Nautel Presents Adaptive Pre-correction in Real Time at the NAB Radio Show HD Radio Workshop

Bangor, ME (October 1, 2004) During the NAB Radio Show HD Radio workshop, Nautel presented a video showing the adaptive pre-correction capabilities of its new M50, direct-to-channel digital FM exciter.

“The high amplifier linearity required for HD Radio can be drastically affected by changes in the transmitter system” said Tim Hardy, Nautel’s Head of Development, during the presentation. Unfortunately, these can easily occur if there is a change in VSWR, an adjustment in the output power of the transmitter, a change in amplifier temperature, or aging and failures of RF amplifiers. Any one of these events can result in serious deviations to the HD Radio mask, poor sound quality, or even interference with other stations.

The M50 exciter monitors the output of Virtuoso transmitters and responds to changes by automatically ‘pre-correcting’ the RF signal. “This is a huge departure from alternative techniques for ensuring spectral integrity because broadcasters don’t have to install a bulky, expensive filter to keep their signals within the mask” commented Scott Martin, Nautel’s Primary Research Engineer, who led the development team.

This flexibility also means that Maestro exciters do not have to be matched to specific transmitters. A fixed pre-correction curve is not a sufficient solution to ensure spectral emissions in a changing environment. Nautel’s digital adaptive pre-correction works continuously to ensure optimum linearity is maintained even under unstable environmental conditions.