NEXUS Digital Audio Routing and Interconnect System

System

Features

Components

System Boards

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XIPA
XRUV

XCPU08 Controller Board

Main Controller Board for NEXUS Base Devices

Base Device and routing control and monitoring
Control-computer communication via RS 232, RS 422, or USB
Synchronisation and clock-generation control
Sample rates of up to 96 KHz
Stores the current system status independently of the control computer
Wordclock I/O, internal clock generator
Test tone and noise generator
Metering-information gathering
Operating indicator
Optional XRUV interface (provides synchronisation to a video-burst signal)

The XCPU board is the main controller of NEXUS Base Devices and is primarily designed for controlling the routing, including redundant lines. It also handles the communication with an external control computer, system management, and controls and monitors all system components including power-supply units and backplanes. The external control computer providing the graphical user interface is connected via an RS 232/422 or USB port. The changeover to the USB port occurs automatically.
Compared with its predecessors, the XCPU08 board incorporates a ColdFire processor and significantly more memory, has a much better performance, and is fully compatible with the NEXUS STAR routing system. Using this XCPU version allows for integrating NEXUS standard Base Devices into a NEXUS STAR routing system with a maximum routing capacity of 16 million crosspoints.
Regardless of size, each Base Device requires just one XCPU controller board.

XCPU08 Controller Board

XIPA NEXUS IP Adapter

XRUV Board

Synchronisation

The XCPU08 board supports internally generated or externally referenced standard sample rates (44.1, 48, 88.2, or 96 kHz; other rates can be implemented on request). Synchronisation and clock generation are achieved using a PLL with an extended time constant for a low-jitter system clock.
The system provides the following sync modes:

The generated wordclock is output via a BNC port for use as studio master clock.
The system synchronises to an external wordclock. A secondary BNC port is provided for this purpose.
Synchronisation to any digital port or to a fibre-optic line.
Video Sync - requires an optional interface board.

Multiple sync sources can be set up. In the event of a sync source failure these sources are automatically selected according to a user-programmed priority list.

Metering

The board provides a peak-metering function that uses a DSP to detect the data of all 256 time slots and transfers this to the connected PC for viewing purposes.

Test Tone Generator

The XCPU comprises a precision digital test tone generator with adjustable rate and level. In addition, the generator can produce white and pink noise. The digital audio signals are produced by a DSP. A D/A converter incorporated on the board makes the signal available in an analogue format.

Memory

The XCPU-board firmware is stored in flash memory and can therefore be updated using a service program running on the PC. Stagetec can perform an update over an ISDN connection, a phone line or the Internet using the optional remote-servicing software.
In case of breakdown, the board can be reprogrammed via the serial interface independently of the NEXUS system. (A supply voltage must be provided.)
All volatile data is stored to a battery-backed SRAM. This ensures the most recent Base Device and system statuses are restored after power failure or shutdown. The SRAM is backed-up by a conventional user-replaceable lithium battery. The system displays a message when the battery needs replacement.

Compatibility

The XCPU08 board was designed for full compatibility with the NEXUS STAR. Existing NEXUS systems can be extended using the XCPU07 version.

XIPA

The NEXUS Matrix 4 or Matrix 5 control software runs on standard PCs connected to NEXUS Base Devices via RS232 or USB lines. A significant drawback of this configuration is that cable-length limitations restrict the computers’ positioning.
However, the NEXUS XIPA board enables NEXUS control computers to be connected over a conventional computer network. Using the XIPA adapter, control computers are connected to the NEXUS via LAN or WLAN. For this purpose, the XIPA (NEXUS IP Adapter) converts NEXUS control information transmitted to and from the computer to the IP format and provides an Ethernet port for connecting to the LAN.
The adapter independently handles all channel encoding of NEXUS messages and monitors transmitted data for errors. The XIPA board can connect to up to four PCs each running two control programs.

