The straight binary (SB) time-of-day code word normally found between position iden-
tifiers P
8
and P
0
is eliminated for FAA IRIGB. All elements between position identifiers P
8
and P
0
are set to Binary0.
5.5.4 IRIG E Output
The IRIG E code contains the Binary Coded Decimal (BCD) time of year and Control Func-
tions. The figure IRIG E Time Code Description illustrates the IRIG E data structure. The
BCD time of year provides the day of year, 1-366, and time of day to tens of seconds. The
hour of the day is expressed in 24 hour format. The Control Function field includes a time
synchronization status bit, year information and SBS time of day.
Time frame: 10 seconds.
Code Digit Weighting:
Binary Coded Decimal time of year.
Code world - 26 binary digits.
Tens of seconds, minutes, hours, and days.
Recycles yearly.
Code Word Structure: BCD word tens of seconds digits begin at index count 6. Bin-
ary coded elements occur between position identifier elements P0 and P5 (3 for
seconds, 7 for minutes, 6 for hours, and 10 for days) until the code word is complete.
An index marker occurs between decimal digits in each group to provide separation
for visual resolution. Least significant digit occurs first.
Control Functions: IRIG formats reserve a set of elements known as Control Func-
tions (CF) for the encoding of various control, identification, or other special purpose
functions. IRIG E has 45 Control Functions located between elements 50 and 98.
The SecureSync uses the Control Function field to encode year data, time syn-
chronization status, and SBS time data. Table B-2 lists the Control Function Field
and each element's function.
Element 55 is the time synchronization status bit. Element 55 is a Binary 1 when the front
panel time synchronization lamp is green, and a Binary 0 when the lamp is red.
Year information consists of the last two digits of the current year (i.e. 98, 99, etc.). Ele-
ments 60 through 63 contain the binary equivalent of year units. Elements 65 through 68
558 SecureSync 2400 User Manual
APPENDIX
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