Artel DigiLink DLC170, Установка и эксплуатация

Страница: 22 / 50

12 DLC170 Function Modules Installation and Operations Manual
DLC170 Function Modules
Figure 6 shows the DLC170AD configuration switch SW5 located on top of the PCB.
Figure 6. DLC170AD Configuration Switch SW5
The possible settings for SW5 are as follows with the factory-set configuration setting shown in bold type:
• ON —75 Ohms
• OFF—High impedance
Configuring Peak Analog Audio Level with Rotary Switch SW6
Rotary switch SW6 controls the peak analog audio level that the DLC170AD can manage without clipping. The
peak audio level is referred to as 0 dB Full Scale (0dBFS). The information that follows provides an
understanding of the 0dBFS concept and how you can adjust for it on the DLC170AD.
When analog audio is converted to digital, the audio is represented by a series of binary values. The highest
signal that can be represented occurs when the values are either all zeros or all ones. Attempting to exceed
these values causes the audio waveform to be clipped and distorted. The maximum level is called full scale
and all audio levels can be described as levels below the full-scale value. If the signal is just at full scale, it is
called 0 dBFS. A normal operating level might be -18 dBFS or 18 dB below clipping.
The rotary switch on the DLC170AD allows the input analog voltage level to be matched to the correct digital
level. This switch setting is expressed as the peak audio input in dBm (into 600 Ohms) required to reach 0 dBFS.
If the peak program level in a typical installation is defined as +20 dBm, then when the switch is set to position
5, a tone at the +20 dBm peak level is converted to a digital signal at 0 dBFS.
When set to embed analog audio, the AUDIO A/B and AUDIO C/D LEDs on the DLC170AD front panel
represent the audio status for channels A and B and channels C and D. Normally, these LEDs should be green. If
the peak level reaches to between -6dBFS and -1dBFS, the LEDs will turn yellow (or flash yellow). If they flash
red repeatedly, the audio peak level is higher than -1dBFS, and the audio program is risking, or experiencing,
clipping.
Figure 7 shows the DLC170AD configuration switch SW6 located on top of the PCB.