126,598 research outputs found
Analysis and equalization of data-dependent jitter
Data-dependent jitter limits the bit-error rate (BER) performance of broadband communication systems and aggravates synchronization in phase- and delay-locked loops used for data recovery. A method for calculating the data-dependent jitter in broadband systems from the pulse response is discussed. The impact of jitter on conventional clock and data recovery circuits is studied in the time and frequency domain. The deterministic nature of data-dependent jitter suggests equalization techniques suitable for high-speed circuits. Two equalizer circuit implementations are presented. The first is a SiGe clock and data recovery circuit modified to incorporate a deterministic jitter equalizer. This circuit demonstrates the reduction of jitter in the recovered clock. The second circuit is a MOS implementation of a jitter equalizer with independent control of the rising and falling edge timing. This equalizer demonstrates improvement of the timing margins that achieve 10/sup -12/ BER from 30 to 52 ps at 10 Gb/s
Design, development and verification of the 30 and 44 GHz front-end modules for the Planck Low Frequency Instrument
We give a description of the design, construction and testing of the 30 and
44 GHz Front End Modules (FEMs) for the Low Frequency Instrument (LFI) of the
Planck mission to be launched in 2009. The scientific requirements of the
mission determine the performance parameters to be met by the FEMs, including
their linear polarization characteristics.
The FEM design is that of a differential pseudo-correlation radiometer in
which the signal from the sky is compared with a 4-K blackbody load. The Low
Noise Amplifier (LNA) at the heart of the FEM is based on indium phosphide High
Electron Mobility Transistors (HEMTs). The radiometer incorporates a novel
phase-switch design which gives excellent amplitude and phase match across the
band.
The noise temperature requirements are met within the measurement errors at
the two frequencies. For the most sensitive LNAs, the noise temperature at the
band centre is 3 and 5 times the quantum limit at 30 and 44 GHz respectively.
For some of the FEMs, the noise temperature is still falling as the ambient
temperature is reduced to 20 K. Stability tests of the FEMs, including a
measurement of the 1/f knee frequency, also meet mission requirements.
The 30 and 44 GHz FEMs have met or bettered the mission requirements in all
critical aspects. The most sensitive LNAs have reached new limits of noise
temperature for HEMTs at their band centres. The FEMs have well-defined linear
polarization characteristcs.Comment: 39 pages, 33 figures (33 EPS files), 12 tables. Planck LFI technical
papers published by JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/1748-022
Parameter estimation of coalescing supermassive black hole binaries with LISA
Laser Interferometer Space Antenna (LISA) will routinely observe coalescences
of supermassive black hole (BH) binaries up to very high redshifts. LISA can
measure mass parameters of such coalescences to a relative accuracy of
, for sources at a distance of 3 Gpc. The problem of parameter
estimation of massive nonspinning binary black holes using post-Newtonian (PN)
phasing formula is studied in the context of LISA. Specifically, the
performance of the 3.5PN templates is contrasted against its 2PN counterpart
using a waveform which is averaged over the LISA pattern functions. The
improvement due to the higher order corrections to the phasing formula is
examined by calculating the errors in the estimation of mass parameters at each
order. The estimation of the mass parameters and are
significantly enhanced by using the 3.5PN waveform instead of the 2PN one. For
an equal mass binary of at a luminosity distance of 3 Gpc,
the improvement in chirp mass is and that of is .
Estimation of coalescence time worsens by 43%. The improvement is larger
for the unequal mass binary mergers. These results are compared to the ones
obtained using a non-pattern averaged waveform. The errors depend very much on
the location and orientation of the source and general conclusions cannot be
drawn without performing Monte Carlo simulations. Finally the effect of the
choice of the lower frequency cut-off for LISA on the parameter estimation is
studied.Comment: 12 pages, 5 figures (eps) significant revision, accepted for
publication in Phys. Rev. D. Matches with the published versio
Clutter rejection for MTI radar using a single antenna and a long integration time
Moving Target Indicators (MTI) are airborne radar systems
designed to detect and track moving vehicles or aircrafts. In this paper, we address the problem of detecting hazardous collision targets to avoid them. One of the best known solutions to solve this problem is given by the so-called Space-Time Adaptive Processing (STAP) algorithms which optimally filter the target signal from interference and noise exploiting the specific relationship between Direction Of Arrival (DOA) and Doppler for the ground clutter. However, these algorithms require an antenna array and multiple reception channels that increase cost and complexity.
The authors propose an alternative solution using a single antenna only.
