A D V A N C E D S Y S T E M S P R O D U C T S ROUTING AUDIO VIA ETHERNET Application Guide Please note: This document, published in 1997, does not incorporate the newer RAVE/s features, functions, and specifications. However, it is still useful as a RAVE overview and implementation guide.
Table of Contents RAVE Digital Audio Router Application Guide Routing: Getting audio from here to there and there, and there to over there … ............................. 3 One problem, three solutions ........................................................................................................................ 3 The RAVE models and how they work .......................................................................................................... 6 Glossary ...................................
Edition 2.
RAVE Application Guide Unless you’re working with a very small sound system, at some point you’ll probably have to deal with routing audio signals, that is, getting audio from someplace to someplace else in real time, typically via wires. There are several ways to do this, and the cost, reliability, performance, and ease of use will be greatly affected by the method you use.
cables and connect them to patch bays in each location. Imagine STUDIO #1 the likelihood of wiring errors and ground loops, and the susceptibility to EMI. On top of that, each room would require eight STUDIO #8 distribution amps. Hopefully, you’ll never need to move or re- STUDIO #2 arrange anything. It’s an unnecessarily complicated, difficult, and expensive way to go. 8 pairs send × 8 8 pairs return × 8 Router control lines × 8 Crosspoint routing Another solution is the crosspoint router.
In review, here are the three routing solutions we’ve looked at.
The RAVE models and how they work There are currently six RAVE models, and each one handles 16 audio channels. Three have analog inputs, outputs, or both, and the other three are digital, using the AES3 (also known as AES/EBU) format. The AES3 digital inputs and outputs are dual channel or stereo.
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.
In a typical Ethernet environment, nodes usually send data packets to other specific nodes, and the data packet headers contain both the source address and the destination address. On a RAVE network, however, the sending units broadcast their data packets, without destination addresses but with addresses identifying the network channels the sending units are set to.
Network design Because a RAVE network uses a 100baseTX Fast Ethernet medium, you would generally use the same approach to designing the RAVE network as you would for a computer network. There are several ways to configure a RAVE network, from very simple to relatively complex. The number of RAVE units in the network, where they are located, and your future expansion plans will determine what net topology would be best.
Network topology examples TWO NODES WITH A DIRECT CABLE CONNECTION Advantages: very low cost; very high reliability; simple to implement Disadvantages: limited to 100 meters (328 feet) total network size; no expandability; uses non-standard wiring of RJ-45 connectors on Ethernet crossover cable The simplest and most direct RAVE network comprises two RAVE units connected by a single crossover cable.
STAR TOPOLOGY Advantages: greater network size—up to 200 meters (656 feet); high reliability; readily expandable; uses standard Ethernet patch cables Disadvantages: higher cost Add nodes—i.e., RAVE units—to the previous net layout and you have the classic star topology. This name comes from the hub being at the center and the nodes radiating out from it like the points of a star.
Longer distance through fiber Sometimes a network may need to span a long distance but there is no practical need for hubs distributed along the way. The computer networking industry, on whom we’re already relying for an economical and rugged transport medium, has an answer to this need also: fiber optics.
Standard Ethernet Patch Cables Category 5 Unshielded Twisted Pair (UTP) Cable < 100 meters (328 feet) per segment* *Although any one fiber segment can be up to 2000 meters long, and any one UTP segment can Using fiber on individual network segments be up to 100 meters long, it may be necessary to impose shorter limits, in consideration of cumulative delays caused by devices and cabling. See text for details. Optical Fiber (×2) 62.5 µm multimode < 2000 meters (6560 ft, or 1.
As mentioned before, the maximum CAT-5 UTP cable length between two network devices—that is, between any RAVE unit, hub, etc., and any other—is 100 meters, or 328 feet. You can cover longer distances by using optical fiber, as mentioned earlier, or by running 100-meter lengths of UTP cable linked by Fast Ethernet hubs.
That’s why this network, despite its apparent complexity, will work … RAVE unit RAVE unit RAVE unit 00 m Class I hub 1 RAVE unit 100 m 0m 10 Class I hub 100 m Class I hub RAVE unit m 100 RAVE unit Class I hub 10 0m RAVE unit 100 m Class I hub RAVE unit RAVE unit B 100 m RAVE unit Class I hub 100 m RAVE unit RAVE unit Class I hub 100 m RAVE unit RAVE unit RAVE unit m 100 The maximum span of this network is from device A to device B.
AND THE EXCEPTION TO THE RULES … There is an exception to the maximum network diameter rule, which assumes that all points on the RAVE network can send and receive equally well—in other words, it allows bidirectional communication anywhere on the network. But if unidirectional communication is acceptable, you can exceed the 2560 bit-period limit as long as you follow all other distance rules (100 m for UTP segments, 2 km for multimode fiber, et al).
