AJA FS1-X - Page 36

FS1-X v1.1 www.aja.com
36
The FS1-X offers four settings shown in the following table. The analog audio levels listed
in the table are defined in reference to 0 dBFS (where FS = full scale), which is the
maximum level that can be represented digitally. Note that the test method for these
levels uses a 1kHz sine wave.
Table 5. FS1-X Audio Level Settings
FS1-X Audio Setting Meaning
+24 dBu analog = 0 dBFS
maximum audio level
SMPTE standard (US)
With digital audio at the maximum possible level (before clipping), the expected
analog audio input level is +24 dBu, and the output is scaled to this level.
Typically, the US Standard Operating Level is +4 dBu analog or -20 dBFS digital. The
FS1-X +24 dBu setting allows 20 dB of headroom (+4 to +24 dBu) per the SMPTE RP-155
standard.
+18 dBu analog = 0 dBFS
maximum audio level
EBU standard (EU)
With digital audio at the maximum possible level (before clipping), the expected
analog audio input level is +18 dBu, and the output is scaled to this level.
Typically, the EU Alignment Level is 0dBu analog or -18 dBFS digital. The FS1-X +18 dBu
setting allows 18 dB of headroom (
0 to +18 dBu) per the EBU R68 standard.
+15 dBu analog = 0 dBFS
maximum audio level
German standard
With digital audio at the maximum possible level (before clipping), the expected
analog audio input level is +15 dBu, and the output is scaled to this level.
+12 dBu analog = 0 dBFS.
maximum audio level
Consumer equipment
With digital audio at the maximum level (before clipping), the analog audio input level
is +12 dBu, and the output is scaled to this level. These levels are provided for
consumer equipment that outputs lower audio levels than professional equipment.
Consumer audio units are often given in dBV, with +12.2dBu equivalent to +10dBV. The
standard operating level corresponds to -10dBV (-7.8dBu). The FS1-X +12dBu setting
provides approximately 20 dB of headroom (+10 to -10 dBV).