US5834986A
Expired / Lapsed
US
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Direct 2nd derivative synthesis method for controlling sidelobe energy in an MSK modulated signal
Assignee: Northrop Grumman Systems Corp
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Filing: 1997-10-06
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Granted: 1998-11-10
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Expires: 2017-10-06
Abstract
Abstract A method for generating minimum shift keying (MSK) modulation signals with relatively reduced energy sidelobes relative to known methods. In one embodiment, a second derivative of the phase waveform is taken and convolved with a selectable smoothing function and integrated twice to generate a smooth phase waveform S2D -- MSK (i)=where .o slashed. (i)=π i d(i)/2T. In the alternate embodiment, the sidelobe energy can be varied by simply changing the smoothing function, which can be stored in a lookup table. In the embodiment, the MSK modulation signal has a constant amplitude envelope allowing it to be transmitted using class C amplifiers. Since the embodiment provides continuous phase derivatives, the frequency and thus the sidelobe energy is sufficiently reduced to minimize interference with cosite equipment and nearby communication channels bands.
Inventors
- 👤 Michael H. Myers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 01:47
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03828; H04L25/03834; H04L27/00; H04L27/18; H04L27/20; H04L27/2003; H04L27/2021; H04L27/2025
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
57 words
A method for generating a minimum shift keying (MSK) signal with reduced sidelobe energy comprising the steps of: (a) differentially encoding data bits; (b) modulating said differentially encoded bits according to a modulation function MSK(t)=exp, where d(i) is ±1, T is the period, I is the interval and t is line, where ##EQU4## T=the period and t=time.
Claim 2
Independent Claim
57 words
A method for generating a minimum shift keying (MSK) signal with reduced sidelobe energy comprising the steps of: (a) differentially encoding data bits; (b) modulating said differentially encoded bits according to a modulation function MSK(t)=exp, where d(i) is ±1, T is the period, I is the interval and t is line, where ##EQU4## T=the period and t=time.
Claim 3
Independent Claim
48 words
A method for generating a minimum shift keying (MSK) signal with reduced sidelobe energy comprising the steps of: (a) differentially encoding data bits; (b) modulating said differentially encoded bits to create a time varying frequency in the form of A Sin (πt/T)/2, where ##EQU5## T=the period and t=time.
Claim 4
Independent Claim
48 words
A method for generating a minimum shift keying (MSK) signal with reduced sidelobe energy comprising the steps of: (a) differentially encoding data bits; (b) modulating said differentially encoded bits to create a time varying frequency in the form of A Sin (πt/T)/2, where ##EQU5## T=the period and t=time.
Claim 5
Independent Claim
39 words
A system for generating minimum shift keying (MSK) signal with reduced sidelobe energy comprising: (a) differentially encoding the data bits; (b) modulating said differentially encoded bits to create a time varying frequency in the form of A Sin (πt/T)/2.
Claim 6
Independent Claim
39 words
A system for generating minimum shift keying (MSK) signal with reduced sidelobe energy comprising: (a) differentially encoding the data bits; (b) modulating said differentially encoded bits to create a time varying frequency in the form of A Sin (πt/T)/2.
Claim 7
Independent Claim
33 words
A system for generating minimum shift keying (MSK) signal with reduced sidelobe energy comprising: (a) differentially encoding the data; (b) modulating said bits to create a time varying frequency term A Sin (πt/T)/2.
Claim 8
Independent Claim
33 words
A system for generating minimum shift keying (MSK) signal with reduced sidelobe energy comprising: (a) differentially encoding the data; (b) modulating said bits to create a time varying frequency term A Sin (πt/T)/2.
Claim 9
Independent Claim
69 words
A method for generating a minimum shift keying (MSK) signal with reduced sidelobe energy comprising the steps of: (a) generating an MSK modulation signal; (b) taking a first derivative of said MSK modulation signal; (c) taking a second derivative of said MSK modulation signal; (d) convolving said derivative signal with a predetermined smoothing function defining a convolved signal; integrating said convolved signal, and (f) second integrating said convolved signal.
Claim 10
Independent Claim
69 words
A method for generating a minimum shift keying (MSK) signal with reduced sidelobe energy comprising the steps of: (a) generating an MSK modulation signal; (b) taking a first derivative of said MSK modulation signal; (c) taking a second derivative of said MSK modulation signal; (d) convolving said derivative signal with a predetermined smoothing function defining a convolved signal; integrating said convolved signal, and (f) second integrating said convolved signal.
Claim 11
Dependent Claim
12 words
The method as recited in claim 5, wherein said smoothing function s(t)=(1-cos)
Claim 12
Dependent Claim
14 words
The method as recited in claim 5, wherein said smoothing function s(t)=(1-cos) 2 .
Claim 13
Dependent Claim
14 words
The method as recited in claim 5, wherein said smoothing function (1-cos) 3 .
Claim 14
Dependent Claim
14 words
The method as recited in claim 5, wherein said smoothing function (1-cos) 4 .
Claim 15
Dependent Claim
14 words
The method as recited in claim 5, wherein said smoothing function (1-cos) 1/2 .
Claim 16
Dependent Claim
27 words
The method as recited in claim 5, wherein a plurality of smoothing functions are stored and said method includes the step of selecting a stored smoothing function.
Claim 17
Independent Claim
33 words
A system for generating an MSK modulation signal with reduced energy sidelobes confirming: means for generating an MSK modulation signal; and means for selectively varying the sidelobe energy of said MSK modulation signal.
Claim 18
Independent Claim
33 words
A system for generating an MSK modulation signal with reduced energy sidelobes confirming: means for generating an MSK modulation signal; and means for selectively varying the sidelobe energy of said MSK modulation signal.
Claim 19
Dependent Claim
34 words
The system as recited in claim 12, wherein said varying means includes means for storing a plurality of predetermined smoothing functions, wherein different smoothing functions result in MSK modulation signals with different sidelobe energies.
Claim 20
Dependent Claim
17 words
The system as recited in claim 13, wherein one of said plurality of smoothing functions is s(t)=(1-cos).
Claim 21
Dependent Claim
19 words
The system as recited in claim 13, wherein one of said plurality of smoothing functions is s(t)=(1-cos) 2 .
Claim 22
Dependent Claim
14 words
The method as recited in claim 13, wherein said smoothing function (1-cos) 3 .
Claim 23
Dependent Claim
14 words
The method as recited in claim 13, wherein said smoothing function (1-cos) 4 .
Claim 24
Dependent Claim
14 words
The method as recited in claim 13, wherein said smoothing function (1-cos) 1/2 .
Claim 25
Dependent Claim
20 words
The system as recited in claim 12, wherein said generating means includes means for generating a conventional MSK modulation signal.
Claim 26
Dependent Claim
29 words
The system as recited in claim 16, wherein said generating means includes means for taking a second derivative of said conventional MSK modulation signal defining a second derivative signal.
Claim 27
Dependent Claim
29 words
The system as recited in claim 20, wherein said varying means includes means for convolving said second derivative signal with a predetermined smoothing signal to define a convolved signal.
Claim 28
Dependent Claim
19 words
The system as recited in claim 21, wherein said varying means includes means for double integrating said convolved signal.
References Cited (Backward Citations)
US3993868A
Cited
US4135057A
Cited
US4438413A
Cited
US4516087A
Cited
US4942592A
Cited
US4897620A
Cited
US5020079A
Cited
US5170131A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-11-09 | 2002-05-11 | 2002-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-09 | 2006-05-11 | 2006-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-09 | 2010-05-11 | 2010-11-10 | $7700.00 | Window Closed / Lapsed |