Leap second may temporarily effect GLONASS on Geode

12 Dec 2016

Juniper Systems, Inc. Geode Technical Bulletin

On December 31st, 2016 at 23h59m59s, a positive leap second will be inserted into the Coordinated Universal Time (UTC). Geode receivers capable of tracking GLONASS may experience issues with GLONASS signal tracking during this event. GLONASS tracking will be temporarily interrupted on receivers operating during the introduction of the leap second on December 31st, 2016.

GPS tracking will not be impacted, and receivers will continue to compute a position using the GPS constellation. GLONASS tracking will return to normal once a new GPS almanac is automatically downloaded by the receiver. Any receiver that has not been powered on for some time prior to the introduction of the new leap second or any receiver that has had its current almanac cleared manually will require a new GPS almanac to be downloaded to ensure proper functionality after the addition of the new leap second.

The duration of the GLONASS tracking interruption should be no greater than 60 minutes. Note this time change will occur at 23h59m59s UTC, which will be offset by your local time. For example, the time change will occur locally at Juniper Systems, Inc. in Logan, Utah, USA at 4:59:59 pm Local (MST). Users may force the Geode receiver to download and install a new almanac after the leap-second event has occurred by connecting to the Geode Connect software, and performing a “Hard Reset” under Advanced Settings, although this is not required.

Under typical use, the receiver updates the almanac automatically when a new almanac signal is received. After a reset, the receiver should be left powered on to collect a new almanac for at least 20 minutes. Full instructions for performing a receiver reset on the Geode may be found in the product manual. Additional information may be found at the US Naval Observatory site at: http://www.usno.navy.mil/USNO/time/gps/gps-timing-data-and-information