Eugen COCA | Stefan cel Mare University of Suceava (original) (raw)
Papers by Eugen COCA
Advances in Electrical and Computer Engineering
Localization or position determination is one of the most common applications for the wireless se... more Localization or position determination is one of the most common applications for the wireless sensor networks. Many investigations have been made during the last decade, most of the effort being concentrated in the direction of improving the accuracy of the positioning results by using complex filtering and correction algorithms, and other techniques such as radio maps or directive antennas for the reference nodes. The most common sources of errors include reflections on nearby objects, radio frequency noise, and variable characteristics of the communication channel. In the vast majority of cases, several assumptions have been made in order to simplify the computing algorithms or the complexity of nodes, and finally their cost. The omnidirectional radiation pattern of the node antennas is such an assumption. In this paper we investigate theoretically and validate by measurements the influence of the radiation pattern on the localization accuracy of a wireless sensor node network. B...
Advances in Electrical and Computer Engineering
Time synchronization in wireless sensor node networks is a hot topic. Many papers present various... more Time synchronization in wireless sensor node networks is a hot topic. Many papers present various software algorithms and hardware solutions to keep accurate time information on mobile nodes. In terms of real life applications wireless sensor nodes are preferred in many domains, starting with simple room monitoring and finishing with pipeline surveillance projects. Positioning applications are far more restrictive on timekeeping accuracy, as for the velocity of nodes calculations precise time or time difference values are needed. The accuracy of time information on nodes has to be always correlated with the application requirements. In this paper, we present some considerations regarding time synchronization linked with specific needs for individual practical applications. A practical low energy method of time keeping at node level is proposed and tested. The performances of the proposed solution in terms of short and long term stability and energy requirements are analyzed and comp...
Rezumat: Deschiderea pieţei de energie a forţat firmele furnizoare de utilităţi să exploreze şi a... more Rezumat: Deschiderea pieţei de energie a forţat firmele furnizoare de utilităţi să exploreze şi ale pieţe în căutarea unor noi oportunităţi de afaceri, fapt ce a marcat în ultimii zece ani evoluţia cercetărilor privind comunicaţiile pe liniile de alimentare cu energie electrică (PLC). Cercetările au fost orientate în primă fază pe oferirea de servicii legate direct de distribuţia de energie
This article presents an analysis of static AC/DC power converter under unbalanced input conditio... more This article presents an analysis of static AC/DC power converter under unbalanced input conditions. In balanced operation mode, the output voltage contains only the sixth and higher order multiple harmonics. Under unbalanced input conditions, we can calculate the amplitude of many other harmonics present in the output voltage. Some measurements where made under a typical three phase static converter supplying
This article presents an energy meter reading interface application. Energy pulses for every quar... more This article presents an energy meter reading interface application. Energy pulses for every quarter of an hour are counted on a microcontroller and stored on a non-volatile medium, all required data being transmitted to the energy dispatcher control unit via an Internet communication embedded controller. We use a combination of very low cost microcontrollers to interface the existing meters and
This article presents an utility meter reading interface application using the Internet as a tran... more This article presents an utility meter reading interface application using the Internet as a transmission medium. For energy meters, pulses for every quarter of an hour are counted on a local microcontroller and stored on a EEPROM memory, all demand data being transmitted to the energy dispatcher control unit via the Internet communication embedded microcontroller. We used a combination of
Advances in Electrical and Computer Engineering, 2010
ABSTRACT Wireless Sensor Networks (WSN) are challenging and efficient in a large field of applica... more ABSTRACT Wireless Sensor Networks (WSN) are challenging and efficient in a large field of applications like object location or distance determination between sensor nodes. In this paper are presented some considerations concerning the method of distance estimation between WSN nodes using the RF power level received by one sensor node. The experimental determinations were made using a WSN system composed of ten wireless modules (one coordinator module and nine WSN nodes). The RF power level received by a sensor node was measured at variable distances, and the dBm values recorded were then used in the distance determination formula. The tests were made in a 3 meters semi-anechoic chamber - in order the results not to be affected by other radio frequency emissions from the surrounding environment - using a 20 Hz-26.5 GHz EMI Test Receiver, a log-periodic antenna and RF cables.
