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5748680 |
Coarse frequency burst detector for a wireline communications system
Briefly, in accordance with one embodiment of the invention, a coarse frequency burst detector for use at the receiving end of a wireline communications system comprises: a digital signal filter...
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5740202 |
Method and apparatus for digitally evaluating the phase of a modulated carrier
The method makes it possible digitally to evaluate the phase of any carrier that has been subjected to rPSK modulation subsequent to clock recovery, sampling, and digitizing the in-phase and...
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5732109 |
Phase detector
Disclosed is a phase detection apparatus for accurately calculating the phase of an input digital complex baseband signal point independently of its amplitude value, without requiring any...
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5727027 |
PSK signal demodulation method and apparatus
In a PSK signal demodulation method of demodulating a received signal by sampling processing, one sampling interval is time-divided. A received signal is detected in different carrier frequency...
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5717722 |
Precision symbol demodulation system for multi-carrier modulation signal
When a signal modulated by a multi-subcarrier modulation scheme is to be demodulated, an amplitude detection unit sequentially detects the amplitudes of a subcarrier-synthesized signal to...
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5717721 |
Demodulation correcting circuit for FSK receiver
A demodulation correcting circuit for an FSK signal receiver which include an AFC for correcting a reception frequency error to provide stabilized demodulation, said demodulation correcting circuit...
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5710720 |
Phase lock loop based system and method for decomposing and tracking decomposed frequency components of a signal, with application to vibration compensation system
Disclosed is a system for decomposing an original signal of arbitrary frequency content into a user determined plurality of signals, each of which signals is centered about a variable center...
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5708682 |
Demodulator control system and a receiver capable of quickly acquiring a desired carrier wave
In a control system being provided with a local oscillator (42) and being for controlling a demodulating arrangement (43, 44, and 45) demodulating a desired one of modulated signals in accordance...
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5706057 |
Phase detector in a carrier recovery network for a vestigial sideband signal
A television signal receiver for processing an HDTV signal transmitted in a vestigial sideband (VSB) format with a one-dimensional data constellation includes a first carrier recovery network (18),...
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5703905 |
Multi-channel timing recovery system
An "N" channel receiver system includes "N" A/D converters, one per channel, sampling the data received by their respective channels. The sampling rate of the A/D converters is controlled by a...
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5703527 |
Frequency modulated signal demodulator circuit and communication terminal equipment
A frequency modulated signal demodulator circuit wherein an in-phase component (I) and an orthogonal component (Q) of a frequency modulated signal output from an orthogonal detector circuit are...
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5699385 |
Method and apparatus for locating and tracking a QPSK carrier
In a receiver for receiving a carrier modulated with data, there is provided a system for locating and tracking said carrier. The carrier is located by sweeping a frequency range containing said...
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5696797 |
Demodulator with baseband doppler shift compensation and method
An apparatus and accompanying method for demodulating with baseband Doppler frequency shift compensation. An RF section (20) down-converts received data communication signals (12) to baseband. A/D...
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5694389 |
OFDM transmission/reception system and transmitting/receiving apparatus
This invention improves the frequency acquisition range and the resistance to multipath interference. In a digital signal transmission system using OFDM, on the transmission side, some or all of a...
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5692014 |
Subsampled carrier recovery for high data rate demodulators
A high performance, low cost technique for carrier recovery and tracking of high rate demodulator (>200 Mbps to multi-gigabits per second) system is presented. The locally generated carrier is...
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5691974 |
Method and apparatus for using full spectrum transmitted power in a spread spectrum communication system for tracking individual recipient phase, time and energy
Method and apparatus for tracking the frequency and phase of signals in spread spectrum communication systems that makes more efficient use of available carrier frequency and phase information by...
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5684836 |
Receiver with automatic frequency control
In a receiver, a frequency offset estimating circuit inputs a received signal and a decision value from a decision circuit, and estimates a frequency offset. A CIR estimating circuit inputs the...
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5684842 |
Digital transmission system comprising a receiver which includes a carrier recovery circuit
A carrier recovery circuit includes a correction circuit for correcting phase differences which appear betwen a complex input signal and a local carrier supplied by a local oscillator. The...
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5675612 |
Method and apparatus for timing recovery
A method and apparatus for recovering a timing phase and frequency of a sampling clock signal in a receiver are disclosed for determining a desired timing phase by minimizing a mean squared error...
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5671253 |
Apparatus for demodulating and decoding video signals encoded in different formats
An adaptive receiver includes an adaptive demodulator and an adaptive decoder for providing demodulated and decoded output data from a video signal encoded for satellite, terrestrial or cable...
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5661761 |
Quasi-synchronous detection and demodulation circuit and frequency discriminator used for the same
The present invention relates to a quasi-synchronous detection and demodulation circuit with a contingent demodulation carrier phase removing function and to a frequency discriminator used in the...
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5656971 |
Phase demodulator having reliable carrier phase synchronization
In a demodulation device for demodulating a phase-modulated wave, a baseband signal producing circuit produces a baseband signal having particular information which is dependent on the...
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5644606 |
Receiver with two synchronization loops
Digital transmission system (10) for digitally modulated signals, comprising a receiving device (14) which includes a demodulator (110), processing apparatus (120) and carrier synchronizing...
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5640125 |
Digital PSK-type demodulator having clock recovery before carrier recovery
For demodulating a phase-modulated signal having 2M states of a carrier (M being an integer), the signal is converted into two baseband signals in quadrature. For that, they are multiplied by a...
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5638140 |
FPLL having AFC filter with limited phase shift
An AFC filter for an FPLL comprises a filter formed of a network of resistors and capacitors exhibiting a predetermined phase response characteristic. The phase response characteristic is limited...
