Results 81 to 90 of about 46,201 (198)

Experimental characterization of frequency dependent squeezed light

, 2005
We report on the demonstration of broadband squeezed laser beams that show a frequency dependent orientation of the squeezing ellipse. Carrier frequency as well as quadrature angle were stably locked to a reference laser beam at 1064nm.
Alexander Franzen, Boris Hage, D. F. Walls, G. Breitenbach, Henning Vahlbruch, K. S. Thorne, K. Schneider, Karsten Danzmann, Nico Lastzka, R. W. P. Drever, Roman Schnabel, Simon Chelkowski, U. Leonhardt, V. B. Braginsky, W. G. Unruh   +14 more
core   +1 more source

IQ-Modulation Using Phase and Amplitude Modulators and Multimode Interference

Photonics
Optical amplitude and phase modulators are an integral part of modern optical communications systems. As optical data formats transitioned from encoding amplitude exclusively to both amplitude and phase, several different methods for creating the ...
Frank H. Peters
doaj   +1 more source

A Space-Time Spreading Assisted Multicarrier DS-CDMA System using OVSF Codes Employing Adaptive Mode Switching Thresholds and Adaptive Modulation

, 2005
The Concept of Space-Time Spreading (STS) assisted, Adaptive Quadrature Amplitude Modulation (AQAM) aidedMC DS-CDMAis introduced. The AQAMmode-switching thresholds are determined using an on-line real-time Bit-Error-Ratio (BER) based learning procedure ...
Hanzo, L., Wei, H, Yang, L-L.
core  

Antimultipath communication by injecting tone into null in signal spectrum [PDF]

, 1987
A transmitter for digital radio communication creates a null by balanced encoding of data modulated on an RF carrier, and inserts a calibration tone within the null. This is accomplished by having the calibration tone coincide in phase and frequency with
Davarian, Faramaz
core   +1 more source

Parallel Mach-Zehnder modulators for quadrature amplitude modulation

IEICE Electronics Express, 2011
This paper describes optical quadrature amplitude modulation techniques using parallel Mach-Zehnder modulators (MZMs). Arbitrary constellations of optical signals can be generated by using a dual-parallel MZM which can independently control real and imaginary components of lightwaves, where each MZM should be driven by multi-level electric signals ...
openaire   +2 more sources

Adaptive minimum symbol error rate beamforming assisted receiver for quadrature amplitude modulation systems

, 2006
An adaptive beamforming assisted receiver is proposed for multiple antenna aided multiuser systems that employ bandwidth efficient quadrature amplitude modulation (QAM).
Chen, S., Du, H.Q, Hanzo, L.
core  

Generalized Secure Superchannels: A Signal Encryption Framework

IEEE Access
In this work, we propose a comprehensive technique to enhance the security of superchannels (SCs). The spectral samples of the signals within a superchannel are shuffled and further encrypted in amplitude and phase, according to cryptographic keys.
Marcelo L. F. Abbade, Marcelo P. Nogueira, Luiz H. Bonani, Eric A. M. Fagotto, Plinio S. Dester, Wilian M. Dos Santos, Ivan Aldaya   +6 more
doaj   +1 more source

Modulation Classification for Overlapped Signals Using Deep Learning

IEEE Open Journal of the Communications Society
Modulation recognition (MR) plays a pivotal role in tasks encompassing spectrum management, security enforcement, and interference mitigation. This research work introduces a deep learning-based MR method tailored for completely overlapped multi-user (MU)
Gaurav Jajoo, Prem Singh
doaj   +1 more source

On the Feasibility of Efficient Multiamplitude Communication [PDF]

Bandwidth constraints in earth-satellite communication systems force consideration of uncoded M-ary modulation to obtain increased data rates. M-ary phase shift keying (MPSK) at first glance seems most promising because of the high transmitter efficiency
Smith, J. G.
core   +1 more source