Components

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 port; RS 422 available on request.
The XCPU07 version is designed for pure NEXUS systems and for CANTUS and CINETRA mixing-console systems running the Matrix 4 control program. Note that for software version »Matrix 5« and above, which also supports the NEXUS STAR routing system, the XCPU08 board is needed.
Regardless of its size or configuration, a Base Device requires only one XCPU controller board.

The XCPU07 controller board provides compatibility and endurance – for a decade of NEXUS systems.

 
Metering

Metering data is displayed in the GUI running on the connected PC. The XCPU uses a DSP to detect the metering data of all 256 time slots of a Base Device.
It is possible to aggregate peak levels within a time window, so no visual information is lost even when using slow PCs or PC links.

Test Tone Generator

The XCPU incorporates a precision digital test tone generator with adjustable frequency and level. The generator signal is available in digital and analogue formats. The frequency can be set between 20 and 15,000 Hz in 1-Hz steps using the control software. The level range is -34 to +6 dBu. In addition to sine wave, the generator can produce white and pink noise.

Synchronisation

NEXUS supports the standard 44.1 and 48 kHz sample rates; other rates can be implemented on request. Synchronisation and clock generation are achieved using a PLL with extended time constant for a low-jitter clock signal.
The system offers multiple sync modes:

• Internal Sync — The wordclock signal is output at a BNC port for use as studio master clock.
• External Wordclock — The system synchronises to an external wordclock. A secondary BNC port is provided for this purpose.
• External Source — Synchronisation to any digital port or to a fibre-optic line.

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.

Memory

The firmware is stored in flash memory and can therefore be updated using a service program running on the PC. The optional remote-service system allows Stagetec to perform an update directly over an ISDN connection, a phone line or the Internet.
All volatile data is stored to battery-backed SRAM. This ensures that the most recent Base Device and system states can always be recovered after power failure or shutdown.

Hot Swap

As with all NEXUS boards, the XCPU can be replaced during operation without affecting any hardware. However, the audio will be interrupted as the control features of the Base Device are disabled.