AAV-MUX
Rev. 1
4.1 DIP switches
The configuration of the card sets a number of parameters: -
•
The input gain for the A/D converters.
•
The audio group number to be embedded.
•
Whether to embed the audio with 20 or 24 bits.
•
Whether the output SDI should contain EDH information.
4.1.1 Input gain
The A/D converter has a defined overload level which can be configured with
the gain switches.
The card has two eight-way miniature DIP switches located near the front of the
card. Groups of 3 switches control the input gain of the analogue inputs.
Switches marked 1L and 1R control the levels for converter 1 while switches
marked 2L and 2R control the levels for converter 2. The settings for the level
switches are presented in the following table. The table is also printed on the
AAV-MUX card.
0 corresponds to off.
1 corresponds to on.
The three numbers in the top row should be read as: S2,S1,S0.
Switches
000
001
010
011
100
101 110 111
dBu @ 0 dBFS
23,9 22,8 21,3
20
19,6
18
15
12
Example: S1 off, S0 on and S2 on gives a maximum input level of +18 dBu.
4.1.2 Group selection
This DIP switch may be used to assign the group number to the embedder
processor. The group number is then set by the combination of the two group
switches, as shown in the following table. The table is also printed on the AAV-
MUX card
Group
Switch G1
Switch G0
1
0
0
2
0
1
3
1
0
4
1
1
4.1.3 20/24
This switch is used to select the embedded audio word length. Embedded
audio is encoded as 20 bits + 4 bits. This switch switches off the encoding of
the last four bits. Some older video equipment cannot tolerate the extra 4 bits.
4.1.4 no EDH
This switch controls whether the EDH packet is embedded or not. Some older
video equipment cannot tolerate the presence of the EDH packet. The card will
remove
an existing EDH packet only if audio group 1 is selected, as the card
completely erases all ancillary data before embedding in this mode. The card
has no way to remove EDH packets if a group other than 1 is selected but it will
not insert new packets if the switch is on. For example, if group 2 is selected,
'no EDH' switch is on and the incoming video contains an EDH packet, the
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