NTP100 – Rev 2.2.0 Oct-12
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© Masterclock
®
, Inc.
GPS Lock Related Issues
The following items are specific to the NTP100-GPS and NTP100-GPS-HS models.
Please remember, for an initial startup at a new location the GPS unit could take up to 30 minutes. After the unit has
acquired satellites at the new location the startup time is greatly reduced to anywhere from a few seconds to several minutes.
Note: All components of the GPS system [NTP100-GPS unit with GPS receiver, power supply, GPS antenna, antenna cable]
are tested as a system at the factory before shipment. If the GPS antenna, the NTP100-GPS unit itself, and the supplied
coaxial antenna cable has not been damaged; And if the installation has been performed such that the GPS antenna has an
unobstructed view of the sky, the power connector is properly installed, and the front panel LED follows the startup sequence
described earlier (on, off & then on) the system will probably work. However, you may have to wait for some time [typically
up to 20-30 minutes] for the unit to achieve a first-lock to and initialize itself to the available GPS satellites at your location.
Problem: Unit is not locking to GPS.
Problem: The LED on the front panel is always steady ON.
Problem: Unit is not serving time
.
Possible reasons/solutions:
1. There are many reasons why the GPS receiver will not lock to the GPS satellites, please see the following items.
2. The LED will stay steady ON when the unit has never locked to GPS and is not serving NTP time.
The status/ GPS lock LED on the front of the unit will flash once per second when locked to GPS, and it will flash twice
per second when freewheeling.
3. The NTP100 must first acquire an initial lock to GPS before it will serve time. Once locked, the unit can continue to
serve time (either while locked to GPS or while freewheeling) as long as the DC input power is not interrupted.
• Wait at least 20-30 minutes if installing the GPS receiver device in a new location. The GPS receiver must find and
acquire the signal from at least 4 GPS satellites simultaneously, and will continue to acquire up to the eight
satellites. When placed in a new location, time to first lock will vary, but can be quite lengthy since the GPS
receiver must update its internal almanac and ephemeris data from the GPS satellites.
• Check the GPS antenna, antenna cable, and connectors. Make sure the cables and connectors are not damaged and
the threaded connectors are tightly coupled.
• If you have not already done so, install or locate the GPS antenna outdoors with a clear/unobstructed view of the
sky. Preferably on a rooftop or similar location such as a large open field or parking lot with an unobstructed view.
While the unit may lock to GPS on some occasions with the antenna located indoors in a window, such use is not
recommended.
• Locate your GPS antenna away from satellite dishes or sources of RF interference such as transmitters or other
antennas. Try relocating your GPS antenna if you are experiencing problems.
• Your antenna/antenna cable installation may be faulty. Your antenna cable or connectors may be shorted or open.
You may be using too long of an antenna cable or improper impedance cable. You may have damaged the cable(s)
or connector(s) during installation.
Masterclock highly recommends using only the pre-made/pre-tested antenna cables provided by Masterclock, Inc.
For best performance, it is best to order these cables (see available antenna packages) at the same time that you order
your NTP100-GPS or NTP100-GPS-HS, since your NTP100 GPS unit has been factory tested as a system with such
cables and antenna before shipment .
Note: The use of customized [altered] or customer provided cables is not covered under warranty or under the free
limited technical support by Masterclock. If your cables have been damaged during installation, please order an
additional cable set or contact technical support at Masterclock to have the cable(s) repaired.
• If necessary, remove the long antenna cable and connect the NTP100 directly to the short cable on the GPS antenna
using the short SMA male to SMA male adapter provided with your antenna package.
4. The GPS receiver located within the unit may have been damaged during the installation or handling.
• Handle the NTP100 GPS receiver as you would any electronic device do not subject the unit, particularly the
antenna input connector, to static discharge (ESD) during handling. When handling or installing the device, observe
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