Electrical Engineering

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Shiv Nadar University

The communication switching system enables the universal connectivity. The universal connectivity is realized when any entity in one part of the world can communicate with any other entity in another part of the world. In many ways telecommunication will acts as a substitute for the increasingly expensive physical transportation. The telecommunication links and switching were mainly designed for voice communication. Traffic handling capacity is an important element of service quality and will therefore play a basic role in this choice Microprocessor/microcontroller (MPMC) system can handle sequential operations with high flexibility and use of Field Programmable Gate Array (FPGA) can handle concurrent operations with high speed in small size area. So combined features of both these systems can enhance the performance of the system. High Performance Hybrid Telephone Network System (HTSS) is designed using combination of stored program control (SPC) and VLSI technology. Touch tone receiver follows DTMF (Dual tone Multifrequency) concept and Time division multiplexing chip is used for the call establishment for inter and intra communication. © 2013 IEEE.

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(SoE) School of Engineering

Proceedings of the 2013 3rd IEEE International Advance Computing Conference, IACC 2013

Network on chip for DTMF Decoder and TDM switching in telecommunication network with HDL environment

In television broadcasting the very high frequency/ultrahigh frequency bands are either not assigned or not used by existing broadcast. The unused television bands can be utilized for rural broadband Internet for larger distances without carrying interference to existing licensed television bands. The IEEE802.22 Wireless Regional Area Network standard involving devices and databases has been developed to utilize unassigned and unused very high frequency/ultrahigh frequency television bands using cognitive radio technology. Cognitive radio utilizes radio spectrum more efficiently. It senses the environment and configures itself accordingly. The cognitive radio technology is heavily dependent upon software defined radio technology as radio needs to be configurable according to the prevailing radio environment. © 2013 IEEE.

2013 International Conference on Signal Processing and Communication, ICSC 2013

Rural wireless broadband Internet access in Wireless Regional Area Network using cognitive radio

This paper proposes a low power voltage reference generator in 0.18μm CMOS technology. The circuit presented here includes MOSFETs in sub threshold mode and uses the temperature dependence of threshold voltages and sub-threshold current of MOSFET to form a temperature-insensitive reference. An input supply voltage of 1.8 Volt is used for the circuit generating a total current of 1.33μA. By varying the device temperature over the range of -20°C to 100°C corresponding variation over the output voltage was found to lie in the range 397.8 to 400.2 mV. Thus a 0.6\% variation in voltage over the considered range of temperature is obtained. © (2013) Trans Tech Publications, Switzerland.

Advanced Materials Research

Design of a Sub-0.4 V reference circuit in 0.18μm CMOS technology

Beacon receiver with better power estimation accuracy is the need for the propagation model development for Ka Band propagation studies experiment. This paper proposes the design philosophy of Digital Receiver, signal processing steps &amp; design of window to achieve the beacon power estimation accuracy of +/- 0.5 dB with measurement rate of 1 Hz up to 30 dBHz C/N0 of a single channel Ka-band beacon receiver working with IPSTAR Ka-band on-board beacon. A custom window with intelligent signal processing steps resulted into improved beacon power measurement accuracy of +/- 0.5 dB over a large programmable bandwidth which is better than the available beacon receiver developed so far under similar signal conditions. A performance comparison with different window functions is also presented. The present receiver design works in closed loop with L-band downconverter to achieve better power estimation accuracy and suitable for unmanned operation. The designed receiver is tested within lab setup with simulated input and also tested in field with 20.199827 GHz beacon onboard IPSTAR. © 2013 IEEE.

International Conference on Communication and Signal Processing, ICCSP 2013 - Proceedings

Digital receiver based Ka Band beacon receiver for improved beacon power estimation

This paper discusses a joint adaptive channel estimation and transceiver design scheme for MIMO two-way relay systems. In order to reduce the computational complexity at the transmitting nodes, the transceiver is implemented at the relay station. Adaptive transceiver consists of an adaptive postequalizer known as receive filter and an adaptive pre-equalizer known as transmit filter. The design of adaptive pre-equalizer requires the knowledge of Channel State Information (CSI) between nodes and relay station. So a channel tracking adaptive filter should be implemented at the relay. Due to the structure of a two-way relay system, the training signals used to train the receive filter can be used to train the channel tracking filter. Thus the adaptive channel estimator and receive filter work simultaneously. The channel estimate is then used to design the transmit filter. The adaptive filters are implemented using the NLMS algorithm. The performance of the proposed scheme is verified by making use of MATLAB simulations. © 2013 IEEE.

