CobraNet digital audio (over Ethernet) BGM/Paging Systems. Limitless possibilities!
16 January 2009
What is CobraNet®?
CobraNet is a combination of software, hardware and network protocol which allows distribution of many channels of real-time, high quality digital audio over an Ethernet network. CobraNet is supported for repeater and switched Ethernet variants. On repeater networks, CobraNet eliminates collisions and allows full bandwidth utilisation of the network. CobraNet uses standard Ethernet packets and network infrastructure (Controllers, hubs, repeaters, switches, cabling, etc.)
CobraNet provides a transparent, digital transmission link over Ethernet. CobraNet is capable of 122.16 dB dynamic range (Signal to noise ratio), and 0.000078% distortion at full level. Used to transmit 24 bit audio, the performance increases to 146.24 dB dynamic range (signal to noise ratio), and 0.0000049% distortion at full level. Frequency response is +0dB, -0dB, 0hz to 24Khz at either bit resolution. Note that these specifications are well beyond those achievable by current A/D and D/A technology. Thus the audio performance is limited only by the quality of the A/D and D/A converters used.
CobraNet can carry up to 64 channels of 48KHz, 20-bit audio can be sent over a single 100Mbit link in each direction. This means 128 audio channels over a single CAT5 cable. Gigabit links provide even greater channel capacity. With the use of fibre optics, signals can be transported up to 2km.
Wembley Stadium, in London's north-western suburbs, is without doubt the world's most famous football (as in soccer) ground. With a capacity of nearly 100,000, it is one of the largest sports stadia in Europe as well as being one of the UK's most instantly recognisable landmarks. The brief was to replace the existing single fibre distribution system (installed in 1989) with a dual-redundant network, incorporating multiple fault detection in each zone, and to replace the many hardware equalisers and limiters in each zone with venue-wide digital domain processing. At the same time, a more sophisticated touchscreen-based paging control system was to be introduced.
MAXIMUM REDUNDANCY: A total of 14 racks - 2 main and 12 subs - are installed around the stadium. In addition to containing the power amplifiers for the immediate area, the sub-racks each contain a Peavey Miniframe 108, and the two main racks a Miniframe 208. These are all networked together via Ethernet for control purposes, and all are fitted with CobraNet interface DSP cards. This network of 14 MediaMatrix units provides totally decentralised processing for the system, providing a very high degree of redundancy in that half of them can fail simultaneously and the system will still function normally. This installation is believed to be the largest MediaMatrix system outside the USA.
CONTINUOUS FAULT MONITORING: Continuous monitoring of every CobraNet unit is carried out by M+D’s proprietary SID units, which are interconnected via two concentric CAT5 rings using the same alternate-connection method as the fibre rings. The SID units’ primary function is to monitor the 20kHz low-level trace tone (superimposed on the audio within the MediaMatrix system) at the amplifier outputs, thus detecting the failure of a single channel of amplification. The CAT5 fault detect ring is monitored by the main server in the Control Room.
CUSTOM CONTROL SYSTEM: A unique aspect of the system is that the entire MediaMatrix system is controlled via the Ethernet network from a main network server PC. This system uses Peak Audio’s RATC (Remote Access Terminal Control) system, which permits full control of every parameter of the system with standard TCP/IP protocol. It also means that the user interface can be designed to be absolutely specific to the installation, thus requiring no knowledge whatever of the MediaMatrix system itself on the part of the operators.
Wembley were provided a set of custom paging stations with large LCD touchscreens for the main control desks. These display a very clear, colour-coded plan of the stadium, enabling an operator to immediately select a single area, multiple areas or the entire stadium for paging. Fault conditions and non-availability of an area are also displayed on the plan. The paging stations themselves consist of a dedicated life-safety-compliant CPU, separately networked to the main server.
With the realisation of digital audio, the possibilities are endless.