f 1 t+3φ), wherein f 1 is a function of the predetermined data rate and φ is a function of the phase relationship.
Claim 81
Dependent Claim
23 words
The method of claim 72 wherein the mathematical relationship further includes a sum of the first sinusoidal waveform and the second sinusoidal waveform.
Claim 82
Dependent Claim
16 words
The method of claim 69 wherein the phase relationship is within a range from 0°to 90°.
Claim 83
Dependent Claim
19 words
The method of claim 69 wherein said step of generating includes the step of generating four adjacent digital channels.
Claim 84
Dependent Claim
35 words
The method of claim 75 wherein said step of generating further includes compressing a spectral bandwidth of the four adjacent digital channels to be approximately equal to a spectral bandwidth of three adjacent digital channels.
Claim 85
Dependent Claim
23 words
The method of claim 76 wherein said step of generating includes compressing a spectral bandwidth of the adjacent digital channels by approximately 25%.
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