Crystal Vision
Using card edge controls
4 Using card edge controls
The front edge of the card provides power rail monitoring, an eight-way configuration
switch bank, analogue audio monitoring outputs and a rotary control to set the silence
threshold.
LED indicators are provided to monitor power rails, input present, input sample rate and
local/remote mode.
Selecting the output clock source
The ADCA412 output clock may be locked to AES reference, word clock, analogue video
(or black and burst) or left to run off a 48kHz internal clock.
The choice is made using SW3-1 and SW3-2 as follows:
Lever 1 Lever 2
Function
UP
UP
AES reference selected
UP
DOWN
Video reference selected
DOWN
UP
Word clock selected
DOWN
DOWN
Internal clock source selected
Selecting the sample rate mode
The ADCA412 channel operates in two main modes. The primary mode is for the output
sample rate clock to be locked to the reference using a 48kHz crystal oscillator to achieve
optimum distortion figures. This is referred to as ‘Xtal’ mode and should be used at all
times if possible.
The second mode uses built-in phase locked loops and VCOs to accept an AES reference
which may vary from below 30 kHz to above 50 kHz. This is referred to as ‘Auto’ mode,
and should be used when the AES reference sample rate is outside 48 kHz +/- 50 PPM.
Note:
‘Auto’ mode can only be used with an AES reference. The ‘Xtal’ mode is designed for use
with a video, word clock or AES reference at 48kHz.
ADCA412 User Manual R2.1
19
30 October 2018
