Browsing by Author "Puranen, Mikko"

Now showing 1 - 6 of 6
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    Design and implementation of fiber-optic transmitter and receiver for radío frequency signal
    (2005) Puranen, Mikko; Kärhä, Petri; Sähkö- ja tietoliikennetekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Ikonen, Erkki
    Tässä työssä toteutettiin yleiskäyttöinen laitteisto radiotaajuisen signaalin siirtämiseksi valokuidussa. Laitteisto sisältää radiotaajuisella signaalilla moduloitavan laserdiodin, virtalähteen ja lämpötilasäätäjän laserille sekä optisen vastaanottimen. Optoelektroniset muunnokset aiheuttavat signaaliin 30 dB vaimennuksen, jonka kompensoimiseksi tehtiin RF-vahvistin. Virtalähteen suunnittelussa laserdiodin vikaantumisherkkyyteen kiinnitettiin huomiota lisäämällä mikrokontrolleri valvomaan käyttöjännitteitä ja virtaa. Virtalähteen syöttämän virran keskihajonnaksi mitattiin 0,007 %. Laserin tehoksi valittiin silmien kannalta turvallinen 1 mW. Lämpötilasäätäjä on PID-tyyppinen, ja sen komponentit sovitettiin käytetyn lasermodulin ominaisuuksiin. Säätäjää käytettäessä laserin lämpötilan keskihajonta on 0,1 mK. Vastaanottimena käytetään valodiodia, jonka korkein käyttötaajuus on 2 GHz. Vastaanottimen virtalähteenä käytetään paristoa. Vahvistimina käytetään kahta erillistä mikropiiriä. Ne ovat vähäkohinaisia ja vahvistavat signaalia yhteensä 37 dB. Toteutetun järjestelmän toiminta testattiin RF-mittauksin. Laitteiston sijoittaminen osaksi RF-signaalin siirtoreittiä ei aiheuta signaalin muuttumista eikä vaimentumista. Lähettimen ja vastaanottimen taajuusvaste on kiiytt6kelpoinen 2,5 GHz asti. Vahvistimet sovitettiin 1,7 -1,9 G Hz taajuuskaistalle. Tällä kaistalla koko järjestelmän taajuusvasteen vaihtelu on alle 4 dB.
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    Development of an intelligent safety gear system for high-rise elevators
    (2017-12-11) Bayat Mokhtari, Bijan; Puranen, Mikko; Insinööritieteiden korkeakoulu; Ekman, Kalevi
    Elevators have been a key element of buildings, especially tall buildings, since their widespread use began in the 19th century. As a matter of fact, high-rise buildings would not have existed without elevators. Elevators have a myriad of safety features and devices to ensure a safe journey for the passengers. One of these devices is the safety gear. Safety gears are emergency brakes that stop speeding elevators by gripping the guide rails. They are adjusted for a safe deceleration range by the technician during installation and exert a constant force. Due to their purely mechanical nature, once triggered, the safety gear is currently unable to actively adjust the braking force to counteract vibrations, to decelerate at different rates, or to stop the elevator at the closest landing. Therefore, the emergency braking event can be harsh and noticeable, leaving the passengers stuck in the elevator shaft after the braking event. This thesis aims to develop an intelligent safety gear system that is able to bring the elevator to a stop with a safe and adjustable deceleration rate. This was achieved by first, modeling a computer simulation of a small-scale elevator to be able to quickly simulate different braking event scenarios. Second, a small-scale elevator test rig was constructed to test the computer simulation with physical components. The test rig was validated by comparing its results with KONE’s high-rise safety gear test. The control system developed was able to safely stop the moving mass with the desired deceleration and a great deal of control over other parameters. Further development of the system could lead to a safer, more comfortable, and energy efficient elevator ride.
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    Measuring concepts and their uncertainties in pulsed radar experiments
    (2007) Puranen, Mikko; Kärhä, Petri; Sähkö- ja tietoliikennetekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Ikonen, Erkki
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    Pulsed radar measurements and related equipment
    (Teknillinen korkeakoulu, 2009) Puranen, Mikko; Signaalinkäsittelyn ja akustiikan laitos
    The purpose of this thesis has been to develop novel methods for pulsed radar measurements, creating practical tools for verifying the operation of a modern pulsed radar, and to build working prototypes suitable for field use. Very little information has been published in the radar field perhaps due to the military nature of many research projects. Methods and equipment are typically researched by different armed forces. In this thesis, some tools for frequency, power and waveform measurements are presented. Even the most modern commercial measuring instruments, however, are not capable of measuring a pulsed radar signal, mostly due to the short (even tens of nanoseconds) pulse length. The limitations of conventional measuring devices are discussed in the overview part of the thesis and also in Publications II and IV. The first publication demonstrates a radar calibration system, based on a fiber-optic delay line. The idea to use an optical delay line for such a purpose is not new, but an operational setup has not been published previously. The calibrator provides a convenient method to use the radar's own signal for calibration. The optical link makes it possible to use long delays, even tens of microseconds, without significant signal attenuation. Furthermore, two frequency measurement methods for short-term stability evaluation are presented. Both are based on a phase detector. The first setup has better frequency uncertainty, even 1.6 Hz, with a sampling speed of 10 000 s-1. The other setup is used to detect frequency differences: A deviation of 200 kHz in the carrier frequency could be detected when the pulse length was 200 ns. This system outperforms the first one when short pulses are evaluated. The phase detector based setup itself is old and familiar technology, but the idea to use it in this application is one thing new. Finally, two new instrumentation radars are also presented. They are used to measure the effects that terrain, weather, vegetation and seasonal changes have on radar clutter or signal propagation. A significant effort has been made by other scientists in developing mathematical models to be able to simulate the effects mentioned, but so far the only reliable method for creating clutter models is to collect data with a real radar. Such instrumentation radars have probably been developed earlier, but until now they have not been published.
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    Radar applications in elevator speed and location measurement
    (2016-08-24) Peltola, Mikko; Puranen, Mikko; Sähkötekniikan korkeakoulu; Eskelinen, Pekka
    Elevator speed and location measurement is traditionally implemented with motor and elevator car encoders. In this thesis, it is studied by radar. The thesis introduces the operating principles of different radars, their advantages and disadvantages. Frequency modulated continuous wave (FMCW) radars are chosen for practical tests based on these findings. The purpose of this thesis was to evaluate the feasibility of employing radar for measuring elevator speed and location, and propose radar as the replacement of the speed and location measuring tool in the present safety system. This was studied with 24 GHz, 60 GHz and 77 GHz radars. In elevator shafts, the measurements were carried out both towards the bottom of an elevator car and a ceiling of a shaft. The measurement results of 77 GHz radar were within the range resolution theory in all stationary cases when measured towards the ceiling. Signal attenuation degraded 60 GHz radar results at long distances. Though the results were also within the range resolution theory below 50 m distances. 24 GHz radar faced operational problems and thus accurate results were not obtained. The ceiling of the shaft was discovered a better reflector of radar signals than the bottom of the elevator car. The elevator shaft was found out to be a suitable environment for radar measurements. Radar is a possible technology for measuring elevator speed and location, but radars tested in this thesis need further development for fulfilling the measurement criteria set by the desired application.
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    Tuotantoprosesseissa ja kustannusten laskennassa tapahtuneiden muutosten vaikutus tuotekustannuksiin. Case Finnair Catering Oy.
    (2007) Puranen, Mikko; Laskentatoimen ja rahoituksen laitos; Department of Accounting and Finance; Kauppakorkeakoulu; School of Business