[BC] Eliminating the flutter (was: X-Banders)

[amstereoexp@yahoo.com]

Peter H. wrote:
 > One incredible fact is Class Cs sometimes get away with 225 degree
 > towers, and yet are still allowed 1/1 kW.
 >
 > The effective power from such a station is remarkable ... about 3,300
 > watts day and night ... ND, too.
 >
 > More than lots of ex-Class III Class Bs.
 >
 > Of course, their NIF may suck.

What makes nighttime co-channel interference on the "graveyard" channels
is not that there are so many stations on the air -- it's that these
stations are all transmitting at slightly different carrier frequencies,
causing carrier-beating that is received as a strong "fluttering" effect.

Thus, real-world NIF's would be drastically improved if all AM stations
locked their carrier to a reference standard, such as WWV or GPS.  There
would still be co-channel interference, but all that horrible fluttering
would virtually disappear.  And as B.E. documented in 1984, doing this
would also largely eliminate "platform motion" on first-generation C-Quam
receivers.

Or, to get this accomplished in a much simpler way, if each station
zero-beated its carrier to that of its nearest co-channel neighbor, then
that would also lead to a signification reduction in the destructive
fluttering.  This would especially help the little Class D's that are
"sharing" a clear channel with a 50 kW'er that infringes upon their
coverage area in the early morning and late afternoon.  For example, if
Willie zero-beated 1500 WFIF's carrier to WTOP's, I'm sure it would help
WFIF gain a few extra miles of useable coverage during "critical hours"
when WTOP's skywave is strong.

p.s. One notorious flutter-maker is 1510 WWZN in Boston.  Their carrier
must be at least 15 Hz off-center.  When it mixes with 1510 WLAC from
Nashville, the result is very strong and choppy fluttering, which not
only hurts WWZN's coverage, but also that of any other 1510'er in the
Northeast, such as 1510 WRNJ in Hackettstown, NJ (with 230 watts at
night).