Proceedings - 2013 3rd International Conference on Advances in Computing and Communications, ICACC 2013

Joint adaptive channel estimation and transceiver design for two-way relay systems

High power light emitting diode (LED) arrays have been investigated as excitation sources for long pulse and lock-in thermography. Images of artificial defects in a carbon fibre reinforced plastic (CFRP) composite sample are compared, by image contrast signal-to-noise ratio estimates, with those obtained using conventional incandescent flash and lock-in excitation sources. The LED arrays had to be mounted on heat sinks with active cooling in to prevent them exceeding their thermal tolerance. Despite this cooling the LED arrays were still found to emit some IR radiation, although far less than conventional incandescent light sources. © 2013 Elsevier Ltd.

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NDT and E International

LED optical excitation for the long pulse and lock-in thermographic techniques

Color stability in multi-emissive layer organic light emitting devices (Me-OLEDs) has been investigated. Me-OLEDs were based on multiple emitters with a common host CBP doped with three dopants, BCzVBi, Ir(ppy)3 and Ir(btp)2acac for blue, green and red emission. A major variation in CIE coordinates were found from (0.312, 0.294) to (0.236, 0.267) with increase in voltage from 6 to 9 V. This coordinate shift in Me-OLEDs has been attributed to the shifting of recombination zone with increase in voltage. In order to support our experimental observation, the EL spectrum of Me-OLEDs has been expressed as a linear combination of EL intensities of OLEDs with its individual constituting layers as emitters. In this way, the contribution of each layer in the EL spectrum of Me-OLEDs has been evaluated at each voltage. It has been observed from these calculations that the contribution of red emitter decreases from 47% to 33.33% and blue emitter increases from 38% to 51.67% with the increase in voltage from 6 to 9 V. This supports our hypothesis of shifting of recombination zone with the change in voltage. This shifting has been attributed to the field dependency of electron mobility in CBP. Me-OLED with CBP layers between the emitters was fabricated to improve the color stability. Significant improvement in color stability was achieved without changes in current efficiency in Me-OLED with interlayers. © 2012 Elsevier B.V.

Journal of Luminescence

Study of shifting of recombination zone in multi-emissive layer organic light emitting devices and its effect on color stability

In this Letter, the effect of F4-TCNQ insertion at the anode/hole transport layer (HTL) interface was studied on joule heating and the lifetime of organic light-emitting diodes (OLEDs). Joule heating was found to reduce significantly (pixel temperature decrease by about 10 K at a current density of 40 mA/cm2) by this insertion. However, the lifetime was found to reduce significantly with a 1 nm thick F4-TCNQ layer, and it improved by increasing the thickness of this layer. Thermal diffusion of F4-TCNQ into HTL leads to F4-TCNQ ionization by charge transfer, and drift of these molecules into the emissive layer caused faster degradation of the OLEDs. This drift was found to reduce with an increase in the thickness of F4-TCNQ. © 2013 Optical Society of America.

Optics Letters

Exciton quenching by diffusion of 2,3,5,6-tetrafluoro-7,7',8,8'-tetra cyano quino dimethane and its consequences on joule heating and lifetime of organic light-emitting diodes

The visualization of electromagnetic field intensity can be easily achieved by infrared thermography using an absorption screen of carbon loaded polymers. The electromagnetic waves falling on the absorption screen increase its temperature which is monitored by an infrared camera. The measured temperature profile can further be correlated to the electric field intensity. Measurement of electromagnetic field distribution is typically done by a small scanning antenna and is a time consuming process. Furthermore the scanning antenna will itself disturb the measurement process which is not the case with an absorption screen, even if the screen is kept very near to the electromagnetic wave source. Therefore fields very near to the source can also be visualized and measured. Also the length of the scanning antenna depends on wavelength of electromagnetic field to be measured, therefore it is improper to apply it to measure various fields. In order to show the utility of the above technique, an example of a patch antenna operating at a frequency of 2.45 GHz is given. Initial experiments show good agreement between simulated and measured results. © 2013 IEEE.

2013 IEEE MTT-S International Microwave and RF Conference, IMaRC 2013

Infrared thermography for electromagnetic field pattern recognition

This paper introduces a low complexity adaptive channel estimation technique for OFDM based two-way relay systems. The adaptive filter used is known as Group Fast Array Multichannel 2D-Recursive Least Square (GFAM 2DRLS) filter. It has a computational complexity comparable to that of 2D-Normalized Least Mean Square (2D-NLMS) algorithm while maintaining the same convergence rate as the classic 2D Recursive Least Square (2D-RLS) algorithm. It considers the correlation of the channel frequency response in both time and frequency, while estimating the channel. In order to reduce the number of training data for time varying channel, the channel estimation is carried out based on the Decision Directed (DD) principle. It is assumed that the relay is capable of performing complex signal processing tasks. Hence the channel estimation is performed at the relay. Since the Channel State Information (CSI) is available at the relay, it could perform Multiple Input Multiple Output (MIMO) precoding of the transmitted data. Hence CSI is not required at the transmitting nodes. The convergence rate of GFAM 2D-RLS is compared with the existing 2D-NLMS algorithm and the computational complexity at each iteration is tabulated. Simulations are performed using MATLAB. © 2013 IEEE.