K. Padmanabhan

Spread Spectrum Communication Using Wavelets of Signal for More Security

Secure communication has a wide range of interesting techniques. Here, a wavelet decomposed data communication packet is used, whose advantages are described. The problems of wide spectrum noise-based jamming, by hostile elements is counteracted. For this, several wavelet coefficients of a data packet are transmitted in non-harmonically related spread frequencies. The reconstruction of the wavelets, despite noisy detection at the received end, is shown to be better, typically for test data packets. The number of frequencies and the coefficients can be varied to suit the detection error limits. Several wavelets have been tired for this purpose and testing has been done even with image data. The results are found to be useful and interesting.

Gabor spectra for Doppler echocardiography

Doppler echocardiography on current ultrasonography machines makes use of short-time Fourier spectrograms (STFTs) to display the patterns of blood vevocities in the heart chamber. From these sonologists infer the functional parameters, such as valve area, that have pathological significance. After mention of the lacuna in such an STFT display, the Gabor transform and associated Gabor spectrogram evaluation techniques are described. Finally, comparative views of ultrasound machine display with PC-based STFT and Gabor displays for two typical patients are shown, with inferences in support of the proposed Gabor display.

Optimal Control with Fuzzy State Space Modeling Using the Riccati Equation

Fuzzy logic has a boon for nonlinear control systems. Normal fuzzy logic control with a proportional integral - Derivative (PID) controller is common. Control systems can be defined through transfer functions and state- space. relations for linear systems. Optimal control to meet a performance index is possible only through State Space analysis. Optimal control in state space is centered around the Riccati Equation with state variable functions that has to be solved to yield the control law or trajectory. In the control scheme of an ozone generator, optimal control with a performance index had to be implemented. The method for finding the control functions by solving the equation graphically is described. The data is used for realizing an embedded control scheme for the generator

Remote Robot Training of Its Artificial Neural Network through GSM Communication

Without building new technology and involved hardware circuit boards, how to develop industrial artificial neural network (ANN) based robotic projects for enterprises is explained with special reference to GSM cell and robotic models. In the process of training to develop enterprise robots, one has to make use of all possible resources. Without the need for development of new circuits or methodology, existing devices, components and services can be used to develop a standard robotic project. There are many examples like traffic control, agricultural plantation and adaptive surveillance. The groundwork of technology for the above robot data collection and control is elucidated and schemes using simple readily available hardware for easy and quick rigging up of robotic systems is the theme of this paper.

Ozone for plant pathological applications

The effect of ozone on Xanthomonas oryzae pv. oryzae, a bacterium causing leaf blight disease in Paddy (Oryza sativa), was studied in culture. Viability of this pathogen was lost by flushing ozone at a flow rate of 300 ml/min for 3 minutes in culture condition. The inhibitory effect was dependant on cell concentration and time. With a cell concentration of 0.008 OD at 540 nm, the inhibition of the bacterium was total and no growth was observed in nutrient agar plates even after 36 hrs. With higher concentrations of cells (0.08 OD and above) the bacterium survived, though there was a bacteriostatic effect initially. Conductivity of the cell suspension increased after ozone treatment owing to altered cell membrane permeability and subsequent release of cellular contents. As the bacterium is seed borne, washing the paddy seeds with ozonized water would help control the bacterial blight of rice, the most serious disease of rice in Asia.

Doppler ultrasound observation of pathological heart valves

A simple, noninvasive technique based on Hilbert transform (HT) time-signal displays is described. The authors discuss methods of showing forward- and reverse-flow Doppler echocardiograph signals as a time course of events relating to valve stenosis and regurgitation for providing additional cardiac insonation diagnostic information. The Doppler ultrasound demodulated signals are separated using the HT technique and then shown as segments of waveforms along with the corresponding electrocardiogram. This allows one to relate cardiac activity events, to assess valve leaflet thickness in severe mitral-valve stenosis cases, and to examine the opening and closing of valve leaflets for diagnosis.

Optimal angular movement of laser beam in SPR using an embedded controller

This paper proposes and implements the PIC microcontroller based Surface Plasmon resonance analysis of bio molecular interaction. Surface Plasmon resonance [SPR] has becoming an important optical bio-sensing technology in the areas of medical, biological , biochemistry, pollution detection, aircraft and laboratory research. The SPR works on the principle of TIR, that when the stepper motor mounted laser beam moving back and forth is focused on the hypotenuse of the gold coated BK-7 prism at an angle greater than the critical angle, hence the laser beam gets reflected back and SPR is generated outward side of the gold coated surface is measured using LDR. The generation of SPR is measured in terms of Refractive index, the refractive index changes with respect to the applied sample (Dielectric loading). Hence even for a small change in molecular interaction can be found using SPR. The laboratory prototype of PIC microcontroller based SPR was characterized in terms of reflectance and intensity with respect to the incident beam. In the design of instrument PIC 16F73 microcontroller is used to control the laser movement back and forth through stepper motor to increase the fastness and accuracy. This paper explains and demonstrates the importance of PIC microcontroller in the design and control of the instrument.

A different scheme of encoding data bits in digital communication using wavelets

Digital data communication uses various modes of encoding the data bits into a frequency signal. Phase shift keying (PSK) of various forms such as Binary PSK, Quaternary PSK etc., are in vogue in several current communication schemes such as GSM. In this paper, a different scheme of encoding digital data using wavelet functions instead of sinusoidal waves is explained. Errors in bits at the received end through a radio channel are common in such data communication. These errors are mainly caused by improper phase changes in the detected audio signal. Since the method presented here with the use of Wavelet functions provides several clues for identification of the data symbol instead of just by one criterion viz., the phase of the carrier as in the PSK schemes, this method is found to be better in performance. Simulation of the scheme was made with Matlab and some preliminary results are presented.

Hilbert Transform Based Time Signal Displays for Doppler Echo Cardiograms

From the echo-Doppler quadrature Signals I and Q of a typical diagnostic ultrasound machine, data processing by using Hilbert Transform enabled the separation of the positive and negative frequency Doppler shift signals as actual typical time-course signals. This provided extra information regarding valve leaflet functioning. Choosing short instants at the T wave fall (Electrocardiogram), the P wave beginning as well the rising edges of the E and A waves (Doppler Spectrogram), such time signals are shown to throw light on the condition of the valves, by means of vibrations typically found in rheumatic mitral valve conditions and even mild mitral stenosis cases. A PC with add on ADC/DSP hardware was used with an ultrasound diagnostic machine in a clinical centre, which enabled the results to be observed on its monitor side by side with the usual B-scan, Colour Doppler and Spectrogram displays on the machine.

A non Fading ECG Display Circuit for Patient Monitoring using Simple TV Picture Tubes

Patient monitors which display ECG waveform continuously as a non-fading waveform make use of digital memory storage and output the pattern on a high resolution CRT. To minimize cost, a design using normal TV tubes is presented in this paper. The details of circuitry and the software which stores and continuously displays the ECG signals are described. The heart rate is calculated based on R-R interval, using an algorithm which takes care of baseline shift also. The rate is displayed on the screen along with waveform using a simple cursor-gated circuit. Software is used to detect the QRS and generate the beep signal. Freeze mode display is also provided.