7.3 Output Signal Description
53
7.3
Output Signal Description
All models can provide three different digital signals and one analog signal. Digital signals consist
of unmodulated IRIG-B, 1 PPS and Programmable Pulse. With option cards installed, many other
digital signals are available; see Appendix C for output options with listed digital signals. Most of
the information in this section is devoted to IRIG-B, its specifications and differences.
1 PPS occurs once each second and has a duration (pulse width) of 10 milliseconds. Programmable
pulse modes are similar to 1 PPS only they have an adjustable period and pulse width. Pro-
grammable pulse modes include seconds per pulse, pulse per hour, pulse per day, single trigger
(once per year) and slow code.
7.3.1
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 1084A/B/C transmits Format B with four variations as seen in Table 7.2. 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.
Designation 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, amplitude modulated, 1 kHz
BCD
T OY
, CF, SBS
B123
Sine wave, amplitude modulated, 1 kHz
BCD
T OY
, SBS
Table 7.2: 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.
7.3.2
Modulated and Unmodulated IRIG-B
Figure 7.2 illustrates the primary differences between modulated and unmodulated IRIG-B. You
will notice that the while modulated IRIG-B is distinctive because of the 1 kHz sinewave carrier,
it is similar to unmodulated IRIG-B since the peak-to-peak values of the carrier follow the same
form as the digital waveform, where the information is contained.
Summary of Contents for 1084A
Page 4: ...iv ...
Page 6: ...vi ...
Page 18: ...xviii LIST OF FIGURES ...
Page 24: ...4 Unpacking the Clock ...
Page 36: ...16 Connecting Inlet Power Input and Output Signals ...
Page 44: ...24 GPS Antenna and Cable Information ...
Page 114: ...94 Startup and Basic Operation ...
Page 123: ...B 4 Physical Dimensions 103 Figure B 1 Suggested Mounting of the AS0094500 Surge Arrester ...
Page 124: ...104 Using Surge Arresters ...
Page 134: ...114 Options List C 6 2 Option 06 Firmware Setup Figure C 3 Option 06 Firmware Setup ...
Page 142: ...122 Options List Figure C 5 Option 06 Output Jumper Settings ...
Page 158: ...138 Options List Figure C 13 Option 17 Board Layout and Jumper Locations ...
Page 163: ...C 13 Option 20A Four Fiber Optic Outputs 143 Figure C 14 Option 20A Jumper Locations ...
Page 170: ...150 Options List Figure C 16 Option 23 Internal Jumper Setup ...
Page 172: ...152 Options List Figure C 17 Option 27 Jumper Locations ...
Page 190: ...170 Options List Figure C 20 Option 29 Connector Signal Locations ...
Page 246: ...226 Options List ...