66
Timing, IRIG-B and Pulses
8.3
Output Signal Description
The Model 1094B has four independent outputs subdivided into two groups: (1) Outputs 1 and
2 can be configured for IRIG-B, 1 PPS or Programmable Pulse A; (2) Outputs 3 and 4 can be
configured for IRIG-B, 1 PPS and Programmable Pulse B. Programmable Pulse A has two modes:
ON and OFF. Programmable Pulse B adds to that two additional modes: Frequency and IRIG-B.
Pulse mode is useful for timing individual pulses at specific intervals or at a specific time of day
or year. Frequency mode provides from 1 to 1000 pulses per second (Prog. Pulse B), at a 50%
duty cycle. Programmable Pulse B may also be used as a second unmodulated IRIG-B configured
independently from the standard IRIG-B.
Programmable pulse modes are similar to 1 PPS only they have an adjustable period and pulse
width. Modes include, pulse per second, pulse per minute, pulse per hour, pulse per day, single
trigger (once per year), slow code and seconds per pulse.
8.3.1
IRIG-B Description
IRIG-B is a complete serial time code that occurs once per second and, depending on the config-
uration, contains the day of year, hours, minutes, seconds, year and other important information.
The Model 1094B transmits Format B with four variations as seen in Table 8.2. Note that with the
newer IRIG Standard 200-04, two of the designations have changed: the older B000 has become
B004 and B120 has become B124.
Code, Old/New
Signal Type
Code Components
B000/B004*
Pulse width code, No carrier
BCD
T OY
, CF, SBS
B003**
Pulse width code, No carrier
BCD
T OY
, SBS
B120/B124*
Sine wave, modulated, 1 kHz
BCD
T OY
, CF, SBS
B123**
Sine wave, modulated, 1 kHz
BCD
T OY
, SBS
*IEEE 1344 ON,
**IEEE 1344 OFF
Table 8.2: IRIG-B Time Code, Types Available
The IRIG-B time code consists of 100 bits produced every second, 74 bits of which contain
various time, date, time changes and time quality information of the time signal. Consisting of
logic ones, zeros and position identifier bits, the time code provides a reliable method of transmitting
time to synchronize various equipment.
There are three functional groups of bits in the IRIG-B time code, in the following order: Binary
Coded Decimal (BCD), Control Function (CF) and Straight Binary Seconds (SBS). The BCD group
contains only time information including the seconds, minutes, hours and days, recycling yearly.
The CF group contains other time-related information including year, time quality, leap year,
pending leap seconds and parity. The SBS consists of the total elapsed seconds, restarting daily.
Position identifiers separate the various components of the IRIG-B time code.
