The CSS513 provides continuous monitoring of five digital MPX sources. Wired as an insert in a digital broadcast chain, it automatically switches to a digital MPX backup source of decreasing priority in the event of a problem, and automatically returns to the priority source once the problems have been resolved.

The CSS513 can handle several types of error, which can be divided into two groups.

1. The first concerns the MPX content of the AES/EBU signal: the CSS513 can detect MPX global, Pilot, RDS, L+R, L-R under- and over-modulation (programmable threshold).
2. The second group concerns digital transmission: the CSS513 can control digital carrier presence, link quality and sampling frequency. The user validates or rejects the checks to be performed.

A monitoring section with integrated demodulator allows the user to check the inputs/outputs of the CSS513 at any time. A 24-bit 192kHz D/A converter provides a balanced analogue output on Sub-D9 on the rear panel and a headphone output for signal monitoring.