LTC

LTC (Longitudinal Time Code) is a continuous signal recorded either on the tape's address track or on an audio track. The higher end formats like D2, Beta SP and 3/4" have an address track devoted exclusively to Time Code onto which LTC is recorded. On 1/2" tape formats such as VHS and SVHS, there is no separate address track so LTC is recorded onto Channel 1 and appears as a consistent, pulsing tone on a VU meter. An advantage to LTC is that it can be laid down after the fact and changed without damaging the original dub. However, on 1/2" tapes you lose one of your audio tracks which is fine if you only have one mono track of dialogue. Most tape decks have difficulty reading LTC at slow speeds and not at all in freeze frame.

See also:

VITC