Abstract
Pulse-Compression or Frequency Modulated (FM) active sonar waveforms provide a significant improvement in range resolution and reverberation suppression (RS) over Continuous Wave (CW) waveforms. The Sinusoidal FM (SFM) waveform modulates its instantaneous frequency (IF) by a sinusoid to achieve high Doppler sensitivity while maintaining desirable RS. This allows the SFM waveform to resolve target velocities much better than the Doppler tolerant Hyperbolic FM waveform. However, the SFM suffers from poor range resolution as the Auto-Correlation Function (ACF) contains many large sidelobes. The periodicity of the SFM IF creates these sidelobes, just as the periodicity of the CW waveform causes its large range sidelobes. Modifying the SFM IF to resemble a Linear FM (LFM) waveform should improve range resolution while preserving Doppler sensitivity. This generalized sinusoidal FM waveform resolves both target range and velocity with RS performance comparable to other well-established FM waveforms.