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4674105 |
Digital signal processor
A digital signal processor for performing phase or frequency signal processes, for example, demodulating processes of modulation signals such as PSK signals. This processor is provided with...
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4669095 |
Maximum distance from zero crossing MSK demodulator
A maximum distance from zero-crossing demodulation method for MSK or OK-QPSK signals is disclosed which utilizes the zero-crossing information for establishing a bit edge reference and an optimum...
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4660213 |
Signal structure for data communication
A signal structure for high speed data communication selects each signal point in the structure to attain a low probability of error in the presence of both additive noise and multiplicative noise....
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4647863 |
Saw transition detector for PSK signals
A phase transition detector for PSK signals which utilizes a dual channel SAW differential delay line to achieve a required delay. Each channel or path of the SAW device comprises an input and an...
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4646325 |
Index decoder for digital modems
In a QAM digital modem decoder section, the received signals (after equalization) are transposed to a preselected quadrant of the signal constellation to generate an index pointer. The index...
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4635279 |
Arrangement for coherently generating sinusoids of different frequencies, and angle modulation data receiver using the arrangement
Data signals are angle-modulated onto a carrier in such a fashion as to suppress the carrier. Such modulation may be BPSK, MSK, QPSK, or OPQSK. The carrier may be subject to anomalous phase shifts,...
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4634990 |
Apparatus for demodulating differential phase shift keyed signals
A demodulating apparatus receives a differential phase shift keyed analog signal which is coupled to the input of a voltage controlled oscillator. The voltage controlled oscillator generates a...
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4631486 |
M-phase PSK vector processor demodulator
A technique for deriving a phase reference for PSK demodulation uses the absolute values of phase vectors as they are received to establish a reference with which the individual phase vectors are...
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4583047 |
Reception circuit for a wave modulated at one time in frequency by an analog signal and at another time in phase by a digital signal
The circuit comprises a surface acoustic wave device. On the substrate (32) f the surface acoustic wave device, are provided two pairs of input transducers (33, 34, 35, 36) connected, in parallel,...
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4577335 |
Coherent data communications technique
A technique for communicating digital data through a noisy medium using phase modulated carrier signals. A multiphase clock drives parallel channels to sample the received signal, avoiding the need...
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4538284 |
Signal structures with data encoding/decoding for QCM modulations
Locations of a desired number of signal points for a double side band-quadrature carrier modulation system occupy the inner intersections of a multiplicity of concentric rings with a triangular...
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4498050 |
Demodulation device for composite PSK-PSK modulated waves
A demodulator for a composite PSK-PSK modulated signal having a 2 n -phase main data signal and a 2-phase subdata signal including a frame signal, said demodulator comprising an orthogonal...
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4414675 |
MSK and OK-QPSK signal demodulator
An MSK or OK-QPSK data signal demodulator includes a filter and limiter for filtering and amplitude limiting the data signal, a timer for generating a timing signal indicating elapsed time and a...
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4379266 |
PSK Demodulator with automatic compensation of delay induced phase shifts
This circuit compensates for phase variation introduced by the delay element in a PSK (phase shift keyed) demodulator. The signal to be demodulated is split. One portion is delayed while the other...
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4371839 |
Differentially coherent signal detector
A differentially coherent signal detector capable of detecting arbitrary-even-ordered phase shift keyed signals, such as quadraphase (QSK), hex (HSK), octo (OSK), etc. In the case of QSK, the...
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4338579 |
Frequency shift offset quadrature modulation and demodulation
A Frequency Shift Offset Quadrature (FSOQ) signal which is a constant envelope frequency-shift keyed version of an offset quaternary phase shift keyed (O-QPSK) transmission is provided. A technique...
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4242641 |
Methods and apparatus for demodulating a differentially phase-modulated signal
The invention relates to methods and apparatus for demodulating a differentially phase-modulated digital input signal to produce an output signal representing the digital signal corresponding to...
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4241454 |
Hard limiting acquisition technique for PSK carrier detector
A carrier recovery scheme for a PSK demodulator through which side locking onto an interference-created sideband is avoided includes a hard-limited upstream of a phase-locked loop which removes...
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4158105 |
Clock extraction device for double-binary phase-shift keying system
A circuit for extracting a clock signal from a double-binary phase-shift keying system is disclosed. The carrier wave form is regenerated at the receiver from the phase-shift keyed (PSK) signal...
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4110706 |
Phase synchronizing circuit
A synchronizing circuit for reproducing a synchronizing carrier wave from a received N-phase (N=2 n , n being a positive real integer where n ≥1) PSK modulated carrier wave and employing a code...
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4071829 |
Coherent phase detector using a frequency discriminator
A coherent phase detector using a frequency discriminator for reducing a frequency encoded signal to baseband, thereby avoiding the necessity of generating a coherent RF phase reference signal. A...
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4065722 |
Demodulation method and circuit for discretely modulated ac signals
Demodulation of an ac signal that has been modulated by discrete changes in its amplitude, frequency or phase, is effected by first feeding the modulated ac signal through an amplitude limiter and...
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4054841 |
Differential demodulators using surface elastic wave devices
A differential demodulator of phase-modulated digital data trains includes a device, for example a piezoelectric substrate, which transmits acoustic surface waves and includes comb-shaped input and...
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3991377 |
Differential phase shift keying demodulator
Disclosed is a Differential Phase Shift Keying demodulator employing a Hjlbert filter. Filtered and unfiltered signals are sampled at the symbol rate of an incoming signal, and the sampled signals...
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3990015 |
Differential phase shift keyed detector utilizing a circulating memory
In the present invention a received DPSK signal is sampled at times corresponding to a peak signal to noise ratio and the sample of signal is passed to a circulating memory. A phase detector is...
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3980962 |
Demodulators
A demodulator for a digital code differential phase shift modulated signal comprising: an input transducer for launching surface acoustic waves corresponding to a received modulated signal; a...
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3973211 |
Combiner-demodulator for phase shift keyed suppressed carrier signals received over two transmission paths
Two signals received by spaced antennas or equivalent diversity receiving systems and having identical data signals, phase modulated on frequency-identical suppressed carrier signals, are combined...
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3971999 |
Coherent phase demodulator for phase shift keyed suppressed carrier signals
Digital data, differentially phase shift keyed on a suppressed carrier, double side band transmission, is recovered by multiplying the input signal by a signal derived from regenerative feedback...
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3919653 |
Automatic frequency corrector for differential phase demodulator
Correcting device ensuring automatically, at the receiving end, an exact timing of the frequency demodulated at the rated value, that timing being necessary for the demodulation to be effected...
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3919651 |
Phase differential modulation frequency automatic correcting device
Correcting device ensuring automatically, at the receiving end, an exact timing of the frequency demodulated at the rated value, that timing being necessary for the demodulation to be effected...
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3855539 |
METHOD AND APPARATUS FOR NOISE REDUCTION IN DISCRETE PHASE MODULATED SIGNALS
A method and apparatus for selectively reducing the phase shift contributions caused by transmission impairments such as noise and phase jitter, takes advantage of the fact that for phase modulated...
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3265813 |
Phase shift keying communication system
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2991354 |
Automatic frequency control for phase shift keying communication system
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