Real-time noise reduction through independent channel averaging for real-time biomedical signal acquisition

Abstract

In this work, a strategy to obtain a lower noise floor from commercial multichannel Sigma-Delta analog-to-digital converters (ADCs) is presented. Specifically, data from ADS131E08, an 8-channel simultaneous sampling 24 bit converter, is captured, processed, and transmitted in real time using a MAX 10 FPGA included in a measurement system with medical grade isolation, thus able to acquire biomedical signals. Noise measurements show that the system is able to reduce the equivalent input voltage noise of the ADC by a factor of 2.8, extending the measurement dynamic range by 9 dB. In this way, the system improves the otherwise minimum available noise floor with no additional analog stages and allows using higher data rates while maintaining signal quality. Experimental electrocardiogram and electromyogram recordings were taken using non-invasive dry electrodes, validating the operation of the system as a biopotential acquisition platform. Under these experimental conditions, a noise reduction factor of 2.1 times for the noise floor of the measured biopotential signals was verified.