Re: [IRCA] Talking house on 1630 ruining DX on channel

["W. Curt Deegan" <WWWR@xxxxxxxxxxxxx>]

Bill,

You probably know all this, but just to be thorough I'll go through it 
anyway.

What you might be hearing is what has been termed a Sub Audible Het 
(SAH).  Two carriers so close in frequency they don't produce a typical het 
with a high enough frequency for a human to hear, hence sub audible.  The 
result is a fluctuating signal strength as the two carriers interfere with 
each other, like the old dueling ripples on a pond routine.  Same thing as 
a normal het, except since you can't really hear the tone, what you do 
perceive is the varying audio level.

The Wobbler is different in that it is the carrier of the Cuban station 
that is fluctuating in frequency, which accounts for the affect not being 
constant as you describe your local talking house.  As the wobbling station 
carrier fluctuates, it produces a varying het against any other stations or 
your receiver BFO.

We have a local TIS/MIS which uses synchronized transmitters across town 
from each other to assure coverage.  Only problem is their off by nearly 30 
Hz.  Where I am I hear both transmitters and the resulting rapidly chugging 
audio is infuriating.  At times the discrepancy has become bad enough the 
SAH turns into a very low AH -- Audible Het -- when heard on an audio 
system with a sub-woofer.

Curt
-------
W. Curt Deegan
Boca Raton, (southeast) Florida


At 04:48 PM 9/23/2006, you wrote:
>There is a Talking House on 1630 in my neighboorhood that is ruining
>DX on the channel.  They are broadcasting the normal message of
>descrbing the house and giving a couple of phone numbers to call, but
>the carrier (or something is wobbling).  It sounds close to the Cuban
>wobbler that DXers hear, except that is it steady and constant. The
>wobbling noise makes reception of anything else on the channel
>difficult.  I tracked down the house in my car and the message
>sounded fine within a few hundred feet, but then the wobbling starts
>once you get outside of a that.  I believe that the carrier is
>beating against the TISs in the daytime and the other more distant
>stations at night and that is causing the wobbling.
>
>A new logging for me, but I hope they sell the house soon.
>
>Bill Harms
>Elkridge, Maryland
>R8B
>K9AY
>300 foot longwire
>Dodge car radio


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