US3843931A
Expired / Lapsed
US
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Method for demodulation of a differentially phase-modulated signal
Assignee: Nokia Oyj
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Filing: 1973-03-13
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Granted: 1974-10-22
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Expires: 1993-03-13
Abstract
Abstract A method for demodulation of a differentially phase-modulated signal. The phase of a received signal is measured digitally during each information-transfer element in relation to an independent reference signal. The phase difference is stored in numerical form in a memory. The final demodulation is carried out by evaluating the difference between the measured phases of two adjacent signal elements.
Inventors
- 👤 R Martti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:49
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/02; H03D3/18; H03D3/20; H04; H04L; H04L27/00; H04L27/18; H04L27/22; H04L27/233; H04L27/2332; H03D2200/00; H03D2200/0001; H03D2200/0039
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
229 words
A method for demodulation of a differentially phase-modulated signal in a receiver, comprising: measuring digitally the phase of the signal as received during each information-transfer element in relation to an independent reference signal, storing the phase difference in numerical form in a memory, subtracting the phase differences measured during two subsequent signal elements from each other, measuring the phase difference between the received signal and the reference signal by first shaping them into rectangular waves which are fed through an Exclusive-Or circuit, the share of the time of the 1-state of the Obtained signal being proportional to the absolute value of the phase angle between the rectangular waves, measuring the ratio digitally by developing a certain number of pulses and by counting the number of pulses that occur at the point of time at which the obtained signal is in the 1-state, obtaining the sign of the phase difference by comparing with each other the received signal and a signal in an angle of +90* to the reference signal, storing the measured phase angle as bits as well as the said sign for the time of the next transfer element, at which time a new measurement is carried out to another memory, and when the new values have been obtained, calculating their difference whereby the conclusion is drawn in accordance with to which expected phase difference it is closest.
Claim 2
Independent Claim
229 words
A method for demodulation of a differentially phase-modulated signal in a receiver, comprising: measuring digitally the phase of the signal as received during each information-transfer element in relation to an independent reference signal, storing the phase difference in numerical form in a memory, subtracting the phase differences measured during two subsequent signal elements from each other, measuring the phase difference between the received signal and the reference signal by first shaping them into rectangular waves which are fed through an Exclusive-Or circuit, the share of the time of the 1-state of the Obtained signal being proportional to the absolute value of the phase angle between the rectangular waves, measuring the ratio digitally by developing a certain number of pulses and by counting the number of pulses that occur at the point of time at which the obtained signal is in the 1-state, obtaining the sign of the phase difference by comparing with each other the received signal and a signal in an angle of +90* to the reference signal, storing the measured phase angle as bits as well as the said sign for the time of the next transfer element, at which time a new measurement is carried out to another memory, and when the new values have been obtained, calculating their difference whereby the conclusion is drawn in accordance with to which expected phase difference it is closest.
Claim 3
Dependent Claim
54 words
A method as claimed in claim 1, wherein the sign of the phase difference is obtained by means of a second Exclusive-Or circuit so that if the ratio of the duration of the 1-state and the 0-state of the signal in this way obtained is below 1, the sign is positive and vice versa.
Claim 4
Dependent Claim
16 words
A method as claimed in claim 1, wherein said reference signal is produced in the receiver.
Claim 5
Dependent Claim
17 words
A method as claimed in claim 1, wherein said reference signal is synchronized to the received signal.
Claim 6
Dependent Claim
20 words
A method as claimed in claim 1, wherein said reference signal is synchronized to the timing of the transfer elements.
Claim 7
Dependent Claim
23 words
A method as claimed in claim 2, wherein the reference signal (d) is developed independently in the receiver, the indication being differentially coherent.
Claim 8
Dependent Claim
22 words
A method as claimed in claim 2, wherein the reference signal (d) is synchronized with the received signal, the indication being coherent.
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) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |