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Dolby Laboratories LM100

Nigel Lord 9 November 2010
Dolby Laboratories LM100

What is it?A broadcast loudness meter for subjective dialogue loudness measurements in applications such as post-production, quality control, final transmission, program turnaround and cable head-end facilities. DetailsThe LM100 addresses the problem of varying audio levels in broadcast environments through the use of Dolby’s ‘Dialogue Intelligence’ technology, developed specifically to measure perceived dialogue loudness. By analysing input signals and monitoring program loudness only during the presence of speech, Dialogue Intelligence can objectively measure what viewers experience subjectively. The LM100 utilises ITU-R BS.1770-1 as its core measurement algorithm though users can also select Leq(A). A software upgrade option is also available which adds the ITU-R BS.1770-1 algorithm to existing units (manufactured prior to August 2008). The LM100 presents its measurements in an “easy-to-understand” numerical format designed to eliminate variations in results when using VU or PPM meters. The LM100 can also determine unweighted peak level and other information about the signal. The unit can simultaneously display the incoming dialogue normalisation (dialnorm) value of a Dolby Digital program (or any program within a Dolby E bitstream) for direct comparison to the actual measured value. Front- and rear-panel serial interfaces provide capabilities for software updates and the LM100 software remote application. The remote application is designed to assist users with advanced loudness measurement, logging features and enhanced error reporting. A set of user-definable alarms and monitoring functions are included to indicate input loss, signal clipping, overmodulation (LM100-NTSC version), high or low signal levels, silence and incorrectly set dialnorm values.

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