Posted by
David Gilbert on
Sep 16, 2010; 6:20pm
URL: http://elecraft.85.s1.nabble.com/K3-Diversity-Reception-and-Antenna-Directivity-tp5537531p5539792.html
Hi, Bill.
All true, but I thought that implementing it at audio might have some
advantages ... assuming at least that someone already had the sub receiver:
a. Cheaper. The DXE unit is $500 ... considerably more than that if
you buy the active antennas as well.
b. More versatile. Since the audio can be easily digitized using the
sound card, almost anything could be done with the result via software.
c. No need for separate receive and transmit antennas, or to maintain a
large spacing between receive and transmit antennas.
Alan has verified your point about relative phase of the two receivers
changing with frequency, so that indeed would have to be accounted for.
It's also true that something like a 4-Square would have a major
advantage by offering gain on transmit as well as pattern on receive.
In any case, I only suggested all of this for possible exploration. I
don't have anything at stake here if it turns out to be a dumb idea.
73,
Dave AB7E
On 9/16/2010 9:49 AM, Bill W4ZV wrote:
>
> David Gilbert wrote:
>>
>> Playing around with this stuff got me thinking, though. What if I fed
>> the output from two VERTICAL antennas into the K3 receivers in diversity
>> mode, fed the audio output of both receivers into the A and B channels
>> of the computer sound card, and used an application that introduced an
>> adjustable delay in one audio channel before summing the two channels
>> and doing the D/A translation back to monaural audio? Wouldn't that
>> have the exact same effect as being able to adjust the phase of the
>> incoming RF, and therefore the directivity of the 2 element vertical
>> array?
>>
> Good idea, already implemented by MFJ, DXE and others:
>
>
http://www.mfjenterprises.com/Product.php?productid=MFJ-1025>
http://www.dxengineering.com/Parts.asp?ID=1227&PLID=215&SecID=114&DeptID=12&PartNo=DXE-NCC-1>
> This reminds me of one SDR guru who proposed using 4 SDR transceivers to
> emulate a 4-square. A multi-K$ solution to a $350 problem (i.e. one 4SQ
> controller box)...not to mention the need for 4 separate feedlines, 4
> amplifiers, etc.
>
> 73, Bill
>
> P.S. I believe one problem with what you proposed above is that phase would
> need to be readjusted every time you touched the VFO...i.e. phase is locked
> (i.e. meaning the phase differential is fixed) but the actual phase offset
> between the two RXs changes each time the synthesizer changes. Lyle can
> correct me if I'm wrong.
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