نتایج جستجو برای: polar modulation
تعداد نتایج: 194640 فیلتر نتایج به سال:
In this paper a two-phase supply modulator suitable for envelope tracking power amplifier is presented. The designed supply modulator has the linear assisted switching architecture. Two-phase architecture is used in order to reduce the output switching ripples. The proposed architecture uses hysteretic control instead of pulse width modulation (PWM) which significantly reduces the circuit compl...
ارتعاشات ناشی از حمل و نقل می تواند بر ویژگی های پس از برداشت محصولات کشاورزی موثر باشد، اما در این مورد تاکنون مطالعه ای بر روی گل های بریده صورت نگرفته است. برای بررسی اثر ارتعاش بر عمر گل بریده و برخی ویژگی های پس از برداشت گل بریده رز، سه آزمایش انجام شد. در آزمایش اول اثر ارتعاش شبیه سازی شده حمل و نقل با دو فرکانس (7/5 و 10 هرتز)، سه موقعیت گل بریده روی مخزن (کف، وسط و بالا) و دو زمان ارت...
Aims. We determine the nature of the intermediate polar candidates XSS J00564+4548, IGR J17195–4100, and XSS J12270–4859. Methods. Pointed RXTE observations searched for intermediate polar characteristics in these candidate systems. Results. XSS J00564+4548 exhibits a period of 465.68 ± 0.07 s, which we interpret as the spin period, an energy dependent modulation depth, and a spectrum that is f...
Aims. We determine the nature of the intermediate polar candidates XSS J00564+4548, IGR J17195–4100, and XSS J12270–4859. Methods. Pointed RXTE observations searched for intermediate polar characteristics in these candidate systems. Results. XSS J00564+4548 exhibits a period of 465.68 ± 0.07 s, which we interpret as the spin period, an energy dependent modulation depth, and a spectrum that is f...
Drifting subpulse patterns in pulsar signals are frequently interpreted in terms of a model in which a rotating ring of sparks on the polar cap gives rise to emission from regions of the magnetsophere connected to the sparks by dipolar magnetic field lines. The spacing of drift-bands in time depends on the circulation rate of the polar cap pattern, but to first order the longitudinal phase depe...
From a set of thirteen cataclysmic binaries that were discovered in the Swift Burst Alert Telescope (BAT) survey, we conducted time-resolved optical spectroscopy and/or time-series photometry of eleven, with the goal of measuring their orbital periods and searching for spin periods. Seven of the objects in this study are new optical identifications. Orbital periods are found for seven targets, ...
Any polar-ordered material with a spatially uniform polarization field is internally frustrated: The symmetry-required local preference for polarization is to be nonuniform, i.e., to be locally bouquet-like or "splayed." However, it is impossible to achieve splay of a preferred sign everywhere in space unless appropriate defects are introduced into the field. Typically, in materials like ferroe...
We report on an analysis of the drifting subpulses of PSR B0320+39 that indicates a sudden step of ∼ 180 degrees in subpulse phase near the centre of the pulse profile. The phase step, in combination with the attenuation of the periodic subpulse modulation at pulse longitudes near the step, suggests that the patterns arise from the addition of two superposed components of nearly opposite drift ...
This paper presents a polar transmitter predistortion technique validated with 2.5G mobile communication signals. The methodology used, [1], complements the drain bias modulation with a proper input drive level variation. This technique is believed to improve the linearity, while maintaining the efficiency of such transmitters, and it was validated in a real laboratory test setup.
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