3 GPS180SV Features
3.7 Time Code (Option)
3.7.1 Abstract of Time Code
The transmission of coded timing signals began to take on widespread importance in the early 1950´s. Espe-
cially the US missile and space programs were the forces behind the development of these time codes, which
were used for the correlation of data. The definition of time code formats was completely arbitrary and left to
the individual ideas of each design engineer. Hundreds of different time codes were formed, some of which were
standardized by the "Inter Range Instrumentation Group" (IRIG) in the early 60´s.
Except these "IRIG Time Codes", other formats like NASA36, XR3 or 2137 are still in use. The board GPS180
however generates the IRIG-B, AFNOR NFS 87-500 code as well as IEEE1344 code which is an IRIG-B123
coded extended by information for time zone, leap second and date. Other formats may be available on request.
A modulated IRIG-B (3 V
pp
into 50W) and an unmodulated DC level shift IRIG-B (TTL) signal are available at
the VG64 male connector of the module.
3.7.2 Block Diagram Time Code
modulated time code
modulated time code
hgh active and low active
driver
50
Ω unbalanced
driver
TTL
D/A
converter
modulator
digital
sinewave
generator
microcontroller
time code
EPLD
10 MHz
PPS
GPS180SV
Date: 21st June 2017
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