High Speed Data across Sliding Electrical Contacts

The transmission of high speed data has become increasingly important in systems that utilize slip rings for the transmission of data from rotating to stationary platforms. Traditional evaluation metrics for the suitability of sliding contacts to carry signals or data have evolved from the D.C. and analog world and do not accurately predict performance with high speed data. Contact "noise", or variation in contact resistance, is universally used to evaluate contact quality, but this standard method requires extensive re-definition and augmentation to accurately predict the efficacy of a high data speed sliding contact system. This paper presents both experimental and analytical data to show the critical characteristics of a sliding contact system that can transmit digital data up to 3 gigabits per second (Gbps). Digital data signal characteristics are reviewed and compared with the features of sliding electrical contacts to identify the potential areas of concern. Data is presented to show performance of a sliding contact system designed expressly for the transmission of high speed data. The influences of micro and macro contact environments are examined and key tribological factors are reviewed.