IQBADX
SECTION 28c
IQBADXOPS
050804
www.snellwilcox.com
Version 1 Issue 5
28c.13
ALIGNMENT OF ANALOG OUTPUT LEVELS
The relationship between audio levels in the digital
and analog domains is set via four multi-turn
trimpots one per output channel.
The adjustment range is +12 dBu to +24 dBu
output for 0 dBFS digital audio level.
The generalised relationship is:
Analog (dBu) = Digital (dBFS) + Headroom (dB)
For Example:
Digital audio level = -20 dBFS
Required analog headroom = +18 dB
Analog level for -20 dBFS = -20 +18 = -2 dB
To re-align the analog outputs for different
headrooms a known digital audio level has to be
applied.
This can be done either by de-embedding an
embedded tone or the card's internal tone
generator may be used.
In all cases the card must be supplied with a valid
SDI digital video source.
Using the card's internal tone generator:
Connect the analog outputs to an audio level
meter.
Via RollCall, set outputs 'A' and 'B' to
'0dBFS_1kHz'.
Adjust the multi-turn trimpots for the required
analog headroom.
Using an SDI feed with embedded tone:
Connect the analog outputs to an audio level
meter.
Via RollCall or the card edge controls configure
de-embedders 'A' and 'B' to extract the test signal.
Adjust the multi-turn trimpots for the required
analog level.
Trimpot Functions
Output_A Left (Analog output 1, Left) ............... RV1
Output_A Right (Analog output 1, Right)........... RV2
Output_B Left (Analog output 2, Left) ............... RV3
Output_B Right (Analog output 2, Right)........... RV4