On the Teager-Kaiser energy operator "low frequency error"

We investigate frequency-dependent frequency estimation errors in the DESA-2 energy separation algorithm associated with the discrete Teager-Kaiser energy operator (TKEO). The TKEO and DESA-2 algorithm associate instantaneous amplitude and frequency functions to a real-valued discrete-time signal. It has been observed informally that there seems to be a frequency dependent error in the instantaneous frequency estimates delivered by the approach, where the error is more pronounced at lower frequencies. By studying quadratic phase signals, we demonstrate that this TKEO "low frequency error" does in fact exist and is related to both the magnitude frequency and the signal chirp rate.