Re: [IRCA] Synching-up--would attempting to revive this 70+ year-oldtechnology make any sense?

["Craig Healy" <bubba@xxxxxxxxxxxxxxxxxxxx>]

> The satellite-based
> scheme should not be extraordinarily expensive to implement. My question
is
> whether it would have any value. Would elimination of the sub-audio
> heterodyne between the carriers improve the listenability of the signal
from
> stations subject to co-channel interference from a single dominant
station?

If you remember from the Broadcast list, Willie at WFIF-1500 in CT went
through his efforts at minimizing the interference from WTWP.  He tried a
number of frequency settings on the WFIF transmitter to see what was most
comfortable.  When things were essentially synched, he said it caused dead
spots.  Anything over 10Hz was unpleasant.  He finally settled on a 5Hz
offset which seemed the best in a bad situation.

Having the carriers exactly synchronized would lead to rolling dead spots,
depending on propagation.

When dealing with predominantly groundwave as in the WLLH scenario, having
the carriers locked is necessary.  The dead spots are hopefully in a
less-populated area, and don't move.

The HD Radio stations I believe are locked to GPS, so are not going to be
offset by any measureable amount.  I can't say as I know of two IBOC
stations on the same channel that are close enough to affect each other, so
that will remain unknown.

Craig Healy
Providence, RI

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