Description

A Clean Switch That’s Glitch-Free

The 9455 module is a clean and quiet protection switch for critical broadcast and satellite feeds. It switches cleanly between asynchronous sources which means it can be used live to air. The module has a full video frame synchronizer, rather than a line delay, ensuring perfect alignment of mis-timed and non-synchronous SDI sources.

Clean and quiet switching between sources requires that they be synchronous and precisely timed to each other. The 9455 accomplishes this automatically, with integral frame synchronization of the inputs, allowing operation with both synchronous and asynchronous (wild) sources. This frame synchronization feature not only means that the output of the 9455 will always be stable and glitch-free, but it also means that in the event of a total loss of both inputs, consistently timed color black will still be output.

These internal frame synchronizers can be genlocked to an external reference signal so that the output of the 9455 is synchronous to local sources. Alternately, in teleports, headends, and other multi-service facilities, where there is no logical common reference, the 9455 will internally generate an accurate reference.

The delay through the 9455 can be adjusted from one to eight frames, with independent control for the Primary and Secondary input paths. By operating with several frames of delay, the fault detection algorithms are given enough time to detect a failure in an input signal and switch to the backup before the fault has actually appeared on-air.

Perfect Audio

Glitch-free, quiet switching of embedded audio signals is achieved with the 9455’s precise synchronization and alignment of audio sources. Digital audio is de-embedded, and if it is linear PCM, sample rate converted, switched, and re-embedded. Encoded audio streams such as Dolby™ E are de-embedded and re-embedded but not processed in any way. PCM audio is supported with asynchronous sources, operation of encoded audio requires all sources to be synchronous, but not necessarily in time.

Switch Logic

When a fault is detected in the primary input to the 9455, and the secondary input is verified as good, the switch will activate, causing the secondary input to be switched to the module’s output. The 9455 includes a passive, fail-safe path that ensures there is an output even in the event of a total power failure. The module can be set to automatically switch back to the primary after the fault condition clears. If both the primary and the secondary inputs signals are faulted, no switch occurs.

The health of a high definition or standard definition video signal is determined by monitoring crucial parameters in order of increasing complexity; Timing Reference Signal (TRS), or a persistent loss of digital sync is tested first. Black, Embedded Audio and Freeze are also evaluated. Each test can be configured by the user. For example, the sophisticated Black Detector includes configurable parameters for black level threshold, pixel count, and duration time.

The Freeze detection system can be set to detect a clean or noisy source. Freeze Time sets the number of seconds for the 9455 to switch to the secondary input after a video freeze condition is detected in the primary input.

Control and Alarms

Module controls are easily accessed through an Avenue Control Panel, Avenue PC software, GPIs, or the module’s front edge controls. GPI inputs allow faults detected in upstream equipment to contribute to the switching logic.