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Spectracom Format 2

This format provides a time data stream with millisecond resolution. The Format 2 data stream consists of indicators for time synchronization status, time quality, leap second and Daylight Saving Time. Time data reflects UTC time and is in the 24-hour format. Format 2 data structure is shown below:

Note: Format 2 cannot be configured for a Time Zone Offset or with automatic Daylight Saving Time adjustment. Attempting to configure a Local clock using Data Format 2 with either a Time Zone Offset or automatic DST rule will result in an error message.

Example message:

CR LF IQYY ^ DDD ^ HH:MM:SS.SSS ^ LD

Where:

CR Carriage Return
LF Line Feed
I Time Sync Status (space, ?, *)
Q Quality Indicator (space, A, B, C, D)
YY Year without century (99, 00, 01, etc.)
^ Space separator
DDD Day of Year (001-366)
HH Hours (00-23 UTC time)
: Colon separator
MM Minutes (00-59)
: Colon separator
SS (00-60)
. Decimal separator
SSS Milliseconds (000-999)
L Leap Second indicator (space, L)
D Daylight Saving Time Indicator (S,I,D,O)

The leading edge of the first character (CR) marks the on-time point of the data stream.

The time synchronization status character (I) is defined as described below:

? When the receiver is unable to track any satellites and the time synchronization lamp is red.
* When the receiver time is derived from the battery backed clock or set manually through the Setup Port Interface.

The quality indicator (Q) provides an inaccuracy estimate of the output data stream. When the receiver is unable to track any GNSS satellites, a timer is started. Quality indicators lists the quality indicators and the corresponding error estimates based upon the GNSS receiver 1PPS stability, and the time elapsed tracking no satellites. The Tracking Zero Satellites timer and the quality indicator reset when the receiver reacquires a satellite.

Quality

Time (hours)

TXCO Error (milliseconds)

OCXO Error
(milliseconds)

Rubidium Error
(microseconds)

Space Lock <1 <0.01 <0.3
A <10 <10 <0.72 <1.8
B <100 <100 <7.2 <18
C <500 <500 <36 <90
D >500 >500 >36 >90

Quality indicators

The leap second indicator (L) is defined as:

(Space) When a leap second correction is not scheduled for the end of the month.
L When a leap second correction is scheduled for the end of the month.

The Daylight Saving Time indicator (D) is defined as:

S During periods of Standard time for the selected DST schedule.
I During the 24-hour period preceding the change into DST.
D During periods of Daylight Saving Time for the selected DST schedule.
O During the 24-hour period preceding the change out of DST.

Example:

?A15 271 12:45:36.123 S

The example data stream provides the following information:

Sync Status The clock has lost GNSS time sync. The inaccuracy code of “A” indicates the expected time error is <10 milliseconds.
Date Day 271 of year 2015.
Time 12:45:36 UTC time, Standard time is in effect.