Can a Leap Second Interfere with GNSS Receivers?

On February 2, 2015, the US Coast Guard Navigation Center (NAVCEN) sent out a warning that some GPS receivers could mishandle an upcoming leap second adjustment. These receivers could mistakenly apply the leap a second earlier than scheduled. One might wonder how something as small as a leap second could interfere with GNSS receivers and throw off the timing and positioning accuracy of such advanced technology. Well, here's how a leap second could make GPS lose its groove.

The Leap Second and its Role in GNSS receivers

A leap second is an extra second added to the Coordinated Universal Time (UTC). This adjustment ensures that the UTC is in line with the mean solar time (UT1). There’s typically an update pushed to GNSS receivers to make sure that systems counting on GNSS timing information stay up-to-date on the most recent UTC.

Mishandled Leap Second Adjustments Can Damage GNSS-Dependent Systems

Systems running a second early may not seem like a big deal by human standards. This, however, is not true for systems that depend on timing and positioning data such as GPS. In fact, even just a one-second offset can make GNSS navigation devices unusable. Any errors caused by the single-second difference may have serious consequences for compliance, profitability, and safety.

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A seemingly minor timing error may also produce a flash crash in financial trading systems. This is because these systems count on nanosecond-level timestamps to run properly. If the timing’s off, it can wipe out thousands of trades, negatively impacting stock prices.

Using a Simulator to Minimize Leap Second Adjustment Mistakes

GNS receiver manufacturers can use a GNSS signal simulator to mimic the leap second correction message and ensure that their receivers apply it correctly. It also ensures that their receivers can effectively manage lead second adjustments. It’s better to determine and resolve the problem upfront rather than wait for a firmware upgrade or software patch, after all.

Leap seconds interfere with GNSS receivers and cause problems with GNSS-dependent systems. Users experiencing leap second abnormalities with their GPS-dependent system should get in touch with their GPS receiver vendor for a solution. They’ll usually push a firmware update to get the timing back on track.