...VOL. 3, NO. 4, DECEMBER 2010 Microcontroller based Power Efficient Signal Conditioning Unit for Detection of a Single Gas using MEMS based Sensor P. Bhattacharyya*, D. Verma and D.Banerjee Department of Electronics and Telecommunication Engineering, Bengal Engineering and Science University, Shibpur- 711103, Howrah, West Bengal, India *Corresponding author: Tel.: +913326684561; fax: +913326682916 E-mail: pb_etc_besu@yahoo.com Abstract-A low power MEMS based sensor along with the embedded power efficient signal conditioning unit (Microcontroller based), which can be used with any suitable sensor-network to detect and quantify variations in a particular gas concentration, has been reported in this paper. The power consumption of the MEMS gas sensor is ~ 70mW to 100mW depending upon its operating temperature (150-250°C) and that of entire signal conditioning unit (consisting of low noise amplifier, switch, microcontroller and power management chip) is ~ 36mW in the ON state and only ~7.2µW in OFF state (sleep mode). The test gas in this particular case was methane for which sensor resistance varied from 100KΩ to 10KΩ. This hybrid sensor system is very much suitable for detecting a single gas with display of corresponding gas concentrations and subsequent alarming if the threshold limit is crossed. Index terms: MEMS, Gas sensor, Low power, Microcontroller, Signal Conditioning I. INTRODUCTION A Signal-conditioning unit for gas Detection has in the recent years been a very...
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...[Fourier analysis of Control System] [Fourier analysis of Control System] Submitted to: Dr. S. K. Raghuwanshi Submitted By: Rishi Kant Sharan Semester: V Branch: Electronics & Communication Engineering Submitted to: Dr. S. K. Raghuwanshi Submitted By: Rishi Kant Sharan Adm. No: 2010JE1117 Semester: V Branch: Electronics & Communication Engineering Abstract The assignment focuses on the Fourier analysis of Control System. Which leads to frequency domain analysis of control system. The scope of estimation and controlling the behavior a system by means of Fourier transformation of its transfer function and analyzing its frequency response. Abstract The assignment focuses on the Fourier analysis of Control System. Which leads to frequency domain analysis of control system. The scope of estimation and controlling the behavior a system by means of Fourier transformation of its transfer function and analyzing its frequency response. ACKNOWLEDGEMENT There is an old adage that says that you never really learn a subject until you teach it. I now know that you learn a subject even better when you write about it. Preparing this term paper has provided me with a wonderful opportunity to unite my love of concept in CONTROL SYSTEM. This term paper is made possible through the help and support from everyone, including: professor, friends, parents, family, and in essence, all sentient beings. Especially, please allow me to dedicate...
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...Primary Cognitive PU4 Frequency Sense the spectral environment over a wide bandwidth Transmit in “white space” & Adapt bandwidth and power Detect if primary user appears Move to new white space Cognitive Radio System Design Network Management Sensing MAC Sensing Signal Processing Sensing radio Spectrum Allocation Network Link Layer Wideband signaling Wideband radio Physical Layer Spectrum sensing is the key enabling functionality How do we implement spectrum sensing in a system? Spectrum Sensing Problem Primary User Cognitive Radio users must guarantee non-interference requirement Tx Rx CR CR Decoding SNR Sensing SNR distance Distance and channel not known Cognitive radio can only observe (sense) primary system Tx signals Need to sense signals in highly negative SNR Sensing SNR < Decoding SNR – worst case channel Sensing SNR < [5dB to 20 dB] – [20 dB to 40 dB] = [-35 to 0 dB] Designing Spectrum Sensors – Sensing Requirements set by Primary User system ● Signal level (dBm) ● Maximum detection time (s) ● Interference protection (%) – Can we use standard detection techniques? ● Energy detection ● Pilot detection ● Feature detection – Can a radio sense primary signals robustly and guarantee noninterference to primary users in negative SNR regimes?...
