Thanks for update on current LTC usage!. In the studios I worked in in college with the old type-c decks we did use IRIG-B but even then everyone was moving to VITC. As editing was moving away from the razor blade and tape era to deck to deck on U-Matic decks!
Scott Sent from my Verizon Wireless BlackBerry -----Original Message----- From: jimlux <jim...@earthlink.net> Date: Wed, 08 Dec 2010 07:20:14 To: <scmcgr...@gmail.com>; Discussion of precise time and frequency measurement<time-nuts@febo.com> Subject: Re: [time-nuts] Time Code generator 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 > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
