A new M-channel DFT filter bank with its analysis and synthesis parts being modified is proposed for arbitrary image scaling, whereby down/up sampling kernels are newly introduced along with a compactly supported sampling function of degree 2. In particular, while only an even number of channels is allowed in the conventional MDFT FB, arbitrary (even/odd) number of channels can be applied in the proposed approach. Furthermore, it is shown that images of arbitrary size can be obtained from an original image without changing the number of channels. Finally, simulation results demonstrate that high-quality images of arbitrary size can be achieved by the proposed approach.
This paper estimates the loss budget of wavelength division multiplexing (WDM) single-fiber loopback access networks that employ a broadband amplified spontaneous emission (ASE) light source at the central office (CO) and an optical modulator with optical amplification function in each optical network unit (ONU). This study considers the backreflection lights from two sources, a broadband ASE light from the CO (Reflection-I) and a modulated signal from the ONU (Reflection-II). A gain-saturated semiconductor optical amplifier (GS-SOA) is placed at the ONU to reduce the excess intensity noise of sliced ASE and the spontaneous-spontaneous beat noise caused by Reflection-II; this technique increases the loss budget of the transmission line and removes an optical pre-amplifier from the optical receiver. Experiments clarify that with the gain compression effect of the GS-SOA the loss budget is 22.7dB.
Inter-frame coding using inter- and intra-predictions plays an important role in achieving high compression efficiency in H.264/AVC. However, most intra-predictions are unnecessary, since the intra-coding mode occupies less than 5% of the overall coding in inter-frame coding. In this paper, we propose an intra mode skip algorithm for inter-frame coding in H.264/AVC as a means of obtaining fast intra mode decision. The algorithm uses the joint entropy (JE) and mutual information (MI) to extract the temporal correlations between the current block and the reconstructed block based on 8 × 8 motion estimation. All or part of the intra-prediction search is omitted by using JE and MI. Experimental results show that the proposed algorithm is capable of reducing the overall coding time by 15-37% and the overall intra-prediction time by 32-78% compared to full search of the reference software, with negligible loss of quality.
Non-audible murmur (NAM) is an unvoiced speech received through body tissue using special acoustic sensors (i.e., NAM microphones) attached behind the talkers ear. Although NAM has different frequency characteristics compared to normal speech, it is possible to perform automatic speech recognition (ASR) using conventional methods. In using a NAM microphone, body transmission and the loss of lip radiation act as a low-pass filter; as a result, higher frequency components are attenuated in NAM signal. A decrease in NAM recognition performance is attributed to spectral reduction. To address the problem of loss of lip radiation, visual information extracted from the talker's facial movements is fused with NAM speech. Experimental results revealed a relative improvement of 39% when fused NAM speech and facial information were used as compared to using only NAM speech. Results also showed that improvements in the recognition rate depend on the place of articulation.
The feasibility of three-dimensional (3D) ultrasound imaging methods that involve computations depends on the performance of a computing system, which requires high-speed image reconstruction. Therefore, we examine the hardware (HW) implementation of the algorithm utilizing a field-programmable-gate-array (FPGA). Subsequently, we analyze the critical path delay of the HW and reduce the delay by modifying the architecture using FPGA resources to increase the maximum frequency. This paper presents a HW implementation approach for performing 3D ultrasound imaging.
A new structure of Folding and Interpolating (F&I) ADC with reduced DNL/INL for low-resolution high-speed applications is presented, which resolves multiple-bits from linear region of each fold to decrease interpolating factor (FI) to two. It is analytically shown that by reducing FI to two, DNL/INL due to systematic mismatch of current-mode interpolators is decreased, and the inherent unsystematic DNL of F&I ADCs is almost eliminated. A 6-bit 960MS/sec ADC in 0.18um CMOS process with 1.8V supply voltage is designed based on this structure. Results show an SNDR of 31.5dB, power dissipation of 88mW, while DNL/INL is below 0.35/0.4LSB.
A new type of optical fiber called heterogeneous multi-core fiber (heterogeneous MCF) is proposed towards future large-capacity optical-transport networks and the design principle is described. In the heterogeneous MCF, not only identical but also non-identical cores, which are single-mode in isolation of each other, are arranged so that cross-talk between any pair of cores becomes sufficiently small. As the maximum power transferred between non-identical cores goes down drastically, cores are more closely packed in definite space, compared to a conventional, homogeneous multi-core fiber (homogeneous MCF) composed of only identical cores.
We demonstrate all-optical NOT and NOR logic gates at 10Gb/s based on gain modulation of a transverse electric (TE) polarized light in a Fabry-Perot laser diode (FP-LD). An FP-LD shows a gain for a TE-polarized injected probe beam. The gain can be modulated by injection of a pump beam. Using the gain-modulation characteristic, we implemented all-optical NOT and NOR logic gates. We investigate double channel out performances as an example of the multicasting function of the gates. We measured around 1.5dB power penalty at a bit-error-rate of 10-9 and observed over 12dB extinction ratio in each of the gate operation.
A multi-stage approach is presented for efficient compensation of TWTA's nonlinear distortion (which belongs to Wiener systems) in wideband OFDM systems. In stages 1 and 2, TWTA's memory effects and memoryless nonlinear distortion are separately modeled, which leads to very fast modeling convergence. Then, TWTA's nonlinear distortion is completely compensated based on the models in stage 3.
Attenuated total reflection (ATR) spectroscopy in the terahertz (THz) region was used to measure the spectra of water, aqueous glycine solution, and glycine powder between 0.5 and 12THz. By subtracting the absorption spectrum of water, we obtained clear absorption peaks for dissolved glycine at 2.1, 5.2, and 9.3THz. In addition, we observed that the frequencies of these absorption peaks differed from the peaks for glycine powder. This indicates that the low-frequency vibrational mode in glycine molecules changes with the hydrogen bonding of glycine to H2O molecules.
A new versatile universal electronically tunable current-mode filter with three inputs and three outputs using three multiple-output current-controlled conveyors (MO-CCCIIs) and two grounded capacitors is proposed. The proposed configuration can be used as either a single-input three-output or three-input single-output. It can simultaneously realize all five different generic filtering signals: lowpass, bandpass, highpass, bandreject and allpass, unlike the previously reported works. It still maintains the following advantages: (i) the employment two grounded capacitors ideal for integrated circuit implementation, (ii) high output impedance good for cascadability for the current-mode circuits, (iii) no need to impose component choice, (iv) no need to employ inverting-type current input signals, and(v) low active and passive sensitivity performances. H-Spice and MATLAB simulations results are provided to demonstrate the theoretical analysis.
In this paper, a lumped directional coupler with a tunable reflector is proposed for an UHF passive RFID front-end system in which the sensitivity is limited by the isolation between transmitter and receiver. The proposed directional coupler can tunably eliminate TX-to-RX leakage caused by both the imperfect isolation of a directional coupler and the mismatch of antenna impedance which may be changed due to near-field environment. The measured result shows excellent TX-to-RX isolation above 70dB at 910MHz and 55dB over Korean UHF-RFID band.