INSTRUCTION BULLETIN
STR-100 Satellite Time Reference
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IB-STR-01
March-2023
Theory of Operation The STR-100 accepts a GPS time signal input from either a Trimble
Acutime 360 GPS smart antenna or from a GPS receiver with IRIG-B
output, and provides a time synchronization output in DCF77 or 1per10
format for multiple devices. Typical power distribution applications
include Sequence of Events Recording (SER) systems in data centers,
hospitals and re neries, and electric utility “Smart Grid” applications
such as Power SCADA and substation automation.
DCF77 is a time synchronization protocol used widely. The DCF77
time synchronization output is a 24Vdc pulse-width modulated signal
that provides a complete date/time string once a minute. The signal
contains a one-pulse-per-second component that is accurate to +/- 50
microseconds in reference to UTC (Coordinated Universal Time). The
pulse string contains a BCD (Binary Coded Decimal) value for minute,
hour, day, day of week, month, and year, as well as other control
parameters such as leap second and Daylight Saving Time.
1per10 is a simpler time protocol that uses one synchronizing pulse
every 10 seconds. Only channel 2 of the STR-100 time output can be
con gured for 1per10. The default output for both channels is DCF77.
On power-up, the STR determines the type of GPS data source, rst
checking for an Acutime antenna signal. If an antenna signal is not
detected, the STR checks for an IRIG-B signal. During the detection
test, the STAT (status) LED ashes twice repeatedly. Once a signal is
detected, the SYNC LED is turned on, and normal operation begins.
During normal operations, the SYNC LED remains lit, and the STAT
LED ashes repeatedly according to the type of receiver: three blinks
for IRIG-B, and four blinks for Acutime. The STR captures the date and
time each second, and outputs the DCF77 date and time at the top of
each minute.
Optional adjustments may be made for local time offset and Daylight
Saving Time (DST). The purpose of the local time offset is to convert
UTC time into local time, and its value depends on the user’s time
zone. If the user sets parameters for Daylight Saving Time, then the
STR makes this adjustment as well.
Catalog Numbers
Catalog no. Description
STR-100 Satellite Time Reference, DCF77 and 1per10 output
STR-100/IRIG-B Satellite Time Reference, unmodulated IRIG-B output
STR-IDM IRIG-B Distribution Module for STR
NOTE:
For information about the STR-100/IRIG-B or STR-IDM, refer also to instruction bulletins IB-STR-02 and IB-IDM-01,
respectively.
Table 1-1 – Catalog Numbers
Modulated
IRIG-B Input
OR
CH 1 CH 2
24 Vdc
control power
Acutime
GPS Antenna Input
DCF77 Output
(optional)
rminal adapter
BNC-2W
DCF77 Output
(or 1per10)
}
24V levels
(5V levels)
Unmodulated
IRIG-B Output
IRIG-B @ 24V levels, plus
24 Vdc control power
(to STR-IDM)
(optional)
BNC-to-screw-te
rminal adapter
Acutime
GPS Antenna Input
24 Vdc
control power
BNC-2W
IRIG-B @ 24 Vdc, plus
24 Vdc control power
(from STR-100/IRIG-B)
IRIG-B @ 24 Vdc, plus
24 Vdc control power
(to next STR-IDM)
Unmodulated IRIG-B
Outputs (x8)
(5V levels)
Figure 1-4. STR-100 Inputs/Outputs
Figure 1-5. STR-100/IRIG-B Inputs/Outputs
Figure 1-6. STR-IDM Inputs/Outputs
