Digital Signal Processing

1510 Submissions

[15] viXra:1510.0489 [pdf] submitted on 2015-10-28 20:23:19

Embedding Data in Images Securely using Chaos

Authors: Sai Venkatesh Balasubramanian
Comments: 15 Pages.

A robust high-fidelity technique to hide data in images using chaos is proposed and implemented. By efficiently harnessing the nonlinearity of a semiconductor device such as a MOSFET, a chaotic carrier signal is generated using extremely simple circuitry. This chaotic carrier forms the secure key of the proposed embedding system. The generated chaotic signal is validated using standard metrics such as Lyapunov Exponent, Fractal dimension and Kolmogorov Entropy. The generated carrier is then modulated with three message signals and are embedded into the three colors of the carrier image using a scaling factor. The exact frequencies and amplitudes used to generate the chaotic carrier are used in the receiver end to regenerate the carrier, using which the message is decoded from the embedded image. Standard measures such as Mean Square Error and Peak Signal to Noise Ratio are used to characterise the fidelity of the embedding process. The observed large PSNR values corresponding with high sensitivity as observed in the Lyapunov exponent of the chaotic carrier indicate the achievement of the golden advantages of Sensitivity, Fidelity and Simplicity which form the highlights of the present work.
Category: Digital Signal Processing

[14] viXra:1510.0488 [pdf] submitted on 2015-10-28 20:23:54

Efficient Steganography Using Spread Spectrum with Integrity Verification

Authors: Sai Venkatesh Balasubramanian
Comments: 5 Pages.

Data hiding techniques are growing stronger day by day, and with even stronger detection techniques, a powerful way of hiding and retrieving data is the need of the hour. In this paper, we first discuss basic steganographic techniques in general and spread spectrum steganography in particular. Then we propose a steganographic method which hides data efficiently using Spread Spectrum techniques and also introduces Verification codes to check the integrity of the message at the receiver side. Finally, we look at the advantages of this system over others.
Category: Digital Signal Processing

[13] viXra:1510.0481 [pdf] submitted on 2015-10-28 20:32:55

A Simple Pseudorandom Bit Generator using Frequency Controlled Digital Chaos

Authors: Sai Venkatesh Balasubramanian
Comments: 4 Pages.

A novel kind of chaos, digital chaos is proposed, and an extremely simple circuit to generate frequency controlled digital chaos using two XOR gates driven by three square signals with mismatched frequencies and duty cycles is designed and implemented in FPGA, with the basic principle that the XOR being a difference circuit, amplifies the mismatches, leading to chaos generation. The presence of chaos is ascertained using Lyapunov Exponent and the effect of driving signal frequency on the chaotic nature is studied. The generated chaotic bit sequence is then tested for randomness using standard tests from the NIST Test Suite. It is found that the generated digital chaotic bit sequence is indeed random, proving capability of the proposed circuit as a pseudo random bit generator for computing and communication applications.
Category: Digital Signal Processing

[12] viXra:1510.0470 [pdf] submitted on 2015-10-28 07:59:32

Chaotic Solitary Wavelets in 45nm CMOS Adaptive Bias Controlled Ring Oscillators

Authors: Sai Venkatesh Balasubramanian
Comments: 14 Pages.

A novel kind of iterative map, the frequency dependent map, offering the crucial advantages of easy tunability and signal dependent control is formulated from the standard circle map, and is studied using the bifurcation and cobweb plots. Following this, the nonlinearity of a MOSFET is explored and a novel modification to a conventional ring oscillator is proposed by adding a potential divider in its feedback path, achieving adaptive bias control. It is seen that such a design gives outputs most closely resembling hyperbolic secant based solitons. The ring oscillators, nonlinearly coupled to a ‘split-gate’ CMOS inverter is seen to generate chaotic signals, which are characterized using standard measures such as phase portrait, Kolmogorov Entropy and Lyapunov Exponent, following which the effect of number of ring oscillator stages on the nature if generated chaos is studied. Finally, the chaotic signal is merged with a hyperbolic secant pulse to form a ‘chaotic solitary wavelet’, which is seen to possess a high number of vanishing moments with a distinct and unique negative logarithmic slope, a very desirable quality in wavelets, leading to applications such as secure communications, image compression and efficient detection of burst-type signals.
Category: Digital Signal Processing

[11] viXra:1510.0469 [pdf] submitted on 2015-10-28 08:00:24

Secure Solitary Wavelets using Simple X-Band Microwave Circuitry

Authors: Sai Venkatesh Balasubramanian
Comments: 5 Pages.

