OPTOELECTRONIC DEVICE FOR MEASURING THE POWER OF LASER RADIATION

A device for measuring the power of the laser radiation.has been designed. The device consists of transmitter and receiving part. The transmitter includes optical radiation source and optical system for collimation of radiation. The receiver part consists of silicon photodiodes, electronic signal processing unit and unit for measurements.

Development of a real-time signal processing unit for diamond detectors of ITER Vertical Neutron Camera

CVD Diamond Detectors are going to be used in a number of neutron diagnostics of the International Thermonuclear Experimental Reactor (ITER) during its power operation phase [1]. One of such diagnostics is the Vertical Neutron Camera (VNC), which is being developed by the ITER Russian Domestic Agency (Institution “Project Center ITER”). In VNC Diamond detectors are used for real-time neutron flux and neutron spectrum measurements. In this paper we present current advancements in the development of a digital signal processing unit for the VNC diamond detector measurement channel. We give an overview of the signal properties, hardware requirements and firmware/software solutions used in the current version of the signal processing unit. We also present preliminary test results for this measurement system and explain the discovered problems and possible solutions.

Optimal nonlinear fi ltering of stochastic processes in rescue radar

Subject and Purpose. Smoke, fog, avalanches, debris of collapsed structures and other optically opaque obstacles in both natural and man-made disasters make optical sensors useless for detecting victims. Electromagnetic waves of the decimeter range penetrate well almost all obstacles, reflect from the trapped people and return to the radar receiver. Due to the breathing and heartbeat, the human-reflected sounding signals get the Doppler phase modulation, which is an information signal. These information signals and their properties provide the subject matter for the present research with the aim to create optimal methods and algorithms of random event processing for the prompt location of survivors by rescuers. Method and Methodology. The method of stochastic analysis of the fluctuation Doppler spectra of reflected sounding signals shows that the information signals have properties of conditional Markov processes. Results. The problem of optimal nonlinear filtering of conditional Markov processes entering the radar signal processing unit has been examined closely. An optimal adaptive filter has been proposed to reduce the masking effect of interferences caused by non-stationary noises and sounding signal reflections from stationary objects. The optimality criterion is the minimum mean square error function whose current value is evaluated in real time during the filtering process as the statistics is accumulated. The filter coefficients are calculated by the recurrent, steepest descent algorithm. The real-time work is carried out through the use of fast Fourier transform algorithms. Conclusion. The structure of the optimal adaptive filter to be built into the radar signal processing unit has been developed. Real radar signals have shown that the optimal filtering during the signal processing in systems designed for detecting live people by their breathing and heartbeat facilitates the interpretation of the observed signals. Some spectra of real signals generated by human breathing and heartbeat are presented.

A Critical Step to Using a Parametric Array Loudspeaker in Mobile Devices

A parametric array (PA) loudspeaker is a highly directional audio source that might grant one's convenience if it is used with mobile devices. However, conventional PA loudspeakers is almost impossible to apply in mobile devices using a battery because of the large power consumption and large device size. In this study, a PA loudspeaker system (PALS) was fabricated and evaluated to show that those difficulties could be overcome to apply it to mobile devices. In order to construct a PALS for demonstration, a power amplifier and signal-processing unit should also be properly designed and built. The PA source transducer should also be designed and built for a mobile device application. These components were integrated into a single PALS. The PALS generated a 125-dB primary wave and 62 dB of a different frequency wave (DFW) through the PA at 0.45 m in a 3 m × 3 m × 2 m semi-anechoic chamber. We confirmed that the half-power bandwidth (HPBW) formed a 6° beam at 83 kHz of DFW and 90 kHz of the primary wave (PW), and the HPBW formed a 7.3° beam at 5 kHz of DFW and a 7.1° beam at 10 kHz of DFW, respectively. Lastly, the power required was 6.65 W without a matching circuit, and 3.25 W with such a circuit.