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4.2.
AUDIO STATUS LEDS
Four LEDs located on the lower end of the module (near the card extractor) indicate which audio channels
are present. Audio channel 1 LED is located closest to the center of the module. Digital audio presence is
determined by the AES receiver lock indicator (when AES input is selected). When embedded audio is
selected, the channel must be present on the selected group for the LED to illuminate.
Audio
Colour
LED
1
Green
2
Green
3
Green
4
Green
5.
AUDIO LEVELS, HEADROOM, AND CLIPPING
This section contains notes to understand how the 7737CE-A4 relates analog audio levels and digital
audio levels.
Before you can calibrate the audio digital to analog converter, you must know a couple of system issues
specific to your application. What is your analog reference level and how much headroom is there in the
digital audio signal? By adding these two values together, you will get the analog output level that will just
begin to saturate the digital word (This is the highest level that can be represented without distortion with
the digital numbers). This level is called 0dB FS (FS stands for "full scale"). For instance, if your analog
program reference level is 4dBu and you have 20dB of headroom in the "digital world", then 0dB FS will
correspond to an analog level of 24dBu. Once the audio output level is calibrated, when you apply a digital
level of –20dB FS, the analog output signal will be 4dBu .
When a full-scale digital signal is input, you will get a peak analog output signal level that is set by the
analog level controls. The following relationship is always maintained:
PGM reference level + headroom = peak output level
6.
ON SCREEN MENUS
6.1.
NAGIVATING THE ON SCREEN MENU SYSTEM
A toggle switch and pushbutton allow card edge navigation of a set of on-screen menus used to configure
the card.
To enter the on-screen menu system, press the pushbutton once. This will bring you to the main setup
menu where you can use the toggle switch to move up and down the list of available sub menus. An arrow
7737CE Composite Encoder with Image Enhancement
Audio Channel Status
Off
No channel 1 present.
Channel 1 present.
Off
No channel 2 present.
Channel 2 present.
Off
No channel 3 present.
Channel 3 present.
Off
No channel 4 present.
Channel 4 present.
Table 1: Audio Channel Status LEDs
Revision 1.0
7700 MultiFrame Manual
7737CE-9
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