Design of Progressive Frequency Discrimination Experiment for Engineering Applications

To address the limitations of traditional frequency modulation (FM) demodulation experiments, an experimental case centered on a slope detection circuit was designed. This experiment is structured into two levels: fundamental and advanced exploratory tasks. Students first construct a prototype slope detection circuit in the foundational stage, then progressively optimize circuit performance in the advanced tasks, with a focus on enhancing the discrimination transconductance. Finally, a measurement system for key FM modulation parameters is implemented to simulate real-world engineering scenarios, utilizing an equal-precision measurement method to evaluate the system’s performance in small frequency deviation measurement range and accuracy. Results demonstrate that the optimized circuit achieves approximately 22.2 mVpp/kHz discrimination transconductance and 75 kHz linear discrimination range. When measuring 100 Hz micro-frequency deviations, the average relative error is about 2.53%. Teaching practice indicates that this experimental case deepens students’ understanding of demodulation circuit principles while cultivating their engineering mindset and applied innovation capabilities. It is suitable for electronics competition training and research-oriented experiments, demonstrating high pedagogical value for widespread adoption in university laboratory education.