A three-phase low-harmonic rectifier configuration is presented. For a large current variation lo... more A three-phase low-harmonic rectifier configuration is presented. For a large current variation load, the circuit designed to improve the waveform of the current drawn from the utility grid. Analytically obtained results are experimentally verified.
2009 15th International Symposium for Design and Technology of Electronics Packages (SIITME), 2009
We present some performance evaluations of two Power Line Ethernet adapter types and several radi... more We present some performance evaluations of two Power Line Ethernet adapter types and several radiated and conducted emissions measurements. The Power Line Communication provides multiple benefits, but there are some disadvantages of connecting through power line network: high noise and voltage disturbances, signal distortion and variance of impedance with time, interferences. The limits for radiated emissions and conducted disturbances at
2012 IEEE 18th International Symposium for Design and Technology in Electronic Packaging (SIITME), 2012
ABSTRACT Object location and movement speed are of interest in real applications, efforts being m... more ABSTRACT Object location and movement speed are of interest in real applications, efforts being made during the last years in the direction of improving the precision of such systems. In this paper we investigate the performances of a location system made of wireless sensor nodes build around the Chipcon CC2431 System on Chip wireless sensor nodes, compare the results obtained with similar systems in almost the same conditions, and investigate the possibility of using the location and time information to determine the movement speed of mobile nodes. Measurement results obtained in an indoor environment are presented. Some remarks regarding the theoretical and practical speed measurement precision are included at the end of the paper.
2012 IEEE 18th International Symposium for Design and Technology in Electronic Packaging (SIITME), 2012
ABSTRACT Location and speed measurement services for industrial applications are still of great i... more ABSTRACT Location and speed measurement services for industrial applications are still of great interest. Filtering algorithms are often used in order to minimize the positioning errors, but they are high energy consuming and difficult to implement in local node low power processors. We propose a filtering algorithm to be implemented in the central control node, based on the real maximum speed a wireless mobile node may have. The operating principle is quite simple as we calculate the speed between two consecutive node positions and eliminate those having values greater than a predefined maximum possible speed. The method is very fast, effective and easy to implement in real applications and with very good results when comparing with similar solutions. The theoretical results demonstrate the method could be a good alternative to existing solutions. Practical measurements setup, results and some conclusions are presented at the end of the paper.
2009 15th International Symposium for Design and Technology of Electronics Packages (SIITME), 2009
Wireless sensors are widely used in applications where small amount of data need to be transmitte... more Wireless sensors are widely used in applications where small amount of data need to be transmitted over distances not exceeding several tens of meters, with low energy requirements. From the definition, the RSSI is the relative received signal strength in a wireless environment. There is a direct link between the RF power level received by one node and the RSSI
To control some phone services at the subscriber end, especially the money consumer ones, is a pe... more To control some phone services at the subscriber end, especially the money consumer ones, is a permanent challenge. The principles described in the article offer some solutions to deny or to selective lock some types of phone calls. The basic idea is to count the number of dialed digits or to detect first (or second) dialed digit. Digital frequency and
RFID location systems for indoor and outdoor positioning are a promise for the future, even the p... more RFID location systems for indoor and outdoor positioning are a promise for the future, even the performances of these systems are affected by many factors. We identified here that for a system working in the RF band near 900 MHz, the objects interposed between the antenna system and the tags to be located may have a great influence in terms of accuracy of the measurement results. In closed areas multiple reflection paths may disturb the measurement systems, a percent of only 40 to 60 of total measurements are enough accurate to locate an object. In such conditions, there are small chances for this kind of systems to be used for high precision indoor applications requiring more than several tens of centimetres accuracy. The results obtained from the measurements we made in open area test sites are more promising, more than 93 percent of total result were not affected by notable errors. For speed measurement of mobile objects by using RFID systems, we may conclude there are many aspec...
