Bursting in adaptive hybrids

Adaptive echo cancellation is being used on shorter telephone circuits. However, while echo cancelers do tend to be effective on the shorter circuits, a new (and undesirable) phenomena called bursting has been observed. Bursting is characterized by long periods of successful echo attenuation alternating with short periods of wildly oscillating signals. The authors studied bursting by constructing a pair of simplified models of adaptive hybrid systems. The models are analyzed when they are excited by various DC and sinusoidal inputs, and the results are related back to the systems of interest, providing insight into the fundamental sources of the bursting problem-an imbalance of excitation and the enclosure of an adaptive filter in a feedback loop. Simulations providing corroborating evidence are discussed