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GE Grid Solutions
One of the D20ME/ME II serial ports is connected to the demodulated IRIG B port (IRIG,
InterRange Instrumentation Group) of a GPS receiver (or other device), as illustrated in Figure
20. The D20ME/ME II obtains accurate time information from the GPS receiver then regularly
distributes this information to the connected substation devices that require it. For example, the
D20ME/ME II can distribute time information to DNP3 serial outstations capable of DNP3 time
synchronization.
To support time synchronization, the D20/D200 must be able to support the device's protocol,
and the device's protocol must support time synchronization.
A sample of the demodulated IRIG B protocol is shown in Figure 21.
0
10
Seconds
1
2
4
8
10 20 40
1
P0
P1
50
60
P6
.01 sec
(Typical)
GE Information
GPS Satellites
D20ME Processor
Distribution of time information to
substation devices and peripherals
Figure 20 D20/D200 Time Synchronization
20
Minutes
Hours
2
4
8
10 20 40
1
2
4
8
P2
70
Control Functions
P7
8 msec
Reference
Marker
Figure 21 Demodulated IRIG B Signal
D20/D200 Technical Overview
GPS Reciever
IRIG-B
30
Day
10
20
1
2
4
8
10
20 40 80
P3
80
Time of Day
2
0
2
1
2
2
2
3
2
4
2
5
2
6
2
7
P8
5 msec
Binary '0'
(Typical)
PRPI-019-3.00-10
40
50
100 200
P4
P5
90
100
2
8
2
9
2
10
2
11
2
12
2
13
2
14
2
15
2
16
P9
P10
2 msec
Binary '1'
(Typical)
35
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