In a system that has devices with digital audio inputs and outputs, each of the devices should be synchronized together. This means that the devices should all operate at the same sample rate, which is locked to a common house reference.

This includes such gear as VTRs, audio analog to digital converters, digital audio mixers, digital audio recorders and players, workstations and outboard processors.

In any facility where video is involved as well, any digital audio reference should be locked to the house video reference (color black). This applies not only to TV stations, but audio and video post-production houses, and even facilities that have both radio and TV operations.

As radio stations upgrade to digital, it's beneficial to incorporate the ability to lock to TV. You never know when one will need to provide digital audio feeds to the other.

What happens if the digital audio devices aren't synchronized? You'll hear pops and clicks as you try to dub from one device to another or run a source through a mixer or processor.

Today video sync generators often have digital audio reference options that generate (depending on the make and model) AES reference, S/PDIF word clock, plus AES tone and AES silence signals.