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4464770 |
Synchronous radio or television receiver with analog high frequency section followed by digital low frequency section
A synchronous receiver comprising a high frequency section realized by analog components, including an input preamplifier followed by two quadrature operated mixers with associated π/2 phase...
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4462108 |
Modem signal acquisition technique
Apparatus, and a related method, for fast carrier acquisition in a modem. The apparatus includes circuitry to speed carrier acquisition by the determination of which of two alternate phasors is...
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4458355 |
Adaptive phase lock loop
An apparatus for processing an information signal representative of information and containing phase error. The apparatus includes a detector for detecting the information in the signal and an...
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4458356 |
Carrier recovery circuit
A carrier recovery circuit is disclosed for use in the receiver of a digital transmission wherein channels of data are formed by demodulating incoming quadrature-related carriers using...
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4455680 |
Method and apparatus for receiving and tracking phase modulated signals
A receiver for tracking and demodulating several types of phase modulated communications, either analog or digital data, for either residual carrier or suppressed carrier signal and for phase...
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4439737 |
Phase locked loop, as for MPSK signal detector
Oscillators phase locked to transitions in the envelope of a bandwidth-limited complex waveform are used, for example, in detecting MPSK signals. The magnitude of the envelope is approximated by...
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4435825 |
Clock signal extracting circuit
A clock extractor is disclosed in which an input data signal is sampled and held in accordance with a sampling frequency, the input data signal thus processed is subjected to equalization and...
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4428061 |
Method and apparatus for receiving carrier-borne digital signals intended to operate remotely-operable switching devices
A receiver, for receiving a signal comprising a carrier signal modulated with a digital signal, comprises a circuit for demodulating the received signal to produce an output signal which contains...
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4424497 |
System for phase locking clock signals to a frequency encoded data stream
In a system having a frequency encoded data stream and a source of clock signals phase locked to the data stream, for subsequent demodulation of the data stream, the clock source is at a frequency...
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4419758 |
Transmission systems for transmitting signals over power distribution networks, and transmitters for use therein
A transmission system, for transmitting signals over an electrical power distribution circuit, comprises a transmitter arranged to produce at least two carrier signals of different frequency and to...
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4419759 |
Concurrent carrier and clock synchronization for data transmission system
The present invention is directed to circuitry for achieving concurrent synchronization of carrier phase and clock timing in double-sideband, suppressed carrier transmissions systems. A phase-lock...
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4388727 |
Receivers suitable for use in remotely-operable switching devices and data transmission systems
A receiver, for receiving a signal comprising a carrier signal modulated with a digital signal, comprises means for demodulating the received signal to produce an output signal which contains the...
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4388730 |
Noise detector and data signal receiver for a frequency modulation system
A noise detector and data signal receiver for a frequency modulation system has a first phaselock loop circuit (300), responsive to the received signal, for providing a signal indicative of the...
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4384357 |
Self-synchronization circuit for a FFSK or MSK demodulator
The self-synchronization circuit splits the incoming signal into two circuit paths where the signals are frequency shifted by a frequency signal equal to the carrier frequency so as to provide an...
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4383324 |
Digital data transmission systems
In a receiver arrangement for a quadrature phase-shift digital data transmission system including an adaptive equalizing regenerator, a phase control signal for the local oscillator is derived from...
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4380815 |
Simplified NRZ data phase detector with expanded measuring interval
A simplified digital NRZ data phase detector is provided with a minimum number of components and with an expanded measuring interval to enable the use of slower speed components. In a phase locked...
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4365205 |
Demodulator for signal which is frequency modulated by digital data
In a device comprising a linear frequency demodulator, the demodulation threshold is improved for demodulation of signals which have been modulated by a digital data item and have an energy line at...
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4361894 |
Band-pass filter circuit
A band-pass filter circuit comprising a band-pass filter for removing noise modulation components from an input signal comprising a carrier sine wave, a phase detector for detecting a phase...
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4344178 |
Costas loop QPSK demodulator
A decision-directed Costas loop demodulator, rather than employing decision circuits, i.e. sample and hold circuits, in the path of each of the I and Q channels, contains a single sample and hold...
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4334312 |
Phase synchronizing circuit for use in multi-level, multi-phase, superposition-modulated signal transmission system
A multi-level, multi-phase, superposition-modulated signal is phase detected in a four-phase phase detector with the output from a voltage controlled oscillator (VC0). The P and Q outputs from the...
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4330863 |
Demodulator arrangement
A demodulator arrangement having a demodulator and a digital phase locked loop responsive to input diphase digitally modulated signals to produce output signals which are applied to the demodulator...
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4322850 |
Sampling system for decoding biphase-coded data messages
A receiving station of a data-transmission system decodes an incoming pulse train in the shape of a differentially biphase-coded carrier wave whose cycles represent rspective message bits; the wave...
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4320345 |
Adaptive differential PSK demodulator
An adaptive differential phase shift keyed (PSK) signal demodulator which optimally tracks changes in the symbol rate of the signal. An input signal is delayed by one symbol period by passing the...
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4308503 |
Phase shift keyed demodulator using recovered carrier with controlled phase offset
This invention relates to an adaptive demodulator for use in a phase shift keyed microwave communication system. The adaptive demodulator improves the system error rate at a particular carrier to...
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4305151 |
Digital discriminator for determining frequency error of an oscillator
An adjustable alternating signal having a desired period, P, is applied to a cycle counter arranged to count n cycles and applied to a timer arranged to time out nP after a first cycle is...
