Keying

About: Keying is a research topic. Over the lifetime, 6598 publications have been published within this topic receiving 82943 citations.

PDM-DQPSK Silicon Receiver With Integrated Monitor and Minimum Number of Controls

Abstract: We demonstrate a novel polarization-division multiplexed differential quadrature phase-shift keying receiver. It has the minimum number of analog controls and an integrated polarization interference monitor for polarization tracking. It can theoretically tolerate polarization-dependent loss in the link. We achieve ~10 times tracking speed improvement, ~6-dB lower loss, and ~100 times lower average bit-error rate during most of the tracking over our previous work for 43-Gb/s PDM-DQPSK.

Digital quadriphase-shift keying modulator

Abstract: A digital quadriphase-shift keying modulator is described which generates a modulated intermediate carrier frequency (IF) based on a desired number of samples for each input information bit. The design includes a ROM (or RAM) look-up table which stores digitized waveforms. The inphase and quadrature components of a complex baseband signal are translated to an IF at a multiple of the sampling rate simply by alternating the inphase and quadrature samples and alternating signs. The real IF output is produced by summing the inphase and quadrature signals.

Keying of rectangular plate anchors in normally consolidated clays

Abstract: The loss in anchor embedment during keying, as it rotates to become normal to the cable load, reduces the uplift capacity of anchors in normally consolidated clay. The keying behavior of plate anchors has been studied previously by using centrifuge and field model tests. In this paper, a large deformation finite-element approach incorporating frequent mesh regeneration and allowing for evolution of the anchor-chain profile, was developed to simulate the keying process of rectangular and strip plate anchors. A parametric study was undertaken to quantify the loss in anchor embedment during keying in terms of the anchor geometry, soil properties, loading eccentricity, and inclination. The embedment loss decreased dramatically with increasing loading eccentricity and decreasing chain angle at the mudline to the horizontal. The loss in anchor embedment during keying increased as the local soil strength increased relative to the weight of the anchor, up to a limit determined by the eccentricity of loading. In c...

Optical Systems With High-Order DPSK and Star QAM Modulation Based on Interferometric Direct Detection

Abstract: Increased interest in novel modulation formats for optical transmission has come up in recent years. Receivers with interferometric direct detection can be used to detect arbitrary modulation formats with differentially encoded phases as differential phase-shift keying (DPSK) and differentially phase-encoded star-shaped quadrature amplitude modulation (Star QAM). In this paper, two novel 16-ary modulation formats, which are the 16 DPSK and the Star 16 QAM (ASK-8 DPSK), are characterized for optical transmission for the first time. To be able to identify clear performance tendencies for high-order optical modulation, the novel formats are compared to a wide range of already investigated formats by conducting comprehensive calculations in a uniform simulation environment. The influence of different transmitter structures and decision schemes is considered, and all the systems are characterized with respect to the optical signal-to-noise ratio requirements, dispersion tolerance, and self-phase-modulation (SPM) performance for nonreturn-to-zero (NRZ) and RZ pulse shapes. Moreover, an inherent problem of Star QAM transmission concerning SPM is illustrated, and compensation techniques are examined. The results give a substantial insight into the properties of high-order optical modulation formats.

Hybrid CPFSK/OQPSK modulation transmission techniques’ performance efficiency with RZ line coding–based fiber systems in passive optical networks

Abstract: This study shows hybrid continuous-phase frequency shift keying (CPFSK)/optical quadrature-phase shift keying (OQPSK) modulation transmission techniques’ performance efficiency with return-to-zero (RZ) line coding scheme–based fiber systems in passive optical networks. Max. Q factor/min. bit error rate variations versus modulation frequency and fiber length are studied in detail for various bits/symbol, based on hybrid proposed modulation transmission techniques. Also, optical power and received electrical power variations are simulated with fiber-length variations at a specified modulation frequency of 300 GHz. Max. Q Factor, min. BER, max. signal power, and min. noise power variations are based on hybrid modulation techniques for CPFSK/OQPSK of 32 bits/symbol and a modulation frequency of 500 GHz through a fiber length of 30 km.