US3739277A
Expired / Lapsed
US
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Digital data transmission system utilizing phase shift keying
Assignee: Northrop Grumman Systems Corp
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Filing: 1969-06-02
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Granted: 1973-06-12
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Expires: 1989-06-02
Abstract
Abstract A digital data transmission system utilizing differential phase shift keying. In the transmitter serial data bits are grouped and the carrier wave is phase shifted by an angle determined from a comparison of successive data groups. In the receiver the successive phase shifts are detected by comparing the received signal in digital form with a digital reference, at a plurality of points in each cycle. When several matches are obtained for one phase, that phase is accepted as the phase of the received signal. The difference between the phases of successive portions of the received signal is utilized to reconstitute the transmitted data. Changes in polarity of the received signal are compared with the local reference signal to generate a control for the reference.
Inventors
- 👤 R Schneider
- 👤 W Levy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:19
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/18; H04L27/20; H04L27/2032; H04L27/2053; H04L27/206; H04L27/2067; H04L27/2075; H04L27/22; H04L27/227; H04L27/2275
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
110 words
In a receiver for a carrier signal phase modulated with digital data, a demodulator comprising: a source of phase modulated received signal; means responsive to the polarity of the received signal for generating a digital signal representing polarity; means responsive to the instantaneous amplitude of the received signal for generating a digital signal representing amplitude; a source of digital polarity and amplitude reference signals representing different phases corresponding with the possible phases of said received signal; means for comparing the digital polarity and amplitude signals representing the received signal with each of the reference signals; and means responsive to said comparing means for determining the phase of the received signal.
Claim 2
Dependent Claim
110 words
In a receiver for a carrier signal phase modulated with digital data, a demodulator comprising: a source of phase modulated received signal; means responsive to the polarity of the received signal for generating a digital signal representing polarity; means responsive to the instantaneous amplitude of the received signal for generating a digital signal representing amplitude; a source of digital polarity and amplitude reference signals representing different phases corresponding with the possible phases of said received signal; means for comparing the digital polarity and amplitude signals representing the received signal with each of the reference signals; and means responsive to said comparing means for determining the phase of the received signal.
Claim 3
Dependent Claim
67 words
The demodulator of claim 1 including means for dividing each cycle of the received signal into plural portions, means for providing phase reference signals in corresponding plural portions, means for comparing each of the portions of the received and reference signals, and means responsive to a plurality of matches between the received signal and one of the reference signals for determining the phase of the received signal.
Claim 4
Dependent Claim
24 words
The demodulator of claim 2 including means for comparing each of the portions of the received and reference signals for both polarity and amplitude.
Claim 5
Dependent Claim
36 words
The demodulator of claim 2 including means for counting the matches between the received signal and each of the reference signals and means responsive to a predetermined count for determining the phase of the received signal.
Claim 6
Dependent Claim
38 words
The demodulator of claim 1 including means for comparing succeeding phases of the received signal to determine the difference therebetween, and means responsive to the phase difference for generating a signal representing the modulation of the received signal.
Claim 7
Dependent Claim
45 words
The demodulator of claim 1 including means responsive to the phase determining means for generating a digital representation of the phase of the received signal, means for comparing successive digital phase representations to generate a series of digital data representing demodulations of the received signal.
Claim 8
Dependent Claim
19 words
The demodulator of claim 6 in which the means for comparing successive digital phase representations includes a summing means.
Claim 9
Dependent Claim
64 words
The receiver of claim 1 for a carrier signal having successive multiple cycle segments of fixed phase, the relative phase of successive segments representing modulating data, including means for detecting a shift in phase between successive segments of the received signal, and means for inhibiting operation of the phase comparing means for a portion of the segment received following detection of a phase shift.
Claim 10
Dependent Claim
71 words
The demodulator of claim 1 in which the means for generating a digital signal representing instantaneous amplitudes of the received signal includes a peak detector responsive to the amplitude of the received signal, means connected with the peak detector for establishing an amplitude reference which is a function of the peak amplitude of the received signal and means for comparing the iNstantaneous amplitude of the received signal with said amplitude reference.
Claim 11
Dependent Claim
73 words
The demodulator of claim 9 in which the amplitude comparing means includes a voltage divider connected with said amplitude reference establishing means, a plurality of amplitude comparators for comparing the instantaneous amplitude of the received signal with each of a plurality of references at different amplitude levels, from said voltage divider, and means responsive to the outputs of said comparators for generating a digital representation of the instantaneous amplitude of the received signal.
Claim 12
Dependent Claim
28 words
The converter of claim 10 in which each of said plural comparators includes two sections, one having a positive reference signal and the other a negative reference signal.
Claim 13
Dependent Claim
98 words
In a heterodyne receiver for a differential phase shifted signal having any one of n discrete phases, having a local heterodyne oscillator with an automatic frequency control, a frequency comparator circuit, comprising: a source of signals representing each polarity change of said received phase shifted signal; a source of reference signal at a frequency which is a harmonic at least 2n times the frequency of the received signal; means for comparing the phase of said polarity change representing signals and said reference signal; and means responsive to said phase comparator for controlling the phase of said local oscillator.