Versions and Options

The XIPA is available as a standalone unit or as a NEXUS slide-in board. The latter has a front panel of 4 HP / 35 mm in width. A ribbon cable connects the XCPU controller board to the XIPA board and supplies the required power.
The standalone XIPA connects to the XCPU via a standard RS232 cable. An external power-supply unit is supplied. Due to the small dimensions (approx. 105 mm × 30 mm × 85 mm/4.13" × 1.18" × 3.35") and the solid aluminium enclosure, the adapter can be used even in narrow spaces, for example, inside a cable duct.

Compatibility

The XIPA Ethernet adapter supports the following Stage Tec controller boards:

RCX 01 (NEXUS STAR)
XCPU 08 (NEXUS)
XCPU 07 (NEXUS)
XCPU 06 (NEXUS)
XCPU 05 (external XIPA only)

Notes: Future XCPU versions will be equipped with Ethernet ports and will not require the Ethernet adapter.
The XIPA uses the same expansion port as the XRUV interface-expansion board (see above). Therefore, the two expanders cannot be used at the same time.

XRUV

The optional XRUV board adds the following interface ports to the XCPU08 standard version:

RS 232/RS 422
USB
Video Sync input
Video Sync Thru output (forwards the input sync data without video content)

The board is connected to the main controller board via a ribbon cable; an XCPU-RUV combo version is also available.

The XRUV uses the same expansion port as the XIPA IP-adapter board. Therefore, the two expanders cannot be used at the same time.

XCPU08 Specifications
CPU	Type	Motorola MCF5307
CPU	Clock rates	Core: 90 MHz, Bus: 45 MHz
Memory	Software memory	2 / 4 Mbyte
Memory	Working memory	1 MB SRAM, battery-buffered; 16 / 64 MB SDRAM
RS232 interface	Port	D-Sub terminal (9-pole), galvanically isolated
	Baud rate	38.4 kBaud (typ.), 115.2 kBaud (max.)
	cable length	10 m / 33' (max., recommended)
RS422 interface, (option)	Port	D-Sub terminal (9-pole), galvanically isolated
	Baud rate	38.4 kBaud (typ.), 115.2 kBaud (max.)
	Input level	-7 to 12 V (max.)
	I/O impedance	120 Ohm
	cable length	100 m / 330' (max.) @ 110-ohm line (±20%)
USB interface (alternative to the RS 232/422 serial interface)	Type	compliant to USB Rev. 1.1, type B; standard pinout; galvanically isolated
	Baud rate	12 Mbps, typ. 38.4 KBaud; 230.4 KBaud (max.)
	Recommended cable length	5 m / 16.4' (max.) @ 90-ohm line (±15%); 25 m/82' with active extension
Wordclock Input	Port	BNC, galvanically isolated
	Level	1 to 5 V
	Impedance	75 / 500 ohm, configurable
	Rate	44.1 KHz, 48 KHz, 88.2 KHz, 96 KHz
	Required frequency stability	min. < ±150 ppm (typ. ±50 ppm; compliant with AES 11, Grade 2)
Wordclock Output	Port	BNC, galvanically isolated
	Level	2.4 V on 75 Ohm
	Rate	44.1 KHz, 48 KHz, 88.2 KHz, 96 KHz
	Frequency stability	min. ±10 ppm (typ. ±5 ppm, internal oszillator)
Sample rates	Supported default rates	44.1 KHz, 48 KHz, 88.2 KHz, 96 KHz
Test tone Generator	Frequency range	20 to 20,000 Hz, adjustable in 1-Hz steps, white and pink noise
	Frequency deviation	< 0,01 Hz
	Level	-34 to +6 dBu in 1-dBu steps
	Level deviation	±0,3 dB @ 1 KHz
	THD&N.	< 0,1%
Metering	Type	digital multichannel metering; audio-bus time-slot metering, consideration of the 14 most significant audio bits
	Channels	256
	Measuring type	peak
	Resolution	0.25 dB
	Retrace	20 dB / 1.5 s

Stage Tec Entwicklungsgesellschaft für professionelle Audiotechnik mbH, D-12459 Berlin, Tabbertstr. 10
Phone: +49 30 639902-0, Fax: +49 30 639902-32, , © 2002-2008 Stage Tec Berlin

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