Ravi Shankar Mishra

Segmenting the Optic Disc in Retinal Images using Thresholding

Segmentation of an optic disk location is a very essential task for retinal image analysis. Most of the pervious method uses the principal component analysis method, which are computationally complex. This paper presents a simple and semi automatic approach for segmentation of the optic disc in retinal images using thresholding and boundary extraction. First, the true colour Retinal images are converted to gray image and then image is enhanced using histogram equalization. This improves the efficiency of the conventional thresholding method. The proposed method of segmentation utilizes gray level thresholding for segmentation and then morphological operators are used for extracting the optical disk. The method is tested on the different optical disc images. The method is less complex and efficiently recognizes the boundary of the optic disc and also evaluates the optical canter. The optical canters are tabulated for original and corrupted images.

PAPR Reduction in OFDM via Separation of Complex Baseband Signal

system is the stronger base for the future wir eless c o m m u n i c a t i o n . The one w i t h the lowest peak to average power ratio (PAPR) among these OFDM signal sequences are selected for transmission. One major Disadvantage of OFDM is the high peak-to-average Power ratio (PAPR). One investigated technique Selected Mapping (SLM) is PAPR reduction techniques for Orthogonal Frequency Division Multiplexing (OFDM). By analyzing separation of complex baseband signal in this paper we proposed a Modernize SLM algorithm (MSLM) scheme to reduce the PAPR by using the complex signal to separate into real & imaginary parts and use as a individually phase sequence multiply real part as well as imaginary part of complex signal. Finally select the minimum PAPR signal which is achieved by real & imaginary part and then combine both of the approach and find one of the lowest peak to average power ratio among these OFDM signal sequences for transmission. After applying different simulation on the MATLAB software it produces less complexity and improved performance.

BER reduction in wireless system using spatial diversity with MRC and linear average filter

The Wireless communication has emerged as leading research sectors of communications industry. The reliability is the major issue of the system. To enhance the reliability of the system researchers working towards the diversity in wireless communication. The two or more communication channel of different characteristics is considered as diversity. It is used in Multiple-input and Multiple-Output (MIMO) systems. In this paper we have implemented spatial diversity technique with equal gain combining(EGC), Selection Combining(SC) and Maximal Ratio Combining(MRC) with Linear Average Filter and this proposed methodology works better when the number of antennas on transmitter as well as receiver is higher. The BER performance of the proposed approach is shown in results.

Multiple T slot compact & ultra wide band Microstrip patch antenna for Wimax Applications

In this paper, a compact Microstrip patch antenna having a slit associated with the slot for WiMAX application is presented. Instead of semi-infinite ground plane, the proposed antenna adopts the partial ground plane. Radiating patch lies on the Glass epoxy PCB substrate which is having low dielectric constant, thereby provides good bandwidth. Microstrip feedline technique is used to feed the antenna with 50Ω impedance. WiMAX (Worldwide Interoperability for Microwave Access) has three frequency bands- the lower band (2.5-2.69 GHz), the middle band (3.2-3.6 GHz), and the upper band (5.2-5.8 GHz). This proposed antenna enhances the return loss to -22.25 dB at the middle frequency range of WiMAX application. Computer simulated results showing the VSWR <;2 in the middle frequency range of WiMAX. The antenna is fed by a coaxial probe feed. The antenna designs and performances are analyzed using Zealand IE3D software. The antenna can be used for many modern communication systems. The bandwidths of the middle frequencies band are 26.5% & the return loss S11 characteristic is -22.24 dB.

Performance Evaluation of Spatial Domain Contrast Enhancement Techniques for Underwater Images

Image enhancement methods are widely used for improving the feature and quality of the images. Researchers have designed various contrast enhancement methods in the past. But since underwater image contain low contrast and resolution due to poor visibility conditions and refractions of light rays. Thus analysis and identification of the underwater object is a challenging and difficult task. In this paper presents a comparative analysis of various contrast enhancement techniques for such underwater images. Performance of contrast limited adaptive histogram equalization (CLAHE) method is compared with contrast stretching, global histogram equalization (HE) Brightness preserving Bi-histogram equalization (BBHE) and finally Dual Sub-Image histogram equalization (DSIHE) methods. Different colour underwater images are enhanced in the RGB colour space. The performance is evaluated based on discrete entropy, signal to noise ratio (SNR) and Standard deviation difference and the mean brightness. Performance of methods is evaluated under various type of underwater image environment. General Terms Image processing, Image enhancement, Underwater Images

