A data logger (or datalogger) is an electronic instrument that records data over time or in relation to location. Increasingly, but not necessarily, they are based on a digital processor (or computer). They may be small, battery powered and portable and vary between general purpose types for a range of measurement applications to very specific devices for measuring in one environment only.It is common for general purpose types to beprogrammable.
Standardisation of protocols and data formats is growing in the industry and XML is increasingly being adopted for data exchange. The development of the Semantic Web is likely to accelerate this trend. A smart protocol, SDI-12, exists that allows some instrumentation to be connected to a variety of data loggers. The use of this standard has not gained much acceptance outside the environmental industry. SDI-12 also supports multi drop instruments.
Some datalogging companies are also now supporting the MODBUS standard, this has been used traditionally in the industrial control area there are many industrial instruments which support this communication standard. Some data loggers utilize a flexible scripting environment to adapt themselves to various non-standard protocols.
Another multi drop protocol which is now stating to become more widely used is based upon CANBUS (ISO 11898) this bus system was originally developed by Robert Bosch for the automotive industry. This protocol is ideally suited to higher speed logging, the data is divided into small individually addressed 64 bit packets of information with a very strict priority. This standard from the automotive/machine area is now seeping into more traditional data logging areas, a number of newer players and some of the more traditional players have loggers supporting sensors with this communications bus.
DATA LOGGING VERSUS DATA ACQUISITION
The terms data logging and data acquisition are often used interchangeably. However, in a historical context they are quite different. A data logger is a data acquisition system, but a data acquisition system is not necessarily a data logger.
" Data loggers typically have slower sample rates. A maximum sample rate of 1 Hz may be considered to be very fast for a data logger, yet very slow for a typical data acquisition system.
" Data loggers are implicitly stand-alone devices, while typical data acquisition system must remain tethered to a computer to acquire data. This stand-alone aspect of data loggers implies on-board memory that is used to store acquired data. Sometimes this memory is very large to accommodate many days, or even months, of unattended recording. This memory may be battery-backed static random access memory, flash memory or EEPROM. Earlier data loggers used magnetic tape, punched paper tape, or directly viewable records such as "strip chart recorders".
" Given the extended recording times of data loggers, they typically feature a time- and date-stamping mechanism to ensure that each recorded data value is associated with a date and time of acquisition. As such, data loggers typically employ built-in real-time clocks whose published drift can be an important consideration when choosing between data loggers.
" Data loggers range from simple single-channel input to complex multi-channel instruments. Typically, the simpler the device the less programming flexibility. Some more sophisticated instruments allow for cross-channel computations and alarms based on predetermined conditions. The newest of data loggers can serve web pages, allowing numerous people to monitor a system remotely.
Wideband Sigma Delta PLL Modulator
Wideband Sigma Delta PLL Modulator
The proliferation of wireless products over past few years has been rapidly increasing. New wireless standards such as GPRS and HSCSD have brought new challenges to wireless transceiver design. One pivotal component of transceiver is frequency synthesizer. Two major requirements in mobile applications are efficient utilization of frequency spectrum by narrowing the channel spacing and fast switching for high data rates. This can be achieved by using fractional- N PLL architecture. They are capable of synthesizing frequencies at channel spacings less than reference frequency. This will increase the reference frequency and also reduces the PLL's lock time.
Fractional N PLL has the disadvantage that it generates high tones at multiple of channel spacing. Using digital sigma delta modulation techniques. we can randomize the frequency division ratio so that quantization noise of the divider can be transferred to high frequencies thereby eliminatory the spurs.
The advantages of this conventional PLL modulator is that they offer small frequency resolution, wider tuning bandwidth and fast switching speed. But they have insufficient bandwidth for current wireless standards such as GSM. so that they cannot be used as a closed loop modulator for digital enhanced codeless (DECT) standard. they efficiently filter out quantization noise and reference feed through for sufficiently small loop bandwidth.
