Guralp Systems CMG-RTM - Manual (Page 4)

CMG-RTM Real-time Clock / GPS Simulator
2 Introduction
The CMG-RTM is a battery backed, high-precision, thermally-
compensated, real-time clock module with simulated GPS output. It
obtains its initial synchronisation from a GPS receiver and, once
locked, starts generating NMEA sentences and a PPS (pulse per
second) signal, making it suitable for use as a time-source for GPS-
synchronised equipment in situations where GPS receivers are
impractical. A large liquid crystal display provides status information.
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Once the initial synchronisation source is removed, the CMG-RTM
continues to run under battery power, maintaining timing through the
use of a high-precision, thermally-compensated, crystal-controlled
oscillator. The CMG-RTM can then be transported to the deployment
site and connected to a digitiser, from which it subsequently draws
power. Once powered, it will generate the NMEA and PPS signals
which are required to synchronise the connected digitiser.
Each unit is individually factory-trained to calculate a temperature
compensation table with 0.1°C granularity, ensuring stability of
operation in a wide range of environments.
4 Issue B