[IRCA] IBOC power

["Dan Strassberg" <dan.strassberg@xxxxxxx>]

Several posters have mentioned incorrect powers for the MW HD Radio digital
sidebands. My understanding is that the combined power in the two digital
sidebands is not supposed to exceed 1/16 (6.25%) of the nominal power of the
analog carrier. Each digital sideband is allocated half of the total
digital-sideband power or 1/32 (3.125%) of the nominal analog-carrier power.
As someone else stated, each sideband contains multiple carriers, each
carrying 16-QAM modulation. The envelope detectors used in most AM receivers
apparently make this form of modulation sound a lot louder than you would
expect based on the relatively low digital-sideband power. I think the
exaggerated loudness occurs because the modulation index of the digital
sidebands is much higher than the average modulation index of the amplitude
modulation on the main carrier. In analog AM, the sideband power is variable
and more power goes into the analog sidebands as the signal gets louder. I
believe that QAM (like FM) is a form of modulation in which the sideband
power is constant (and therefore always maximum). If anything I've said in
this message is incorrect, please set me straight.

--
Dan Strassberg, dan.strassberg@xxxxxxx
eFax 707-215-6367






_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://dallas.hard-core-dx.com/mailman/listinfo/irca

Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers

For more information: http://www.ircaonline.org

To Post a message: irca@xxxxxxxxxxxxxxxx