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5638406 |
Carrier detector
A carrier detector which is capable of performing high-accuracy carrier detection even with patterns other than a CR pattern by processing signals on the frequency axis, regardless of the existence...
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5633898 |
Automatic frequency control apparatus for FSK receiver and FSK receiver including the same
A first AFC apparatus receives and detects I and Q signals from a received first FSK signal with a local osc signal; demodulates the I and Q signals; F/V-converts I or/and Q signals into a voltage;...
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5629960 |
Method for reducing distortion effects on DC off-set voltage and symbol clock tracking in a demodulator
A method for reducing the effects of transients on the DC off-set tracking stage and the symbol timing recovery stage in a full duplex or half duplex packet switched data communication system-in...
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5621767 |
Method and device for locking on a carrier signal by dividing frequency band into segments for segment signal quality determination and selecting better signal quality segment
The present invention provides a method and device for locking onto a carrier signal located within a frequency band of a digitally modulated analog signal. More particularly, the method includes...
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5614861 |
N-phase modulated signal demodulation system with carrier reproduction
A phase modulated signal demodulation system which is not affected by noise and distortion of an input signal. The system includes a carrier reproduction PLL circuit for generating a reproduction...
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5612981 |
Apparatus and methods for improving timing recovery of a system clock
Apparatus and methods for improving timing recovery of a system clock by causing its frequency to be within a specified tolerance range during a timing recovery acquisition period for the system...
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5612976 |
Detectors
A direct conversion Binary FSK radio receiver has an AFC loop comprising an Exclusive-Or phase detector 104 responsive to the I 3 and Q 3 signals. I and Q filters 100, 101 are not identical but...
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5604768 |
Frequency synchronized bidirectional radio system
A bidirectional radio system for low-cost high-throughput accumulation of data from a large number of site units. Frequency synchronization is achieved at low cost by transmitting a high accuracy...
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5604746 |
Digital data receiver
A digital data receiver having a converter for frequency conversion of the input high frequency digital orthogonal modulation signal in a fixed intermediate frequency band, a demodulator for...
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5604771 |
System and method for transmitting sound and computer data
A system transmits computer data by converting and modulating the data into a sound file, allowing the sound file to be stored for later retrieval and transmission. The system includes a sound file...
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5598439 |
Method and apparatus for symbol clock phase recovery
A method and apparatus for recovering the phase of a symbol clock operating at a predetermined symbol rate is described. A modulated RF signal which has been downconverted or a modulated baseband...
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5596605 |
Radio receiver for use in the reception of digital multiplexing signals
In the case where a received multi-level orthogonal amplitude signal is not synchronized with a local carrier frequency signal, a digital multiplexing radio receiver recognizes that an...
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5594389 |
Carrier regeneration circuit including area judging device
A carrier regeneration circuit achieves quick frequency synchronization without using a sweeper. An area judging device judges whether a baseband signal, quadrature-demodulated with a regenerated...
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5583886 |
Method for determining a plurality of channel responses and modifying a received signal therewith
Each of a plurality of transmitters (31-37) transmits (62) one of a plurality of known signals. The known signals being known to a receiver (40). The receiver (40) then measures the known signals...
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5581582 |
Automatic frequency control method and apparatus therefor
An automatic frequency control apparatus includes a sampling portion for sampling the signal transmitted according to a phase-shift keying method, a phase difference detector for detecting the...
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5579338 |
Spread spectrum receiver using partial correlations
A complex baseband signal as long as one period of PN signal is divided into three sequences. The three partial signals are input to three correlators which then calculate the correlations between...
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5579352 |
Simplified window de-skewing in a serial data receiver
A serial data receiver includes a clock recovery circuit, a data latch, and a selectable clock inversion mechanism coupled between the clock recovery circuit and the data latch. In one embodiment,...
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5572550 |
Decision directed carrier recovery circuit using phase error detector
A decision directed carrier recovery circuit comprising a demodulator for adjusting a frequency and a phase of an input carrier to demodulate an original signal therefrom, a signal decision unit...
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5572551 |
Carrier loop acquisition for staggered phase shift keying
An arrangement for acquiring an input signal has a complex multiplier (30) which receives two staggered channels (42I and 42Q). The first channel is delayed (31). A phase error estimator (22) then...
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5572553 |
Digital apparatus for broadband carrier-recovery
A method of controlling a digital carrier recovery apparatus designed to be integrated in a demodulation stage of a receiver for receiving a digital signal. The demodulation stage includes a...
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5541965 |
Carrier frequency synchronization device using two different B/W filters
A carrier synchronization device determines and compensates for differences in synchronization between a local carrier and a received modulated signal to be demodulated by the local carder. The...
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5537437 |
Initialization equalization for modulation and demodulation using special training pattern
A modulation and demodulation system suitable for use with a modem (modulator and demodulator apparatus) of a first polling type. The system allows reproduction of a signal necessary for...
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5533050 |
System for receiving a phase and amplitude modulated digital signal
A system for receiving a complex modulation digital signal using a temporal equaliser including an estimator supplying correction parameters. This system includes: at least one peripheral control...
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5533062 |
Method and apparatus for carrier tracking and demodulation
A frequency shift keyed receiver (214, 220, 218) estimates a carrier frequency and demodulates (1020) a symbol value associated with the carrier frequency. During symbol intervals, the receiver...
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5528633 |
Tuner with quadrature downconverter for pulse amplitude modulated data applications
A Radio Frequency (RF)-band tuner stage is combined with a quadrature downconverter stage in a single shielded enclosure as an RF-to-baseband pulse amplitude modulated tuner suitable for receiving...
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