Improving the noise performance of adaptive delta modem

By reducing the slope overload error drastically, a cost-effective adaptive delta modulator has been proposed recently (1999). For any sudden transition in the analog signal, the step size is doubled on every clock until the accumulated signal reaches the level of the analog input signal. This enables the accumulated signal to grow fast in capturing the analog input signal quickly and thereby reduces the slope overload error in the received signals. However, the spikes generated in the receiver of this ADM are, by and large, larger due to the process of doubling the step size each time. Although these kinds of spikes could be filtered by a well designed post-filter, it is advisable to reduce the spikes as much as possible. This paper proposes a modification for he previous ADM to reduce the mean value of the spikes to a lower value. The architecture of the ADM is the same as before and only a step register is changed to accommodate the new algorithm. Simulated experiments are made to show that the average spike level is reduced considerably