You're right that the zero crossing is important, and you're theoretical wrong that distortion at top and bottom won't be a problem.
In fact you are right, it is a blockwave so overmodulating can't harm it, but you could overload 'some' part(s) of your electronics.
(Mentioned by me on this, or the previous list) as ' Zelinise your levels, look it up in the archives...)
With modern equipment it's probably hard / close to impossible to do so i believe.
(And in therory there is no difference between theory and practice. In practice however..)
Here is a bit for your memory:
http://www.philrees.co.uk/articles/timecode.htm
Especially the rise time part is fun to read. (Yes, i'm a nerd, but a good looking one...)
Bouke
VideoToolShed
van Oldenbarneveltstraat 33
6512 AS NIJMEGEN, the Netherlands
+31 24 3553311
----- Original Message -----
From: John Moore
To: Avid L2
Sent: Wednesday, July 10, 2013 1:54 AM
Subject: [Avid-L2] "Other" button on Tek WFM-7020 displays LTC
Just an FYI for the Tektronix WFM-7020 and probably other Tek scopes. I found that the "Other" button displays LTC on a + and - 16dBu scale. Fortunately I built a remote box to fire scope presets and I wired it for the scope LTC in. Feeding the Avid LTC out into the scope shows time code waveform peaking at + and - approc 3.7 dBu. I never knew this was there. What fun but now I'm trying to remember what the spec for LTC level is. I remember recording it at approx -3db on the Vu meters on 3/4 inch machines and sometimes going lower on record level and or playback level to avoid cross talk into channel 1 of the 3/4 machine. IIRC we recorded time code on the Ampex one inch machines at 0 or +3 db. I think the theory was the hotter signal was fine because time code readers look at the zero crossing to detect the information from the bits of time code information so distortion on the top and bottom was not an issue and probably made for a
better square wave and helped to maintain a readable level at high speed shuttle. Anybody remember the specifics in better detail.
John Moore
Barking Trout Productions
Studio City, CA
bigfish@pacbell.net
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