Real-time and high accuracy frequency measurements for intermediate frequency narrowband signals

Area of Science:

• Signal Processing
• Microprocessor Technology
• Computational Mathematics

Background:

• Real-time measurement of intermediate frequency (IF) signals is challenging due to computational demands and time limits.
• Existing methods like Discrete Fourier Transform (DFT) and Fast Fourier Transform (FFT) face limitations in speed and resource efficiency.

Purpose of the Study:

• To design and implement a fast and precise methodology for real-time IF signal measurement.
• To overcome the computational complexity and time constraints of conventional microprocessor-based signal analysis.

Main Methods:

• A novel recursive scheme is employed to generate twiddle factors, minimizing multiplications and additions.
• The methodology integrates the Discrete Fourier Transform (DFT) with the Rife algorithm and Fourier coefficient interpolation.
• A sigma-delta modulator forms the core of the implemented system for signal measurement.

Main Results:

• The proposed method achieves zero multiplications and approximately half the addition operations compared to conventional DFT/FFT.
• Experimental results demonstrate a measurement mean squared error of ±2.4 Hz for IF and narrowband signals at a 10 MHz sampling frequency.
• The entire measurement system completes a single measurement in approximately 0.3 seconds.

Conclusions:

• The developed methodology offers a significant improvement in speed and precision for real-time IF signal measurements.
• This approach effectively reduces computational load, making it suitable for microprocessor-based systems.
• The system achieves fast iteration, high precision, and reduced calculation time, addressing key challenges in signal processing.