scmcgr...@gmail.com wrote:
When audio/video time code is specified if its on a audio track its called LTC or
Longitudinal Time Code and is generally IRIG-B, This is very uncommon these days
as it went out of common use about the time 1" reel to reel was discontinued.
IRIG is uncommon in the audio/video industry, but still used in the
telemetry and lab environment (IRIG is the Inter-Range Instrumentation
Group, at White Sands Missile Range, after all). I confess I doubt
anyone is still using magnetic tape with FM subcarriers on the range
these days, but you never know.. government facilities tend to use
really old equipment for a long, long time since the accounting rules
don't use depreciation (you buy it once, and it's free after that),
there's limited capital budgets for replacement, but often labor is
available to repair/limp along.
At JPL, we use IRIG to transfer time around between racks, particularly
for things like MIL-STD-1553B monitors, which timestamp the bus traffic
to the nearest microsecond or fraction, sync'd by the IRIG input.
There's something really convenient about needing just one cable/fiber
to perform the function.
Audio LTC is encoded differently than IRIG.. Biphase manchester,
different bit stream, different time encoding, etc. Conceptually
similar though. Any programmable hardware that can generate IRIG can
probably generate LTC as well. OTOH, if you built your IRIG generator
out of discrete 7400 series TTL, you've got a lot of "white wires" to
convert to LTC.
Most common today on NTSC is VITC or vertical interval time code. Its encoded
as a series of pulses in the vertical blanking interval. The display is
generally called a 'Screen Burner'
Sent from my Verizon Wireless BlackBerry
-----Original Message-----
From: "Collins, Graham" <coll...@navcanada.ca>
Sender: time-nuts-boun...@febo.com
Date: Fri, 3 Dec 2010 07:28:13
To: Discussion of precise time and frequency measurement<time-nuts@febo.com>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Subject: [time-nuts] Time Code generator
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