Specifications

24
LEDOM
stropXT
)PTU5TAC(
stropXF
)citporebif(
0/5EF
50
0/8EF
80
1/3EF
31
1/5EF
51
2/2EF
22
2/5EF
52
4/2EF
24
RAVE peripherals
QSC FE HUBS
As a convenience to RAVE users, QSC offers a series of seven Fast Ethernet hub models that feature especially
low latency (
<0.46 µs; equal to <46 bit periods) and various combinations of 100baseTX and 100baseFX (multi-
mode fiber) ports for built-in media conversion. The hubs are 1 RU high and feature an auto-sensing switching
power supply that automatically adapts to AC service from 100 to 240 VAC.
Other features:
• Manufactured to QSC specifications by a
leading network hardware manufacturer to
work specifically with RAVE audio distribu-
tion networks
• Supported by QSC’s full 3-year warranty
• Includes a switchable uplink port for cascad-
ing hubs
• Heavy-duty rack-mount chassis
• High-speed cooling fan for demanding envi-
ronments
• Individual activity sensor for each port
• Overtemperature sensor with buzzer alarm
Latency and audio
The latency (how long it takes for an audio signal to get from the input of a RAVE unit to the output of another
RAVE unit on the same network) or propagation delay of a RAVE network is 6.3 milliseconds. What happens in
that time? An analog audio signal has go go through an analog-to-digital converter first, and its digital data then
goes on to a buffer, a temporary memory location. An AES3 digital signal doesn’t need A-to-D conversion, so
it goes right into the buffer.
The buffer briefly holds the 20-bit data from the audio channel while it gets lined up with the 20-bit data from
the other seven audio channels in the block, which is assigned to a particular network channel. The RAVE unit
adds identifying and managing bits to the data, and then when the block’s turn to be transmitted comes around
(as it does 48,000 times per second), the RAVE device sends the whole packet out onto the network and then
immediately lines up the next packet.
The data traverses the network, traveling through UTP cable at almost the speed of light and through optical