METER ZL6 - GPS Receiver (ZL6 Select Models); Timekeeping

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SYSTEM
light, the incoming energy may be lower than the energy needed to operate the logger. The
batteries will buffer the energy needs of the logger for several months and will return to full
capacity as the incoming energy exceeds the energy needed to operate the logger.
The ZL6 and ZL6 Pro will also harvest energy from the USB connection to a computer.
Plugging the logger into a USB port for several hours will help restore NiMH batteries to
full capacity.
Use alkaline batteries if the ZL6 or ZL6 Pro will be installed indoors or in a location where
the harvested solar energy is not sufficient to keep the NiMH batteries charged. Alkaline
batteries will last longer than NiMH batteries that are not being charged (6 to 7 months for
typical configurations).
The ZL6 and ZL6 Pro are designed to prioritize sensor measurements over both the GPS
and cellular communications features. If the battery level reaches a critical threshold
(showing 0% in software), the logger will continue to make sensor measurements until the
battery charge is too low to provide excitation power to the sensors. When new batteries are
installed or recharged, the GPS receiver and cellular radio functionality will automatically
start working again.
Logged data are stored with nonvolatile flash memory and will not be lost if battery power
fails. However, power must be restored to the logger to download data.
3.2.6 GPS RECEIVER ZL6 SELECT MODELS
The ZL6 logger has a built-in GPS receiver that provides the latitude, longitude, and altitude
of the logger. It is designed to provide time fix and location metadata for the environmental
monitoring location. The ZL6 does not record the location of each individual sensor reading
and is not optimized for applications such as geotagging a moving sensor platform.
The ZL6 enables the GPS receiver once per day. If the logger determines its location has not
changed, it turns off the GPS receiver to save power. If the ZL6 detects a change, it keeps
the GPS receiver powered for as long as 15 min to improve the accuracy of the location
fix. Pressing the TEST button on the ZL6 triggers the logger to evaluate changes in location
(Section3.2.3).
3.2.7 TIMEKEEPING
The ZL6 keeps track of time using Universal Time Coordinated (UTC) seconds. All ZL6 models
can synchronize time using ZENTRA Utility and ZENTRA Utility Mobile. Additionally, the
ZL6 and ZL6 Pro synchronize time using the GPS receiver or the cellular network. The
ZL6 prioritizes using GPS time since this will be the most accurate; however, the logger will
fall back to the other sources of time when the ZL6 does not have a good GPS time fix.
NOTE: The ZL6 Basic requires a time sync to accurately save a time and date stamp with each sensor measurement
record. This time sync happens when the logger connects to ZENTRA Utility or ZENTRA Utility Mobile. The time must be
reset any time the logger loses power (when batteries are removed or replaced).