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7593487 |
Non-redundant differential MSK demodulator with double error correction capability
A non-redundant differential MSK demodulator with double-error correction capability includes a differential detection stage, an error signal generator stage, and an error detection-and-correction...
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7570719 |
Receiver and a receiving method
A receiver for receives transmitted signals and each transmitted signal contains at least two known portions which are spaced from one another in the signal and at least one other portion. The...
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7570705 |
GMSK modulation using a dual-port memory
A GMSK modulator includes a dual-port memory, an address generator and a signal provider, where the dual-port memory respectively outputs in-phase and quadrature phase waveform data to first and...
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7551701 |
Frequency domain training of prefilters with interference suppression
Prefilters for a receiver with multiple input branches are trained in the frequency domain. The frequency response B of a conditioned channel is determined without reference to the prefilters, and...
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7508884 |
System and method for communicating data using constant amplitude equalized waveform
A system communicates data and includes an encoder for encoding communications data with a forward error correction code. A data randomizer randomizes the communications data with a random bit...
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7492839 |
Efficient implementation of GSM/GPRS equalizer
The disclosed invention provides a method, a system and a computer program product for the maximum likelihood sequence estimation of transmitted MSK symbols. The disclosed invention provides a set...
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7158588 |
System and method for obtaining accurate symbol rate and carrier phase, frequency, and timing acquisition for minimum shift keyed waveform
The present invention relates generally to communication systems, both wired and wireless, employing a continuous phase modulation (“CPM”) waveform with a minimum shift keying (“MSK”)...
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7065157 |
GMSK modulation techniques
This disclosure is directed to digitally implemented GMSK modulation techniques. The digital GMSK modulation techniques make use of a lookup table (LUT) and mapping logic to digitally generate GMSK...
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7035354 |
CDMA multi-user detection with a real symbol constellation
A method for multi-user detection includes receiving a complex input signal due to a superposition of waveforms encoding symbols in a real-valued constellation, which are transmitted respectively...
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6879647 |
Radio receiver AM-MSK processing techniques
A radio receiver ( 10 ) adapted to receive an AM-MSK modulated carrier signal includes an envelope detector ( 24 ) and a transformer ( 28 ) which restores the real signal to complex MSK format. A...
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6711218 |
System and method for received signal decoding
A system and method for sequence estimation decoding allows a receiver to decode a received signal modulated according to one of plurality of possible modulating methods. In a preferred approach, a...
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6411661 |
Digital timing recovery loop for GMSK demodulators
A GMSK timing recovery loop in a receiver of a Gaussian Minimum Shift Keying (GMSK) link with a low channel Bit Signal-to-Noise Ratio (BSNR) and a small bandwidth-bit period BT product in a high...
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6323727 |
Apparatus and method for detecting digital FM
A symbol detector for frequency modulated (FM) symbols includes a section determiner, a direction of movement determiner and a data symbol determiner. The section determiner receives a sample of...
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6160858 |
MSK signal processing in a GPS correlator channel
A method and apparatus for demodulating and decoding an MSK signal utilizing synchronous accumulation and simultaneous synchronization of reference carrier and MSK data clocks enables a GPS...
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5991346 |
Method for determining the best time to sample an information signal
A method for determining the best time to sample data bits of a data bit stream of a received information signal in a digital communication system includes the steps of determining the current...
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5963586 |
Method and apparatus for parallel noncoherent correlation of a spread spectrum signal
A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams...
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5963585 |
MSK spread-spectrum receiver which allows CDMA operations
A method for demodulating a received spread-spectrum signal using a minimum-shift-keyed (MSK) receiver. Using the method, an in-phase-component and a quadrature-phase-component of the received...
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5903186 |
Demodulator of MSK signal
A demodulator for demodulating an MSK signal constituted by a sequence of MSK modulated symbols is disclosed. An exclusive OR signal obtained by delay detection is delayed by delay times shorter...
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5881100 |
Method and apparatus for coherent correlation of a spread spectrum signal
A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams...
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5875213 |
GMSK communication device test system
A communication device test system is unnecessary to consider a phase offset between reproduced ideal data and phase data to be measured. The communication device test system includes AD converters...
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5867059 |
Demodulating system for MSK and GMSK signal using a fast fourier transform converter
A demodulating system for estimating frequency offset and sampling time error by a Fast Fourier Transform operation, which receives a modulated signal sent from a GMSK (Gaussian Low-Pass Filtered...
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5856998 |
Method and apparatus for correlating a continuous phase modulated spread spectrum signal
A technique for modulating and demodulating continuous phase modulation (CPM) spread spectrum signals and variations thereof. A transmitter encodes M data bits using a selected spread spectrum...
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5848105 |
GMSK signal processors for improved communications capacity and quality
A method and apparatus for separating and removing distortion from interfering co-channel signals and suppressing adjacent-channel interfering signals of the Gaussian Minimum-Shift Keyed (GMSK) or...
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5796780 |
Coherent modulation of CPM signals
Coherent modulation schemes for CPM signals. The disclosed schemes avoid the error probability increase due to the differential encoding by using a coherent encoder. A simple demodulator can be...
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5784416 |
Method and apparatus for detection of a communication signal
The disclosed communication unit functions to detect a signal by detecting the zero crossing of a current sample (and prior samples) and determining a sample value for each sample, and to determine...
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5754585 |
Method and apparatus for serial noncoherent correlation of a spread spectrum signal
A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams...
