A Dual-Channel STFT-Based Instantaneous Frequency Measurement Method

To address the abnormal estimation of conventional instantaneous frequency measurement based on short-time Fourier transform channelization and phase-difference estimation in overlap regions, where channel jitter and frequency aliasing jointly degrade performance, this paper proposes a dual-channel short-time Fourier transform-based instantaneous frequency measurement method. Two short-time Fourier transform branches with a half-hop temporal offset are constructed, and the outputs of the same channel are interleaved to increase the effective sampling rate of each channel without increasing the channel number or changing the single-channel bandwidth. As a result, the unambiguous frequency representation range of each channel is enlarged to twice that of the conventional method. The proposed structure requires only one additional delayed branch and a small amount of control logic, achieving this improvement with low implementation overhead. Joint MATLAB and Vitis System Generator simulations show that the proposed method can effectively suppress the estimation distortion caused by channel jitter and frequency aliasing in channel transition regions, and can still correctly recover the target frequency when channel-selection jitter occurs, thereby significantly improving the continuity, robustness, and reliability of instantaneous frequency measurement.