Custom Veroshield 19-inch rack case helps BBC improve codec performance

15-01-2015 | Verotec | Design Applications

BBC Research and Development is at the forefront of the global broadcast
industry’s mission to improve the quality of both video and audio
programmes. Their recent research into further improvements in the
performance of the widely-used NICAM Codec has been supported by a
customised EMC-screened 3U 19-inch rack cases from Verotec.

The modifications to the standard unit included a four-ink CMYK digitally
printed front panel, which enabled a very subtle image with more than 64000
different colours to be faithfully reproduced across the complete surface of
the panel, without any margins being needed around the periphery. A very
dense pattern of connector cut-outs was required on the rear panel; these
were laser cut to maintain the flatness of the panel, an issue if the more
usual punching had been employed. A ventilation aperture was required in
each side panel, these were created using an EMC-compliant hole pattern to
minimise any loss of attenuation.

Given the application, good EMC performance was a key criterion, easily
achieved by the Veroshield rack case, which as typical attenuation figures
in excess of 110dB up to 10MHz, falling linearly to 40dB at 1GHz. Veroshield
is constructed from 0.9 mm zinc plated steel to maintain electrical
conductivity throughout the unit; an additional 19-inch aluminium front
panel, external to the screened enclosure, is provided to improve the
appearance when the unit is mounted in a rack or desktop case. Removable top
and bottom covers facilitate easy access to the internal components; they
are secured with multiple fixings around their periphery to ensure that slot
lengths are kept to a minimum to preserve the high levels of attenuation.

Verotec use ArtCAM Express middleware in conjunction with their CAD systems.
It allows customers to send Pro Eng, Solid Works, AutoCAD or PDF files of
their modified panels; these drawings are then automatically translated into
the standard MCR file format required to control the CNC manufacturing
machines, avoiding any potential inaccuracies. A further benefit is that the
data path from customer to machining centre is homogeneous, ensuring that
ISO9001 traceability is preserved to allow batch traceability if required,
says the company.

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