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4292800 |
Textile machine data link apparatus
An improvement in a data link, such as is used for continuously transferring data concerning operations of textile yarn forming machines such as ring spinning frames, wherein a transmitter and...
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4283682 |
Erasure zone decision feedback phase lock loop for carrier recovery in data modems
An improved decision feedback phase lock loop having an erasure zone detector and a feedback loop interrupting switch responsive to the output of the erasure zone detector which cooperate to...
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4270221 |
Phaselocked receiver with orderwire channel
A radio receiver includes a phaselocked loop including a main phase detector which accomplishes both carrier extraction and demodulation of an FM orderwire signal. The loop bandwidth characteristic...
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4255713 |
Carrier regeneration circuit for polyphase modulation system
An n (=8, 9)-valued polyphase modulation system having circuit construction for carrier regeneration in which not only correct phase demodulation is effected but also any AM components of the...
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4254503 |
Radio receiver for tone modulated signals
A radio receiver for frequency modulated (FM) tones. Received signals are split and one split portion of the signal is phase shifted relative to the other and mixed with a local oscillator. The...
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4243941 |
Digital signal receiver having a dual bandwidth tracking loop
A DPSK digital signal receiver is disclosed that has a dual bandwidth offset Costas loop that is switchable from an acquire bandwidth to a narrower tracking bandwidth in response to detection of a...
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4238783 |
Telemetry system for transmitting analog data over a telephone line
An FSK receiver for a single channel analog telemetry system comprises an FSK demodulator, a frequency multiplier, and a frequency-to-voltage converter. An FSK transmitter comprises a...
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4229822 |
Data detector for a data communication system
A data communication system for use in the control and monitoring of mobile stations, for example, in a bus monitoring system, from a central station over a communication channel carrying both data...
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4217551 |
Phase modulated data transmission system
A data transmission system, particularly useful for transmission of computer data by radio frequency cables, makes use of a phase demodulator which eliminates the usual requirement for a coherent...
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4143322 |
Carrier wave recovery system apparatus using synchronous detection
A carrier wave recovery apparatus of the decision feedback type having analog multipliers of lower dynamic range. The modulated signal is phase detected by comparison with a VCO signal. The analog...
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4142241 |
Harmonic insensitive phase sensitive demodulator
A harmonic insensitive phase sensitive demodulator which converts complex AC waveforms to a DC voltage proportional to the fundamental component at an arbitrary phase with respect to a reference...
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4105975 |
Offset correction circuit for phase detectors
An offset error correction circuit for improved reception of signals by compensating for any offset error voltage produced by a phase detector in the absence of an input signal to the detector. The...
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4100499 |
Carrier synchronization system for coherent phase demodulators
This invention concerns a carrier synchronization system for a four-phase coherent PSK demodulator. The four-phase PSK signal is demodulated by an in-phase reference carrier and a quadrature...
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4091331 |
Arrangement for compensating carrier phase errors in a receiver for discrete data values
In a receiver for PSK modulated signals, carrier phase tracking is achieved by a feedback loop comprising a phase error predictor. Means are provided for adaptively setting the gain factor in the...
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4087628 |
Carrier lock detector
Apparatus for indicating a phase lock condition between an incoming multiphase carrier signal and a local oscillator in a phase-locked loop demodulator. A phase error signal is generated by phase...
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4086539 |
First-order phase-lock loop
A first order phase-lock loop that provides lower phase-error variance than classical systems at all frequencies when operated above threshold. The linear, minimum-variance filter described, in...
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4085378 |
QPSK demodulator
An improved quadraphase shift keyed (QPSK) adaptive demodulator includes a Costas loop modified to independently cross couple the inphase (I) and quadraphase (φ) channels so that minimum cross...
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4079329 |
Signal demodulator including data normalization
A digital demodulator for recovering a baseband signal from a selectable bit rate PSK modulated signal. Carrier recovery and bit timing recovery are accomplished by using the digital equivalent of...
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4072905 |
Wide acquisition range MSK demodulator input circuit
An input circuit for a wide acquisition range minimum shift keying demodulator includes a pair of phase-locked loops (PLL). Each PLL is designed to receive from a frequency doubler a respective one...
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4066978 |
Digital phase-locked loop filter
A phase processing system which includes at least one digital phase-locked loop wherein the phase of the input signal to the loop is compared with the phase of the loop output signal to produce a...
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4057762 |
Device for phase synchronizing a reproduced reference carrier signal with windows specified for preselected ones of amplitude and phase modulated signal points
A phase synchronizer for a reference carrier signal reproduced in a receiver for a combined amplitude and phase modulated signal comprises a window specifier for specifying windows for preselected...
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4054838 |
QAM phase jitter and frequency offset correction system
A system is provided for correcting phase jitter and frequency offsets in QAM modems. The system comprises (i) a narrow bandwidth, decision directed, phase-locked loop for tracking the average...
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4053836 |
Device for transmission of information by pulse code frequency shift modulation
A device for transmission of information by pulse code frequency shift modulation. The device incorporates a phase-locked superheterodyne receiver including a single voltage controlled oscillator,...
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4042884 |
Phase demodulator with offset frequency reference oscillator
A phase-locked demodulator for demodulating a phase-difference modulated carrier having a repeated phase offset increment introduced therein. The demodulator includes, in common with conventional...
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4037171 |
High speed tone decoder utilizing a phase-locked loop
A narrow-band tone decoder has a controllable oscillator, connected in a fast-capture phase-locked loop, for generating a signal having a frequency determined by a control signal produced within...
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