RFID Eurasia, 2007 1st Annual, Jan 1, 2007
Journal of Applied Physics, Jan 1, 2009
Relation between noise and hysteresis has been recently under intensive research focus due to the... more Relation between noise and hysteresis has been recently under intensive research focus due to the fundamental challenges posed by noise and fluctuations in ultrasmall semiconductor and magnetic devices. However, a systematic analysis of hysteretic materials and devices driven by noisy input has been rather limited. On the one hand, this situation is related to lack of general analytical tools for
Advances in Electrical and Computer Engineering
Localization or position determination is one of the most common applications for the wireless se... more Localization or position determination is one of the most common applications for the wireless sensor networks. Many investigations have been made during the last decade, most of the effort being concentrated in the direction of improving the accuracy of the positioning results by using complex filtering and correction algorithms, and other techniques such as radio maps or directive antennas for the reference nodes. The most common sources of errors include reflections on nearby objects, radio frequency noise, and variable characteristics of the communication channel. In the vast majority of cases, several assumptions have been made in order to simplify the computing algorithms or the complexity of nodes, and finally their cost. The omnidirectional radiation pattern of the node antennas is such an assumption. In this paper we investigate theoretically and validate by measurements the influence of the radiation pattern on the localization accuracy of a wireless sensor node network. B...
Advances in Electrical and Computer Engineering
Time synchronization in wireless sensor node networks is a hot topic. Many papers present various... more Time synchronization in wireless sensor node networks is a hot topic. Many papers present various software algorithms and hardware solutions to keep accurate time information on mobile nodes. In terms of real life applications wireless sensor nodes are preferred in many domains, starting with simple room monitoring and finishing with pipeline surveillance projects. Positioning applications are far more restrictive on timekeeping accuracy, as for the velocity of nodes calculations precise time or time difference values are needed. The accuracy of time information on nodes has to be always correlated with the application requirements. In this paper, we present some considerations regarding time synchronization linked with specific needs for individual practical applications. A practical low energy method of time keeping at node level is proposed and tested. The performances of the proposed solution in terms of short and long term stability and energy requirements are analyzed and comp...
Rezumat: Deschiderea pieţei de energie a forţat firmele furnizoare de utilităţi să exploreze şi a... more Rezumat: Deschiderea pieţei de energie a forţat firmele furnizoare de utilităţi să exploreze şi ale pieţe în căutarea unor noi oportunităţi de afaceri, fapt ce a marcat în ultimii zece ani evoluţia cercetărilor privind comunicaţiile pe liniile de alimentare cu energie electrică (PLC). Cercetările au fost orientate în primă fază pe oferirea de servicii legate direct de distribuţia de energie
This article presents an analysis of static AC/DC power converter under unbalanced input conditio... more This article presents an analysis of static AC/DC power converter under unbalanced input conditions. In balanced operation mode, the output voltage contains only the sixth and higher order multiple harmonics. Under unbalanced input conditions, we can calculate the amplitude of many other harmonics present in the output voltage. Some measurements where made under a typical three phase static converter supplying
This article presents an energy meter reading interface application. Energy pulses for every quar... more This article presents an energy meter reading interface application. Energy pulses for every quarter of an hour are counted on a microcontroller and stored on a non-volatile medium, all required data being transmitted to the energy dispatcher control unit via an Internet communication embedded controller. We use a combination of very low cost microcontrollers to interface the existing meters and
This article presents an utility meter reading interface application using the Internet as a tran... more This article presents an utility meter reading interface application using the Internet as a transmission medium. For energy meters, pulses for every quarter of an hour are counted on a local microcontroller and stored on a EEPROM memory, all demand data being transmitted to the energy dispatcher control unit via the Internet communication embedded microcontroller. We used a combination of
Advances in Electrical and Computer Engineering, 2010
ABSTRACT Wireless Sensor Networks (WSN) are challenging and efficient in a large field of applica... more ABSTRACT Wireless Sensor Networks (WSN) are challenging and efficient in a large field of applications like object location or distance determination between sensor nodes. In this paper are presented some considerations concerning the method of distance estimation between WSN nodes using the RF power level received by one sensor node. The experimental determinations were made using a WSN system composed of ten wireless modules (one coordinator module and nine WSN nodes). The RF power level received by a sensor node was measured at variable distances, and the dBm values recorded were then used in the distance determination formula. The tests were made in a 3 meters semi-anechoic chamber - in order the results not to be affected by other radio frequency emissions from the surrounding environment - using a 20 Hz-26.5 GHz EMI Test Receiver, a log-periodic antenna and RF cables.
