Tunable Filter Bank Research Articles

Wavelet energy feature based source camera identification for ear biometric images

In this paper a source camera identification algorithm for ear biometric images has been proposed based on tunable filter bank as a feature extractor. Maintaining the frequency selectivity property, distinct features are extracted by this filter bank, based on a half-band polynomial of 14th order. With the help of four ear databases, it is demonstrated that tunable filter bank based features correctly identify the sources of ear images with an average accuracy of 99.25% when there are limited number of camera sources available. It is also shown that accuracy would fall when significantly large number of cameras are introduced to acquire ear images. Depending on the experimental results, it can be well concluded that tunable filter bank based feature, apart from its recognition performance, is also a promising candidate to support forensic validation of camera source.

APR Reduction Technique based on OFDM Pilot Filter Bank Limiting for Satellite Mobile Communications

Combined with OFDM (Orthogonal Frequency Division Multiplexing), satellite mobile communications will effectively achieve on-demand communication in areas with an ultra-low density of users. With OFDM multiple access optimization, the bandwidth utilization efficiency can be increased by 5 to 10 times. However, satellites are power-constrained systems, so higher PAPR requires greater power backoff, resulting in a decline in satellite transmission capacity. To use OFDM technology in satellites, there are problems such as reduced transmission capacity resulted from high PAPR, complication of lowering PAPR, and difficulty in hardware implementation. In order to deal with the problem of high bit error rate and hardware implementation difficulties in PAPR reduction technique of non-orthogonal frequency division multiplexing, this paper proposes a limiting PAPR reduction technique with OFDM pilot filter banks for satellite mobile communications. Firstly, the applicability of OFDM in satellite mobile communications is analyzed, and the influence of high PAPR on satellite power utilization and the influence of frequency shift sensitivity on inter-satellite communication interference are obtained. Then design the PAPR reduction technique based on the pilot filter bank. By setting the tunable filter bank to the pilot, the sideband power suppression in the OFDM frequency domain is realized, and the PAPR of the OFDM signal is reduced. Finally, the experimental results show that the PAPR performance is improved by 3dB without reducing the bit error rate.

On Applicability of Tunable Filter Bank Based Feature for Ear Biometrics: A Study from Constrained to Unconstrained.

In this paper, an overall framework has been presented for person verification using ear biometric which uses tunable filter bank as local feature extractor. The tunable filter bank, based on a half-band polynomial of 14th order, extracts distinct features from ear images maintaining its frequency selectivity property. To advocate the applicability of tunable filter bank on ear biometrics, recognition test has been performed on available constrained databases like AMI, WPUT, IITD and unconstrained database like UERC. Experiments have been conducted applying tunable filter based feature extractor on subparts of the ear. Empirical experiments have been conducted with four and six subdivisions of the ear image. Analyzing the experimental results, it has been found that tunable filter moderately succeeds to distinguish ear features at par with the state-of-the-art features used for ear recognition. Accuracies of 70.58%, 67.01%, 81.98%, and 57.75% have been achieved on AMI, WPUT, IITD, and UERC databases through considering Canberra Distance as underlying measure of separation. The performances indicate that tunable filter is a candidate for recognizing human from ear images.

Iris recognition with tunable filter bank based feature

In this paper, a tunable filter bank is proposed to extract region based features from non-cooperative iris images. The proposed method is based on half band polynomial of 14th order. The existing iris recognition algorithms work well with highly good quality images acquired under constraint and cooperative environments. These well-known techniques fail to perform well, when the raw images encounter segmentation failure during preprocessing. Their accuracy falls drastically, especially when the iris images are highly occluded due to different artifacts. Apart from that, segmentation failure during iris normalization makes the feature extraction more difficult. In our work, a tunable biorthogonal filter bank is proposed, for which the filter co-efficients are extracted from polynomial domain instead of z-domain. The proposed filter bank provides an opportunity to tuning and optimize the filter co-efficients. Experimental results using publicly available databases like CASIAv3, UBIRISv1, and IITD show the superiority of the proposed feature over the existing ones given its low template size, low feature extraction and feature matching time. Though accuracy yielded by the proposed filter bank is of the same order as found with existing features, achieving similar accuracy as state-of-the-art methods with less time and computation is a substantial development due to real-time usage of biometric systems.

ALMA's view of maser emission

AbstractALMA, the Atacama Large Millimeter/submillimeter Array, provides a large collecting area at a location on a high dry site, endowing it with unparalleled potential for sensitive spectral line observations. Its wide frequency coverage, superb receivers and flexible backend will ensure that that potential is met. Although in the Southern Hemisphere, its tropical latitude ensures good coverage of the northern sky. Since the last meeting on astrophysical masers, the ALMA team has substantially enhanced its capability for line observations. Japan's entry into ALMA has provided increased sensitivity with the addition of the 16 antennas of the Atacama Compact Array, equivalent to eight additional 12m telescopes. The first four cartridges for the baseline ALMA receiver packages (to be augmented by three other bands owing to Japanese participation) have been accepted, with performance above the already-challenging specifications. At first light, ALMA will offer nearly complete frequency coverage of the millimeter and submillimeter spectral windows, ensuring coverage of a variety of masering transitions. ALMA's flexibility as a spectrometer has increased with the enhancement of the baseline correlator with tunable filter banks, and with the addition of a separate correlator for the ACA. As an example of the increased flexibility, ALMA is now capable of multi-spectral-region and multi-resolution modes. With the former, one might observe e.g. four separate transitions anywhere within one of four 2 GHz bands with a high resolution bandwidth. With the latter, one might simultaneously observe with low spectral resolution over a wide bandwidth and with high spectral resolution over a narrow bandwidth. Thus, one could simultaneously cover an extremely broad velocity range while providing high spectral resolution of groups of lines within that range. Several science examples will be presented illustrating ALMA's potential for transforming the millimeter and submillimeter study of masers.

A modem in CMOS technology for data communication on the low-voltage power line

This paper presents a CMOS 0.8 μm mixed-signal half-duplex Modem ASIC for data transmission on the low-voltage power line. It includes all the analog circuitry needed for input interfacing and modulation/demodulation (low-noise amplifier, PLL-based frequency synthesis, tunable filter banks, and decision circuitry), logic circuitry for control purposes, and an output amplifier used as front-end for an off-chip line driver. The chip demodulates signals down to 283μV rms (these are worst case values among 30 randomly-selected samples used as vehicles for detailed electrical characterization; most of the samples featured 200 μV rms sensitivity; bit error rate (BER) is below 0.5×10 −5) at 10 kbps, and operates correctly in the whole industrial temperature range, from −45°C to 80°C, under 5% variations of the 5 V supply voltage. This ASIC is now in commercial production.