FCC approves nighttime IBOC for AM

Larry Weil kc1ih@mac.com
Fri Mar 23 09:55:05 EST 2007

At 2:41 AM -0500 3/23/07, Bob Nelson wrote:

>The FCC voted to allow nighttime IBOC for AM (so much for DX-ing?) 
>and also to allow
>"HD multicasting without prior approval from the commission". Does 
>the latter mean
>they are no longer "experimental" (HD) and ads can now be run on them?
>for details:
>see "FCC Unanimous In Approval Of HD Radio Rules"

This probably strengthens the arguments by Sirius and XM in favor of 
their merger, in that they can now claim that there will still be 
competition for digital radio after their proposed merger.

On the subject of Hybrid Digital, but for FM, there is definitely a 
problem when there is a strong adjacent channel signal.  I realized 
the extent of this problem after I wrote to WUMB engineer Grady 
Moates about not being able to receive that station in HD.  He said 
(paraphrasing) that while HD is supposed to work if the receiver is 
able to receive one of the adjacent channels OK even if there is a 
signal on the other adjacent channel, but in practice he (and I) have 
found that if there is a strong signal on one of the adjacent 
channels you will not receive HD.

Thus, if I aim my antenna at Boston and tune to 91.9, WMWM on 91.7 
keeps me from receiving WUMB in HD.  And if I point my antenna at 
Newburyport and tune to 91.7 for their satellite station WNEF, WMWM 
is no longer a factor but WUML on 91.5 keeps me from hearing WNEF in 
HD.  And to think that I purchased the HD tuner primarily so I could 
hear WUMB more clearly!

Larry Weil
Lake Wobegone (North Salem), NH

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