5.3
Output Signal Description
The Model 1095A/C provides one unmodulated IRIG-B, one modulated
IRIG-B and two programmable pulse signals.
Programmable Pulse
A has two modes: ON and OFF. Programmable Pulse B adds 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.
5.3.1
IRIG-B Description
IRIG-B is a complete serial time code that occurs once per second
and, depending on the configuration, contains the day of year, hours,
minutes, seconds, year and other important information. The Model
1095A/C transmits Format B with four variations as seen in Table 5.2.
Code
Signal Type
Code Components
B000*
Pulse width code, No carrier
BCD
T OY
, CF, SBS
B003**
Pulse width code, No carrier
BCD
T OY
, SBS
B120*
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 5.2: 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
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