SBS consists of the total elapsed seconds, restarting daily. Position
identifiers separate the various components of the IRIG-B time code.
5.3.2
Modulated and Unmodulated IRIG-B
Figure 5.2 illustrates the primary differences between modulated and
unmodulated IRIG-B. You will notice that while modulated IRIG-B is
distinctive because of the 1 kHz sinewave carrier, it is similar to unmod-
ulated IRIG-B since the peak-to-peak values of the carrier follow the
same form as the digital waveform, where the information is contained.
ON-TIME 1 PPS
IRIG-B
B000
REFERENCE
REFERENCE
IRIG ZERO
IRIG-B
B120
IRIG ONE
Unmodulated
Modulated
Figure 5.2: IRIG-B Waveforms
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