Technology

Synchronisation

All Base Devices on the network share a freely selectable clock source. The sync clock is distributed among the Base Devices via the optical lines, so there is no requirement for a separate wordclock line.
The sync clock is conditioned on the XCPU controller board on each Base Device to ensure a low-jitter Base Device clock signal. This signal is available at the wordclock output of each Base Device for use as a studio master clock or for synchronising external machines.
The absence of a separate wordclock network simplifies the installation of large-scale systems and mobile operation.

Sample Rates

NEXUS uses the standard sample rates of 44.1, 48, 88.2, and 96 kHz. The sample rate of the Base Device network is selected in the control program running on a control computer.

Sample-rate Converters

To support devices that cannot be synchronised to the system clock, the various digital boards can be equipped with optional sample-rate converters.

Sync Sources

• The wordclock input of any Base Device
• Any digital input on the system
• The internal clock generator of any Base Device
• An external video signal

The clock signal of an external source is conditioned by the XCPU controller board of the connected Base Device and is then distributed on the system as a low-jitter Base Device clock.

Generator

The clock generator integrated on the XCPU board is based on a precision quartz crystal and can be used as a master clock for the entire studio. The standard version provides a frequency accuracy of better than ±10 ppm, thus meeting the requirements of AES-11, Grade 2.

Auto Sync Search

At sync-source failure, a new clock source will automatically be selected. The change occurs smoothly and without interruption. If no appropriate sync source is found (for example, if wrong sample rates are used), the system will change to a Base Device internal clock generator.
A freely configurable priority list determines the order of up to eight sync sources to be considered during auto sync search.

Synchronisation Separate from the NEXUS

An extra line allows AES devices to use their own rate regardless of the system clock. This is accomplished by using sample-rate converters on the inputs and the outputs. This feature is also supported by the XAF and XTF boards.