Simple synchronic detection at audio frequencies through a PC sound card

Area of Science:

• Electronics
• Signal Processing
• Instrumentation

Background:

• Lock-in amplifiers are crucial for detecting weak signals in noisy environments.
• Traditional lock-in amplifiers can be expensive and complex.
• There is a need for accessible and affordable signal detection methods.

Purpose of the Study:

• To develop a low-cost, personal computer-based system emulating a lock-in amplifier.
• To enable precise signal measurements at audio frequencies.
• To provide an alternative to commercial benchtop lock-in amplifiers.

Main Methods:

• Utilizing a personal computer's sound card for data acquisition.
• Implementing a synchronic detection system with dual-phase detection.
• Deriving quasiorthogonal signals from a reference input.

Main Results:

• The system successfully emulates a lock-in amplifier at audio frequencies.
• Achieved average amplitude errors below 1% and phase errors below 0.1 degrees from 100 Hz to 20 kHz.
• Demonstrated performance comparable to benchtop lock-in amplifiers.

Conclusions:

• A simple, PC-based synchronic detection system offers a viable and accurate alternative for audio frequency measurements.
• This approach democratizes access to precise signal detection techniques.
• The developed system provides a cost-effective solution for research and educational purposes.