Unfortunately the mechanics of the VTR are not always able to detect every video field which passes during a change in the direction of the tape transport. It is therefore necessary to have an additional mechanism for keeping track of the video fields to provide exact position of the VTR. DigImage achieves this by preformatting a tape with pulses on one of the audio tracks. By monitoring these pulses, DigImage is able to trap any errors due to changing direction of tape transport before they have any unwanted affects. The immediate mode commands in the VTR control menu (ie. numeric menu items) do not utilise the time code pulses. However, the move, jump and grab commands (G, J, K, M & T) utilise the pulses - if present - to provide exact positioning.
After recording pulses with [A Add time code pulses to tape], it is wise to check them with [X Examine time code pulses] to ensure they are correct as incorrect time code pulses will lead to larger errors than not having the pulses at all.
It is often helpful to have the CH1 Audio Out playing through a speaker while recording the pulses. You should hear a regular click-click-click. If the rhythm is syncupated, then try adjusting the TRACKING knob until a regular rhythm is achieved.
For further details, refer to the Trouble Shooting section at the end of the help text for [X Examine time code pulses].
By selecting this option, the VTR is placed in audio dub mode (channel 1 dubbing should be enabled and the input level set to max). For further details, refer to the help text after starting [A Add time code pulses to tape].
This option forces the system to forget the current time code offset so that the next operation which makes use of this facility will rezero the offset. See the other options in this menu for further details.
This option allows examination of a tape containing time code pulses (on one of its audio channels) to check for any glitches in the pulses or signal drop out. See [A Add time code pulses to tape] for how to write the time code pulses to the tape initially.