Frequency-Modulated Signal Measurement Using Closed-Loop Methodology

Area of Science:

• Electrical Engineering
• Signal Processing
• Measurement Science

Background:

• Frequency-modulated (FM) signals are crucial for sensing and signal detection.
• Existing high-precision measurement methods for dynamic FM signals and high-sampling systems require improvement.
• Traditional equal-precision methods are limited by quantization error and sampling gate time.

Purpose of the Study:

• To propose a high-precision feedback frequency measurement system for dynamic FM signals.
• To overcome the limitations of traditional methods, specifically ±1 word quantization error.
• To enhance measurement accuracy in high-sampling rate systems.

Main Methods:

• A two-stage system combining a rough measurement stage and a precise measurement stage.
• Utilizing an equal-precision measurement method for initial frequency estimation.
• Employing a negative feedback loop with a phase-frequency detector (PFD) and direct digital synthesizer (DDS) for precise tracking.

Main Results:

• The proposed system effectively eliminates ±1 word quantization error.
• Demonstrated significant improvement in frequency measurement accuracy.
• Achieved over 30 dB accuracy improvement at a 2 kHz sampling rate.

Conclusions:

• The developed feedback system offers enhanced precision for dynamic FM signal measurement.
• The system's effectiveness is validated through both simulations and experimental results.
• This advancement addresses the need for improved accuracy in high-sampling rate measurement systems.