Meinberg GPS167TGP, Руководство по эксплуатации

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10
Time Zone and Daylight Saving
GPS system time differs from the universal time scale UTC (
U
niversal
T
ime
C
oordi-
nated) by the number of leap seconds which have been inserted into the UTC time
scale after GPS has been initiated in 1980. The current number of leap seconds is part
of the navigation message supplied by the satellites, so GPS167´s internal real time is
based on UTC. Conversion to local time including handling of daylight saving year by
year can be done by the receiver´s microprocessor if the corresponding parameters are
set up by the user.
Pulse and Frequency Outputs
The pulse generator of GPS167 generates pulses once per second (P_SEC) and once
per minute (P_MIN). Additionally, master frequencies of 10 MHz, 1 MHz and 100
kHz are derived from the OCXO. All the pulses are available with TTL level at the
rear connector. The included synthesizer generates a frequency from 1/8 Hz up to 10
MHz synchronous to the internal timing frame. The phase of this output can be shifted
from -360° to +360° for frequencies less than 10 kHz. Both frequency and phase can
be setup from the front panel or using the serial port COM0. Synthesizer output is
available at the rear connector as sine-wave output (F_SYNTH_SIN), with TTL level
(F_SYNTH) and via an open drain output (F_SYNTH_OD). The open drain output
can be used to drive an optocoupler when a low frequency is generated.
In the default mode of operation, pulse outputs and the synthesizer output are
disabled until the receiver has synchronized after power-up. However, the system can
be configured to enable those outputs immediately after power-up. An additional TTL
output (TIME_SYN) reflects the state of synchronization. This output switches to
TTL HIGH level when synchronization has been achieved and returns to TTL LOW
level if not a single satellite can be received or the receiver is forced to another mode
of operation by the user.