Specifications

18-428 | OWNER’S GUIDE
GPS Measurement Mode
The base of any GPS receiver is precise time measurement. In addition to the position information a precise
PPS (pulse per second) is generated by the GPS engine. This pulse is used to synchronize a 40 MHz
oscillator with software PLL (phase locked loop). The result is an ultra-stable 40 MHz clock source which is
completely free of drift over time.
Out of this 40 MHz base clock, the programmable clock divider generates the clock frequency for the stan-
dard data acquisition system which is being output on the 9-pin DSUB connector.
For A/D-boards with over-clocked delta sigma converters (e.g. DEWE-ORION-DSA series), a special output
clock is required for synchronized sampling. This is available on a RJ45 connector.
The communication to the host is provided over USB interface.
IRIG Based Operation
The IRIG signal contains the binary-coded time (year, day of year, hours, minutes, seconds, fractions of
a second) modulated on a sine wave carrier. This signal is decoded to the PPS and the drift-free 40 MHz
clock.
The following IRIG time codes are supported:
 IRIG-A (10 Hz)
 IRIG-B (1 Hz)
Functionality of the LEDs
Power Green
The power LED is solid green when the DEWE-CLOCK is in normal operation.
Status (red)
Indicates current status of device. At normal operation - when DEWE-CLOCK is locked to
the selected time source - it shortly blinks once a second.
When the time source signal is missing (neither GPS or IRIG time code signal), the device
automatically goes to ying-wheel operation. This is indicated by inverted blinking.