Interference (wave propagation)

About: Interference (wave propagation) is a research topic. Over the lifetime, 26086 publications have been published within this topic receiving 321110 citations.

High-order optical vortex generation in a few-mode fiber via cascaded acoustically driven vector mode conversion.

Abstract: We propose a method to generate the high-order optical vortex in a few-mode fiber via cascaded acoustically driven vector mode conversion Theoretical analysis showed that the vector mode conversion induced by the acoustically induced fiber grating (AIFG) could occur between two HE modes with adjacent azimuthal numbers In the experiment conducted at 532 nm, two AIFGs were simultaneously induced in the same segment of the fiber by a radio frequency source containing two different frequency components One AIFG was used to convert the left- and right-handed circular polarization fundamental modes to the ±1-order vortex modes, which were then further converted to the ±2-order vortex modes by the other AIFG The topological charges of the vortex modes were verified using both coaxial and off-axial interference methods, showing typical signature patterns of spiral forms and forklike fringes, respectively

Interference suppression via orthogonal projections: a performance analysis

Abstract: Several recent studies indicate the promise of subspace separation principles when applied to adaptive jammer suppression in phased array antennas. This paper theoretically analyzes the performance of a subspace separation technique based on orthogonal projections (OP) for adaptively suppressing interference in phased arrays; the theoretical performance predictions are validated using computer simulations. This analysis holds for the case when it is possible to differentiate between the vector spaces spanned by jammers and additive noise. The performance parameters used are (a) the average residual interference (jammer plus noise) power at the output of the adapted array as a function of the number of jammer snapshots used for calculating the weight vector, and (b) the similarity of the adapted array pattern to the design pattern away from the jammer locations. The performance of the OP-based subspace separation technique is compared with the sample matrix inversion (SMI) algorithm. It is shown that the weight vector calculated using OP converges more quickly to the optimal solution (infinite number of interference snapshots) than the SMI weight vector. Further, in contrast to the SMI adapted pattern, which exhibits large sidelobe levels away from the jammer locations, the OP adapted pattern closely follows the design pattern both in the mainbeam and in the sidelobe region away from the jammer locations. >

Near-end, far-end and echo cancellers in a multi-channel transceiver system

Abstract: A transceiver according to the present invention receives data from a plurality of frequency separated transmission channels from a complementary transmitter and includes an interference filter for correcting for interference from transmitters other than the complementary transmitter. The interference filter, for example, can correct for near-end cross-talk and echo interference filtering and/or far-end crosstalk interference filtering is presented. A transceiver can include a transmitter portion and a receiver portion with one or more receivers coupled to receives signals in the plurality of frequency separated transmission channels. A baseband transmitter can be combined with one or more transmitters that transmit data into one of the frequency separated transmission bands. Any combination of modulation systems can be utilized (e.g. PAM for the baseband and QAM for the frequency separated bands). In some embodiments, one baseband PAM transmitter is combined with one or more frequency separated QAM transmitters.

Performance of infrared transmission systems under ambient light interference

Abstract: Optical transmission systems are mainly impaired by the shot noise induced by ambient light, the transmitted optical power limitations (high path losses), the channel bandwidth limitations owing to multipath dispersion and the interference produced by artificial light sources. Several modulation and encoding schemes have been proposed for this channel and their performance has been studied and presented by several authors while neglecting the effects of the artificial light interference. The work reported extends the previous analysis by taking into account the optical power penalty induced by artificial light interference. An analytical approach is used to estimate this. In practical systems, the effect of the interference is usually mitigated using electrical highpass filters. In the paper the combined effect of interference and highpass filter is evaluated. The presented results show that the interference produced by fluorescent lamps driven by electronic ballasts induce high power penalties in OOK and L-PPM systems, even when electrical highpass filtering is used, for data rates up to 10 Mbit/s. For the interference produced by incandescent lamps and fluorescent lamps driven by conventional ballasts, the power penalty induced in OOK systems can be effectively reduced using highpass filtering, while PPM is very tolerant to that interference even without any highpass filtering. The major conclusion is that artificial light interference have to he considered both in system design and performance evaluation.