10,777 research outputs found
Subtraction-noise projection in gravitational-wave detector networks
In this paper, we present a successful implementation of a subtraction-noise
projection method into a simple, simulated data analysis pipeline of a
gravitational-wave search. We investigate the problem to reveal a weak
stochastic background signal which is covered by a strong foreground of
compact-binary coalescences. The foreground which is estimated by matched
filters, has to be subtracted from the data. Even an optimal analysis of
foreground signals will leave subtraction noise due to estimation errors of
template parameters which may corrupt the measurement of the background signal.
The subtraction noise can be removed by a noise projection. We apply our
analysis pipeline to the proposed future-generation space-borne Big Bang
Observer (BBO) mission which seeks for a stochastic background of primordial
GWs in the frequency range Hz covered by a foreground of
black-hole and neutron-star binaries. Our analysis is based on a simulation
code which provides a dynamical model of a time-delay interferometer (TDI)
network. It generates the data as time series and incorporates the analysis
pipeline together with the noise projection. Our results confirm previous ad
hoc predictions which say that BBO will be sensitive to backgrounds with
fractional energy densities below Comment: 54 pages, 15 figure
Supermassive Black Hole Tests of General Relativity with eLISA
Motivated by the parameterized post-Einsteinian (ppE) scheme devised by Yunes
and Pretorius, which introduces corrections to the post-Newtonian coefficients
of the frequency domain gravitational waveform in order to emulate alternative
theories of gravity, we compute analytical time domain waveforms that, after a
numerical Fourier transform, aim to represent (phase corrected only) ppE
waveforms. In this formalism, alternative theories manifest themselves via
corrections to the phase and frequency, as predicted by General Relativity
(GR), at different post-Newtonian (PN) orders. In order to present a generic
test of alternative theories of gravity, we assume that the coupling constant
of each alternative theory is manifestly positive, allowing corrections to the
GR waveforms to be either positive or negative. By exploring the capabilities
of massive black hole binary GR waveforms in the detection and parameter
estimation of corrected time domain ppE signals, using the current eLISA
configuration (as presented for the ESA Cosmic Vision L3 mission), we
demonstrate that for corrections arising at higher than 1PN order in phase and
frequency, GR waveforms are sufficient for both detecting and estimating the
parameters of alternative theory signals. However, for theories introducing
corrections at the 0 and 0.5 PN order, GR waveforms are not capable of covering
the entire parameter space, requiring the use of non-GR waveforms for detection
and parameter estimation.Comment: 13 pages, 5 figure
Sparse Signal Processing Concepts for Efficient 5G System Design
As it becomes increasingly apparent that 4G will not be able to meet the
emerging demands of future mobile communication systems, the question what
could make up a 5G system, what are the crucial challenges and what are the key
drivers is part of intensive, ongoing discussions. Partly due to the advent of
compressive sensing, methods that can optimally exploit sparsity in signals
have received tremendous attention in recent years. In this paper we will
describe a variety of scenarios in which signal sparsity arises naturally in 5G
wireless systems. Signal sparsity and the associated rich collection of tools
and algorithms will thus be a viable source for innovation in 5G wireless
system design. We will discribe applications of this sparse signal processing
paradigm in MIMO random access, cloud radio access networks, compressive
channel-source network coding, and embedded security. We will also emphasize
important open problem that may arise in 5G system design, for which sparsity
will potentially play a key role in their solution.Comment: 18 pages, 5 figures, accepted for publication in IEEE Acces
AM-baseband telemetry systems. Volume 5 - Summary
Demodulation process for AM baseband telemetry system
A Foreground Masking Strategy for [CII] Intensity Mapping Experiments Using Galaxies Selected by Stellar Mass and Redshift
Intensity mapping provides a unique means to probe the epoch of reionization
(EoR), when the neutral intergalactic medium was ionized by the energetic
photons emitted from the first galaxies. The [CII] 158m fine-structure
line is typically one of the brightest emission lines of star-forming galaxies
and thus a promising tracer of the global EoR star-formation activity. However,
[CII] intensity maps at are contaminated by
interloping CO rotational line emission () from
lower-redshift galaxies. Here we present a strategy to remove the foreground
contamination in upcoming [CII] intensity mapping experiments, guided by a
model of CO emission from foreground galaxies. The model is based on empirical
measurements of the mean and scatter of the total infrared luminosities of
galaxies at
selected in -band from the COSMOS/UltraVISTA survey, which can be converted
to CO line strengths. For a mock field of the Tomographic Ionized-carbon
Mapping Experiment (TIME), we find that masking out the "voxels"
(spectral-spatial elements) containing foreground galaxies identified using an
optimized CO flux threshold results in a -dependent criterion (or ) at and makes a [CII]/CO power ratio of at
/Mpc achievable, at the cost of a moderate loss of total
survey volume.Comment: 14 figures, 4 tables, re-submitted to ApJ after addressing reviewer's
comments. Comments welcom
Noisy pre-processing facilitating a photonic realisation of device-independent quantum key distribution
Device-independent quantum key distribution provides security even when the
equipment used to communicate over the quantum channel is largely
uncharacterized. An experimental demonstration of device-independent quantum
key distribution is however challenging. A central obstacle in photonic
implementations is that the global detection efficiency, i.e., the probability
that the signals sent over the quantum channel are successfully received, must
be above a certain threshold. We here propose a method to significantly relax
this threshold, while maintaining provable device-independent security. This is
achieved with a protocol that adds artificial noise, which cannot be known or
controlled by an adversary, to the initial measurement data (the raw key).
Focusing on a realistic photonic setup using a source based on spontaneous
parametric down conversion, we give explicit bounds on the minimal required
global detection efficiency.Comment: 5+16 pages, 4 figure
AM baseband telemetry systems. Volume 1 - Factors affecting a common pilot system
Coherent demodulation in single and double side bands with frequency modulation telemetry system
- …