Wide Band PLL
For wider loop band width applications bandwidth is increased. but this will results in residual spurs to occur. this due to the fact that the requirement of the quantization noise to be uniformly distributed is violated. since we are using techniques for frequency synthesis the I/P to the modulator is dc I/P which will results in producing tones even when higher order modulators are used. with single bit O/P level of quantization noise is less but with multi bit O/P s quantization noise increases.
So the range of stability of modulator is reduced which will results in reduction of tuning range. More over the hardware complexity of the modulator is higher than Mash modulator. In this feed back feed forward modulator the loop band width was limited to nearly three orders of magnitudes less than the reference frequency. So if it is to be used as a closed loop modulator power dissipation will increase.
So in order to widen the loop band width the close-in-phase noise must be kept within tolerable levels and also the rise of the quantization noise must be limited to meet high frequency offset phase noise requirements. At low frequencies or dc the modulator transfer function has a zero which will results in addition of phase noise. For that the zero is moved away from dc to a frequency equal to some multiple of fractional division ratio. This will introduce a notch at that frequency which will reduce the total quantization noise. Now the quantization noise of modified modulator is 1.7 times and 4.25 times smaller than Mash modulator.
At higher frequencies quantization noise cause distortion in the response. This is because the step size of multi bit modulator is same as single bit modulator. So more phase distortion will be occurring in multi bit PLLs. To reduce quantization noise at high frequencies the step size is reduced by producing functional division ratios. This is achieved by using a phase selection divider instead of control logic in conventional modulator. This divider will produce phase shifts of VCO signal and changes the division ratio by selecting different phases from the VCO. This type of divider will produce quarter division ratios.
Voice morphing means the transition of one speech signal into another. Like image morphing, speech morphing aims to preserve the shared characteristics of the starting and final signals, while generating a smooth transition between them. Speech morphing is analogous to image morphing. In image morphing the in-between images all show one face smoothly changing its shape and texture until it turns into the target face. It is this feature that a speech morph should possess. One speech signal should smoothly change into another, keeping the shared characteristics of the starting and ending signals but smoothly changing the other properties.
The major properties of concern as far as a speech signal is concerned are its pitch and envelope information. These two reside in a convolved form in a speech signal. Hence some efficient method for extracting each of these is necessary. We have adopted an uncomplicated approach namely cepstral analysis to do the same. Pitch and formant information in each signal is extracted using the cepstral approach. Necessary processing to obtain the morphed speech signal include methods like Cross fading of envelope information, Dynamic Time Warping to match the major signal features (pitch) and Signal Re-estimation to convert the morphed speech signal back into the acoustic waveform.
INTROSPECTION OF THE MORPHING PROCESS
Speech morphing can be achieved by transforming the signal's representation from the acoustic waveform obtained by sampling of the analog signal, with which many people are familiar with, to another representation. To prepare the signal for the transformation, it is split into a number of 'frames' - sections of the waveform. The transformation is then applied to each frame of the signal. This provides another way of viewing the signal information. The new representation (said to be in the frequency domain) describes the average energy present at each frequency band.
Further analysis enables two pieces of information to be obtained: pitch information and the overall envelope of the sound. A key element in the morphing is the manipulation of the pitch information. If two signals with different pitches were simply cross-faded it is highly likely that two separate sounds will be heard. This occurs because the signal will have two distinct pitches causing the auditory system to perceive two different objects. A successful morph must exhibit a smoothly changing pitch throughout.
The pitch information of each sound is compared to provide the best match between the two signals' pitches. To do this match, the signals are stretched and compressed so that important sections of each signal match in time. The interpolation of the two sounds can then be performed which creates the intermediate sounds in the morph. The final stage is then to convert the frames back into a normal waveform.
The VISNAV system uses a Position Sensitive Diode (PSD) sensor for 6 DOF estimation. Output current from the PSD sensor determines the azimuth and elevation of the light source with respect to the sensor. By having four or more light source called beacons in the target frame at known positions the six degree of freedom data associated with the sensor is calculated.
