Meinberg GPS167LCD-MP - Manual (Page 14)

14
Antenna Short-Circuit
In case of an antenna line short-circuit the following message appears in the display:
ANTENNA SHORT-CIRCUIT
DISCONNECT POWER !!!
If this message appears the clock has to be disconnected from the mains and the defect
is to eliminate. After that the clock can be powered-up again. The antenna supply
voltage must be in a range of 18.5V
DC
(free) and 17V
DC
(connected GPS antenna).
Powering Up the System
If both the antenna and the power supply have been connected the system is ready to
operate. About 10 seconds after power-up the receiver´s OCXO has warmed up and
operates with the required accuracy. If the receiver finds valid almanac and ephemeris
data in its battery buffered memory and the receiver´s position has not changed
significantly since its last operation the receiver can find out which satellites are in
view now. Only a single satellite needs to be received to synchronize and generate
output pulses, so synchronization can be achieved maximally two minutes after
power-up. After 20 minutes of operation the OCXO is full adjusted and the generated
frequencies are within the spezified tolerances.
If the receiver position has changed by some hundred kilometers since last operati-
on, the satellites´ real elevation and doppler might not match those values expected by
the receiver thus forcing the receiver to start scanning for satellites. This mode is
called Warm Boot because the receiver can obtain ID numbers of existing satellites
from the valid almanac. When the receiver has found four satellites in view it can
update its new position and switch to Normal Operation. If the almanac has been lost
because the battery had been disconnected the receiver has to scan for a satellite and
read in the current almanacs. This mode is called Cold Boot. It takes 12 minutes until
the new almanac is complete and the system switches to Warm Boot mode scanning
for other satellites.