Spectracom NetClock 9489 - Page 442

Element identification: The "on time" reference point for all elements is the pulse leading
edge.
Index marker (Binary 0 or uncoded element): 20 millisecond duration.
Code digit (Binary 1): 50 millisecond duration.
Position identifier: 80 millisecond duration.
Reference marker: 80 millisecond duration, 1 per 10 seconds. The reference marker
appears as two consecutive position identifiers. The second position identifier or ref
erence marker is the on-time point for the succeeding code word.
Figure 5-12: IRIG E time code description
Additional information
The beginning of each 10 second time frame is identified by two consecutive 80 ms elements
(P
0
and P
R
). The leading edge of the second 80 ms element (P
R
) is the "on time" reference point
for the succeeding time code. 1PPS position identifiers P
0
, P
1
… P
9
(80ms duration) occur
0.1s before 1PPS "on time" and refer to the leading edge of the succeeding element.
The time code word and the control functions presented during the time frame are pulse-width
coded. The binary "zero" and index markers have a duration of 20ms, and the binary "one"
has a duration of 50ms. The leading edge is the 10 pps "on time" reference point for all ele
ments.
426 NetClock User Reference Guide
APPENDIX