Meinberg GPS165, Руководство пользователя

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6.4 Powering Up the System
If both the antenna and the power supply have been connected the system is ready to operate. About 10 seconds
to 3 minutes after power-up the receiver 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 one to 10 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 operation, 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 discon-
nected 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.
In the default mode of operation, neither pulse and synthesizer outputs nor the serial ports will be enabled after
power-up until synchronization has been achieved. However, it is possible to configure some or all of those
outputs to be enabled immediately after power-up. If the system starts up in a new environment (e. g. receiver
position has changed or new power supply) it can take some minutes until the OCXO´s output frequency has
been adjusted. Up to that time accuracy of frequency drops to 10
-8
reducing the accuracy of pulses to +-3 µ s.
28 Date: 5th November 2019 GPS165XHS