Functional Description and Specifications RUB SW
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2.4 Real-Time Reference Monitoring
2.4.1
Overview
The inputs PPS IN and RXD IN at the REF/GPO connector are provided to connect signals of a
real-time reference.
PPS IN:
“Pulse Per Second” input, electrical
- for example - a TTL pulse (see chapter
‘
Specifications
’
). Positive edge = Time reference mark.
This signal is used to measure the drift of the word clock signals against the real-time
reference.
RXD IN: Serial data string, electrical - for example - RS232 (see chapter
‘
Specifications
’
). The
data protocol can be selected utilizing one of the configuration tools: At “Reference
Format“ on the “Switcher“ page.
For example, the following GPS units require the
following protocols:
GPS 10 MHz
Meinberg Std 2400/7e2 + PPS
GPS16, GPS17, GPS35
NMEA $GPRMC 4800/8n1 + PPS
This signal is used to display the time & date of the last changeover event.
Example: PPS IN (yellow) and RXD IN (blue):
Errors and status information will be indicated at the
Reference
page of the status monitor
(chapter ‘
Status Monitor
’
→
‘
Status of the Real-Time Reference
’
).
An LED (e.g. SET
–
RUB1 modules only) programmed as “
Switcher Set
“ lights up if the modul
e
receives valid signals (PPS and RXD).
