Adrian Ioan Lita

Remote communication interface for sound and vibration sensors

In this paper are presented the results regarding the implementation of a communication interface dedicated for conditioning and remote transmission of measurement signals acquired from sound and vibration sensors. The interface contains two parts, an analog section, responsible with long distance signal transmission and a digital section that realize demodulation and analog-to-digital conversion of the received signal. The analog part of the interface uses the frequency modulation technique that is well known for its ability to operate in environments characterized by high levels of electrical perturbations, even when are realized high speed data transmissions. The acquisition of signals from sensors is realized with a resolution of 16 bits with a maximum speed of 200kS/s. In order to ensure the compatibility with various communication media and different types of sensors, the proposed circuit has adjustable carrier frequency in the range [0,01 - 0,5] MHz and offers also the possibility to select the carrier signal waveforms: square or sinusoidal wave. In addition, for increased versatility, the communication interface combines two alternative configurations, one based on phase-locked-loop (PLL) structure and the second based on quadrature oscillator with analogue multipliers. Both configurations were thoroughly tested for evaluating the performances of the proposed design. In comparison with other structures, the remote communication interface proposed in this work revealed good stability, accuracy and reliability. Also, the robustness and simplicity of the interface due to the use of frequency modulation technique represent other significant advantages.

Real time system for instrumental sound extraction and recognition

This article presents a “smart sound sensor” solution. More specifically it is a system on a chip capable of extracting sound patterns from an input signal captured by a microphone, patterns that correspond to certain musical instruments. The aim is to identify sounds like: voices, ambient sounds or musical sounds. Such applications generally involve the presence of a computer that analyzes offline the audio sequence. There are also smartphone security applications that rely on voice recognition templates that were previously stored and which work by processing the input sequence offline, after recording. Unlike these methods, our solution enables online real time identification of a group of musical instruments and allows extracting of certain sound sequences that belong to a particular instrument so that it can be isolated for sole playing. The solution was implemented in an integrated system “sound sensor” that analyzes the input signal in real time and can give output data without additional elements.

Microcontroller based thermal enclosure for electronic boards testing

In this paper is presented a new approach for implementing a versatile temperature control and monitoring system for thermal enclosures based on Peltier thermoelectric elements. The system is intended to be used for temperature testing of equipped or unequipped electronic printed circuit boards (PCB). These types of tests regarding thermal aging and endurance are very important for verifying the long term reliability of the PCBs because they must be designed for different categories of applications which impose certain operational time periods in various thermal conditions. The control module of the thermal enclosure described in this paper is realized with PIC16F877 microcontroller that communicates through serial interface with a dedicated software application running on PC. The functional parameters of the system can be monitored either on a local LCD or on PCs display. The testing procedures can be configured only from the software application. The power of the heating and cooling elements is around 36Wallowing an effective temperature control in the range [−15-100] °C. Compared with classical implementations, the design using Peltier elements has the important advantage of been capable to operate within a wide range of temperatures, including negative values, which allows more accurate tests and a realistic characterization of the electronic boards.

Conditioning and transmission module for resistive bridge sensors

This paper presents an enhanced conditioning and transmission unit aimed for interfacing resistive bridge sensors with remote data acquisition and control systems. The proposed module uses a simple but reliable communication technique based on a combination between frequency and pulse width modulations. This design, based on two transmission methods, ensures the multiplexing on a single carrier of the information regarding the temperature and the unbalance of a resistive bridge sensor. The circuit is practically implemented around a relaxation oscillator architecture, having a central frequency of operation of 8kHz. The polarization of the sensor is realized with a pair of constant current sources for alleviating the influences introduced by the parasitic resistance of the connection wires but also for reducing the influences of the electrical noise. The immunity against perturbations is also inherently increased by the robust transmission method which allows easy and accurate recovering of the measured signals using a proper receiver structure. Compared with existing solutions, the proposed circuit has an improved architecture which makes it compatible with the implementation in integrated circuits technology for improved linearity, stability and compactness.