Bandwidth Enhancement of a Backfire Microstrip Patch Antenna for Pervasive Communication

Backfire antenna 0.265λ for bandwidth enhancement is proposed and investigated. The proposed antenna is fed by a 50u2009Ω coaxial feed. The bandwidth of proposed antenna for S and C band is investigated. The performance of backfire antenna is investigated by performing numerical calculation by using various mathematical formulas to determine necessary dimensions of the antenna and simulation by using commercially available Method of Moments software. Here we design proposed geometry for 3u2009GHz. For this geometry we achieved 52.8% bandwidth for VSWR <2, minimum return loss −20u2009dB, and maximum directivity 7.2u2009dBi.

Challenge-Response Pair (CRP) Generator Using Schmitt Trigger Physical Unclonable Function

Physically unclonable function (PUF), a hardware security module, generates a unique response for each challenge by embodying a hardware feature into the computation. In the proposed Schmitt trigger(ST)-based PUF, the response is a function of circuit-based two different feature; triggering nature of ST generates a defined saturation level for changing input, and delay rises through cascading structure of STs. Multi-feature-based PUF sustains better unclonability and retains average reliability 99.725% with temperature variation, 99.86 with supply variation, and average uniqueness 47%. Another part of work is to enhance the response rate; rising and falling input sample individually generates five responses for rising and five responses for falling input. The proposed ST-PUF can generate ten numbers of 32-bit responses in one input period, and it enhances response generation rate by 10 times.

Design of a high performance 4 bit multiplier using UT algorithm with domino logic

4×4 Vedic multiplier using domino logic is proposed in this paper. The designs are implemented in GPDK 90nm technology on cadence virtuoso tool using spectre simulator. Multiplication is a fundamental operation, which is widely used in many digital signal processing systems, multimedia applications, computers and many digital systems. Power and delay are two important design constraints but there is always a trade-off between them, so power delay product (PDP) is the better constrain to evaluate the circuit performance. The performance of the multiplier is improved by improving the performance of basic blocks of multipliers .i.e. full adders and half adders. Here the extra signal is required to control the inputs .i.e. clock signal. Due to the introduction of clock signal in circuit, the complexity of the circuit is increases. Although it uses a clock signal, the total average power consumption of 4×4 multiplier is very less compared to any other circuit in the present. From the simulation results, the average power consumption of 4×4 multiplier is in 19.5 μw and delay is in 1.67ns. The proposed design having the good performance all over the circuit at present.

Challenge-response generation using RO-PUF with reduced hardware

Cryptography looks forward to generate secrete key from integrated circuit. A silicon based device having uncontrollable feature in term of measurable output can turned into physically unclonable function (PUF). Multiplexer based PUF works on unpredictable delay difference between two parallel paths, while Ring oscillator based PUF works on frequency deviation generated due to random variation of CMOS fabrication process. Hardware based intrinsic features must include to generate a random response which fuzzified to generate a reliable secret key. Our design incorporates PUF based on circuit variation instead of process variation, PISO shift register reduce the hardware compared to existing RO-OUF. A 4-bit challenge generates 16-bit random response with measured reliability in term of intra hamming distance approx to mid value.

Current distribution and dispersion analysis for different dielectric substrates of microstrip line by using SONNET

This paper we mainly emphasize on simulation & synthesis of micro strip line by using powerful simulation tool sonnet. Many researchers have investigated the dispersion characteristics current distribution of micro strip lines at different higher frequency range. This paper we analyzed the micro strip line with characteristic impedance 50Ω at frequency range 1 to 20GHz for FR-4, Roger 3001, Teflon, Polyimide and Taconic RF-30, substrate materials. All parameters of the micro strip lines are exactly determined from the empirical formula of micro strip line. Here we compare the results of the current distribution on the software tools.