The beacon channel separation and demodulation are done on a fixed point digital signal processor (DSP) Texas Instruments TMS320C55x  using digital down conversion, synchronous detection and multirate signal processing techniques. The demodulated sensor currents due to each beacon are communicated to a floating point DSP Texas Instruments TMS320VC33  for subsequent navigation solution by the use of colinearity equations.
Among other competitive systems  a differential global positioning system (GPS) is limited to midrange accuracies, lower bandwidth, and requires complex infrastructures. The sensor systems based on differential GPS are also limited by geometric dilution of precision, multipath errors, receiver errors, etc.These limitations can be overcome by using the DSP embedded VISNAV system
FACTORS AFECTING MEASUREMENT
There is likely to be a large amount of ambient light at short wavelength and low carrier frequencies due to perhaps the sun, its reflections, incandescent or discharge tube lights, LCD and cathode ray tube displays etc. In many cases this ambient energy would swap a relatively small beacon signal and the PSD centroid data would mostly correspond to this unwanted background light.
In order to avoid this problem by modulating the beacon controller current by a sinusoidal carrier of high frequency. The resulting PSD signal currents then vary sinsuoidally at approximately the same frequency and have to be demodulated to recover the actual current proportional to the beacon light centroid. This modulation or demodulation scheme leads high degree of insensitivity to variations in ambient light and it is a key to make the PSD sensing approach practical.
Speed Detection of moving vehicle using speed cameras
Speed Detection of moving vehicle using speed cameras
Although there is good road safety performance the number of people killed and injured on our roads remain unacceptably high. So the roads safety strategy was published or introduced to support the new casualty reduction targets. The road safety strategy includes all forms of invention based on the engineering and education and enforcement and recognizes that there are many different factors that lead to traffic collisions and casualties. The main reason is speed of vehicle. We use traffic lights and other traffic manager to reduce the speed. One among them is speed cameras.
Speed cameras on the side of urban and rural roads, usually placed to catch transgressors of the stipulated speed limit for that road. The speed cameras, the solely to identify and prosecute those drivers that pass by the them when exceed the stipulated speed limit.
At first glance this seemed to be reasonable that the road users do not exceed the speed limit must be a good thing because it increases road safety, reduces accidents and protect other road users and pedestrians.
So speed limits are good idea. To enforce these speed limit; laws are passed making speed an offence and signs are erected were of to indicate the maximum permissible speeds. The police can't be every where to enforce the speed limit and so enforcement cameras art director to do this work; on one who's got an ounce of Commons sense, the deliberately drive through speed camera in order fined and penalized .
So nearly everyone slowdown for the speed Camera. We finally have a solution to the speeding problem. Now if we are to assume that speed cameras are the only way to make driver's slowdown, and they work efficiently, then we would expect there to be a great number of these every were and that day would be highly visible and identifiable to make a drivers slow down.
Optical Satellite Communication
Optical Packet Switching Network
Wearable sensors and systems have evolved to the point that they can be considered ready for clinical application. The use of wearable monitoring devices that allow continuous or intermittent monitoring of physiological signals is critical for the advancement of both the diagnosis as well as treatment of diseases. Wearable systems are totally non-obtrusive devices that allow physicians to overcome the limitations of ambulatory technology and provide a response to the need for monitoring individuals over weeks or months.
They typically rely on wireless miniature sensors enclosed in patches or bandages or in items that can be worn, such as ring or shirt. The data sets recorded using these systems are then processed to detect events predictive of possible worsening of the patient's clinical situations or they are explored to access the impact of clinical interventions.
It is a pulse oximetry sensor that allows one to continuously monitor heart rate and oxygen saturation in a totally unobtrusive way. The device is shaped like a ring and thus it can be worn for long periods of time without any discomfort to the subject. The ring sensor is equipped with a low power transceiver that accomplishes bi-directional communication with a base station, and to upload date at any point in time.
