Topband: Back Scatter ?

[K1FZ-Bruce]

Thanks john,
 
Caught  a station ID and confirmed the station I am hearing on the 
back is the same as on the front. 
 
Closely watched the ground wave signal and there were a few DB of QSB. 
Would indicate there was some sky wave mixing. 
 
As you mentioned, when the reverse signal is ~ 8 S units down, the 
arrival angle of any sky wave can vary the  strength quite a lot. 
 
Between you,  Nick, and better monitoring, now understand what is happening. 
 
Appreciate the help. 
 
73
Bruce-K1FZ
 

On Mon, 20 Jun 2016 13:17:06 -0500, john battin  wrote:

       My observations using diversity reception with my 9 element 
array and very long phased beverages was that on the back side the 
qsb from the antennas was not in phase.  My explanation is that the 
nulls are very dependent on arrival angle and hence as the 
propagation wiggles the arrival angles a bit, the signal goes up and 
down. Only a few degrees of change  in arrival angle can easily take 
a 40db null down several db. 
 
John K9DX
 

 
> From: k1fz at myfairpoint.net
> To: topband at contesting.com
> Date: Mon, 20 Jun 2016 10:49:20 -0400
> Subject: Re: Topband: Back Scatter ?
> CC: nhp at ieee.org
>
>  
>  Nick.  The overall timing was irregular, but the slope of QSB took 
> a couple of seconds. This was at local noon time, so had not 
> considered other  stations.  
> We do not have high power BCB stations here in Maine. Only a little 
> over 1 million residents that widely  placed. Some  1 KW, 5 KW BCB 
> stations.  It is however possible in mid-coast Maine to hear WBZ 
> 1030 KHZ in Boston, at mid-day...  
> Thanks for the heads up. Appreciate your input. Will do more testing
>  
>  
> 73
> Bruce-K1FZ
>  
>
> On Thu, 16 Jun 2016 05:41:41 +0000, Nick Hall-Patch wrote:
>
> Hi Bruce,
>
> Does the QSB vary regularly at say a 0.5Hz or 1Hz rate? Could it be 
> another station on the channel that is not exactly the same 
> frequency, not strong enough to deliver audio, but strong enough to 
> create a sub-audible beat note?
>
> If it is irregular, shouldn't the traditional explanation of a touch 
> of high angle skywave interfering with the small amount of ground 
> wave remaining after nulling the station be sufficient to explain the 
> QSB?
>
> 73,
>
> Nick
>
> VE7DXR
>
> At 15:20 15-06-16, K1FZ-Bruce wrote:
>
> Been working to optimize the F/B on some antennas, using ground wave 
> stations in the upper BCB band. Noticed that some weaker ~20 mile 
> distant 5 KW stations that the back (reverse) signal
> has QSB on them. Think we used to call it back scatter years ago. 
> Some are down in the noise and QSB up to about 1 S unit. We used to 
> think back scatter was reflective variations in the ionosphere. Is 
> there any more recent information ? Maybe carbon in varying cloud 
> layers ?
>
> 73
> Bruce-k1fz
>
> http://www.qsl.net/k1fz/beverage_antenna.html
>
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