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Background: Carrier generation based on optical heterodyning techniques where a beat signal is generated from the mixing of two light sources can be interesting solution due to ease on tunability. The free running heterodyning scheme benefits with a very wide tuning capability and the generated carrier can be freely adjusted. However, the drawbacks come in the form of frequency stability. Heterodyning of two optical frequencies coming from a single laser cavity has shown its potential on improvement of frequency stability. Methods: The impact of the laser parameters (i.e., optical power and linewidth) on the quality of the generated carrier (i.e., phase/frequency stability and carrier-to-noise ratio) is analyzed for a 25 × 64 elements PAA system. An optically generated carrier signal using a dual-frequency distributed feedback waveguide laser in ytterbium doped aluminum oxide (Al 2 O 3 :Yb 3+ ) is analyzed and experimentally demonstrated in this paper. The carrier signal is used for downconversion of the signal received from a phased array antenna (PAA) of a DVB-S (Digital Video Broadcasting-Satellite) system. Results: An optical frequency locked loop (OFLL) to stabilize the generated carrier is implemented which results in a microwave frequency at ∼14 GHz with a phase noise of -75 dBc/Hz at 1 MHz offset from the center frequency and gives a loop settling time of 12 μs. By using the proposed OFLL, the long term and the short term frequency stability of the generated carrier has an Allan deviation of more than 1 × 10 −10 for an averaging time of 1000 s and a standard deviation of 39.4 kHz, respectively. The lasers linewidth should be in the order of tens of Hz, with a maximum relative intensity noise (RIN) of -107 dB/Hz and a minimum optical power of 0.94 mW. Conclusions: The optical carrier generation by OFLL using a DFL to comply with the requirements of the standard carrier used in commercial LNBs has been investigated. The detailed analysis of the OFLL scheme is presented. Specifications requirement on carrier power, linewidth and relative intensity noise of the optically generated carrier have been addressed. The optical carrier generation is experimentally demonstrated and the requirements on CNR have been determined by measuring the noise floor and the optical carrier power. The measured values are compared with the calculated values and found to be very close.

A new topology of single-phase AC-DC converter using Buck-Boost conversion with high efficiency at extremely low duty cycle is proposed. Proposed double stage converter consists of single phase rectifier followed by a switched capacitor buck-boost DC-DC converter. The input current THD is kept low and the input power factor is kept high with two-loop feedback control. The proposed scheme can be used for new generation LED lighting.

A novel topology of Integrated Boost-SEPIC (IBS) AC-DC converter using common part sharing method (CPSM) has been proposed in this paper. Conventional boost converters with bridge rectifier configuration are inefficient due to limited voltage step-up ratio which may not be applicable for high step-up applications as in the case of micro generators. The proposed IBS topology is based on the common part sharing method capable of operating both for positive and negative half cycle of the input signal. Result and simulation were conducted using PSIM environment. The proposed AC-DC IBS topology eliminates the requirement of bridge rectifier achieving high efficiency (about 99%), improved power factor (0.75, leading) and lower THD (about 38.8%) which is within IEEE standard.

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Abstract-This paper describes the design and engineering of a wireless control system for smoke and fire detection with alarming provision, sms sending and fire extinguishing by a vehicle. We chose the PIC microcontroller for the controlling of the system. The implemented design is so cheap and effective. The sms sending feature included in the design increases the reliability of the system so that it can notify the fire hazard when there is no person available nearby. The fire extinguishing vehicle is a unique feature and it gives a provision to extinguish fire during its very early stage. The design will increase the safety and reliability with reducing the risks to life and property.

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