30 September 1988
a. Advance or delay between two video signals is dependent on which
signal is identified as the reference. Advance on VTR 1 means its output
occurs earlier in time than VTR 2's output. To look at it another way, VTR
2 is delayed when referenced to VTR 1. For example, you have video tape on
VTR 1 and the same video duplicated on VTR 2. If you reference VTR 1, its
output occurs earlier in time than VTR 2's output even though tapes are
b. You must understand that advance is really not possible.
(or a time delay) does not exist. Video signals take time to move just as
you or I do. A race car driver with the least delay in running time wins
the race. On the other hand, the car was the most advanced at the finish
line, but only because the other car racers had more delay in their running
Frame synchronizers only make video advance appear possible, but
what they really do is introduce "delay" to achieve the apparent "advance".
This is proven by the fact that the audio associated with the video going
through a frame synchronizer must also be delayed to avoid lip-sync errors.
Learning Event 2:
DESCRIBE HOW STUDIO EQUIPMENT IS INTERCONNECTED BY USE OF COAXIAL CABLE
Most state-of-the-art studio equipment is made to be interconnected
with coaxial cable that has a nominal impedance value of 75 ohms. In the
simplest form of connection, (point-to-point), two pieces of equipment will
use a continuous length of coaxial cable that is driven from one 75-ohm
source and then terminated on to a 75-ohm load (or, one output to another
a. When it is necessary to distribute a signal from one point to many
other destinations (i.e. Studio A to Studio B), two possibilities exist.
One way is to take one end of the cable, which is driven from a 75-ohm
source, and make a "loop-through" connection (fig 1-7) instead of the load.
This loop-through connection is carried to the next piece of equipment, and
so on, until the last piece of equipment on line is terminated to 75 ohms.
However, this approach will work only if the equipment