QSC Audio RAVE 81 Benutzerhandbuch

Therefore, the CobraNet™ technology used in a

RAVE system employs a regulated, deterministic

system of packet timing to ensure consistent and

reliable transmission without dropouts or glitches.

The RAVE devices on a common network will auto-

matically negotiate the time slots among them-

selves. For efficiency, the sample data from eight

audio channels are grouped together in each packet.

RAVE units will synchronize themselves over the

network, and they have BNC connectors on the rear

panels for sending sync signals. This allows them to

synchronize external digital audio equipment to the

RAVE network.

Ethernet networks are most often used for computer systems; a typical application would be in an office with

servers, workstations, and shared printers. These devices use the Ethernet medium in an unregulated, non-

deterministic way. This means that they transmit data messages (called “packets”) only when necessary, and

the length of the messages may vary depending on the sending device and on the type and amount of data being

sent. When it has a message to send on the network, a device, or node, waits until there is no traffic, then sends

it. If two or more nodes try to send messages at the same time, a collision occurs; each node then waits a random

length of time before trying again. In this type of application, reasonable latency (the length of time from when

the transmitting node has a message ready to send, to when the receiving node actually receives it) is not a

problem, since a second or two delay in the

transmission of a print job or an e-mail mes-

sage won’t have any noticeable effect.

Audio signals (especially multi-channel), how-

ever, generally can’t tolerate a delay of even

a significant fraction of a second, or even

worse, a varying, unpredictable delay. This

would cause glitches, dropouts, noise, and

other nasty and undesirable artifacts in the

final audio signal.