Trans-European experiments in DSP education

The Commission of European Communities (CEC) has put in place an interlocking set of initiatives aimed at enhancing the skillsbase European industry will require in order to sustain a competitive posture. One of these programs, COMETT II, is aimed at continuing education for small and medium enterprises. Another program, TEMPUS, aims to increase links between western and eastern Europe, and strongly focuses on academic interchanges and updating undergraduates/postgraduate curricula. DSP-forum, a COMETT II partnership between several European industrial firms and educational establishments, which primarily concentrates on short industrial training courses at a multiplicity of sites is discussed. Eleven partners in seven countries are currently involved with DSP-forum. Four additional partners presently complete the network of cooperating groups under TEMPUS sponsorship (primarily for development and validation of courseware and labware suitable for supporting remote interactive learning of DSP topics)     

Optimal two-term offset windowing for fractional delay

Fractional-sample delay in discrete-time systems is often provided by special FIR filters which are asymmetric about mid-sequence. Here we preserve the appeal of sine-sequence fractional delayers (simplicity and single-parameter delay tuning) by devising a two-term raised-cosine window which delivers fractional-delay filters comparable to the best obtainable by highly regarded optimisation approaches     

Two new cascade resonator-in-a-loop filter configurations fortracking multiple sinusoids

Two adaptive configuration arrangements for tracking multiple sinusoids are introduced: a simple cascade of resonators-in-loops and a more elaborately interconnected structure. Simulation results demonstrate that these structures can successfully track and enhance multiple sinusoids, especially effectively when using the latter adaptive configuration     

Determination of 7,12-dimethylbenz[a]anthracene in orally treated rats by high-performance liquid chromatography and transfer stripping voltammetry

A number of polycyclic aromatic hydrocarbons (PAHs) have been shown to be toxicants, and induce carcinogenic and immunotoxic effects. As a model PAH agent, 7,12-dimethylbenz[a]anthracene (DMBA) was the strongest one tested in terms of its biological activities and biotransformation. A new and simple high-performance liquid chromatographic (HPLC) method with diode-array detection at 290 nm was developed and validated for monitoring of DMBA in different matrices (serum, liver and kidney) of rats orally treated with DMBA. Furthermore, the applicability of adsorptive transfer stripping voltammetry (AdTSV) on the pencil-lead graphite electrode to these samples was illustrated using our previously reported data for bulk aqueous solutions of DMBA. HPLC and AdTSV methods, which were compatible with each other, allowed DMBA to be detected down to the levels of 3.82x10-9 M (0.98 ppb) and 6.73x10-9 M (1.73 ppb), respectively. Olive oil solutions of DMBA in dose 50 mg/kg were orally administered. 60 days after a single dose of DMBA, its concentrations in these biological samples from rats were measured by means of both methods. Because of rapid biotransformation, DMBA could not be detected in serum. Only low levels of the compounds were deposited unchanged in kidney whereas its levels were considerably higher in liver. These methods were also applied to the assay whether there is an influence of the intake of aqueous extracts of Hypericum Perforatum L. plant on the parent DMBA levels accumulated in rat tissues.     

Sequential geoacoustic inversion at the continental shelfbreak

Environmental parameters can have large spatial and temporal variability in shelfbreak regions. The capability of sequential Bayesian filters in tracking this variation is investigated. Particle filtering (PF) is used to extract the environmental parameters and their uncertainties. The method tracks the environment with fewer particles relative to conventional geoacoustic inversion methods using successive independent inversions. As an example, data from the Shallow Water 2006 Experiment are processed. The PF approach first is used to track the source and the environment with little spatial variation just northwest of the shelfbreak. Then the strongly range-dependent shelfbreak region is analyzed and the PF results are compared to previous geoacoustic inversion studies from the region.     

Probability density functions of amplitude-modulated random signals

The probability density function arising from multiplication of two independent random variables has been extensively treated by statisticians, yet some common signal processing product situations have not been analysed. An important example of this omission is the amplitude modulation of a Gaussian process. Here, a little-known Hankel transform-based procedure provides a ready solution for this problem and many other types of random modulation signals. Several new modulation results are tabulated in graphical form and it is also shown that half-amplitude sinusoidal processes added yield the same distribution as their (unit-amplitude) product     

Frequency-sampling design of delay-root-Nyquist filters

The frequency sampling design technique is applied in the design of fractional-delay root-Nyquist filters. Comparisons are made with three alternative design styles, showing that favourable frequency sampling selections easily outperform these contenders with respect to composite impulse response zero-crossing errors and approach the quality provided by purpose-optimised alternatives     

Particle filtering for passive fathometer tracking

Seabed interface depths and fathometer amplitudes are tracked for an unknown and changing number of sub-bottom reflectors. This is achieved by incorporating conventional and adaptive fathometer processors into sequential Monte Carlo methods for a moving vertical line array. Sediment layering information and time-varying fathometer response amplitudes are tracked by using a multiple model particle filter with an uncertain number of reflectors. Results are compared to a classical particle filter where the number of reflectors is considered to be known. Reflector tracking is demonstrated for both conventional and adaptive processing applied to the drifting array data from the Boundary 2003 experiment. The layering information is successfully tracked by the multiple model particle filter even for noisy fathometer outputs.     

Tracking Refractivity from Clutter Using Kalman and Particle Filters

We address the problem of tracking the spatial and temporal lower atmospheric variations in maritime environments. The evolution of the range and height-dependent index of refraction is tracked using the sea clutter return from sea-borne radars operating in the region. A split-step fast Fourier transform based parabolic equation approximation to the wave equation is used to compute the clutter return in complex environments with varying index of refraction. In addition, regional statistics are incorporated as prior densities, resulting in a highly nonlinear and non-Gaussian tracking problem. Tracking algorithms such as the extended Kalman, unscented Kalman and particle filters are used for tracking both evaporative and surface-based electromagnetic ducts frequently encountered in marine environments. The tracking performances and applicability of these techniques to different types of refractivity-from-clutter problems are studied using the posterior Cramer-Rao lower bound. Track divergence statistics are analyzed. The results show that while the tracking performance of the Kalman filters is comparable to the particle filters in evaporative duct tracking, it is limited by the high non-linearity of the parabolic equation for the surface-based duct case. Particle filters, on the other hand, prove to be very promising in tracking a wide range of environments including the abruptly changing ones.     

Optimal receive filters for the suppression of ISI and adjacentchannel interference

A new efficient method for the design of finite impulse response (FIR) digital receive filters is proposed. The authors formulate a cost function which minimises the total mean square error and thus reduces the effect of channel noise, intersymbol interference (ISI), and adjacent channel interference (ACI) simultaneously. Also, arbitrary fractional-sample delay can be compensated. The resulting filters are analysed in terms of bit error rate (BER) and implementation loss (IL) performance