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5727030 |
Automatic frequency control circuit applicable to a mobile communication system
An automatic frequency control circuit comprises an quadrature demodulation unit for creating an in-phase signal and an antiphase signal by quadrature-demodulating a Gaussian Minimum Shiftkeying...
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5659574 |
Multi-bit correlation of continuous phase modulated signals
A technique for demodulating CPM spread spectrum signals and variations thereof. A receiver receives a CPM spread spectrum signal, splits it into two signals, demodulates the signals (either...
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5652541 |
Data demodulator employing decision feedback for reference parameter recovery and method used therin
A data demodulator operating to recover symbols from a data signal including, an estimator, coupled to the data signal, for estimating a reference parameter, and a decision function that is...
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5633895 |
Communication device with synchronized zero-crossing demodulator and method
A communication device with a synchronized zero-crossing demodulator is described. A synchronizer system (123, 223, 125, 227) and method derives symbol transition timing information from a...
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5629956 |
Method and apparatus for reception and noncoherent serial correlation of a continuous phase modulated signal
A technique for modulating and demodulating continuous phase modulation (CPM) spread spectrum signals and variations thereof. A transmitter encodes M data bits using a selected spread spectrum...
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5602877 |
Method and apparatus for information recovery in a radio communication device
A radio communication device (100) for recovering information from a received signal includes a demodulator (110) for demodulating the received signal into in-phase (I) and quadrature (Q)...
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5592514 |
Method of performing signal reconstruction at the receiving end of a communications system, such as for GSM
The invention provides a method of performing signal reconstruction at the receiving end of a communications system that uses a discrete channel estimate of the communications channel for the...
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5583890 |
Error correction of MSK signals dependent on sample quality
A method and corresponding apparatus for error correction of MSK-coded data receives a signal (101) partitionable into adjacent frames (111,113) each subdividable into three tridents (103, 105,...
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5557643 |
Automatic frequency control system for GMSK-modulated signals
An AFC system and method of detecting and compensating frequency drift in the carrier frequency of a Gaussian filtered Minimum Shift Keying (GMSK) signal by demodulated frequency compensated...
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5514998 |
Method and system for demodulating GMSK signals in a cellular digital packet data system
A decision feedback multiple symbol differential demodulator for Gaussian filtered Minimum Shift Keying (GMSK) has a performance very close to theoretical limit even under a fading channel. The...
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5459762 |
Variable multi-threshold detection for 0.3-GMSK
A variable multi-threshold detection circuit for a sampled baseband signal in the receiver of a communication system using GMSK modulation is disclosed. The circuit comprises an integrate/dump...
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5450446 |
Demodulator for digital modulation signals
The demodulator for digital modulation signals comprises a frequency detection device, an integral discharge filter, a summing device, a discrimination device, and a noise-compensating signal...
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5448594 |
One bit differential detector with frequency offset compensation
A one-bit differential detector for a GMSK signal operates independently of an offset frequency. In particular, a decision signal used by a decision circuit to distinguish between logic "0" and...
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5444415 |
Modulation and demodulation of plural channels using analog and digital components
In the modulation and demodulation of a plurality of frequency separated channels on a radio frequency carrier by digitally coded speech or data, the speech or data is modulated on a digitally...
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5425058 |
MSK phase acquisition and tracking method
An MSK receiver includes a downconverter for downconverting the received MSK signals. The phase drift or phase error per bit of the message preamble is determined. The reference carriers are...
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5309480 |
Non-coherent quadrature demodulation of MSK signals
Briefly, according to the invention, a receiver (100) for receiving a carrier signal MSK (minimum shift keying) modulated with a bit stream of a digital information signal (302) is disclosed. The...
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5278514 |
MSK demodulator using one synchronous detector
An MSK signal demodulating circuit including a carrier reproducing circuit for reproducing a carrier phase-synchronized with a component of a mark frequency or a space frequency of an MSK signal, a...
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5274672 |
Optimized clock recovery for an MSK system
A clock recovery system for radio communication inserts a synchronization signal (102) at a frequency of 1/2 the baud rate, at the spectral null of an MSK data signal (108), which is also at 1/2...
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5260671 |
Receiving circuit for demodulating an angle modulated signal
A receiving circuit is designed for an MSK (Minimum Shift Keying) receiver and a QPSK (Quadrature Phase Shift Keying) receiver. The circuit provides a synchronous state determining device and a...
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5170131 |
Demodulator for demodulating digital signal modulated by minimum shift keying and method therefor
Disclosed is a demodulation circuit for demodulating a modulated signal obtained by minimum shift keying. The demodulation circuit includes two synchronous detection circuits for detecting the...
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5144256 |
Method and apparatus for demodulating a GMSK signal
A method for demodulating a GMSK signal and the apparatus thereof is disclosed. The apparatus is applied to a digital communication system and demodulates a GMSK signal which is received from the...
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5142551 |
Signal weighting system for digital receiver
A signal weighting system for associating a confidence level with portions of a communication signal transmitted upon a multipath channel and received by a receiver. A signal received by the...
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5132986 |
CSK communication system
The present invention provides new arrangements for various components of a CSK communication system: modulator, correlators, demodulator, carrier detection circuit, and synchronization control...
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5117441 |
Method and apparatus for real-time demodulation of a GMSK signal by a non-coherent receiver
The GMSK real-time demodulation apparatus and process of the present invention demodulates a coherent quadrature phase modulated GMSK signal in real-time using a non-coherent receiver. The GMSK...
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