Most SCADA systems (Supervisory Control And Data Acquisition) provide a means of the Master end sending a time sync signal to all the remotes in the field. The Master can get its reference from WWVB, GPS, or other means. The remotes can then send time-stamped data back to the Master. We don't use this scheme so our data come back referenced to the time that a given RTU was polled, perhaps several seconds after a status or analog change outside of the deadband.
Our Master is sometines referenced within a second to WWVB. This happens when Power Control gives me a call about the SCADA clock needing set. I look at my WWVB referenced watch and correct the Master from my desktop. But again, when your acquired data might be time stamped several seconds late, fractions of a second accuracy of a Master doesn't gain you anything. Have you ever heard a news report of a train derailing or storm damage causing service interruptions at 09:15:27.3 hours? I didn't think so.
Joe
