Specifications

7
GLOSSARY
Below are some terms used in this manual that might not be familiar to all RAVE users.
AES3 —A technological specification for inter-device conveyance of a dual-channel (stereo) digital audio
signal. Also called AES/EBU.
Crossover cable —A type of twisted-pair Ethernet patch cable, but somewhat analogous in function to a
null modem cable. Unlike a normal patch cable, however, the transmit and receive wire pairs are
swapped at one end, permitting a direct connection of two nodes without a hub in between. A crossover
cable is also suitable for cascading hubs that don’t have an available uplink port. It also has nothing
to do with an audio crossover.
Network channel —A RAVE network group of eight audio channels, with a channel number designated by
a switch on the sending unit. Don’t confuse this term with actual audio channels. A RAVE network
multiplexes eight audio channels onto a single network channel and routes the entire network channel
as a whole. A receiving RAVE unit set to a particular network channel will output all eight of the network
channel’s audio signals.
Uplink port —A special port on a hub, used for cascading to another hub. Usually it’s offered in tandem with
a normal port so you can use one or the other, but not both. For example, a 5-port hub with an uplink
allows you to connect to five nodes via the normal ports, or to four nodes via normal ports plus one
hub via the uplink port.
HOW IT WORKS
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. Each device, or node, on the network that has a message to send 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 message won’t have any
noticeable effect.
Audio signals (especially multi-channel), however, 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.
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 automatically negotiate the time slots among themselves; one unit will act as the
“conductor” and broadcast a clock signal over the network to synchronize all the other RAVE units. For efficiency,
the sample data from eight audio channels are grouped together in each packet.