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The modulation characteristics of high-performance In0.1Ga0.9N/GaN continuous-wave (CW) ridge laser diode were demonstrated. The laser epitaxial structure was grown on (202̄1̄) by metal organic chemical vapor deposition (MOCVD) for high-power CW operation by adopting low-resistance top-side n-type contact design. The threshold current density of 1200 µm long and 3 µm wide cavity was 6.1 kA/cm2 in...
Analysis of ring modulator helps to gain a better perception of modulator operation. There are extracted equations for transmission and modulation depth. These equations are based on loss, index and coupling modulation. Since the size of optoelectronic circuits is concern in nowadays industry, by using these extracted equations the effects of changes in ring radius on bandwidth is studied. In this...
In conventional tunable band pass delta sigma modulators one parameter is used to only tune the center of desired frequency band. This paper presents a new method for tuning both the center frequency and bandwidth by using separate independent tuning parameters for each pair of NTF complex conjugate zeros. Spreading NTF zeros in signal band results in higher SQNR. A 4th order low distortion band pass...
Thispaper describes the design of a wideband acquisition technique for a Quadrature Phase Shift Keying (QPSK) demodulator. The demodulator is designed at a frequency of 70 MHz to cater data rates up to 6 Mbps. The most important requirement of the design process is to have wide acquisition range of ±125 KHz under narrow Phase Lock Loop (PLL) bandwidth and low input Signal to Noise Ratio (SNR). Hence,...
A significant problem in a phase locked loop (PLL) is the initial acquisition. High resolution is a major requirement in phase modulation (PM) receivers; however, such accuracy is hindered by side band locking in the existing PM detectors. A Fast Fourier Transform (FFT) based anti-sideband locking scheme is proposed for wide band acquisition in PM receivers. It takes into purview the problems encountered...
Conventional stepped-frequency (SF) waveform achieves wideband via inter-pulse frequency diversity, however its frequency step is limited below the reciprocal of its pulse duration to avoid grating lobes. Applying modulated pulse, e.g. phase coded modulation (PCM) or linear frequency modulation (LFM), to stepped-frequency overcome the above limitation and makes it possible to obtain a wider band with...
A non-repeating FMCW waveform was recently developed and experimentally demonstrated to provide a feasible instantiation of FM noise radar. This emission scheme was subsequently examined in terms of the impact of both stationary and hopped spectral gaps with the prospect of enabling in-band interference avoidance for cognitive sensing and possibly tandem hopped radar/communications. Here this gap-hopped...
It was reported for specific bats, that they use a certain scheme to shift the frequencies of their echo location calls to counteract interferences with conspecifics. As in road traffic, an increasing number of cars is equipped with radar sensors, there is also the problem of mutual interference. The available frequency bands are limited, so a randomized frequency hopping will not be the best solution...
Global Navigation Satellite System (GNSS) jammers generally broadcast frequency modulated signals which are instantaneously narrow band and can sweep several tens of MHz in few microseconds. The frequency band swept by a jamming signal can be significantly larger than the input bandwidth of the victim receiver. In this way, the jamming signal is significantly filtered and periodically enters and exits...
This study investigates the design issues of a phase-locked loop (PLL)-based point-to-point (P2P) high-speed interface with periodically embedded clock encoding (PECE). Interfaces of this type are the mainstream serial links for 4K2K or higher resolution applications in the display industry. Early works mainly focus on delay-locked loop (DLL)-based or Hogge-type CDR implementation, while this work...
A non-repeating, spectrum-optimized FM waveform suitable for radar pulse agility is described. The waveform is an alternative manifestation of the recently developed pseudo-random optimized (PRO) FMCW framework for FM noise radar, now implemented in a pulsed form. Each pulsed FM waveform is iteratively optimized to match a spectrum shape with low range sidelobes and good spectral properties, while...
In response to bandwidth-hungry applications, the field of Elastic Optical Networks (EON) has emerged. In this paper we investigate the provisioning and allocation problem in EONs, which presents a number of new and exciting challenges not otherwise present in optical networking solutions. We propose a novel technique for solving the Routing and Spectrum Allocation (RSA) problem which improves resource...
A newer technique in the field of direction finding (DF) is the use of time modulated array (TMA) switching harmonics to detect angle of arrival. A switch is used to introduce harmonics to an incoming signal, which are measured and compared to determine angle of arrival (AoA). The work done on this technique has been mostly theoretical and effects such as signal modulation, symbol rate and signal...
In this paper, the bandwidth properties of the modes obtained using the variational mode decomposition (VMD) are analyzed to detect arrhythmia electrocardiogram (ECG) beats. The VMD is an enhanced version of the empirical mode decomposition (EMD) algorithm to analyze non-linear and nonstationary signals. It decomposes the signal into a set of bandlimited amplitude and frequency modulated oscillations...
Linear Frequency Modulated (LFM) pulses are used in radar because of its good range resolution capability. Range resolution can be further improve by introducing a frequency step between consecutive pulses. Resultant signal is known as Stepped Frequency Pulse Train (SFPT). When the product of pulse duration and frequency step become more than one, Autocorrelation Function (ACF) of SFPT shows undesirable...
Precise understanding of the sea bottom characteristics and accurate identification of objects on the seabed are critical in many underwater applications. The severe multi-path along with the time varying and random reflections from the surface and the bottom of shallow waters, present an interesting and complex signal processing problem. A thin line hydrophone array, deployed from small Autonomous...
We present a robust method to predict full radiation patterns over a large frequency bandwidth using the knowledge of the pattern at a few frequency points. The frequency points are selected adaptively such that a set of linearly independent basis functions, called characteristic basis function patterns (CBFPs), is obtained. The model consists of a linear combination of CBFPs where expansion coefficients...
This paper describes a hybrid frequency/phase-locked loop (F/PLL) in which a PLL operates as a nested digitally-controlled oscillator (DCO). The nested DCO based on the wideband PLL not only offers a constant gain but also enables low noise clock generation even with a very low reference frequency. A digital FLL with a 1-bit AZ frequency detector (FD) is designed as a main loop to avoid having a linear...
The purpose of intercept sonar is to detect the active transmissions from ships, submarines and torpedoes, using which fine target discrimination, recognition and classification is performed. Intercept signal detection and identification techniques continuously become more advanced and sophisticated. Signal's intelligence aims at extracting as much information as possible on detected sonar signals...
We describe a scheduler based on deficit-round robin (DRR) for multiple servers of multiple packet-flows, where each packet-flow may be served by only a subset of available (preferred) servers. The scheduler uses a token allocation algorithm that is weighted max-min fair, and so we've called it Multi-Server Max-min Fair DRR (MSMF-DRR). The scheduler also compensates for potential errors in estimates...
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