The operation of various contemporary communication systems such as WiMax in the Microwave X-Band, coupled with the information explosion in recent times has enforced a high pressure in the capacity and security handling aspects, where it would be convenient to provide these facilities at the physical level itself. The present work proposed a radically new solution to this issue, by developing a Secure Solitary Wavelet. Specifically, a Gunn Oscillator Microwave source is fed to a microwave transistor, and by using a slave low frequency signal, the nature of the output is tuned and the envelope is observed to be chaotic, and is characterized using Kolmogorov Entropy and Lyapunov Exponents. This envelope is modulated onto a hyperbolic secant function to create a Secure Solitary Wavelet. It is seen that the solitary nature induces extreme compactness and smoothness as seen by the vanishing higher moments, while the chaotic envelope is controlled by the slave frequency acting as a key and providing a layer of security to the wavelet. A Secure Solitary Wavelet based Orthogonal Frequency Division Multiplexing (OFDM) is proposed and compared with conventional OFDM in terms of performance assessment. The extreme simplicity of the proposed design coupled with the compactness and security of the Secure Solitary Wavelet form the highlights of the present work.
Category: Digital Signal Processing

[10] viXra:1510.0463 [pdf] submitted on 2015-10-28 09:14:45

Design of Terahertz Radio over Fiber – Beyond 4G

Authors: Sai Venkatesh Balasubramanian, Ganapathy R, Porsezian K
Comments: 2 Pages.

A Radio-over fiber communication system operating at Terahertz frequency is designed, considering the underlying physics of nanoelectronic and nanophotonic devices, and performance of non-conventional soliton based carriers is evaluated, accounting for novelty of this work.
Category: Digital Signal Processing

[9] viXra:1510.0462 [pdf] submitted on 2015-10-28 09:16:04

Modeling and Evaluation of Radio over Fiber Communication Systems on Employing Nanophotonic Devices

Authors: Sai Venkatesh Balasubramanian, Ganapathy R, Porsezian K, Easwaran M, Joshva RG
Comments: 6 Pages.

Radio over Fiber refers to a technology whereby light is modulated by a radio signal and transmitted over an optical fiber link to facilitate wireless access. The present work purports to the modeling of radio over fiber systems in the MATLAB environment on employing specially designed photonic crystal fibers, consisting of subwavelength-core dielectric photonic nanowires embedded in their cladding, as optical channels between the main central station and the set of base stations and silicon photonic based electro-optic modulators. Data transmission at terahertz frequencies using orthogonal frequency division multiplexing schemes with cyclic error control coding along with digital modulation schemes such as amplitude shift keying and binary phase shift keying have been implemented. Different carrier signals such as solitons, similaritons, square, and sine waves are considered. In simulating the radio over fiber system, three different media are considered. In the first stage of signal propagation, photonic crystal fibers embedded with photonic nanowires in their cladding are considered and signal propagation through them is numerically modeled using the predictor-corrector symmetrized split step Fourier method. In the second stage, electrical transmission lines that are modeled as microstrips using S-parameters are considered. In the last stage of signal propagation, wireless channel modeled using additive white Gaussian noise and multipath fading, is considered. The performance of the aforementioned communication system is reviewed using standard metrics such as bit error rate and eye diagrams. It is shown that solitons are more robust carriers for terahertz communications compared to the other carriers and that it is possible to achieve a relatively distortion free communication system even amidst the worst possible SNR levels.
Category: Digital Signal Processing

[8] viXra:1510.0461 [pdf] submitted on 2015-10-28 09:17:03

Non-Conventional Carrier Waveforms in a four user OFDMA Communication System

Authors: Sai Venkatesh Balasubramanian, T. Venkata Subba Reddy, B. Madhava Reddy, R. K. Karn, G. Ramanathan
Comments: 4 Pages.

Conventional communication systems use either sinusoids (pass band) or square waves (baseband) as carriers. However tradeoffs have to be made with regards to bandwidth, fidelity, power consumption and system complexity. This paper explores using Non-conventional waveforms including Gaussian like pulses as carrier waveforms using a 4-user OFDMA system as the benchmark. SPICE simulations are done at the deep submicron VLSI level (120 nm) using MicroWind. The performance of the various carrier waveforms are assessed by using standard metrics such as Bit Error Rate, Signal to Noise ratio and eye-diagram. The results presented in this work give valuable insights into Non-conventional carrier waveforms and their impact on SNR and BER leading to more robust.
Category: Digital Signal Processing

[7] viXra:1510.0460 [pdf] submitted on 2015-10-28 09:17:58

Soliton Carriers in CDMA and OFDM Communication Systems

Authors: Sai Venkatesh Balasubramanian
Comments: 4 Pages.

