Spectracom SecureSync - Page 563

Format Encoding Modulation Carrier Coded Expressions Bit rate
Time Frame Inter-
val
IRIG-G G005 DCLS N/A BCD
TOY
, BCD
YEAR
, and CF 10000
pps
10 msec
IRIG-G G006 DCLS N/A BCD
TOY
, BCD
YEAR
10000
pps
10 msec
IRIG-G G141 AM 100
kHz
BCD
TOY
, CF 10000
pps
10 msec
IRIG-G G142 AM 100
kHz
BCD
TOY
10000
pps
10 msec
IRIG-G G145 AM 100
kHz
BCD
TOY
, BCD
YEAR
, and CF 10000
pps
10 msec
IRIG-G G146 AM 100
kHz
BCD
TOY
, BCD
YEAR
10000
pps
10 msec
NASA-
36
N/A AM 1msec UNKNOWN 100 pps 1 sec
NASA-
36
N/A DCLS 10msec UNKNOWN 100 pps 1 sec
The Spectracom IRIG formats use the control functions for BCD year information and a Time
Sync Status bit and in format E the control functions are used for straight binary seconds (SBS).
Refer to individual IRIG Time Code description figures and text. IRIG Standard 200-98 format B
had 27 control bits and format E had 45 bits for control functions. These control bits could be
used for any use and there was no defined function. Spectracom used the control function ele-
ment at index count 55 as the TIME SYNC STATUS and the sub-frame after position identifiers
P6 and P7 as the year info and for format E the sub-frame after P8 and P9 for the straight bin-
ary seconds (SBS). The position of the BCD year information does not conform to the newer
IRIG Standard 200-04. IRIG Standard 200-04 incorporated the year information after P5 and
reduced the allocated control bits to 18 for format B and 36 for format E.
Note: DCLS is DC Level Shifted output, pulse width modulated with a position
identifier having a positive pulse width equal to 0.8 of the reciprocal of the bit
rate, a binary one (1) having a positive pulse width equal to 0.5 of the reciprocal
of the bit rate and a binary zero (0) having a positive pulse width equal to 0.2 of
the reciprocal of the bite rate.
SecureSync can provide IRIG A, IRIG B, IRIG E and IRIG G code in amplitude modulated (AM)
or pulse width coded (TTL) formats. A signature control feature may be enabled for any IRIG
output. Signature control removes the modulation code when a Time Sync Alarm is asserted.
SecureSync User Reference Guide 547
APPENDIX