S
YSTEM
P
ARAMETERIZATION AND
O
PERATION
System 6844(RC) - V03.00
77 / 157
hopf
Elektronik GmbH
Nottebohmstr. 41
• D-58511 Lüdenscheid • Tel.: +49 (0)2351 9386-86 • Fax: +49 (0)2351 9386-93 • Internet: http://www.hopf.com • E-Mail: [email protected]
5.5.5 IRIG-B (Digital) Output
This Chapter describes the structure and configuration of the digital IRIG-B signal that is
available in the System.
5.5.5.1 IRIG Time Code, Structure and Timing Diagram
The IRIG time code format consists of a time code with 74 bits and has a repetition rate of
one second. The bit frame is 10 msec. The bit rating is represented by pulse width modula-
tion and is a multiple of one millisecond.
In the case of analog output, the positive zero crossing of a sine wave (carrier frequency
1000 Hz) is modulated with the rising edge of the IRIG signal. The modulation depth should
be between 3:1 and 6:1 for signal information of H/L level.
For synchronization at the start of the second, a neutral logical state - referred to as an iden-
tifier - is required.
Logic 0
= 2 msec H level
Logic 1
= 5 msec H level
Identifier = 8 msec H level
low
high
PPS
IRIG-B
digital
IRIG-B
analog
2msec
5msec
reference bit
position identifier
8ms
8ms
The 74 time code bits are divided into:
30 bits for the BCD value of seconds, minutes, hours, and the current day of the year
27 bits for the input of control information
17 bits for the binary value of the current day seconds
100 bit frames can be transmitted in one second. Unused bit frames are filled with a logical
zero.
