BSO on the radio - not for me anymore

Bob DeMattia
Thu Oct 14 12:54:25 EDT 2010

*is HD2 the same or lower quality [bitrate] than HD1?  Or will that vary
depending on the station [WGBH in this case]?*

It depends on how the station wants to divide up the available bandwidth.
 Hybrid HD offers
100 - 150 kB/s which must be divided amongst the subchannels.

WGBH has three subchannels.  The HD3 rebroadcast of WCAI is news/talk, so
they are probably using a small
bit rate there (this is also why you see AM simulcasts like WBZ on 98.5 and
WEEI on 93.7 on the third subchannel).

Assuming they use an AM-quality bit rate (12 kB) for this one, that leaves
them with
80 - 138 kB to split amongst the two remaining channels.  Ibiquity considers
100kB to be CD quality and 50kB
to be FM quality.  So you could have two better-than-FM subchannels, or one
CD-quality subchannel and one
sub-par subchannel.

Maybe you can call the station and ask.  I imagine some better quality HD
receivers may also indicate the
bit rate of the received channel (I don't have one of these).


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