HD24/96 Technical Reference

100

Word Clock

Time Code Resolver

LTC Time Code

Analog

24-TrackClock Slave /

Time Code Slave

Time Code Master

Another common setup is to use a transport synchronizer that is genlocked to video. In this scenario, the synchronizer reads time code from the multitrack and regulates the speed of the tape transport so that the time code coming off the tape is resolved to the video signal. The synchronizer works just like the cruise control mechanism on your car: it monitors the tape’s playback speed and regulates the capstan motor to keep the tape moving at a constant speed. A typical setup using a synchronizer looks like this:

Video / Word Clock Generator

Blackburst

Synchronizer

Blackburst

Transport Speed

O R

ControlLTC TimeWord Clock

Code

LTC Time Code

Analog

24-TrackVideo or Clock Slave / Time Code Slave

Time Code Master

It is important to note that MTC should not be used when resolving sample clock to time code; LTC is the preferred choice. This is because the LTC signal has much greater timing resolution than MTC.

LTC is a continuous signal that has a timing resolution of 80 subframes per frame, effectively producing 2400 “ticks” per second for 30 fps time code (20 samples per subframe at 48 kHz). On the other hand, MTC is a non-continuous computer data signal that is sent out in “packets” 4 times per frame. The timing of these packets is often jittery and irregular due to the nature of the hardware that generates MTC. Resolving to MTC