Each time the heart muscle contracts,blood is ejected from the ventricles and a pulse of pressure is transmitted through the circulatory system.This pressure pulse when traveling through the vessels,causes vessel wall displacement which is measurable at various points.inorder to detect pulsatile blood volume changes by photoelectric method,photo conductors are used.normally photo resistors are used, for amplification purpose photo transistors are used.
Light is emitted by LED and transmitted through the artery and the resistance of photo resistor is determined by the amount of light reaching it.with each contraction of heart,blood is forced to the extremities and the amount of blood in the finger increases.it alters the optical density with the result that the light transmission through the finger reduces and the resistance of the photo resistor increases accordingly.The photoresistor is connected as a part of voltage divider circuit and produces a voltage that varies with the amount of blood in the finger.This voltage that closely follows the pressure pulse.
Oxygen enables pervasive, human-centered computing through a combination of specific user and system technologies.
Oxygen's user technologies directly address human needs. Speech and vision technologies enable us to communicate with Oxygen as if we're interacting with another person, saving much time and effort. Automation, individualized knowledge access, and collaboration technologies help us perform a wide variety of tasks that we want to do in the ways we like to do them.
Oxygen's system technologies dramatically extend our range by delivering user technologies to us at home, at work, or on the go. Computational devices, called Enviro21s (E21s), embedded in our homes, offices, and cars sense and affect our immediate environment. Hand-held devices, called Handy21s (H21s), empower us to communicate and compute no matter where we are. Dynamic networks (N21s) help our machines locate each other as well as the people, services, and resources we want to reach.
Oxygen's user technologies include:
The Oxygen technologies work together and pay attention to several important themes:
" Distribution and mobility - for people, resources, and services.
" Semantic content - what we mean, not just what we say.
" Adaptation and change - essential features of an increasingly dynamic world.
" Information personalities - the privacy, security, and form of our individual interactions with Oxygen.
Oxygen is an integrated software system that will reside in the public domain. Its development is sponsored by DARPA and the Oxygen Alliance industrial partners, who share its goal of pervasive, human-centered computing. Realizing that goal will require a great deal of creativity and innovation, which will come from researchers, students, and others who use Oxygen technologies for their daily work during the course of the project. The lessons they derive from this experience will enable Oxygen to better serve human needs.
Polymers are organic materials consisting of long chains of single molecules. Polymers are highly adaptable materials, suitable for myriad applications. Until the 1970s and the work of Nobel laureates Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa, polymers were only considered to be insulators. Heeger et al showed that polymers could be conductive. Electrons were removed, or introduced, into a polymer consisting of alternately single and double bonds between the carbon atoms. As these holes or extra electrons are able to move along the molecule, the structure becomes electrically conductive.
Thin Film Electronics has developed a specific group of polymers that are bistable and thus can be used as the active material in a non-volatile memory. In other words, the Thin Film polymers can be switched from one state to the other and maintain that state even when the electrical field is turned off. This polymer is "smart", to the extent that functionality is built into the material itself, like switchability, addressability and charge store.
This is different from silicon and other electronic materials, where such functions typically are only achieved by complex circuitry. "Smart" materials can be produced from scratch, molecule by molecule, allowing them to be built according to design. This opens up tremendous opportunities in the electronics world, where "tailor-made" memory materials represent unknown territory Polymers are essentially electronic materials that can be processed as liquids. With Thin Film's memory technology, polymer solutions can be deposited on flexible substrates with industry standard processes like spin coating in ultra thin layers.
Digital memory is an essential component of many electronic devices, and memory that takes up little space and electricity is in high demand as electronic devices continue to shrink Researchers from the Indian Association for the Cultivation of Science and the Italian National used positive and negative electric charges, or space charges, contained within plastic to store binary numbers Research Council. A polymer retains space charges near a metal interface when there is a bias, or electrical current, running across the surface.
These charges come either from electrons, which are negatively charged, or the positively-charged holes vacated by electrons. We can store space charges in a polymer layer, and conveniently check the presence of the space charges to know the state of the polymer layer. Space charges are essentially differences in electrical charge in a given region. They can be read using an electrical pulse because they change the way the devices conduct electricity