Linking Multiple Devices - Polycom EF2201 Brochure & Specs

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One of the most important features of the Vortex is its ability to be linked with other Vortex's when your design requires more than
8 microphones. The Vortex allows the user to link up to 8 devices and have it operate as a single 64-channel automixer with 32
line level inputs, sharing signals across the EF bus.
The EF bus is a high-speed network protocol that allows up to 8 Vortex units (any combination) to be linked together – in addition,
up to 8 EF2280's and 8 EF2201's can be linked together for a total of 16 devices. The EF bus is used for both command and control
information between devices and for high speed data linking. Each Vortex can place 4 or 5 output signals on the EF Bus – the P, W,
X, Y, and Z signals – and use 14 mixes of the up to 40 input signals from the bus in its local matrix. In addition one device can
place its echo canceller reference on the bus so the linked devices can use it. Only the telephony products have the ability to put
signals on the P bus.
Since each device (up to 8) can place 4 or 5 channels of audio on the bus, there are a total of 40 (5 for each device times 8 devices)
full-bandwidth signals that are accessible by all the devices. Each linked Vortex can access the bus and choose which signals to
read from the bus and use with its local matrix.
To understand the linking, each of these busses will be introduced and then described from both an output view and an input view.
P bus An audio bus that is used to share telephony signals between devices. Only Vortex devices with telephony options
(EF2241, EF2211, and EF2201) can put signals on this bus. All Vortex devices can read data from the P bus.
W bus An audio bus that includes signal information and information about the number of open microphones for each
device that puts microphone information into this bus.
X bus An audio bus that includes signal information and information about the number of open microphones for each
device that puts microphone information into this bus.
Y bus An audio bus that includes signal information and information about the number of open microphones for each
device that puts microphone information into this bus.
Z bus An audio bus that includes signal information and information about the number of open microphones for each
device that puts microphone information into this bus.
EC Ref An audio bus that allows one device to put its echo cancellation reference on the bus to be used by other devices.
Expansion Outputs Example
Let's assume the Vortex EF2280 we are using is
device id 0 (the device id's can range from 0 to 7).
As described above, Vortex EF2280:00 has an
output signal that it can place on each of the four
busses: W, X, Y, and Z. Each of these four outputs
is created through the matrix by mapping input
signals to the output signals through the matrix
mixer. Figure 18 shows a portion of an EF2280:00
matrix and shows outputs 1-8, A-D and the
expansion busses W, X, Y, and Z. In this example output W is a gated sum of inputs 1-8 (the blue background signifies the
microphone signals are "gated" through the automatic microphone mixer), output X is the codec audio from input C, output Y is the
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Figure 18. A screen shot of the Conference Composer software showing the mapping
input signals to the expansion busses.
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