GPS10RBN-16 BCD Timer Unit. This unit generates a BCD
(binary coded decimal) output with 100 ns resolution and typically 100 ns
accuracy to UTC world time. It is usually used with the GPS10RBN Frequency
Standard but can be used as a stand alone model as well. The BCD timer output
is in the form HH:MM:SS.sssssssss where HH is hours, MM is minutes, SS is
seconds and ss is decimal seconds to 100 ns resolution.
Time
Codes
Time Codes, generally in serial
form, are used to convey time information from one point to another. Many
different time code formats have been developed over the years, by both
commercial and military agencies. Many of our products support one or more of
these time codes as a standard feature; we can also address less common formats
on a custom basis. Here
is a description of the more common formats:
BCD Time Code
BCD or binary coded decimal is an old fasion
time code but still in use today by some companies. Precision Test Systems is
unique in it provides a ultra high resolution BCD time code. The format is
HH:MM:SS.sssssssss, where H is hours, M is minutes, S is seconds and s is
decimal seconds. Resolution of oure BCD time code is 100 ns and accuracy can be
as accurate as plus/minus 200 ns.
ESE Time Code™
ESE Time Code™ was
originally developed in the mid 70's as an inexpensive way to send time of day
to remote digital slave displays. The original format, TC76™, was capable of
sending six digits of time data, or four digits of elapsed timer data (using a
slightly altered bit format). The time can be sent in 12 or 24 hour format. No
AM/PM data is sent in 12 hour mode, however. The newer, TC89™ time code adds two
bits of information to convey AM/PM and display mode information. TC89 is
compatible with old non-microprocessor slaves, although the older slaves don't
recognize the mode bits. Subsequent to this, TC90™ time code was developed to
take advantage of the new microproceesor based slaves. It is not compatible with
the old slaves, but provides both Time and Date, and Auxiliary data when
required. The ES160A and ES185A provide both TC89 and TC90 codes on separate
connectors. With a few exceptions, TC89 is the standard output on most other
products which feature ESE output.
SMPTE / EBU Time
Code
SMPTE / EBU time code is used by the video & audio industries for
providing frame-accurate time references for editing video & audio tape, or
as a master time reference for radio / TV stations. When used for editing, the
code is typically recorded on a spare audio or time code track on the tape.
SMPTE (Society of Motion Picture & Television Engineers) code runs at 29.97
frames/second; EBU (European Broadcasting Union) code runs at 25 frames/second.
These codes send Hour, Minute, Second and Frame data. These codes are basically
audio in nature. Another variety of these editing codes known as "VITC"
(Vertical Interval Time Code or "vit-see") is video in nature; it is recorded on
unused lines in the Vertical Interval of the video signal. ESE manufactures a
number of VITC products, primarily for military clients; we can support VITC for
other applications on a custom
basis.
IRIG Time
Codes
The Inter-Range Instrumentation Group codes, originally developed for
sending time or other data around missile test ranges, finds use in government,
military and commercial fields. These digital codes are typically amplitude
modulated on an audio sine wave carrier (though not always). The most common
version is IRIG-B, which sends Day of Year, Hour, Minute and Second data on a
1000 Hz carrier, with an update rate of one second. Other "IRIG" codes, as well
as related codes such as "NASA", "XR3" and "2137" can be supported on a
custom
basis.
ASCII Time Code
ASCII Time Code is simply
time data sent in serial ASCII form using either an RS-232 or RS-422 interface.
It is typically used for interfacing time data to a computer (ESE provides
software for synchronizing the clock of a PC computer to ESE Master Clocks). The
data format & baud rate can vary depending on the product or intended
application. For example, the format sent by the ES-160A and ES-185/185A, if
displayed directly on a computer terminal, would appear thus:
04-18-96 109:12:57:15
This data is sent once per second at 9600 baud
using an RS-232 interface; it transmits Month-Day-Year, Day-of-Year, Hour,
Minute & Second.
