Zasnova in izvedba RLC metra z zvočno kartico kot sistemom za zajemanje signalov

KRIŽMAN, MARTIN (author), Beguš, Samo (mentor)

Diplomska naloga je obsegala izdelavo RLC merilnika z zvočno kartico kot sistemom za zajemanje signalov. Hkrati smo z zvočno kartico tudi generirali testni signal in z njim napajali merilno vezje. Vezje vsebuje napetostni delilnik, ki je sestavljen iz referenčnega upora znane upornosti in merjenega elementa neznane impedance, napetostna signala na obeh elementih pa potem zajemamo preko dvojnega linijskega vhoda na zvočni kartici. Z uporabo metode lock-in ojačevalnik smo določili amplitudo in fazo posameznega signala. S temi podatki smo kasneje lahko izračunali parametre merjenega elementa (upornost, kapacitivnost, induktivnost). Z uporabo dodatnih referenčnih uporov smo razširili merilno območje RLC metra, preklapljanje med območji pa smo izvedli z reed releji in pomikalnim registrom, katerega smo krmilili z računalnikom preko RS232/USB pretvorniškega vmesnika. Diplomsko delo smo razdelili na tri dele. V prvem delu smo najprej definirali impedanco, nato pa obravnavali osnovne pasivne elektronske elemente in njihove lastnosti. Opisali smo tudi nekaj splošno znanih principov merjenja impedance. V drugem delu smo se posvetili zasnovi in izdelavi programskega in strojnega dela RLC merilnika. Programski del smo napisali v okolju Labview, ki omogoča enostavno obdelavo signalov v realnem času. Merilno vezje pa smo realizirali na univerzalni ploščici in ga vstavili v aluminijasto ohišje. V tretjem delu smo najprej izračunali znane prispevke negotovosti in zapisali merilni rezultat za vsak merjen element. Na koncu smo meritve posameznih veličin primerjali z laboratorijskim Agilent 4263B.

• Language: Slovenian
• Keywords: RLC meter, zvočna kartica, lock-in ojačevalnik, merjenje upornosti, merjenje kapacitivnosti, merjenje induktivnosti
• Work type: Undergraduate thesis
• Organization: FE - Faculty of Electrical Engineering
• Year: 2016
• PID: 20.500.12556/RUL-85129
• Publication date in RUL: 13.09.2016

Secondary language

• Language: English
• Title: Design and implementation of the RLC meter with a sound card as a signal acquisition unit

Abstract

Thesis work consists of design of a RLC measuring device with a sound card, which was used as a signal acquisition unit and also for a test signal generation sent to a test element. RLC measuring device consists of voltage divider, comprised of a reference resistor of known value and a measured element of unknown impedance. Signals on both elements are measured using two channel sound card line input. Using lock-in amplifier method, amplitude and phase of each signal have been measured. Using this data parameters of a measured element, such as resistance, capacitance and inductance, can be calculated. Using additional reference resistors, RLC measurement range was expanded. Switching between multiple measuring ranges was implemented using reed relays and a shift register, controlled via RS232/USB interface. First part of this work defines impedance and presents basic passive electronic elements and their properties. This section also covers different methods of impedance measurement. Second part presents design and creation of hardware and software parts of RLC measuring device. Labview environment has been used for software development, enabling easy real time signal processing. Measuring device has been constructed on a development board and packaged into an aluminium case. In the last part of this work we have calculated known contributions to the uncertainty of measurement and calculated final measurement result for each measured element. At the end we have compared results with Agilent 4263B.

• Keywords: RLC meter, sound card, lock-in amplifier, measurement of resistance, measurement of capacitance, measurement of inductance