Using Sigma-Delta conversion for velocity estimation in bio-inspired detection system

The Sigma-Delta converter is an analog to digital converter (ADC) with oversampling pulse code modulation (PCM) integrated with noise shaping technique. The bio-inspired motion detector Reichardt Correlator has low computation complexity and is commonly used in velocity estimation for detected objects. Conventionally, the received signals in receptors in a Reichardt Correlator are often digitized at bit depths of 8 or greater and sampled at Nyquist rate. Its implementation requires relatively complicated hardware units to cope with the processing of the samples. This paper presents a new approach for using Sigma-Delta converter to pre-process the input signals to Reichardt Correlator for velocity estimation. In this new approach, the aim is to have a scheme whereby the required hardware arithmetic units can be made simpler. This is achieved by considerably reducing the bit depth of the received signals. The presented results show that the proposed approach offers good velocity estimation performance as compared to the higher bit depth representations.