THE MEASUREMENT OF VOLTAGE SIGNAL PHASE USING LOCK-IN AMPLIFIER BASED ON LABVIEW

• Main Author: PUJI ASTUTI (NIM: 90214010), RINI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/24009
• Institution: Institut Teknologi Bandung

Lock-In Amplifier (LIA) is an instrument used to measure small signals buried in noise. The working principle LIA is applying a technique called phase-sensitive detection (PSD) which is a technique to reduce interference by way match the frequency and phase of the signal interference with the frequency and phase of the signal reference is modulated by the input signal, so the disorder that has no value frequency and the same phase with the frequency and phase of a reference signal will be filtered to produce a value of the measured input signal amplitude. Therefore, in the LIA are part of a phase shifter to change the phase of a reference signal that is adjusted to the phase of the input signal. Generally LIA also consists of two types: analog and digital. Related to the phase shifter, analog LIA relatively more difficult to operate when compared to digital LIA. Because LIA analog phase shifter is not equipped with automatic (auto phase) as well as on digital LIA so when taking measurements there are several buttons on the LIA operated to equalize the phase reference signal with the phase of the input signal. From simple issues then made program that can be used to help shift the phase automatically (scan phase) at LIA analog. With this program is expected to help facilitate the process of measurement using the instrument SR510 LIA. The trial program conducted on the experimental measurement of absorption (absorption) with a light transmission method and analyzed using Lambert-Beer law. The sample used in the form of printer ink in yellow, blue, and red were dissolved in distilled water. The experimental results are plotted in graphical form a relationship with the voltage phase difference, absorbance relationship with transmittance, absorbance relationship with concentration. To graph the relationship transmittance by absorbance get exponential regression values are: yellow (0.9648), blue (0.9214), and red (0.9965). To graph the solution concentration by absorbance values obtained linear regression are: yellow (0.9214), blue (0.9191), red (0.0022).