title: Simple synchronic detection at audio frequencies through a PC sound card.
abstract: We present a simple personal computer based, synchronic detection system that emulates a lock-in amplifier at audio frequencies. The inputs of the sound card are used to acquire two sets of samples: the one to be measured, previously preamplified, and the reference. From the last one, two "quasiorthogonal" signals are derived to perform dual-phase detection. The procedure is fast and compares favorably with a benchtop lock-in amplifier. In the band from 100 Hz to 20 kHz we obtained average amplitude and phase errors below 1% and 0.1 degrees, respectively.
authors.affiliation: Laboratorio Láser, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850, 1063 Buenos Aires, Argentina.
authors.forename: Martín G
authors.initials: MG
authors.lastname: González
authors.forename: Guillermo D
authors.initials: GD
authors.lastname: Santiago
authors.forename: Verónica B
authors.initials: VB
authors.lastname: Slezak
authors.forename: Alejandro L
authors.initials: AL
authors.lastname: Peuriot
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D016287:Computer Peripherals; D004581:Electronics / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008838:Microcomputers; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013018:Sound Spectrography / Q000295:instrumentation* / Q000379:methods