Analog domain adaptive equalizer for low power 40 Gbps DP-QPSK receivers

Electrical domain equalization of chromatic and polarization mode dispersion is attractive in coherent optical communication links. Digital coherent receivers used for this purpose are based on high speed ADCs followed by DSP, which dissipate excessive amount of power and are very costly to implement. We propose analog coherent receiver to drastically reduce the power consumption, size and cost. An adaptive feed forward equalizer for 40 Gbps dual polarization quadrature phase shift keying (DP-QPSK) systems, which processes signals in analog domain itself, is demonstrated using circuit and system simulations. The equalizer, designed in 90 nm CMOS technology, consumes 450 mW of power and occupies 1.8 mm × 1.1 mm chip area. System simulations are used to show that blind equalization is also possible when this approach is used in decision directed mode.     

Nearest neighbour classification of Indian sign language gestures using kinect camera

People with speech disabilities communicate in sign language and therefore have trouble in mingling with the able-bodied. There is a need for an interpretation system which could act as a bridge between them and those who do not know their sign language. A functional unobtrusive Indian sign language recognition system was implemented and tested on real world data. A vocabulary of 140 symbols was collected using 18 subjects, totalling 5041 images. The vocabulary consisted mostly of two-handed signs which were drawn from a wide repertoire of words of technical and daily-use origins. The system was implemented using Microsoft Kinect which enables surrounding light conditions and object colour to have negligible effect on the efficiency of the system. The system proposes a method for a novel, low-cost and easy-to-use application, for Indian Sign Language recognition, using the Microsoft Kinect camera. In the fingerspelling category of our dataset, we achieved above 90% recognition rates for 13 signs and 100% recognition for 3 signs with overall 16 distinct alphabets (A, B, D, E, F, G, H, K, P, R, T, U, W, X, Y, Z) recognised with an average accuracy rate of 90.68%.     

High-speed 3D imaging using photorefractive holography with novel low-coherence interferometers

The paper reports recent progress in developing high speed 3D imaging systems based on low coherence photorefractive holography with high-speed depth-sectioned imaging at 476 frames per second. It is demonstrated that photorefractive holography can utilize a wide variety of sources of differing spatial and temporal coherence, including a novel all-solid-state broadband laser. Also presented is a novel real-time optical sectioning technique based on structured illumination combined with photorefractive holography that provides real-time optical sectioning when imaging with reflected light or with fluorescence.     

Stability of differential-difference equations representing heat exchanger and certain other systems†

Conditions for the stability of certain typos of first-order nonlinear difTerential-difforonce equations are derived. Some of the results are applicable to a simplified model of certain distributed parameter systems, such as heat exchanger.     

Characterization of SnO2-based H2 gas sensors fabricated by different deposition techniques

Thick and thin films of SnO2 are extensively used for resistive gas sensors. Characteristics are compared for films produced by four different techniques – chemical vapour deposition (CVD), spray pyrolysis, vacuum evaporation and screen printing. The films are characterized for H2 sensing only, using a static measurement system to investigate their temperature selectivity. The samples are tested at a concentration of 300 p.p.m. H2 gas, a typical value for comparison. No selective peak is observed for CVD and spray deposited samples, and the selective peak for vacuum evaporated samples has a low sensitivity. But the selective peak for screen printed samples has a sensitivity of 55% (δR/Rair). And what is more, the screen printed samples have a repeatable response. This revised version was published online in August 2006 with corrections to the Cover Date.