Recursive short-time Hartley transform

The short-time Hartley transform (STHT) is a powerful tool for the spectral analysis of time-varying signals, where a portion of the signal is extracted by windowing, and the Hartley transform of the windowed signal is then taken. Moving the window by appropriate steps, the entire signal may be covered. The recursive short-time Hartley transform (RSTHT) developed by the authors updates the new transform contents between two successive windowed frames, using less computation than that required in directly evaluating the new transform. For some cases such as the Hamming, Hanning, and Blackman windows, the recursive formulas are also derived for demonstration.