Stadium analog system The analog solution The analog design uses 4600 feet of 32-pair cables run between the control room and each equipment room in 2300 feet of 3-inch steel EMT conduit. RAVE solution A This solution uses existing cable tray, so the only conduit cost is 300 feet of ¾-inch conduit from the cable tray to the equipment rooms. Cabling is 2300 feet of 4-strand multimode optical fiber.
AIRPORT TERMINAL The airport terminal in this example has a main equipment room which houses the signal processing equipment, along with four remote equipment rooms 250 feet apart along the length of the terminal. Each of the remote rooms serves four gate areas, and each gate area is served by four audio channels—two in, and two out. There are a total of 16 gates.
100baseT hub with fiberoptic I/O Fiber optic cable in ¾" conduit Remote equipt. room 1 Rave 188 (typ.) Analog audio lines (typ.) Audio processing equipment 1 16 16 1 16 1 16 Central control room ¾" conduit, one 4-pr cable (typ.) 100baseT hub with fiber-optic I/O Counter /jetway ¾" conduit, one 4-pr cable (typ.) ¾" conduit, one 4-pr cable (typ.) Counter /jetway ¾" conduit, one 4-pr cable (typ.) Counter /jetway ¾" conduit, one 4-pr cable (typ.) Counter /jetway Rave 188 (typ.
Convention center analog system Ballrooms: Each ballroom has a 12-pair and a four-pair cable home run to the central equipment room in a 1½-inch conduit, an average run of 500 feet each. Total materials are 2,000 feet of 1½-inch conduit, 4,000 feet of 12pair, and 4,000 feet of 4-pair copper cable. RAVE In the RAVE system design, the microphone preamplifiers will be located in remote equipment closets.
Remote equipment closet 1 4-strand fiber optic cable in ¾" conduit (typ.) Analog audio lines (typ.) 1 16 1 16 Audio processing equipment 1 16 1 16 1 16 1 16 1 16 1 16 RAVE 161 (typ.
BROADCAST FACILITY UPGRADE An FM radio station has a studio facility located next to a hill; to gain antenna height, the station takes advantage of the hilltop’s extra 300 meters in elevation for its transmitter location. But the distance between the studio and transmitter sites is slightly over a mile, making a studio-transmitter link (STL) necessary.
1 2 3 4 5 6 7 8 L R QSC FE 5/1 hub 2 km of dual multi-mode optical fiber spare optical fiber link SCA audio L R L R ENCODER Satellite receiver remote control QSC FE 2/2 hub Audio monitor Satellite receiver 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Audio monitor point L R telemetering L R Audio from satellite downlink Stereo generator SCA gen. DECODER Transmitter telemetering Studio site FM exciter & transmitter Transmitter site To sat.
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 (multimode 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.
fiber at even closer to the speed of light. Hubs and other intermediate devices have their own propagation delay and slow the data down by no more than one or two microseconds. The receiving RAVE unit, when it sees a data packet with the identifier of the network channel it is set to, pulls that packet into its buffer, separates the data into all eight audio channels, and feeds the data directly to the outputs, if it’s a digital unit, or to digital-to-analog converters if it’s an analog one.
Specifications Analog Audio Sample rate A/D converters D/A converters Network transmission THD Signal to noise RAVE 161 and 188 inputs: RAVE 160 and 188 outputs: 48 kHz 20 bits 20 bits 20 bits 0.007% worst case, 0.004% @ 1 kHz 104 dB typical; 102 dB worst case, 22 Hz–22 kHz 102 dB typical; 101 dB worst case, 22 Hz–22 kHz Network Data Format Header Packet trailer Standard Ethernet header 4 byte CRC.
Appendix ETHERNET CABLING This diagram shows the pinout for standard unshielded twisted-pair (UTP) network cable. Both ends of the cable are wired identically. 1 Tx + 2 Tx – 3 Rx + 4 not used 5 not used 6 Rx – 7 not used 8 not used White/orange Orange White/green Blue White/blue Green White/brown Brown RJ-45 pinout for a standard Ethernet patch cable (both ends indentical) A crossover cable has the RX and TX wire pairs switched around at one end.
Address & Telephone Information Address: QSC Audio Products, Inc. 1675 MacArthur Boulevard Costa Mesa, CA 92626-1468 USA Telephone Numbers: Main Number (714) 754-6175 Sales Direct Line (714) 957-7100 Sales & Marketing (800) 854-4079 (toll-free in U.S.A. only) Technical Services (714) 957-7150 (800) 772-2834 (toll-free in U.S.A.
www.qscaudio.com 1675 MacArthur Boulevard, Costa Mesa, CA 92626 USA • Ph: 714/754-6175 ”QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office. © QSC Audio Products, Inc.
