US3660764A
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Non-coherent differential phase detection
Assignee: AT&T Inc
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Filing: 1969-11-26
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Granted: 1972-05-02
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Expires: 1989-11-26
Abstract
Abstract A differentially phase modulated (DPM) information signal, such as a binary differentially coherent phase shift-keyed signal, is detected without the need for a synchronous local oscillator by decomposing the carrier information signal into its baseband conjugate in-phase and out-of-phase components, I(t) and Q(t), respectively, generating from the components the functions F(t) Q(t)I(t-T)-I(t)Q(t-T) and G(t) I(t)I(t-T)+Q(t)Q(t-T) and subsequently forming H1(t) F(t)+G(t) tan Alpha 1, and H2(t) F(t)+G(t) tan Alpha 2, where T is the bit interval and Alpha 1 and Alpha 2 are arbitrary but generally unequal. In the binary case, however, Alpha 1 Alpha 2 0 and F(t) is the differentially phase detected signal. In higher order DPM systems the equations for H1(t) and H2(t) are simultaneously solved to recover the differential phase information.
Inventors
- 👤 James E Goell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:20
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/18; H04L27/22; H04L27/233; H04L27/2331
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
113 words
A method for the detection of a differentially phase modulated carrier information signal comprising the steps of: decomposing said signal into its conjugate baseband in-phase and out-of-phase components, I(t) and Q(t), respectively, and first generating from these components the functions F(t) and G(t) given by Q(t)I(t-T) - I(t)Q(t-T) and Q(t)Q(t-T) + I(t)I(tT), respectively, where T is the bit interval of said information signal, secondly generating from F(t) and G(t) the signals H1(t) and H2(t) given by F(t) + G(t) tan Alpha 1 and F(t) + G(t) tan Alpha 2, respectively, where Alpha 1 and Alpha 2 are arbitrary but generally unequal, and solving simultaneously H1(t) and H2(t) to recover the differential phase information.
Claim 2
Independent Claim
113 words
A method for the detection of a differentially phase modulated carrier information signal comprising the steps of: decomposing said signal into its conjugate baseband in-phase and out-of-phase components, I(t) and Q(t), respectively, and first generating from these components the functions F(t) and G(t) given by Q(t)I(t-T) - I(t)Q(t-T) and Q(t)Q(t-T) + I(t)I(tT), respectively, where T is the bit interval of said information signal, secondly generating from F(t) and G(t) the signals H1(t) and H2(t) given by F(t) + G(t) tan Alpha 1 and F(t) + G(t) tan Alpha 2, respectively, where Alpha 1 and Alpha 2 are arbitrary but generally unequal, and solving simultaneously H1(t) and H2(t) to recover the differential phase information.
Claim 3
Dependent Claim
63 words
The method of claim 1 wherein said decomposing step comprises the steps of: dividing said signal into two signal portions, phase shifting by 90* one of said signal portions, mixing both said phase shifted signal portion and said other portion with a non-synchronous local oscillator signal to generate at baseband Q(t) from said phase shifted signal portion and I(t) from said other portion.
Claim 4
Dependent Claim
50 words
The method of claim 2 for use in an nth order systeM, including the additional step of maintaining the phase difference delta (t) between the phase of the undeviated carrier of said information signal and the phase of said local oscillator such that delta (t)- delta (t-T)< < pi /n.
Claim 5
Dependent Claim
22 words
The method of claim 3 for use in a binary differentially coherent phase shift-keyed system and wherein n is equal to 2.
Claim 6
Dependent Claim
92 words
The method of claim 1 wherein said first generating step comprises the steps of: dividing I(t) and Q(t) into two separate signal portions, time delaying one of each of said signal portions of I(t) and Q(t) by an amount T, multiplying the undelayed portion of I(t) with the delayed portion of Q(t) to generate a first signal product, multiplying the undelayed portion of Q(t) with the delayed portion of I(t) to generate a second signal product, subtracting said first signal product from said second signal product, thereby to produce the signal F(t).
Claim 7
Dependent Claim
34 words
The method of claim 5 wherein said information signal is a frequency modulated binary differentially coherent phase shift-keyed signal, Alpha 1 Alpha 2 0, and F(t) is the differentially phase-detected version of said signal.
Claim 8
Dependent Claim
95 words
The method of claim 5 including the additional steps of multiplying I(t) and its time-delayed portion together to produce a third signal product, multiplying Q(t) and its time-delayed portion together to produce a fourth signal product, adding said third and fourth signal products to produce G(t), generating tan Alpha 1 and tan Alpha 2, multiplying each of tan Alpha 1 and tan Alpha 2 by G(t) to produce G(t) tan Alpha 1 and G(t) tan Alpha 2, adding F(t) to each of G(t) tan Alpha 1 and g(t)tan Alpha 2 to produce H1(t) and H2(t).
