The Ef Bus - Polycom Vortex EF2201 Reference Manual

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The EF Bus is a high speed, low delay digital bus that includes the W, X, Y, and Z
audio busses, the P bus, as well as the echo canceller bus reference and remote control
information (for other EF devices).
On the EF Bus page in Conference Composer, the inputs coming in to each submatrix
labelled WB0, WB1, ... WB7 correspond with the device ID of the bus that is trans-
mitting. The "B" denotes Bus. The submixes themselves, denoted as WM0, WM1,
and WM2 are mixes that are input into the main matrix. The "M" denotes Mix.
The EF Bus can link up to 8 devices that can transmit on W, X, Y, and Z outputs
(such as the EF2280) and up to 8 devices that can transmit on the P output (such as the
EF2201). Note that the EF2241 counts as one of both types. If the device can trans-
mit on a particular bus, it cannot bring its own mix back into itself. For example, an
EF2201 with ID 00 cannot add the input PB0 into PM0 or PM1 (see example in Fig-
ure 6 below).
The W, X, Y, and Z busses include NOM information and can be used for sharing
microphone inputs, or for sharing mono or stereo program information. See "Device
IDs on the EF Bus" on page 8 for more information on how this affects Device IDs.
The P Bus.
The P Bus is provided specifically to allow devices to share digital
phone audio from the EF2201. The EF2201 and EF2241 can both transmit and
receive signals on the P bus, while the EF2280 can only receive signals from the P
bus.
The W, X, Y and Z Busses.
create four output mixes (transmit on W, X, Y, and Z) and place them on the bus.
Each EF2201, EF2241, and EF2280 device also can create three input (receive) mixes
each from the W, X, Y, and Z busses of the other devices (for a total of 12 mixes).
The mixes can have crosspoint gains on the signals from the other devices. See Fig-
ure 6 below.
All 14 mixes (2 mixes on P, 3 mixes each on W, X, Y, and Z) become inputs to the
main matrix of the EF2201 and can be mixed with other inputs to create outputs to the
phone and P bus output.
13
Each EF2241 or EF2280 device in a system can
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