[Elecraft] Diversity Reception

Mon Aug 3 16:31:32 EDT 2015

I tend to agree with  Brian.

However, in my world, "true diversity" is attained from 2 identical 
receivers,  each having a separate antenna in two different locations.  
The source signal is a single transmitter.   The output of each receiver 
is fed to a circuit that determined the best signal-to-noise ratio and a 
couple of other qualitative factors. Then the "best" signal of the two 
was switched to the single output.  That determination and switching, 
all done electronically, could occur several hundred times per second.  
The result is the output signal appeared totally seamless to the 
listener.    There were no A+B or A-B configured signals.  That's 
another methodology.

I would suppose with two receivers, each feeding output to a single ear, 
one could use "brain power" to focus on one or the other of the two 
signals.  I think most would all agree, even today, the "brain filter" 
is still one of the best available.    However, if the receivers aren't 
identical, then the result can seemingly be totally random.   This would 
appear to present a condition where excessive listening fatigue might occur.

A similar method I employed some 25+ years ago was indeed using two 
antennas, one being a HF vertical and one being a  HF horizontal. These 
were configured with a switching network feeding one receiver.  This was 
done during the earlier days of Packet, AMTOR and such modes.  I devised 
a circuit that counted the error correction requests.  After a value of 
N, the system during a receive cycle, switched antennas.    It was 
interesting to watch as signals would fade on one antenna was observed 
to likely rise on the other.  The system greatly enhanced "through put" 
of the data transmissions.    Later I added a transmit power control to 
the system such that the transmitter reduced power in steps until the 
error rates increased.    Again this relied on the error correction 
request from the controller.   The system then stepped the power up in 
steps to a reliable power value.  The objective was to operate at 
minimum power based on propagation etc.  Ahhhh,  the days of "rolling 
your own" equipment and methods.

73 Bob, K4TAX

On 8/3/2015 1:32 PM, brain wrote:
> I really wonder about ab ab audio in diversity.   That is both rx 
> audio in both ears.  The "diversity" comes from the antenna. What does 
> the brain do worse in "diversity" with this ab ab mode of receiving?
>
> Since you can't do it with the current K3 software, where is the A/B 
> testing shows the superiority of listening to separate signals in each 
> ear.   I suppose there are papers out there on this.
>
> Unlike many,  in split mode I listen to both RX in both ears.   No 
> problem.  Adjustment of audio gain optimizes this situation on a per 
> station basis.
>
> 73 de Brian/K3KO
>
>
> On 8/3/2015 18:00 PM, Guy Olinger K2AV wrote:
>> Respectfully,
>>
>> This is not an issue of definition. I'm sure everyone agrees that
>> on-purpose listening to A-A is not diversity. What they are talking 
>> about
>> is a situational coping mechanism when using diversity as the main
>> listening mode in a contest.
>>
>> This occurs in diversity mode when one ear has a very weak desired 
>> signal
>> and the other a very loud undesired signal. My current coping 
>> mechanism for
>> this is to push one headphone bell forward off my ear. It would be 
>> better
>> to temporarily switch to both ears on desired signal, but this is *very*
>> clumsy using the front panel.
>>
>> A discussion on how to deal with it would be helpful. Using diversity in
>> contesting is a newly emerging skill that is only really emerging with
>> common usage of two receiver K3's.
>>
>> There needs to be a non-dismissive serious response to these 
>> concerns. If
>> there are hard technical reasons why this should be done external to 
>> the K3
>> it would be good to known these and move on to an external solution. It
>> does seem though like the straightforward treatment is somewhere 
>> inside the
>> K3 digital number soup.
>>
>> 73, Guy K2AV
>>
>> On Monday, August 3, 2015, Don Wilhelm <w3fpr at embarqmail.com> wrote:
>>
>>> Arie,
>>>
>>> The K3 may be in diversity, but you will only hear in diversity mode 
>>> when
>>> the audio is A-b.
>>> The diversity effect is 'in your head' as your ears naturally pick 
>>> up the
>>> differences between the two receivers and your brain figures out 
>>> which is
>>> the best to hear.
>>>
>>> When you have the audio set to A-A or b-b, you are hearing the audio 
>>> from
>>> only one receiver, and by definition, that is not diversity reception.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 8/3/2015 10:30 AM, Arie Kleingeld PA3A wrote:
>>>
>>>> Don,
>>>>
>>>> to set things up, I use a macro programmed in the F12-key in N1MM 
>>>> to copy
>>>> the freq/mode/BW  From A to B,  switch on the SubRx, set audio to A-b
>>>> listening and Link the VFO's. Switching of the audio is done in 
>>>> F9-F10-11
>>>> to A-b, A-A, or b-b respectively.
>>>>
>>>> Of course I would like that I could switch the audio when the K3 is in
>>>> diversity mode, but That cannot be done in current Firmware. In 
>>>> diversity
>>>> the audio is fixed to A-b.
>>>>
>>>>
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>
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