IEEE 1344
Encyclopedia
IEEE 1344 is a standard that defines parameters for synchrophasors for power systems. The standard added extension to the IRIG-B time code to cover year, time quality, daylight savings time, local time offset and leap second information. IEEE 1344 was superseded by IEEE C37.118 in 2005 and the time extensions were adopted as part of the IRIG
timing standard in the 2004 edition.
IRIG-B timecode consists of 100 bits, repeated each second. Every tenth bit is a "position identifier", and most of the remainder encode the current time (date, hour, minute and second). Bits 60–68 and 70–78 are reserved for other uses; IEEE 1344 is such a use. It defines the bits as follows:
The DST and leap warning bits are set no more than 59 seconds before the indicated change, and indicate the change at the end of the minute. During a leap second,
the warning bit should be set, the seconds field should show "60", and the Straight Binary Seconds field should equal 60 + 60 × minutes + 3600 × hours. The next second, the leap second warning bit should be clear, and the SBS field will repeat. Since negative leap seconds have never happened, and almost certainly never will, the LS bit is always 0.
The clock quality indication is a binary value. 0 means the clock is locked to a UTC-traceable source, without specifying a particular accuracy, and 15 means the clock has failed and the time is not reliable. Values between 1 and 11 indicate the time is accurate to within 10x−10 seconds of UTC, i.e. x=1 indicates UTC±1 ns, while x=14 indicates UTC±10 s.
The time zone offset indicates the difference UTC – timecode, so UTC = timecode + offset. This value changes when DST is active. The Straight Binary Seconds field also jumps by 3600 when this happens.
(Note that the related standard C37.118-2005 uses the opposite sign convention for time zone offset: offset = timecode – UTC, UTC = timecode – offset.)
The parity bit is even parity over all data bits from 1 through 74. Marker bits are ignored (or, equivalently, read as 0).
The standard also calls for indicating 2 digits of year in bits 50–58, which has been incorporated into the latest revision of the IRIG standard itself.
IRIG
The Inter Range Instrumentation Group is the standards body of the Range Commanders Council . They publish a number of standards through the RCC Secretariat at White Sands Missile Range ....
timing standard in the 2004 edition.
IRIG-B timecode consists of 100 bits, repeated each second. Every tenth bit is a "position identifier", and most of the remainder encode the current time (date, hour, minute and second). Bits 60–68 and 70–78 are reserved for other uses; IEEE 1344 is such a use. It defines the bits as follows:
| Bit | Weight | Meaning |
|---|---|---|
| 60 | LSP | Leap second pending at end of minute |
| 61 | LS | Leap second type (0=add, 1=delete) |
| 62 | DSP | DST change pending at end of minute |
| 63 | DST | DST Daylight saving time Daylight saving time —also summer time in several countries including in British English and European official terminology —is the practice of temporarily advancing clocks during the summertime so that afternoons have more daylight and mornings have less... in effect |
| 64 | ± | Time zone offset sign (0=+) |
| 65 | 1 | Time zone offset (0–15.5) |
| 66 | 2 | |
| 67 | 4 | |
| 68 | 8 | |
| 69 | P7 | |
| 70 | 0.5 | |
| 71 | 1 | Time quality (Binary, 0–15) |
| 72 | 2 | |
| 73 | 3 | |
| 74 | 8 | |
| 75 | PAR | Even parity of all preceding data bits |
| 76 | 0 | Unused |
| 77 | 0 | |
| 78 | 0 | |
| 79 | P8 | Position identifier |
The DST and leap warning bits are set no more than 59 seconds before the indicated change, and indicate the change at the end of the minute. During a leap second,
the warning bit should be set, the seconds field should show "60", and the Straight Binary Seconds field should equal 60 + 60 × minutes + 3600 × hours. The next second, the leap second warning bit should be clear, and the SBS field will repeat. Since negative leap seconds have never happened, and almost certainly never will, the LS bit is always 0.
The clock quality indication is a binary value. 0 means the clock is locked to a UTC-traceable source, without specifying a particular accuracy, and 15 means the clock has failed and the time is not reliable. Values between 1 and 11 indicate the time is accurate to within 10x−10 seconds of UTC, i.e. x=1 indicates UTC±1 ns, while x=14 indicates UTC±10 s.
The time zone offset indicates the difference UTC – timecode, so UTC = timecode + offset. This value changes when DST is active. The Straight Binary Seconds field also jumps by 3600 when this happens.
(Note that the related standard C37.118-2005 uses the opposite sign convention for time zone offset: offset = timecode – UTC, UTC = timecode – offset.)
The parity bit is even parity over all data bits from 1 through 74. Marker bits are ignored (or, equivalently, read as 0).
The standard also calls for indicating 2 digits of year in bits 50–58, which has been incorporated into the latest revision of the IRIG standard itself.