Mixing Filter Research Articles

Multichannel Blind Music Source Separation Using Directivity-Aware MNMF With Harmonicity Constraints

In this paper we present a harmonic constrained Multichannel Non-Negative Matrix Factorization (MNMF) method for the task of blind music source separation. In this model, the mixing filter encodes the spatial information in terms of magnitude and phase differences between channels whereas the source variances are modelled using a harmonic constrained NMF structure. In this work, the spatial covariance matrix is obtained from the constant-Q transform to account for the frequency logarithmic scale inherent in music signals and reduce the dimensionality of the parameters. Moreover, to mitigate the strong sensitivity to parameter initialization, we propose to initialize the spatial weights with the output of the steered response power (SRP) with the phase transform (PHAT) algorithm. The proposed method has been evaluated for the task of music source separation using a multichannel classical chamber music dataset with several polyphony and reverberation setups. Furthermore, a comparison with other state-of-the-art signal decomposition methods has been accomplished showing reliable results in terms of BSS_EVAL metrics.

Parallel multichannel blind source separation using a spatial covariance model and nonnegative matrix factorization

In this paper, we present a multichannel nonnegative matrix factorization (MNMF) system for the task of source separation. We propose a novel signal model using spatial covariance matrices (SCM) where the mixing filter encodes the spatial information and the source variances are modeled using a NMF structure. Moreover, the proposed model is initialized with the estimated source direction of arrival (DoA) in order to mitigate the strong sensitivity to parameter initialization. The proposed system has been evaluated for the task of music source separation using a multichannel classical chamber music dataset showing that it is possible to reach real time in the tested scenarios by combining multi-core architectures with parallel and high-performance techniques.

Idler-free microwave photonic mixer integrated with a widely tunable and highly selective microwave photonic filter

A novel structure consisting of an idler-free microwave photonic mixer integrated with a widely tunable and highly selective microwave photonic filter is presented, which is comprised of a spectrum-sliced broadband optical source, a dual-parallel Mach-Zehnder modulator (DPMZM), and a spatial light amplitude and phase processor (SLAPP). By adjusting the optical phase shift in the DPMZM, the dispersion-induced mixing power fading can be eliminated. By applying a phase processor with the SLAPP, the distortion of the mixing filter brought upon by third-order dispersion is also compensated. Experiments are performed and show that the up/down-conversion signal has a clean spectrum and the mixing filter can be tuned from 12 to 20 GHz without any change to the passband shape. The out-of-band suppression ratio of the mixing filter is more than 40 dB, and the 3 dB bandwidth is 140 MHz.

The Impact Mechanism of Fractal Noise on PN Code Detection System

Taking the pseudo-random phase modulated CW radar for example, this paper studies the impact mechanism of a class of non-stationary fractal noise on PN code detection system, especially signal mixing and matching filter. The cross correlation function, power spectrum function and average power of pseudo-random signal and fractal noise are deduced, compared with the impact of white noise on the pseudo code detection system. We analyze the impact mechanism of three kinds of sea clutter model, namely fractal Brownian model (FBM), the multifractal (MF) model and the non-stationary random fractal model (e.g., infinitely divisible cascades, IDC), on the pseudo-random code detection system, and demonstrate the reason why the multi-scale filtering method in wavelet domain and the MF methods fail to eliminate the effect of sea clutter. Based on the natural sea clutter data, we simulate and analyze the influence of white noise and fractal noise comparatively on detection system, which indicates that the effect of fractal noise cannot be inhibited effectively by the traditional correlation detection and MF analysis, and finally we put forward possible solutions.

Inertial Navigation Position and Orientation Estimation with Occasional Galileo Satellite Position Fixes and Stereo Camera Measurements

Abstract In this paper an adaptive unscented Kalman filter based mixing filter is used to integrate kinematic satellite aided inertial navigation system with vision based measurements of five representative points on a runway in a modern receiver that incorporates carrier phase smoothing and ambiguity resolution. Using high resolution multiple stereo camera based measurements of five points on the runway, in addition to a set of typical pseudo-range estimates that can be obtained from a satellite navigation system such GPS or GNSS equipped with a carrier phase receiver, the feasibility of generating high precision estimates of the typical outputs from an inertial navigation system is demonstrated. The methodology may be developed as a stand-alone system or employed in conjunction with a traditional strapped down inertial navigation systems for purposes of initial alignment. Moreover the feasibility of employing adaptive mixing was explored as it facilitates the possibility of using the system for developing a vision based automatic landing controller.

