Measurement Automation Library for HP4395A Spectrum Analyser Written in Python Programming Language

Avtomatizacija meritvenih postopkov in digitalizacija merjenih podatkov pospeši proces opravljanja meritev in obdelavo podatkov. Brez komunikacije med instrumentom in osebnim računalnikom je meritve potrebno odčitati iz grafikona na instrumentu, kar pripelje do možnih napak. Z digitalizacijo prejetih podatkov, se napakam odčitavanja izognemo saj so prejeti podatki natanko enaki kot jih je instrument izmeril. Poleg tega je človek počasen pri zbiranju meritev v primerjavi z računalnikom. V diplomski nalogi, je opisan postopek izdelave komunikacije med instrumentom HP4395A in osebnim računalnikom. Spektralni analizator se z osebnim računalnikom pogovarja preko komunikacije GPIB (ang: General Purpose Interface Bus). Za pretvorbo iz vrat USB (ang: Universal Serial Bus) na GPIB skrbi vmesnik GPIB, ki je bil razvit na Fakulteti za elektrotehniko Univerze v Ljubljani. Med osebnim računalnikom in vmesnikom poteka komunikacija preko USB vodila, ki je konfiguriran kot navidezni serijski vmesnik (ang: VCP – Virtual Com Port) Logika komunikacije in uporabniški vmesnik, sta napisana v programskem jeziku Python. Kljub temu, da je Python počasnejši jezik je izvajanje programa dovolj hitro, saj je spektralna analiza signala relativno počasna meritev. Knjižnico sestavljajo trije podprogrami, ki omogočajo upravljanje z inštrumentom. Prvi del vzpostavi serijsko komunikacijo med osebnim računalnikom in instrumentom. Drugi del omogoči GPIB vodilo. Zadnji podprogram pa vsebuje funkcije za nadzor in kontrolo instrumenta HP4395A. V dodatku diplomskega dela je priložen primer uporabe knjižnic za izgradnjo uporabniškega vmesnika. Vmesnik omogoča kontrolo instrumenta in prikazuje merjene podatke v grafični obliki.Measurement procedure automation and data digitization speeds up measurement performance and data processing. The lack of communication between an instrument and a personal computer requires a person to read the data from the chart of the instrument, which can lead to errors. In addition, people collect data more slowly compared to computers. In this diploma thesis, the process of building communication between HP4395A instrument and personal computer is described. The spectrum analyzer communicates with a computer via GPIB (General Purpose Interface Bus) communication. The conversion from USB (Universal Serial Bus) to GPIB is handled by GPIB interface developed at the Faculty of Electrical Engineering. Communication between the personal computer and the interface takes place via a USB bus, which is configured as a virtual serial interface (VCP - Virtual Com Port). The communication logic and user interface are written in the programming language Python. Despite the fact that Python is a slower language, program execution is fast enough, as spectral circuit analysis is a relatively slow measurement. The library consists of three subprograms that enable the management of the instrument. The first part establishes serial communication between personal computers and instruments. The second part allows GPIB communication. The last subroutine contains the control and monitoring functions of the HP4395A instrument. The appendix of diploma thesis encloses an example of the use of libraries to build a user interface. The interface allows control of the instrument and displays the measured data in graphical form