Delivery the common sense of the time to stand alone Measurement Instrument by PDA

In the paper is proposed the use of the personal digital assistant (PDA) to share the common sense of time to the measurement instruments (MIs) not reachable, or not convenient to reach, by wired or wireless connections to the distributed measurement system (DMS). For this reason is not possible to use the standard synchronization protocol, or the propagation of a electromagnetic signal used as reference one. Therefore, once synchronized to the common reference node clock of the DMS, the PDA is used to physically bring the common sense of time to inaccessible and stand alone MI. The suitable synchronization method is pointed out. It is based on the system frequency in the place of the system time. The procedure to synchronize the PDA to the DMS, and that performed into the PDA to operate in synchronized manner are described. To validate the synchronization method and to highlight the advantages, the results of preliminary experimental tests are shown.