Custom 19" rack case aids BBC codec improvement

15th January 2015

Verotec Ltd

Nat Bowers

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A customised EMC-screened 3U 19" rack cases has been introduced by Verotec, supporting BBC R&D into further improvements in the performance of the widely-used NICAM codec. Modifications included a four-ink CMYK digitally printed front panel, which enabled a very subtle image with more than 64,000 different colours to be faithfully reproduced across the complete surface of the panel, without margins around the periphery.

A very dense pattern of connector cutouts was required on the rear panel; these were laser cut to maintain the flatness of the panel, an issue if the more common punching had been employed. A ventilation aperture was required in each side panel, created using an EMC-compliant hole pattern to minimise attenuation loss.

EMC performance was a key requirement, given the application, which was easily achieved by the Veroshield rack case. This features typical attenuation figures in excess of 110dB up to 10MHz, falling linearly to 40dB at 1GHz. The rack case is constructed from 0.9mm zinc plated steel to maintain electrical conductivity throughout the unit. An additional 19” aluminium front panel, which is external to the screened enclosure, improves the appearance when the unit is mounted in a rack or desktop case.

Facilitating easy access to the internal components, removable top and bottom covers are secured with multiple fixings around their periphery. This ensures that slot lengths are kept to a minimum to preserve the high levels of attenuation.