High-Precision Kinematic Satellite and Doppler Aided Inertial Navigation System

In this paper an adaptive unscented Kalman filter based mixing filter is used to develop a high-precision kinematic satellite aided inertial navigation system with a modern receiver that incorporates carrier phase smoothing and ambiguity resolution. Using carrier phase measurements with multiple antennas, in addition to a set of typical pseudo-range estimates that can be obtained from a satellite navigation system such as GPS or GLONASS, the feasibility of generating high precision estimates of the typical outputs from an inertial navigation system is demonstrated. The methodology may be developed as a stand-alone system or employed in conjunction with a traditional strapped down inertial navigation system for purposes of initial alignment. Moreover the feasibility of employing adaptive mixing facilitates the possibility of using the system in an interoperable fashion with satellite navigation measurements.

Polynomial operators for spectral approximation of piecewise analytic functions

We propose the construction of a mixing filter for the detection of analytic singularities and an auto-adaptive spectral approximation of piecewise analytic functions, given either spectral or pseudo-spectral data, without knowing the location of the singularities beforehand. We define a polynomial frame with the following properties. At each point on the interval, the behavior of the coefficients in our frame expansion reflects the regularity of the function at that point. The corresponding approximation operators yield an exponentially decreasing rate of approximation in the vicinity of points of analyticity and a near best approximation on the whole interval. Unlike previously known results on the construction of localized polynomial kernels, we suggest a very simple idea to obtain exponentially localized kernels based on a general system of orthogonal polynomials, for which the Cesàro means of some order are uniformly bounded. The boundedness of these means is known in a number of cases, where no special function properties are known.

Autotransfusion in aortic surgery: the Haemocell System 350 cell saver.

Autotransfusion was performed during elective abdominal aortic reconstruction in ten patients using the recently developed Haemocell System 350. A mean of 60 per cent of total blood loss was salvaged, and during operation each patient was autotransfused 1 unit. Good preservation of cellular components, including platelets, was seen after processing with the device, which uses a vortex mixing filter for cell separation. There was no evidence of coagulopathy; mean free plasma haemoglobin levels were slightly raised (17 mg/dl) and plasma heparin concentration was negligible (0.10 units/ml) 4 h after surgery. A transient drop in plasma fibrinogen levels and the appearance of fibrin degradation products in low concentrations (mean 1.5 mg/l) were seen. Oxyhaemoglobin dissociation curves showed the salvaged red blood cells to have a normal affinity for oxygen. Renal and hepatic function remained unaltered and there were no complications attributable to autotransfusion. The device was easy to handle and a trained operator was not required.

Effect of benthic mixing on the information content of deep-sea stratigraphical signals

Benthic mixing or bioturbation affects sediments in various ways, including: (1) the production of trace fossils, (2) mechanical and/or chemical alteration of the sediment, and (3) filtering or smearing stratigraphical signals1. Because mixing alters both the slopes and amplitudes of any recorded events, some knowledge of the process is essential for the correct interpretation of the signals. In view of recent trends towards high-resolution stratigraphy2,3 and signal unmixing4–6, the frequency characteristics of the benthic mixing filter must be understood to determine which types of signals can be detected after mixing. Analyses of ash and tektite profiles in deep-sea cores from various geographical regions indicate that even signals from cores having sedimentation rates as high as 7 cm kyr−1 will show severe attenuation of frequencies higher than 0.35 cycles kyr−1 (periods shorter than 2.9 kyr) resulting in loss of ability to resolve closely-spaced events. Most signals will experience much more serious high-frequency attenuation, however. The severity of high frequency loss is directly related to sedimentation rate (R = 0.97 for the cores examined), suggesting that this is the most important variable to take into account when considering a core for palaeoceanographic or palaeoclimatic study.