Continuous phase modulation

About: Continuous phase modulation is a research topic. Over the lifetime, 3199 publications have been published within this topic receiving 37245 citations. The topic is also known as: CPM.

Methods and Systems for Removing Undesired Artifacts in Fourier Domain Optical Coherence Tomography (FDOCT) Systems Using Continuous Phase Modulation and Related Phase Modulators

Abstract: Methods, fourier domain optical coherence tomography (FDOCT) interferometers and computer program products are provided for removing undesired artifacts in FDOCT systems using continuous phase modulation. A variable phase delay is introduced between a reference arm and a sample arm of an FDOCT interferometer using continuous phase modulation. Two or more spectral interferograms having different phase delay integration times are generated. The spectral interferograms are combined using signal processing to remove the undesired artifacts. Systems and methods for switching between stepped and continuous phase shifting Fourier domain optical coherence tomography (FDOCT) and polarization-sensitive optical coherence tomography (PSOCT) are also provided herein.

Method and device for the demodulation of signals with constant envelope and continuous phase angle modulation by a train of binary symbols tolerating frequency drifts

Abstract: The continuous phase angular demodulation method disclosed digitally processes the signal in baseband after having over-sampled it with reference to the bit period. The processing consists in routinely demodulating sub-sets of differential phases at the bit period T b shifted with respect to one another by fractions T b /q of this period, in correcting them, a priori, by the phase deviations associated with a set of pre-defined d frequency drifts and in computing, for the d.q sets thus obtained, a noise criterion. The set of demodulated bits chosen is the one that reduces this noise criterion to the minimum. The set of bits then enables computation of the phase variation emitted and, using this variation and the measured variation, the real frequency drift. Another demodulation taking this drift into account is done for the q sets of initial differential stages and the set minimizing the noise criterion is then chosen and fixes the synchronization bit by the sampling instants associated with it.

Photorefractive response time measurement in GaAs crystals by phase modulation in two-wave mixing.

Abstract: We describe a new method for photorefractive response time measurement in fast photorefractive crystals based on continuous phase modulation in two-wave mixing. We report experimental results for undoped semi-insulating GaAs that are in good agreement with theory. Values obtained for the response time and photoelectron generation quantum efficiency are consistent with previously published data.

Co-channel demodulation for continuous-phase modulated signals

Abstract: Cochannel interference, which occurs when two or more signals share the same spectral and temporal channels, is a major problem in frequency- and time-division multiple access systems. We focus on the development and evaluation of a joint maximum likelihood algorithm for simultaneously detecting two cochannel continuous phase modulated (CPM) signals. Particular attention is given to GMSK, a class of CPM employed in the pan-European cellular communications system.

Method and apparatus for efficient bandwidth communication

Abstract: A method and apparatus for improving the bandwidth efficiency of a constant envelope continuous phase modulation waveform and transmitting data in a bandwidth efficient manner is disclosed. The method and apparatus utilizes a non-constant envelope continuous phase modulation signal which possesses many of the advantages of a multiple modulation index continuous phase modulation signal. One such advantage is the natural trellis structure of a multiple modulation index continuous phase modulation signal. In comparison to a constant envelope continuous phase modulation waveform, the non-constant envelope continuous phase modulation signal possesses a reduced transmit signal spectra and may also be demodulated by a standard maximum likelihood demodulator without any loss of performance.