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The CobraNet System

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Digital audio is a technology that has arrived for good. It seems that digital audio as peer-to-peer data is an even better and more efficient way of transmitting, routing, and managing an audio signal.

The drastic reduction in installation time; the enormous amount of wire that doesn’t need to be cut, prepped, and terminated (or pulled); the ease of design, and the increased possibilities of data manipulation are all advantages that networked audio has over the traditional analog or digital signal. Some of the equipment that gets used for networking audio can be more expensive than some of the equipment that gets used in the analog or 75 and 110-ohm signal, but over the long haul, the benefits and attributes of networked audio are notably superior. The CobraNet System is a combination of software, hardware, and network protocols designed to deliver uncompressed, multi-channel, low-latency digital audio over a standard Ethernet network. Developed in the 1990s, CobraNet is widely regarded as the first commercially successful audio-over-Ethernet implementation.

CobraNet® technology has emerged as the de-facto standard in audio networking technology with over 1,000,000 channels of uncompressed, low latency, real-time professional-grade audio installed to date. Cirrus Logic is recognized worldwide as a leading supplier of signal-processing components for audio and energy applications. Founded in 1984 with headquarters in Austin, Texas. The most respected global manufacturers such as Yamaha, Sony, Whirlwind, Shure, Telex, Symetrix, RTS, Rane, Crown, JBL, Bose, and dbx, to mention just a few, are incorporating this amazing technology into their devices and systems to expand their attributes and make them easier to install and operate. Seems like a contradiction but it isn’t. And here’s why.

CobraNet(the CobreNet System) delivers and distributes high-quality, uncompressed digital audio using a standard Ethernet network. Unlike other audio networking or distribution technologies, CobraNet is a true network and exists on standard Ethernet networks using standard Ethernet hardware. Since it is a true network, audio routing is highly flexible between network nodes and can be used in a variety of audio distribution applications. It also can monitor and control devices remotely. This is a key feature that is highly important in fixed installation applications where the audio distribution equipment may not be readily accessible. All CobraNet devices on the network can be controlled and monitored from a central location (a laptop) by sending control commands and monitoring device-specific parameters. Please read on to understand how this is achieved.

This protocol sends information to all points within the system using data bundles. Each bundle is capable of holding up to 8 logical audio channels and every device has some bundle transmitters and bundle receivers. These transmitters and receivers are the tools used to send and receive bundles between devices. To incorporate the information into the bundle it needs to be converted from an existing digital signal. This means that to sing or play into a CobraNet system you first have to convert your source signal into digital using an A to D converter and then include that signal into a bundle by converting it again. Your digital signal processor can be in your mic or in your preamp. Once you have a bundle, you can then transmit it to any other CobraNet device within the system. To do this, every CobraNet device has up to 4 bundle transmitters. Each bundle transmitter has a transmit mode that must first be selected. This affects how many devices may receive that particular bundle at a time. Each device has eight bundle receivers. To enable a device to receive a bundle, simply allocate one of that device’s bundle receivers the same bundle number as a transmitted bundle. By doing so, a virtual link is created and audio should now be passed from one device to the other. What follows are the transmission modes.

Unicast – In this mode, only one receiver at a time can receive this bundle. Once a link is established from this transmitted bundle to a receiver, any future requests for that bundle from other potential receivers will fail. – Multicast – This mode broadcasts its contents over the entire network. There is no restriction on the number of receivers. However, the downside is that the CobraNet System packets are distributed to all nodes on the network, whether they need them or not thus creating possible network bandwidth issues. – Multi-unicasts – This is the most efficient method for getting a bundle to multiple receivers in terms of network bandwidth, but it requires more processing power on the CobraNet device so in this mode there is a maximum limit of four receiver connections (this can be reduced if required). If more connections are required than the limit, the node can be configured to automatically switch to multicast.

It is also important to note that the CobraNet technology supports simultaneous bidirectional audio distribution in each device. Not only can audio be sent from Device A to Device B but at the same time, should it be needed, it could also be sent from Device B to Device A. The exact bundle and routing configuration will be determined by the needs of each installation. An installation may have multiple units transmitting multiple bundles. The only restriction is the bandwidth available on the network to transfer the audio.

And… the CobraNet system does more than just transfer audio data. It can be used to pass serial information as well. A feature called serial bridging has been incorporated that allows the passage of serial data between nodes. Each node can pass serial data to a specific node or multicast the data to multiple nodes. A node can also receive data from either a single source or multiple sources. Baud rates, data bits, stop bits, parity, and so on are all configurable. There is also support for multi-drop serial buses as well. Finally, CobraNet can alter all of the above options in real time making the whole system completely dynamic. By use of control software, all of the bundle assignment parameters can be configured with no need to change cables, switch out connectors, or pull new wiring. Most importantly, this control capability can be implemented from a single location!

We at ConnTech have installed traditional analog and digital audio systems in Recording Studios, TV Stations, Radio Stations, Stages, Churches, Ships, Schools, Pubs, Bars, Discotheques, Homes and Yards, and even Roman style Amphitheaters built with stones. We have worked all over the United States and in five or six other countries in South America and the Caribbean. We have seen every kind of dirt and dust possible, we have seen rats and mice eating Mogami cable, and we have run, terminated, and connected cable indoors and outdoors in all kinds of temperatures. We feel that CobraNet is a giant technological step, and its implementation in all areas of audio and video transmission will completely change all the fields related to audio and video systems integration.

For more information go to http://www.cirrus.com/en/products/pro/techs/T9.html or http://www.cobranet.info/

Jan Tholenaar is an Audio-Video-Network-Control Systems Integrator living and servicing the Dade and Broward areas of Southern Florida. He is the founder and owner of ConnTech Incorporated a trustworthy installation and staffing organization offering well-trained, fully insured, and well-paid technicians. He has been servicing the Dade and Broward local markets since 1997, and the National, South American, and Caribbean markets since 1989. He can be reached here, or send him a note here.

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