In addition to the standard Doppler shift related to the radial speed, the orthoradial speed of any target can be estimated if using a long integration time. Dangerous targets and ground clutter have different signatures in the radial-orthoradial velocity plane. An optimal detector is then proposed based on the oblique projection onto the signal subspace orthogonal to the clutter subspace. The theoretical performances of this detector are derived and a realistic radar scene simulation shows the benefits of this new MTI detector
Science Requirements and Conceptual Design for a Polarized Medium Energy Electron-Ion Collider at Jefferson Lab
This report presents a brief summary of the science opportunities and program
of a polarized medium energy electron-ion collider at Jefferson Lab and a
comprehensive description of the conceptual design of such a collider based on
the CEBAF electron accelerator facility.Comment: 160 pages, ~93 figures This work was supported by the U.S. Department
of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177,
DE-AC02-06CH11357, DE-AC05-060R23177, and DESC0005823. The U.S. Government
retains a non-exclusive, paid-up, irrevocable, world-wide license to publish
or reproduce this manuscript for U.S. Government purpose
SYMPA, a dedicated instrument for Jovian Seismology. II. Real performance and first results
Context. Due to its great mass and its rapid formation, Jupiter has played a
crucial role in shaping the Solar System. The knowledge of its internal
structure would strongly constrain the solar system formation mechanism.
Seismology is the most efficient way to probe directly the internal structure
of giant planets. Aims. SYMPA is the first instrument dedicated to the
observations of free oscillations of Jupiter. Principles and theoretical
performance have been presented in paper I. This second paper describes the
data processing method, the real instrumental performance and presents the
first results of a Jovian observation run, lead in 2005 at Teide Observatory.
Methods. SYMPA is a Fourier transform spectrometer which works at fixed optical
path difference. It produces Doppler shift maps of the observed object.
Velocity amplitude of Jupiter's oscillations is expected below 60 cm/s. Results
Despite light technical defects, the instrument demonstrated to work correctly,
being limited only by photon noise, after a careful analysis. A noise level of
about 12 cm/s has been reached on a 10-night observation run, with 21 % duty
cycle, which is 5 time better than previous similar observations. However, no
signal from Jupiter is clearly highlighted.Comment: 13 pages, 26 figure
A comprehensive radial velocity error budget for next generation Doppler spectrometers
We describe a detailed radial velocity error budget for the NASA-NSF Extreme
Precision Doppler Spectrometer instrument concept NEID (NN-explore Exoplanet
Investigations with Doppler spectroscopy). Such an instrument performance
budget is a necessity for both identifying the variety of noise sources
currently limiting Doppler measurements, and estimating the achievable
performance of next generation exoplanet hunting Doppler spectrometers. For
these instruments, no single source of instrumental error is expected to set
the overall measurement floor. Rather, the overall instrumental measurement
precision is set by the contribution of many individual error sources. We use a
combination of numerical simulations, educated estimates based on published
materials, extrapolations of physical models, results from laboratory
measurements of spectroscopic subsystems, and informed upper limits for a
variety of error sources to identify likely sources of systematic error and
construct our global instrument performance error budget. While natively
focused on the performance of the NEID instrument, this modular performance
budget is immediately adaptable to a number of current and future instruments.
Such an approach is an important step in charting a path towards improving
Doppler measurement precisions to the levels necessary for discovering
Earth-like planets.Comment: 20 pages, 12 figures, published in Proc. of SPIE Astronomical
Telescopes + Instrumentation 201
A Fully-Integrated Reconfigurable Dual-Band Transceiver for Short Range Wireless Communications in 180 nm CMOS
© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.A fully-integrated reconfigurable dual-band (760-960 MHz and 2.4-2.5 GHz) transceiver (TRX) for short range wireless communications is presented. The TRX consists of two individually-optimized RF front-ends for each band and one shared power-scalable analog baseband. The sub-GHz receiver has achieved the maximum 75 dBc 3rd-order harmonic rejection ratio (HRR3) by inserting a Q-enhanced notch filtering RF amplifier (RFA). In 2.4 GHz band, a single-ended-to-differential RFA with gain/phase imbalance compensation is proposed in the receiver. A ΣΔ fractional-N PLL frequency synthesizer with two switchable Class-C VCOs is employed to provide the LOs. Moreover, the integrated multi-mode PAs achieve the output P1dB (OP1dB) of 16.3 dBm and 14.1 dBm with both 25% PAE for sub-GHz and 2.4 GHz bands, respectively. A power-control loop is proposed to detect the input signal PAPR in real-time and flexibly reconfigure the PA's operation modes to enhance the back-off efficiency. With this proposed technique, the PAE of the sub-GHz PA is improved by x3.24 and x1.41 at 9 dB and 3 dB back-off powers, respectively, and the PAE of the 2.4 GHz PA is improved by x2.17 at 6 dB back-off power. The presented transceiver has achieved comparable or even better performance in terms of noise figure, HRR, OP1dB and power efficiency compared with the state-of-the-art.Peer reviewe
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