Claim 9
Dependent Claim
115 words
A differential phase detector comprising means for decomposing a differentially phase modulated carrier information signal into its conjugate baseband in-phase and out-of-phase components, I(t) and Q(t), respectively, and first means for generating from these components the functions F(t) and G(t) given by Q(t)I(t-T)-I(t)Q(t-T) and Q(t)Q(t-T)+I(t)I(t-T), T), respectively, where T is the bit interval of said information signal, means for generating tan Alpha 1 and tan Alpha 2, where Alpha 1 and Alpha 2 are arbitrary and generally unequal, second means for generating the functions H1(t) and H2(t) given by F(t) + G(t)tan Alpha 1 and F(t) + G(t)tan Alpha 2, respectively, and means for simultaneously solving H1(t) and H2(t) to recover the differential phase information.
Claim 10
Dependent Claim
115 words
A differential phase detector comprising means for decomposing a differentially phase modulated carrier information signal into its conjugate baseband in-phase and out-of-phase components, I(t) and Q(t), respectively, and first means for generating from these components the functions F(t) and G(t) given by Q(t)I(t-T)-I(t)Q(t-T) and Q(t)Q(t-T)+I(t)I(t-T), T), respectively, where T is the bit interval of said information signal, means for generating tan Alpha 1 and tan Alpha 2, where Alpha 1 and Alpha 2 are arbitrary and generally unequal, second means for generating the functions H1(t) and H2(t) given by F(t) + G(t)tan Alpha 1 and F(t) + G(t)tan Alpha 2, respectively, and means for simultaneously solving H1(t) and H2(t) to recover the differential phase information.
Claim 11
Dependent Claim
112 words
The detector of claim 8 wherein said decomposing means comprises means for dividing said signal into two separate portions, means for phase shifting by 90* one of said portions, first and second down-converters, a non-synchronous local oscillator which generates a signal of phase which differs from the phase of said carrier information signal by an amount delta (t), means for coupling said phase-shifted portion of said information signal and a portion of said local oscillator signal into said first down-converter to generate I(t) at its output, and means for coupling said other signal portion and a portion of said local oscillator signal into said second Down-converter to generate Q(t) at its output.
Claim 12
Dependent Claim
20 words
The detector of claim 9 wherein said dividing means and said phase shifting means comprise a resistively terminated hybrid coupler.
Claim 13
Dependent Claim
33 words
The detector of claim 9 for use in an nth order differentially phase-modulated system, in combination with means for maintaining said phase difference delta (t) such that delta (t)- delta (t-T)<< pi /n.
Claim 14
Dependent Claim
19 words
The detector of claim 11 wherein said system is a binary differentially coherent phase shift-keyed system and n 2.
Claim 15
Dependent Claim
97 words
The detector of claim 8 wherein said generating means comprises means for dividing both I(t) and Q(t) into two separate signal portions, means for time delaying by an amount T one portion of each of I(t) and Q(t), means for multiplying the undelayed portion of I(t) and the delayed portion for Q(t) to generate a first product signal, means for multiplying the undelayed portion of Q(t) and the delayed portion of I(t) to generate a second product signal, and means for subtracting said first signal product from said second product signal, thereby to produce the signal F(t).
Claim 16
Dependent Claim
24 words
The detector of claim 13 wherein said time delaying means comprises a delay line of length adapted to produce a delay of T seconds.
Claim 17
Dependent Claim
15 words
The detector of claim 13 wherein said each of multiplying means comprise a diode multiplier.
Claim 18
Dependent Claim
34 words
The detector of claim 13 for use in a frequency modulated binary differentially coherent phase shift-keyed system wherein Alpha 1 Alpha 2 0 and F(t) is the differentially phase detected version of said signal.
Claim 19
Dependent Claim
122 words
The detector of claim 13 wherein said first means for generating G(t) comprises means for multiplying the delayed and undelayed portions of Q(t) together to produce a third signal product, means for multiplying the delayed and undelayed portions of I(t) together to produce a fourth signal product, means for adding said third and fourth signal products together to generate G(t), means for multiplying G(t) by tan Alpha 1 and tan Alpha 2 to generate G(t) tan Alpha 1 and G(t) tan Alpha 2, means for adding F(t) to each of G(t) tan Alpha 1 and G(t) tan Alpha 2 to produce H1(t) and H2(t), respectively, and means for simultaneous solving the equations for H1(t) and H2(t) to recover the differential phase information.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-02 | 1975-11-01 | 1976-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-02 | 1979-11-01 | 1980-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-02 | 1983-11-01 | 1984-05-02 | $7700.00 | Window Closed / Lapsed |