Tunable diode Laser Absorption Spectroscopy ,Nir Overtone and Life Studies of Some Organic Compound

The present work is mainly concentrated on setting up a NIR tunable diode laser absorption (TDLA) spectrometer for high-resolution molecular spectroscopic studies. For successfully recording the high-resolution tunable diode laser spectrum, various experimental considerations are to be taken into account like the setup should be free from mechanical vibrations, sample should be kept at a low pressure, laser should be in a single mode operation etc. The present experimental set up considers all these factors. It is to be mentioned here that the setting up of a high resolution NIR TDLA spectrometer is a novel experiment requiring much effort and patience. The analysis of near infrared (NIR) vibrational overtone spectra of some substituted benzene compounds using local mode model forms another part of the present work. An attempt is made to record the pulsed laser induced fluorescence/Raman spectra of some organic compounds. A Q-switched Nd:YAG laser is used as the excitation source. A TRIAX monochromator and CCD detector is used for the spectral recording. The observed fluorescence emission for carbon disulphide is centered at 680 nm; this is assigned as due to the n, p* transition. Aniline also shows a broad fluorescence emission centered at 725 nm, which is due to the p,p* transition. The pulsed laser Raman spectra of some organic compounds are also recorded using the same experimental setup. The calibration of the set up is done using the laser Raman spectra of carbon tetrachloride and carbon disulphide. The observed laser Raman spectra for aniline, o-chloroaniline and m-chlorotoluene show peaks characteristics of the aromatic ring in common and the characteristics peaks due to the substitutuent groups. Some new peaks corresponding to low-lying vibrations of these molecules are also assigned

RNS based programmable multi-mode decimation filter for WCDMA and WiMAX

The recent trends envisage multi-standard architectures as a promising solution for the future wireless transceivers to attain higher system capacities and data rates. The computationally intensive decimation filter plays an important role in channel selection for multi-mode systems. An efficient reconfigurable implementation is a key to achieve low power consumption. To this end, this paper presents a dual-mode Residue Number System (RNS) based decimation filter which can be programmed for WCDMA and 802.16e standards. Decimation is done using multistage, multirate finite impulse response (FIR) filters. These FIR filters implemented in RNS domain offers high speed because of its carry free operation on smaller residues in parallel channels. Also, the FIR filters exhibit programmability to a selected standard by reconfiguring the hardware architecture. The total area is increased only by 24% to include WiMAX compared to a single mode WCDMA transceiver. In each mode, the unused parts of the overall architecture is powered down and bypassed to attain power saving. The performance of the proposed decimation filter in terms of critical path delay and area are tabulated.

Dual-mode RNS based programmable decimation filter for WCDMA and WLANa

The recent trends envisage multi-standard architectures as a promising solution for the future wireless transceivers. The computationally intensive decimation filter plays an important role in channel selection for multi-mode systems. An efficient reconfigurable implementation is a key to achieve low power consumption. To this end, this paper presents a dual-mode Residue Number System (RNS) based decimation filter which can be programmed for WCDMA and 802.11a standards. Decimation is done using multistage, multirate finite impulse response (FIR) filters. These FIR filters implemented in RNS domain offers high speed because of its carry free operation on smaller residues in parallel channels. Also, the FIR filters exhibit programmability to a selected standard by reconfiguring the hardware architecture. The total area is increased only by 33% to include WLANa compared to a single mode WCDMA transceiver. In each mode, the unused parts of the overall architecture is powered down and bypassed to attain power saving. The performance of the proposed decimation filter in terms of critical path delay and area are tabulated