نتایج جستجو برای: signal modulation
تعداد نتایج: 549152 فیلتر نتایج به سال:
Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation form...
چکیده ندارد.
We present a novel high-speed transmitter consisting of a frequency modulated DBR laser and optical filters. The refractive index modulation in the phase control region of the DBR laser allows highspeed frequency modulation. The generated frequency modulated signal is converted to an intensity modulated signal using the edge of the optical filter pass band. We present theoretical simulations of...
In this paper, we propose an optical millimetre wave radio-over-fibre (mm-wave RoF) system that uses a dual drive Mach Zehnder modulator (DD-MZM), which is biased at the maximum transmission biasing point, to generate an optical double sideband-suppressed carrier. The input to the DD-MZM are binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 8-phase shift keying (8-PSK) and...
Modulation type is one of the most important characteristics used in signal waveform identification. In this paper, an algorithm for automatic digital modulation recognition is proposed. The proposed algorithm is verified using higher-order statistical moments (HOM) of continuous wavelet transform (CWT) as a features set. A multilayer feed-forward neural network trained with resilient backpropa...
Delta modulation plays a key role in data communication; the problem encountered in delta modulation is the slope over load error, which is inherent in the system. In order for the signal to have good fidelity, the slope-overload error needs to be as small as possible. Adaptive delta modulation reduces the slope over load error to a greater extent. ADM attempts to increase the dynamic range and...
Adaptive Modulation and Coding technique has emerged as a bandwidth efficient transmission scheme. It is motivated by its ability to improve spectral efficiency by adapting the transmission rates to the variations in channel signal-to-noise ratio. The implementation of apt rate adaptation algorithms based on either signal to noise ratio or successful packet transmission has been the crucial fac...
Types of Modulation. Figure 7.1 illustrates two alternative ways to generate a modulated optical signal. In Fig. 7.1 (a), the laser is turned on and off by modulating its current; this method is known as direct modulation. In Fig. 7.l(b), the laser is on at all times, a so-called continuous wave (CW) laser, and the light beam is modulated with a kind of optoelectronic shutter, a so-called modul...
The first signal model for a single photon avalanche diode (SPAD)-array communication receiver multilevel modulation schemes is reported. This paper proposes novel, generalised SPAD array and noise both digital analogue, synchronous asynchronous readout arrays, which includes the competition between input photons, dark counts after-pulsing counts. With this contention model, signals including v...
A joint design scheme has been proposed to optimize the source encoder and the modulation signal constellation based on the minimization of the end-to-end distortion including both the quantization error and channel distortion. The proposed scheme first optimizes the vector quantization (VQ) codebook for a fixed modulation signal set, and then the modulation signals for the fixed VQ codebook. T...
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