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...LTE Initial Access [pic] Like all mobile communication systems, in LTE a terminal must perform certain steps before it can receive or transmit data. These steps can be categorized in cell search and cell selection, derivation of system information, and random access. The complete procedure is known as LTE Initial Access and is shown in the Figure below. After the initial access procedure, the terminal is able to receive and transmit its user data. [pic] Initial synchronization [pic] Successful execution of the cell search and selection procedure as well as acquiring initial system information is essential for the UE before taking further steps to communicate with the network. For this reason, it is important to take a closer look at this fundamental physical layer procedure. This section focuses on the cell-search scheme defined for LTE and the next chapter describes reception of the essential system information. As in 3G (WCDMA), LTE uses a hierarchical cell-search procedure in which an LTE radio cell is identified by a cell identity, which is comparable to the scrambling code that is used to separate base stations and cells in WCDMA. To avoid the need for expensive and complicated network and cell planning, 504 physical layer cell identities of is sufficiently large. With a hierarchical cell search scheme, these identities are divided into 168 unique cell layer identity groups in the physical layer, in which each group consists of three...
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...Imagining a robot to behave just like a human is one of those new-age fantasies of almost everyone who can bottle even a tiny glimpse of a vision of the future. For people like us who sometimes manage to think of things other than just the daily survival have a lot of room for all kinds of strange dreams. Sometimes this also leads us to build all kinds of blue-sky thinking. Stepping off the quicksand let me classify ourselves as a group of individuals who have much time to think so as to recycle all kinds of emotions into this moment all over again. We very well know how it does feel when we are ecstatic about something, or when we are embarrassed, or sometimes get a shock of our lives, sometimes feel like crying our hearts out or sometimes plain bored to death. We can relate to all kind of feelings that ranges between these exaggerated memes, can’t we? But how do you relate if you were a robot? I would say that this is where you would feel the hint of a brainteaser, even if I assume your IQ to surpass Einstein’s. The fact that there is even a problem here seem to elude most people, it's hard to realize what it is and even harder to explain it. There is this default position that consciousness is, in principle, knowable and explainable in the framework of modern neurology and that there are no reasons to think otherwise. But did I mention earlier that I, for some daunting series of events, have started conceiving myself as a robot?! You might and should guffaw over this, but...
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...EE225C Introduction to OFDM l Basic idea » Using a large number of parallel narrow-band subcarriers instead of a single wide-band carrier to transport information l Advantages » Very easy and efficient in dealing with multi-path » Robust again narrow-band interference l Disadvantages » Sensitive to frequency offset and phase noise » Peak-to-average problem reduces the power efficiency of RF amplifier at the transmitter l Adopted for various standards – DSL, 802.11a, DAB, DVB 1 Multipath can be described in two domains: time and frequency Time domain: Impulse response time time time Impulse response Frequency domain: Frequency response time time time Sinusoidal signal as input f Frequency response time Sinusoidal signal as output Modulation techniques: monocarrier vs. multicarrier Channel Channelization Guard bands N carriers Similar to FDM technique B Pulse length ~ N/B – Data are shared among several carriers and simultaneously transmitted Advantages Furthermore – Flat Fading per carrier – N long pulses – ISI is comparatively short – N short EQs needed – Poor spectral efficiency because of band guards – It is easy to exploit Frequency diversity – It allows to deploy 2D coding techniques – Dynamic signalling B Pulse length ~1/B – Data are transmited over only one carrier Drawbacks – Selective Fading – Very short pulses – ISI is compartively long – EQs are then very long – Poor spectral efficiency because of band guards ...
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...Simplified block diagram of the test setup for assessing the absolute and relative pulse response of the measuring receivers The RF generator provides a continuous wave signal at the different frequencies selected for bands C and D. Then, the AWG produces the gating signal that modulates the carrier by switching on and off the CW signal, creating a pulse according to CISPR16-1-1 requirements. Finally, the modulated pulse is feed directly to the EMI measuring receiver. The amplitude of the CW signal and the gating duration are defined in Table IV for bands A to D. TABLE IV. REFERENCE PULSE DURATION AND AMPLITUDE SPECIFICATION Frequency Band Td (μs) Urms (mV) A 100 95,5 B 2,2 101,6 C 0,167 186,3 D 0,167 186,3 The specific carrier frequency...