Claim 14
Dependent Claim
98 words
In a heterodyne receiver for a differential phase shifted signal having any one of n discrete phases, having a local heterodyne oscillator with an automatic frequency control, a frequency comparator circuit, comprising: a source of signals representing each polarity change of said received phase shifted signal; a source of reference signal at a frequency which is a harmonic at least 2n times the frequency of the received signal; means for comparing the phase of said polarity change representing signals and said reference signal; and means responsive to said phase comparator for controlling the phase of said local oscillator.
Claim 15
Dependent Claim
58 words
The receiver of claim 12 including means for deriving from said received signal a series of pulses corresponding with polarity changes of said received signal and wherein said reference signal is a square wave, said phase comparing means having means for comparing the time of occurrence of the pulses with the shift of condition of said square wave.
Claim 16
Dependent Claim
77 words
The receiver of claim 13 wherein said means for comparing the time of occurrence of the pulses with the shift of condition of the square wave includes a gate circuit opened by one of the signals and closed by the other, a source of pulses at a frequency higher than said reference frequency connected with said gate circuit and means for utilizing the pulses passed by said gate to provide a control signal for said local oscillator.
Claim 17
Dependent Claim
46 words
The receiver of claim 12 in which said phase comparing means has two paths, one operative when the phase of the received signal leads the phase of the reference and the other operative when the phase of the received signal lags the phase of the reference.
Claim 18
Dependent Claim
90 words
The receiver of claim 15 including means connected with said one path for counting said pulses occurring between the time of said phase shift and the polarity change of said reference and utilizing said count to provide a control signal for the local oscillator, and means connected with said second path for counting the pulses which occur between said phase shift and the end of a reference cycle and for subtracting the count from the total count for the reference signal to provide a control signal for the local oscillator.
Claim 19
Dependent Claim
112 words
In a digital data transmitter having a source of serial digital data bits and a source of carrier signal, phase modulation means, including: means for deriving from said source of carrier signal a plurality of signals at different phases; means responsive to a b-bit data group for selecting a signal phase to be transmitted; means for converting the serial digital data bits into successive b-bit groups; and means including a b-bit adder for summing each data group from said converting means with the data group which determined the selection of the previous transmitted signal phase, the sum being connected with said selecting means to determine the next signal phase to be transmitted.
Claim 20
Dependent Claim
112 words
In a digital data transmitter having a source of serial digital data bits and a source of carrier signal, phase modulation means, including: means for deriving from said source of carrier signal a plurality of signals at different phases; means responsive to a b-bit data group for selecting a signal phase to be transmitted; means for converting the serial digital data bits into successive b-bit groups; and means including a b-bit adder for summing each data group from said converting means with the data group which determined the selection of the previous transmitted signal phase, the sum being connected with said selecting means to determine the next signal phase to be transmitted.
Claim 21
Dependent Claim
80 words
The digital data transmitter of claim 17, including a b-bit phase control storage register having an input connected with the output of said b-bit adder, said b-bit phase control storage register having a first output connected with sAid means for selecting the signal phase to be transmitted and a second output, and a b-bit adder storage register having an input connected with the second output of said b-bit phase control storage register and an output connected with said b-bit adder.
Claim 22
Dependent Claim
158 words
In a receiver for a signal having successive signal portions of differing phases, each signal portion having any one of n discrete phase positions, a circuit for generating timing signals in a predetermined phase relation with each successive portion of the received signal, comprising: a source of timing reference signal at a frequency which is a harmonic of the product of n times the frequency of the phase shifted received signal; a frequency divider responsive to said timing reference signal, having the timing signals as an output; means for detecting a shift in phase between successive portions of the received signal; means for modifying the timing reference signal to said frequency divider to shift the phase of said timing signals; and means responsive to the detection of a shift in phase of said received signal to actuate said modifying means to establish said predetermined phase relation between the timing signals and each successive portion of said received signal.
Claim 23
Dependent Claim
158 words
In a receiver for a signal having successive signal portions of differing phases, each signal portion having any one of n discrete phase positions, a circuit for generating timing signals in a predetermined phase relation with each successive portion of the received signal, comprising: a source of timing reference signal at a frequency which is a harmonic of the product of n times the frequency of the phase shifted received signal; a frequency divider responsive to said timing reference signal, having the timing signals as an output; means for detecting a shift in phase between successive portions of the received signal; means for modifying the timing reference signal to said frequency divider to shift the phase of said timing signals; and means responsive to the detection of a shift in phase of said received signal to actuate said modifying means to establish said predetermined phase relation between the timing signals and each successive portion of said received signal.
Claim 24
Dependent Claim
72 words
The timing signal generating circuit of claim 19 including: means responsive to detection of a received signal phase shift for generating a signal in phase synchronism with the received signal; means for comparing a timing signal with the signal in synchronism with the received signal; and means responsive to detection of a phase difference between the timing signal and the signal in synchronism with the received signal for operating said actuating means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-11 | 1976-12-11 | 1977-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-11 | 1980-12-11 | 1981-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-11 | 1984-12-11 | 1985-06-12 | $7700.00 | Window Closed / Lapsed |