[AMRadio] Propagation question


johndtate at post.com johndtate at post.com
Wed Aug 18 16:23:53 EDT 2010


The culprit is selective fading....  You have a constant carrier on AM. 
  When it arrives at your antenna from more than one path (for instance 
ground wave and skywave) the singals arriving at different angles are 
likely out of phase causing attenuation or they may be in phase causing 
a brief gain.  It happens on all modes but because of the carrier, it's 
more pronounced in our ears on AM.  Popular methods to combat this is 
to use synchronous detection or diversity reception.

This is really a primitive explanation and I'm sure others can add to 
the subject.

73 John KX5JT


-----Original Message-----
From: Brian - KF5CCN <bzwiener at sbcglobal.net>
To: AMRadio at mailman.qth.net
Sent: Wed, Aug 18, 2010 12:23 pm
Subject: [AMRadio] Propagation question


This has been bugging me. Why do signals QSB up and down worse at times 
on AM
than SSB? Even on or near the same frequency. I was talking with a 
friend on
3890 KHz AM and we switched to 3897 KHz LSB and there was little or no 
fading.
Things that make me go, hmmmm.

73
Brian/KF5CCN


  
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