GPS sentences carry the UTC time information. In the case of extended sensor grids or world wide sensor networks the UTC information appears to be very attractive but one risk is to have degraded timing accuracy imputable to much noise on the signal transmission path. Well known problems are time delays due to ionosphere, troposphere or receiver hardware specifics. The software phase instead is often skipped although it can represent actually a noisy element for the correct synchronization. This paper presents a GPS-based lightweight low-cost system architecture that can support multi-sensor data synchronization through an accurate timestamp of the incoming data streams. The proposed architecture handles both hardware and software problems in order to achieve correct post-processing data synchronization by means of software timestamping. Particular attention is paid to the combined hardware/software solution that minimises the overall delay time before the software timestamp event. The proposed architecture is also suitable to provide accurate evaluation of software algorithms impact over multi-sensor measurements.