The concept of solitons has been successfully utilized in optical communications to handle signal distortion. In this light, the present work explores modulation using soliton carriers and subsequently, prototype wireless communication system based on Orthogonal Frequency Division Mutiplexing (OFDM) and Code Division Multiplexing (CDMA) at 11GHz involving Additive White Gaussian Noise Channel is implemented using LabVIEW. The performance of Soliton carriers are compared with sinusoidal counterparts using eye diagrams. The low distortion values observed for solitons form the novelty of the present work.
Category: Digital Signal Processing

[6] viXra:1510.0453 [pdf] submitted on 2015-10-28 09:27:03

Signal Analysis Using The Solitary Chirplet

Authors: Sai Venkatesh Balasubramanian
Comments: 5 Pages.

In the present work, the solitary chirplet, formed by modulating a frequency modulated signal with a hyperbolic secant envelope is formulated. It is seen that this solitary chirplet possesses a high number of vanishing moments. Sample analysis of sinusoidal and FM signals using the solitart chirplet confirms its efficacy in detecting frequency changes and discontinuities, following which the analysis of an earthquake signal is presented. It is seen that the proposed solitary chirplets come in handy while analyzing frequency variations and breaks in signals.
Category: Digital Signal Processing

[5] viXra:1510.0449 [pdf] submitted on 2015-10-28 09:32:49

All-Optical THz OFDM Communications using Photonic Crystal Fibers

Authors: Sai Venkatesh Balasubramanian
Comments: 8 Pages.

An all-optical Orthogonal Frequency Division Multiplexing Communication system at 2 THz is modelled using photonic crystal fiber of length 1km, and the performance of four carrier waveforms - hyperbolic secant, square of hyperbolic secant, square and sinusoidal is evaluated using standard metrics such as eye diagram and bit error rate. From the above mentioned valuations, one can deduce the minimal distortion in hyperbolic secant based carriers, hence leading to unconventional carrier waveforms, which forms the novelty of the present work.
Category: Digital Signal Processing

[4] viXra:1510.0442 [pdf] submitted on 2015-10-27 21:06:47

Genesis of the Solitary Wavelet

Authors: Sai Venkatesh Balasubramanian
Comments: 6 Pages.

A solitary wavelet, based on the hyperbolic secant function is proposed, characterized and applied to real-time data. Numerical analysis of the solitary wavelet reveals that it has a huge number of vanishing higher order moments, tending rapidly towards zero with a negative logarithmic slope. It is seen that the wavelet has a very low number of oscillatory sub-lobes, thus making it the ideal candidate to perform signal analysis of burst-type phenomena without undergoing multiple levels of filtering and approximation, and this concept is illustrated by effectively detecting the QRS complex of an ECG cycle without undergoing multiple filtering levels. The ability of the proposed wavelet to perform analysis of a diverse variety of real time data without multiple levels of decomposition and reconstruction forms the novelty of the present work.
Category: Digital Signal Processing

[3] viXra:1510.0422 [pdf] submitted on 2015-10-27 09:04:47

Soliton based Return to Zero Logic using 180nm CMOS

Authors: Sai Venkatesh Balasubramanian
Comments: 12 Pages.

A Return-to-Zero Logic consisting of Soliton based clock is proposed, and is seen to exhibit more robustness in propagation through interconnects compared with conventional square pulses at microwave and illimetre wave frequencies. The generation of solitons using the nonlinearity of a single transistor is discussed and various combinational and sequential logic circuits based on soliton logic are implemented and characterized using Deep Submicron VLSI SPICE implementations at 180nm CMOS Technology. In addition, Pulse Compression based on single transistor is also discussed. The simplicity of implementation of the soliton logic, coupled with the compatibility with existing CMOS technologies form the key highlights of the present work, paving the way for a futuristic low distortion computing era.
Category: Digital Signal Processing

[2] viXra:1510.0399 [pdf] submitted on 2015-10-26 08:32:11

Supercontinuum Based All-Optical Digital Communication System at 2THz

Authors: Sai Venkatesh Balasubramanian
Comments: 5 Pages.

An all-optical Supercontinuum based communication system at 2 THz is modeled using photonic crystal fiber of length 1km, and its performance using digital modulation techniques such as Amplitude Shift Keying (ASK) is evaluated using standard metrics such as eye diagram and bit error rate. From the above mentioned valuations, one can obtain its robustness, hence leading to secure communication systems at Terahertz data rates, which forms the novelty of the present work.
Category: Digital Signal Processing

[1] viXra:1510.0175 [pdf] submitted on 2015-10-18 06:26:31

Survey on Intelligent Data Repository Using Soft Computing

Authors: A. Prema, A.Pethalakshmi
Comments: 20 Pages.

Data warehouse is one of the components of the overall business intelligence system. An enterprise has one data warehouse, and data marts source has their information from the data warehouse.
Category: Digital Signal Processing