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...A Novel Channel Estimation Algorithm for 3GPP LTE Downlink System Using Joint Time-Frequency Two-Dimensional Iterative Wiener Filter Jinfeng Hou, Jian Liu School of Communication and Information Engineering University of Electronic Science and Technology of China (UESTC) Chengdu 611731, China Email: houjinfeng@gmail.com, liuj@uestc.edu.cn Abstract—The channel estimation algorithms are employed in 3GPP Long Term Evolution (LTE) downlink system to assist the coherent demodulation of Orthogonal Frequency Division Multiplexing (OFDM) symbols. Based on the comparison of several exiting different channel estimation algorithms, we propose a joint time-frequency two-dimensional iterative Wiener filter (IWF) channel estimation algorithm for 3GPP LTE downlink system. In this scheme, we first apply the linear minimum mean square error (LMMSE) algorithm based on singular value decomposition (SVD) for IWF in frequency domain, and then the values after the first filtering in frequency domain are used to achieve the second IWF in time domain. Comparing to the conventional algorithms, the channel estimation algorithm proposed by this paper brings up lower bit error rate (BER) and adds little computational complexity. I. I NTRODUCTION In December 2004, the Third Generation Partnership Program (3GPP) members started a feasibility study on the enhancement of the Universal Terrestrial Radio Access (UTRA) in the aim of continuing the long time frame competitiveness of the 3G Universal Mobile Telecommunications...
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...Optimal Power Allocation in Multi-Relay MIMO Cooperative Networks: Theory and Algorithms Abstract Cooperative networking is known to have significant potential in increasing network capacity and transmission reliability. Although there have been extensive studies on applying cooperative networking in multi-hop ad hoc networks, most works are limited to the basic three-node relay scheme and single-antenna systems. These two limitations are interconnected and both are due to a limited theoretical understanding of the optimal power allocation structure in MIMO cooperative networks (MIMO-CN). In this paper, we study the structural properties of the optimal power allocation in MIMO-CN with per-node power constraints. More specifically, we show that the optimal power allocations at the source and each relay follow a matching structure in MIMO-CN. This result generalizes the power allocation result under the basic three-node setting to the multi-relay setting, for which the optimal power allocation structure has been heretofore unknown. We further quantify the performance gain due to cooperative relay and establish a connection between cooperative relay and pure relay. Finally, based on these structural insights, we reduce the MIMO-CN rate maximization problem to an equivalent scalar formulation. We then propose a global optimization method to solve this simplified and equivalent problem. Architecture Existing System In Existing System, the multi-hop ad hoc networks...
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...speech signal enhancement is needed to obtain clean speech signal from noisy signal. For multimodal optimization we better to use natural-inspired algorithms such as Firefly Algorithm (FA). We compare the firefly algorithm with particle swarm optimization technique. The proposed algorithm contains three module techniques. Those are preprocessing module, optimization module and spectral filtering module. The signals are taken from Loizou’s database and Aurora database for evaluating proposed technique. In this paper we calculate the perceptional evolution of speech quality (PESQ) and signal to noise (SNR) of the enhanced signal. The results of firefly algorithm and PSO are to be compare then we observe that the proposed technique...
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...Bandwidth (signal processing) From Wikipedia, the free encyclopedia Jump to: navigation, search Baseband bandwidth. Here the bandwidth equals the upper frequency. Bandwidth is the difference between the upper and lower frequencies in a contiguous set of frequencies. It is typically measured in hertz, and may sometimes refer to passband bandwidth, sometimes to baseband bandwidth, depending on context. Passband bandwidth is the difference between the upper and lower cutoff frequencies of, for example, an electronic filter, a communication channel, or a signal spectrum. In case of a low-pass filter or baseband signal, the bandwidth is equal to its upper cutoff frequency. The term baseband bandwidth always refers to the upper cutoff frequency, regardless of whether the filter is bandpass or low-pass. Bandwidth in hertz is a central concept in many fields, including electronics, information theory, radio communications, signal processing, and spectroscopy. A key characteristic of bandwidth is that a band of a given width can carry the same amount of information, regardless of where that band is located in the frequency spectrum (assuming equivalent noise level). For example, a 5 kHz band can carry a telephone conversation whether that band is at baseband (as in your POTS telephone line) or modulated to some higher (passband) frequency. In computer networking and other digital fields, the term bandwidth often refers to a data rate measured in bits per second, for example network...
