Clock Synchronization (1Pps) - Kongsberg EM 712 Maintenance Manual

Clock synchronization (1PPS)

The Processing Unit has a 1PPS (one pulse per second) input for clock synchronization.
This is a generic photo. The CBMF board used by the EM 712 may look slightly different
due to minor design changes on the protective lid and/or the front panel.
It can be selected in the operator software SIS wether the falling edge or the rising edge
of the 1PPS signal is used by the Processing Unit to synchronize the internal clock. The
1PPS signal must be minimum 1 microsecond long.
The 1PPS signal is connected to the coax connector on the CBMF board. This connection
is marked . If the Processing Unit has two CBMF boards the lower one must be
1PPS
used for .
1PPS
The CBMF board is equipped with an optocoupler at this input. The input series resistor
is tuned for a TTL signal (Low level<0.6 V, High level>3.2 V).
Optically isolated input signals
Note
The input signals must not be negative, that is no RS-232 signals can be used for these
inputs.
Input from external system
A
Processing Unit input
B
circuitry
The input current must be approximately 10 mA. Depending on your input signal
additional resistance must be applied to achieve the required input current.
451106/B
Cable layout and interconnections
177