Data synchronization for independent USB devices

This paper deals with solving of the data synchronization problem during the data retrieval from independent devices. The data-oscillometry and photoplethysmography signals - are acquired using three independent measuring devices connected to PC via USB ports. The task is to obtain synchronized data. It means the problem is to sample signals in each device at the same time. The sampling of signals is triggered by internal counters independently in each device, the counters are commonly synchronized by general synchronization packets. The presented sampling method is robust and independent of the state of operating system on superordinate PC.