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...improve your understanding of a signal. This tutorial is part of the Instrument Fundamentals series. Table of Contents 1. 2. 3. 4. Understanding the Time Domain, Frequency Domain, and FFT Windowing Summary Additional Instrumentation Resources 1. Understanding the Time Domain, Frequency Domain, and FFT The Fourier transform can be powerful in understanding everyday signals and troubleshooting errors in signals. Although the Fourier transform is a complicated mathematical function, it isn’t a complicated concept to understand and relate to your measured signals. Essentially, it takes a signal and breaks it down into sine waves of different amplitudes and frequencies. Let’s take a deeper look at what this means and why it is useful. All Signal Are the Sum of Sines When looking at real-world signals, you usually view them as a voltage changing over time. This is referred to as the time domain. Fourier’s theorem states that any waveform in the time domain can be represented by the weighted sum of sines and cosines. For example, take two sine waves, where one is three times as fast as the other—or the frequency is 1/3 the first signal. When you add them, you can see you get a different signal. Figure 1. When you add two signals, you get a new signal. Now imagine if that second wave was also 1/3 the amplitude. This time, just the peaks are affected. 1/11 www.ni.com Figure 2. Adjusting the amplitude when adding signals affects the peaks. Imagine...
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...technical papers is also appended for a quick reference. Streszczenie. Techniki PLL i synchronizacji są ważnymi elementami przetworników w systemach sieciowych, takich jak: rozproszonych systemach mocy, FACTs czy HVDC. Artykuł przedstawia przegląd tego typu metod a następnie porównanie tych metod. Na końcu ponad 40 podstawowych artykułów z tej tematyki jest przedstawionych.(Metody synchronizacji i PLL w przetwornikach sieciowych – przegląd). Keywords: Grid-interfaced converters, phase locked loop, synchronization Słowa kluczowe: uchłady PLL, synchronizacja. Introduction The basic phase locked loop (PLL) concept was originally published by Appleton in 1923 and Bellescize in 1932, which was mainly used for synchronous reception of radio signals [1-2]. After that, PLL techniques were widely used in various industrial fields such as communication systems [36], motor control systems [7-8], induction heating power supplies [9] and contactless power supplies [10]. Recently, PLL techniques have been used for synchronization between grid-interfaced converters and the utility network. An ideal PLL can provide the fast and accurate synchronization information with a high degree of immunity and insensitivity to...
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...two different hydrogen sensors from Neodym Technologies, is documented and finally the method of sensor calibration is outlined. 1 INTRODUCTION The University of Western Australia’s Renewable Energy Vehicle (REV) project aims to show the viability of using renewable energy as a means of transport. The vehicle will resemble the cars of today, but will be solely powered by a hybrid of hydrogen fuel and solar energy. The proposed car’s completion date is late 2005, allowing it to be driven around Australia in 2006. The REV requires numerous amounts of measured physical quantities for both data logging and controlling the car’s systems. For each measured physical quantity, a sensor is required to convert this quantity into an electrical signal. Safety is always first priority, and for this reason hydrogen leak safety sensors were given the highest priority on the list of required sensors. 2 HYDROGEN CONCENTRATION MEASUREMENT Hydrogen gas is extremely flammable having an EL1 of 4.1–74.8 % by volume in air. The minimum energy of hydrogen gas ignition in air at atmospheric pressure is about 0.02 mJ and it has been shown that escaped hydrogen is very easily ignited [1], the ignition temperature in air is 520–580 ◦ C. In high concentrations,...
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...by lady ada Last updated on 2016-01-04 12:09:26 PM EST Guide Contents Guide Contents Overview 2 3 DHT11 vs DHT22 3 Connecting to a DHTxx Sensor Using a DHTxx Sensor Downloads © Adafruit Industries https://learn.adafruit.com/dht 5 7 10 Page 2 of 10 Overview This tutorial covers the low cost DHT temperature & humidity sensors (http://adafru.it/aJU). These sensors are very basic and slow, but are great for hobbyists who want to do some basic data logging. The DHT sensors are made of two parts, a capacitive humidity sensor and a thermistor (http://adafru.it/aHD). There is also a very basic chip inside that does some analog to digital conversion and spits out a digital signal with the temperature and humidity. The digital signal is fairly easy to read using any microcontroller. DHT11 vs DHT22 We have two versions of the DHT sensor, they look a bit similar and have the same pinout, but have different characteristics. Here are the specs: DHT11 (http://adafru.it/386) Ultra low cost 3 to 5V power and I/O 2.5mA max current use during conversion (while requesting data) © Adafruit Industries https://learn.adafruit.com/dht Page 3 of 10 Good for 20-80% humidity readings with 5% accuracy Good for 0-50°C temperature readings ±2°C accuracy No more than 1 Hz sampling rate (once every second) Body size 15.5mm x 12mm x 5.5mm 4 pins with 0.1" spacing DHT22 (http://adafru.it/385) Low cost 3 to 5V power and I/O 2.5mA max current...
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