Virtual instrumentation based acquisition and synthesis module for communication signals

This paper presents a versatile implementation of a reconfigurable module for acquisition and synthesis of modulated signals that are specific to the modern communication equipments. The hardware structure of the system is elaborated mainly around the TDA 8702 high speed video digital-to-analog converter and ADC 0820 analog-to-digital converter, both connected in a configuration that is controlled by a dedicated virtual instrumentation application realized in LabVIEW. The external module of the system is connected to a PC through the parallel port. The designed structure can operate with a wide range of modulation techniques including double-sideband with suppressed or conserved carrier, frequency and phase modulations. In addition, the proposed module offers the possibility to acquire and study complex waveforms that are specific to various communications systems and also to test different circuits and configurations using the synthesized signals as input stimuli. Besides the intrinsic advantages resulting from the usage of virtual instrumentation based on LabVIEW graphical programming, the conversion hardware of the proposed module is relatively simple and can be implemented with low costs.

Remote measurements in educational laboratories using LabVIEW and DAQ cards

This paper presents an application used in educational laboratory for multiple waveform measurement and display, for analysing of the operation of electronically circuits. It was implemented as virtual instrument in LabVIEW and uses a data acquisition card for electrical signals acquisition. The application can be used in educational laboratory for multiple signals measurement, record and time correlated displaying to help students to better understand the operation of the complex electronic circuits. Using the facilities offered by LabVIEW, this application was implemented to be accessed remotely for online measurement.

Simulation of signals in digital television using LabVIEW

This paper presents an application for generating of all the signals in case of digital televisions corresponding to standard colour bar patterns, from primary RGB signals to YCbCr colour space digital signals. It was implemented in LabVIEW and can represents D1 and D2 format for DTV signals on 8 and 10 bits resolution. The application can be used for DTV signals teaching and analysing in case of different image patterns.

GSM based remote control for distributed systems

In this paper are presented the results regarding the implementation and testing of a novel type of remote control based on the data transmission facilities offered by the GSM network infrastructure and the processing power achieved by new generation of microcontrollers. The system is intended to be used in the development of complex distributed control applications that are specific to various automated industrial processes, including the manufacturing of printed circuit boards and electronic modules. The proposed control system was designed using a prototype board equipped with Atmega 328 microcontroller. For implementation of data communication between the remote modules that compose the distributed control system a Quectel M10 quad-band GSM/GPRS radio modem was used. The quality of the proposed design was evaluated through extended performances analysis focused on the delay time, maximum transfer rate, failure tolerance and reliability. The system allows versatile configuration of commands structure and can operate with an extended set of commands for the remote modules. Also, compared with other implementation solutions the proposed design can be used almost in any location due to the large availability of the GSM infrastructure.

Reconfigurable signal generator and simulator for testing the digital transmission circuits

In this article is presented the implementation of a new type of reconfigurable signal generator and simulator used for testing digital transmission circuits that requires complex modulated waveforms. In our experiments we choose as an example the quadrature amplitude modulation or quadrature phase shift keying (QAM/QPSK) signals. The proposed solution is based on a high-speed NI-USB-6251Mdata acquisition board connected to a computer running a LabVIEWapplication. The analog outputs of the board are used for applying the predefined test signals to the circuits that are under test. The response of the tested circuit is monitored using the inputs of the data acquisition board. The novelty of the proposed system is given by the association between a very flexible and user friendly graphical programming environment such as LabVIEW and a general purpose data acquisition board which lead to an attractive implementation solution for a virtual instrument capable to simulate, generate, and also test a multitude of circuits using various signals. Compared with the classical approaches, the system presented in this paper represents a versatile platform, with large spectrum of applications because, with proper configuration of the software application, can be generated a broad range of modulated signals, including arbitrary waveforms, the only limitation being the speed of the data acquisition/generation module.

LabVIEW application used for remote control of a mobile robot with xbee communication

This paper presents an application for remote control of a mobile robot with XBEE wireless communication. The control of the mobile robot is realized by a PC within a software interface or by using a user mobile remote control. The application is implemented in LabVIEW and can be used for robot control and robot movement tracking.