A three-phase low-harmonic rectifier configuration is presented. For a large current variation lo... more A three-phase low-harmonic rectifier configuration is presented. For a large current variation load, the circuit designed to improve the waveform of the current drawn from the utility grid. Analytically obtained results are experimentally verified.
2009 15th International Symposium for Design and Technology of Electronics Packages (SIITME), 2009
We present some performance evaluations of two Power Line Ethernet adapter types and several radi... more We present some performance evaluations of two Power Line Ethernet adapter types and several radiated and conducted emissions measurements. The Power Line Communication provides multiple benefits, but there are some disadvantages of connecting through power line network: high noise and voltage disturbances, signal distortion and variance of impedance with time, interferences. The limits for radiated emissions and conducted disturbances at
2012 IEEE 18th International Symposium for Design and Technology in Electronic Packaging (SIITME), 2012
ABSTRACT Object location and movement speed are of interest in real applications, efforts being m... more ABSTRACT Object location and movement speed are of interest in real applications, efforts being made during the last years in the direction of improving the precision of such systems. In this paper we investigate the performances of a location system made of wireless sensor nodes build around the Chipcon CC2431 System on Chip wireless sensor nodes, compare the results obtained with similar systems in almost the same conditions, and investigate the possibility of using the location and time information to determine the movement speed of mobile nodes. Measurement results obtained in an indoor environment are presented. Some remarks regarding the theoretical and practical speed measurement precision are included at the end of the paper.
2012 IEEE 18th International Symposium for Design and Technology in Electronic Packaging (SIITME), 2012
ABSTRACT Location and speed measurement services for industrial applications are still of great i... more ABSTRACT Location and speed measurement services for industrial applications are still of great interest. Filtering algorithms are often used in order to minimize the positioning errors, but they are high energy consuming and difficult to implement in local node low power processors. We propose a filtering algorithm to be implemented in the central control node, based on the real maximum speed a wireless mobile node may have. The operating principle is quite simple as we calculate the speed between two consecutive node positions and eliminate those having values greater than a predefined maximum possible speed. The method is very fast, effective and easy to implement in real applications and with very good results when comparing with similar solutions. The theoretical results demonstrate the method could be a good alternative to existing solutions. Practical measurements setup, results and some conclusions are presented at the end of the paper.
2009 15th International Symposium for Design and Technology of Electronics Packages (SIITME), 2009
Wireless sensors are widely used in applications where small amount of data need to be transmitte... more Wireless sensors are widely used in applications where small amount of data need to be transmitted over distances not exceeding several tens of meters, with low energy requirements. From the definition, the RSSI is the relative received signal strength in a wireless environment. There is a direct link between the RF power level received by one node and the RSSI
To control some phone services at the subscriber end, especially the money consumer ones, is a pe... more To control some phone services at the subscriber end, especially the money consumer ones, is a permanent challenge. The principles described in the article offer some solutions to deny or to selective lock some types of phone calls. The basic idea is to count the number of dialed digits or to detect first (or second) dialed digit. Digital frequency and
RFID location systems for indoor and outdoor positioning are a promise for the future, even the p... more RFID location systems for indoor and outdoor positioning are a promise for the future, even the performances of these systems are affected by many factors. We identified here that for a system working in the RF band near 900 MHz, the objects interposed between the antenna system and the tags to be located may have a great influence in terms of accuracy of the measurement results. In closed areas multiple reflection paths may disturb the measurement systems, a percent of only 40 to 60 of total measurements are enough accurate to locate an object. In such conditions, there are small chances for this kind of systems to be used for high precision indoor applications requiring more than several tens of centimetres accuracy. The results obtained from the measurements we made in open area test sites are more promising, more than 93 percent of total result were not affected by notable errors. For speed measurement of mobile objects by using RFID systems, we may conclude there are many aspec...
RFID Eurasia, 2007 1st Annual, Jan 1, 2007
Journal of Applied Physics, Jan 1, 2009
Relation between noise and hysteresis has been recently under intensive research focus due to the... more Relation between noise and hysteresis has been recently under intensive research focus due to the fundamental challenges posed by noise and fluctuations in ultrasmall semiconductor and magnetic devices. However, a systematic analysis of hysteretic materials and devices driven by noisy input has been rather limited. On the one hand, this situation is related to lack of general analytical tools for