514 research outputs found
Prefilter bandwidth effects in data symbol phase synchronizers of open loop
This work studies the effects of the prefilter
bandwidth on the open loop symbol synchronizers. We consider
three different prefilter bandwidth, namely, B1=¥ ( infinite),
B2=2.tx and B3=1.tx, where tx is the transmission rate. We
consider also four open loop symbol synchronizers, namely, the
tank (tank), the SAW (SAW), the monostable (mon), and the
astable (ast). The objective is to study the prefilter bandwidth
with the four open loop symbol synchronizers and to evaluate
their output jitter UIRMS (Unit Interval Root Mean Square)
versus input SNR (Signal to Noise Ratio)
Prefilter bandwidth effects in sequential symbol synchronizers based on clock sampling by positive transitions
This work studies the effects of the prefilter bandwidth in the sequential symbol synchronizers based on clock sampling by positive transitions. The prefilter bandwidth B is switched between three values, namely B1=∞, B2=2. tx and B3=1. tx, where tx is the bit rate. The synchronizer has two variants, one discrete and other continuous. Each variant has two versions, one manual and other automatic. The objective is to study the prefilter bandwidth with the four synchronizers and to evaluate their output jitter UIRMS (Unit Interval Root Mean Square) versus input SNR (Signal to Noise Ratio)
Effects of the previous pulse shift and filter on the symbol synchronizer PLL
We will study the effects of the shift of the previous
pulse temporal position (between P1 and P2) on the
symbol synchronizers jitter behavior.
Each pulse temporal position (P1 and P2), with the
same previous filter, forms a group with four different
carrier PLL (Phase Lock Loop) namely the analog,
hybrid, combinational and sequential.
The main objective is to study the synchronizers output
jitter UIRMS (Unit Interval Root Mean Squared) as
function of the input SNR (Signal to Noise Ratio)
Sequential symbol synchronizers based on pulse comparison operating by positive transitions at quarter rate
This work presents the sequential symbol
synchronizer based on pulse comparison by positive transitions
at quarter rate (txp/4). Their performance is compared with a
reference synchronizer by both transitions at the rate (tx).
For the reference and proposed synchronizer we consider two
versions which are the manual (m) and the automatic (a).
The objective is to study the four synchronizers and evaluate
their output jitter UIRMS (Unit Interval Root Mean Square)
versus input SNR (Signal Noise Ratio)
Sequential symbol synchronizers based on clock sampling by positive transitions
This work presents a sequential symbol
synchronizer, that was discovered by us, and its functioning principle is based on the clock sampling by the input positive data transitions.
This synchronizer has two topologies, namely the discrete and the continuous. Also, each topology has two versions which are the manual and the automatic. These synchronizers are very interesting, because the previous
adjust of the manual version isn’t critical.
The objective is to study the four synchronizers and to evaluate their output jitter UIRMS (Unit Interval Root Mean Square) versus input SNR (Signal to Noise Ratio)
Sequential symbol synchronizers based on pulse comparation at Half Rate
This work presents a synchronizer based on
pulse comparation, between variable and fixed pulses.
We consider four synchronizers, divided in two variants,
one variant operate at the rate and the other at half rate.
Each synchronizer variant has two versions which are
the manual and the automatic.
The objective is to study the synchronizers and evaluate
the output jitter UIRMS (Unit Interval Root Mean
Square) versus the input SNR (Signal Noise Ratio)
Deterministic and random phase synchronizers
This work study two groups of synchronizers, namely
the Deterministic Phase Synchronizer and the Random
Phase Synchronizer. The difference between them is only
inside of the phase comparator.
In the first group, the VCO (Voltage Controlled
Oscillator) synchronizes with the input deterministic
phase of an expected periodic transition. In the second
group the VCO synchronizes with the input random
phase of an unexpected no periodic transition.
Each group is studied under four topologies (analog,
hybrid, combinational and sequential).
The objective is to evaluate the two synchronizers
groups with the four topologies and to observe their jitter
behaviors with the noise
Inflationary models inducing non-Gaussian metric fluctuations
We construct explicit models of multi-field inflation in which the primordial
metric fluctuations do not necessarily obey Gaussian statistics. These models
are realizations of mechanisms in which non-Gaussianity is first generated by a
light scalar field and then transferred into curvature fluctuations. The
probability distribution functions of the metric perturbation at the end of
inflation are computed. This provides a guideline for designing strategies to
search for non-Gaussian signals in future CMB and large scale structure
surveys.Comment: 4 pages, 7 figure
The discontinuous nature of chromospheric activity evolution
Chromospheric activity has been thought to decay smoothly with time and,
hence, to be a viable age indicator. Measurements in solar type stars in open
clusters seem to point to a different conclusion: chromospheric activity
undergoes a fast transition from Hyades level to that of the Sun after about 1
Gyr of main--sequence lifetime and any decaying trend before or after this
transition must be much less significant than the short term variations.Comment: 6 pages, 1 figure, to be published in Astrophysics and Space Scienc
Relativistic effects and quasipotential equations
We compare the scattering amplitude resulting from the several quasipotential
equations for scalar particles. We consider the Blankenbecler-Sugar, Spectator,
Thompson, Erkelenz-Holinde and Equal-Time equations, which were solved
numerically without decomposition into partial waves. We analyze both
negative-energy state components of the propagators and retardation effects. We
found that the scattering solutions of the Spectator and the Equal-Time
equations are very close to the nonrelativistic solution even at high energies.
The overall relativistic effect increases with the energy. The width of the
band for the relative uncertainty in the real part of the scattering
matrix, due to different dynamical equations, is largest for
backward-scattering angles where it can be as large as 40%.Comment: Accepted for publication in Phys. Rev.
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