Installation & Operation Manual TC 30 AS-GPS
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1 Introducing the TC
TCTC
TC
30
3030
30
AS
ASAS
AS-
--
-GPS
GPSGPS
GPS
1.1 Overview
TC 30 AS-GPS monitors and analyses the data received from two external time references.
These references mostly are GPS or DCF77 receivers with a built-in clock, which will be
synchronised from the antenna signals. The time references output a 10MHz frequency, a
second’s pulse and a serial data string containing time, date and status information. The
time references will be referred to as unit 1 and unit 2 in this document.
TC 30 AS-GPS consists of:
•Two data inputs. Data = 10MHz (single or double), seconds pulse P_SEC, serial data
for time, date and status. These data are switched to outputs by relays: 10MHz = BNC,
P_SEC and serial data = DSUB9F.
•Two relays to indicate errors: error of unit 1 or unit 2.
•An 8-digit display to display status data. LED’s to indicate status.
TC 30 AS-GPS operates as „analyser“ or as „switcher“.
The main function is to work as “analyser“, i.e. to supervise both data inputs. With this
operating mode, all important data may be displayed at the front display to provide an
optical means of control. The serial data are checked with regard to plausibility. The unit
decides which input will be switched to the output. A failure is defined as a lack of plausible
data for a duration of some seconds or as a lack of the status ‘synchronisation’ during a
period of 24 hours. In the event of a failure, the data source will be switched over (if the
other source is without failures), a visible error indication at the main display and an error
LED will be lighting, the error relay will switch, the error counter will be incremented.
The serial data are also checked for a correct up-counting sequence of seconds. If an error
is detected, another error counter will be incremented. Such errors will not produce a
switch-over to the other source, since such “errors“ may as well occur in the event of leap
seconds, Daylight Saving Time switching, or the change from unlock to lock mode mode.
The serial data as well contain information of lock or unlock. Lock means, that the receiver
has a good quality signal input from the antenna. The unlock state is indicated at the main
display.
In the “switcher“ mode the automatic change-over between the sources is disabled, but
each source may be manually selected. This mode also permits to remove a defect TC 30
AS-GPS unit from the failure-proof system without causing a considerable dropout of the
system as a whole.
