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IRIG E Output

The IRIG E code contains the Binary Coded Decimal (BCD) time of year and Control Functions. 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. Binary 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 Functions (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 VersaSync uses the Control Function field to encode year data, time synchronization 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.). Elements 60 through 63 contain the binary equivalent of year units. Elements 65 through 68 contain the binary equivalent of tens of years. In keeping with IRIG formats, the least significant bit occurs first.

Elements 80 through 97 are encoded with the Straight Binary Seconds (SBS) time data. The SBS time data is incremented in 10-second steps and recycles every 24 hours.

  • Pulse rates:
    • Element rate: 10 per second.
    • Position identifier rate: 1 per second.
    • Reference marker rate: 1 per 10 seconds.
  • 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 reference marker is the on-time point for the succeeding code word.

IRIG E time code description

IRIG E control function field

BIT No. CF ELEMENT No. FUNCTION
50 1 SPACE
51 2 SPACE
52 3 SPACE
53 4 SPACE
54 5 SPACE
55 6 TIME SYNC_STATUS
56 7 SPACE
57 8 SPACE
58 9 SPACE
59 PID P6 POSITION IDENTIFIER
60 10 YEAR UNITS Y1
61 11 YEAR UNITS Y2
62 12 YEAR UNITS Y4
63 13 YEAR UNITS Y8
64 14 SPACE
65 15 YEAR TENS Y10
66 16 YEAR TENS Y20
67 17 YEAR TENS Y40
68 18 YEAR TENS Y80
69 PID P7 POSITION IDENTIFIER
70 19 SPACE
71 20 SPACE
72 21 SPACE
73 22 SPACE
74 23 SPACE
75 24 SPACE
76 25 SPACE
77 26 SPACE
78 27 SPACE
79 PID P8 POSITION IDENTIFIER
80 28 SBS 20
81 29 SBS 21
82 30 SBS 22
83 31 SBS 23
84 32 SBS 24
85 33 SBS 25
86 34 SBS 26
87 35 SBS 27
88 36 SBS 28
89 PID P9 POSITION IDENTIFIER
90 37 SBS 29
91 38 SBS 210
92 39 SBS 211
93 40 SBS 212
94 41 SBS 213
95 42 SBS 214
96 43 SBS 215
97 44 SBS 216
98 45 SPACE
99 PID P0 POSITION IDENTIFIER