Patent
Frame synchronizing apparatus for quadrature modulation data communication radio receiver
TLDR
In this paper, a data correlation circuit is proposed for a digital data radio communications system in which data are transmitted in frame periods with a fixed data sequence contained each frame, and a phase comparator which periodically indicates whether a detected phase difference between the correlation signal and frame synchronizing signal is effectively zero, positive or negative.Abstract:
In a frame synchronizing apparatus for a receiver apparatus of a digital data radio communications system in which data are transmitted in frame periods with a fixed data sequence contained each frame, a data correlation circuit obtains successive sequences of values of vector difference between vector values constituting a demodulated digital baseband signal, and successively compares these sequences with a fixed vector difference sequence corresponding to the fixed data sequence, to derive a correlation signal substantially unaffected by any phase rotation in the baseband signal. A frame synchronizing circuit formed as a PLL for generating a frame synchronizing signal, includes a phase comparator which periodically indicates whether a detected phase difference between the correlation signal and frame synchronizing signal is effectively zero, positive or negative, and a counter holding a count value indicating a cumulative phase error between these signals. So long as the detected phase differences are successively effectively zero and the cumulative phase error is sufficiently small, the phase of the frame synchronizing signal is held unchanged, thereby achieving a high degree of phase stability.read more
Citations
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Patent
Demodulator apparatus for digital radio communication receiver providing pseudo-coherent quadrature demodulation based on periodic estimation of frequency offset
TL;DR: In this paper, a demoodulator for a TDM radio receiver successively compares a sampled quadrature baseband signal with a known pilot symbol sequence, with a resultant correlation signal being used in generating a frame synchronizing signal as a basic timing reference signal.
Patent
Apparatus and method for achieving symbol timing and frequency synchronization to orthogonal frequency division multiplexing signal
TL;DR: In this paper, a frequency and symbol timing synchronization apparatus for orthogonal frequency division multiplexed (OFDM) signals is presented, which consists of an autocorrelation unit, a comparator, a peak flat detector, a frequency offset estimator and a cross correlation unit.
Patent
Method and system for rapid initial signal detection in a wireless communications system
TL;DR: In this article, a correlator produces a peak output that can be used to detect the presence of the reference sequence, which can then be used for time alignment, for signal quality estimation, and to directly obtain a frequency offset estimate.
Patent
Wireless multimedia carrier system
Masood K. Tayebi,Baya Hatim,Chi Nche,Ismail Lakkis,Cathal O'Scolai,Deirdre O'Shea,Ulun Karacaoglu,Saeid Safavi,Hoang Xuan Bui,Joseph J. Roy +9 more
TL;DR: In this article, the authors proposed a wireless multimedia carrier (WMC) system capable of receiving a variety of standardized input signals, such as DSO/EO, T1/E1, T2/E2, and/or T3/E3 for transmission using RF channels.
Patent
Fine timing acquisition
TL;DR: In this article, a method for synchronizing timing of a receiver to a received orthogonal frequency division multiplexing (OFDM) signal is presented, where the accumulated energy of channel taps over a detection window is determined.
References
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Patent
Technique for acquiring timing and frequency synchronization for modem utilizing known (non-data) symbols as part of their normal transmitted data format
TL;DR: In this article, a signal processing scheme through which the receiver may, at any time, synchronize or resynchronize itself to the transmitted data signals that are received over a dynamic dispersive channel is presented.
Journal ArticleDOI
Fast adaptive equalizers for narrow-band TDMA mobile radio
TL;DR: In this paper, the authors examined a few theoretical aspects of the application of recursive least squares (RLS) adaptation algorithms to the narrowband TDMA mobile radio system and gave the relevant performance results for the fast Kalman algorithm, which turns out to be suitable for the considered application.
Patent
Rapid reference acquisition and phase error compensation for radio transmission of data
TL;DR: In this paper, a method and apparatus for rapid phase acquisition and random radio channel phase error compensation for a TDMA QPSK receiver is disclosed, where the output correlation detection signals are held for the duration of the TDMA timeslot and multiplied by the received quadrature signals to produce two pairs of products.
Patent
Modem with improved timing recovery using equalized data
TL;DR: In this paper, an interpolator interpolates T1 and T2 data samples from the equalizer and provides data signals R and S equally spaced relative to the peak baud amplitude which can be easily processed by the timing recovery circuit.
Patent
Frequency offset estimation using the phase rotation of channel estimates
TL;DR: In this article, a receiver for extracting complex values by reference to a local frequency reference determines the frequency offset between a local oscillator and the carrier by employing a circuit (40) for determining a phase rotation.