Elecraft

Linked VFO's -- usage?

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Joe Subich, W4TV-4

Re: Linked VFO's -- usage?

> My microHam box doesn't treat a/b audio in this manner. "B" audio is
> radio 2 with its own stereo audio output. and it labels a pair of
> stereo lines RX1 and RX2.

*Single radio* microHAM interfaces do *nothing* with headphone audio.

The microHAM MK2R+ (SO2R controller) can be programmed to switch any
combination of Radio 1 Left, Radio 1 Right, Radio 2 Left, Radio 2
Right, *unused* sound card Left, *unused* sound card right to the
user's left and/or right earphones. The programming uses microHAM's
proprietary command language available to legitimate developers under
NDA.

73,

... Joe, W4TV

On 2015-08-03 5:29 PM, Guy Olinger K2AV wrote:

> The counter to yet another mechanical outside box is that the ability
> to write firmware and update it inserts another very major
> possibility, that it can be done in the digital stream without need of
> extra cords and boxes.
>
> To use the mechanical box, we must physically route the audio to the
> box and plug in the headphones there. We have to mount the box so it
> doesn't move around. And worst of all, I have to make it.
>
> My microHam box doesn't treat a/b audio in this manner. "B" audio is
> radio 2 with its own stereo audio output. and it labels a pair of
> stereo lines RX1 and RX2. That deals with a pair of radios, not
> left/right stereo audio switching. So if I actually have two radios
> hooked up to it, no way to use it "creatively" to do the tricks just
> with the K3 in diversity.
>
> If I take my K3 anywhere else, like NY4A for multi contesting, I lose
> the function as what I get at NY4A is main antenna, RX antenna and
> power from the station, rather than a double of my now unique home
> station.
>
> Putting it in the digital functions makes it instantly portable.
>
> So, understanding your suggestion completely, and with no malice
> whatsoever, I decline, and still lean to the future with something
> that can be put in a macro stream sent to it from MM+ or whatever. I
> CAN take my MM+ macros with embedded K3 program commands.
>
> Feeding the A stream to the b audio just seems to be too easy in
> firmware, it's already done for non-diversity.
>
> Use of the diversity hold is problematic because it assumes that the
> unwanted half of the headphone audio is in the subRX side.
>
> 73, Guy
>

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Edward R Cole

Re: Diversity Reception

In reply to this post by Bob McGraw - K4TAX

Interesting statements from both Bob-K4TAX and Jim-K9YC. In both
cases they were addressing modes that one "hears" such as CW or voice
(SSB/AM/FM). I remember the commercial systems that used satellite
Rx and "voted" the best SNR signal to be passed to the audio
channel. And I also agree with the notion of listening to each
channel of a two RX diversity receivers sent to one's ears giving a
stereo "spacial" effect which the brain quickly adapts to.

However it is not always bad for the two diversity channels to be
combined for best signal. The example is digital signals which the
human brain cannot process. The example was given of using two
antennas of differing polarity for HF. The two signals received will
have orthogonal information which a computer program can process
(very similar to how I and Q signals are processed).

The phase angle can be recovered and the sum of the two signals
combined for best SNR signal. MAP65 does exactly that when fed by
two diversity Rx tied to the same LO so both phase and intensity info
reflect the polarity of the received signal. That's how my 2m
adaptive polarity receiving system works (and the K3 + KRX3 are
central in my diversity system).

I know of CW eme operators who use dual-pol diversity Rx and listen
to the signal using the A/B setup cited. As the signal changes
polarity it seems to move around the room (stereo effect).

At present there are two dual-pol diversity receiving systems
available for eme:
1. My system that uses the K3 as central Rx, and
2. The IQ+ which is a 2m dual channel SDR with direct conversion to baseband.

I believe I am the only one in the world currently using the K3 in
this application (mainly due to lack of dual-channel transverters; I
have a custom-made DEMI L144-28HP-DRX).

So many ways to enjoy diversity reception!

73, Ed - KL7UW
---------------------------------
On Mon,8/3/2015 1:31 PM, Bob McGraw - K4TAX wrote:
> I tend to agree with Brian.

I do as well. It's important to realize that a large percentage of
fading is the result of signals arriving from multiple paths, resulting
in slightly different travel times from the source. This time difference
results in phase shift directly proportional to the time difference and
to the frequency.

When heard on VHF/UHF, we call this "picket fencing," and the fading is
much more rapid because of the higher frequency/shorter wavelength. On
the much lower bands (AM broadcast, 160M) we call it selective fading,
and the time between peaks and nulls is much greater (proportional to
wavelength differences). Diversity reception for this kind of fading
depends on antennas at different locations -- the time differences, and
thus the phase shifts, will be different at the two locations, so a fade
(strong cancellation) at one location will usually not be a strong
cancellation at the other.

The most critical thing about diversity is that separation, and keeping
the two receivers close enough in frequency so that the ear/brain is not
bothered by the difference in the note.

Another point -- It is generally a bad idea to COMBINE (sum) the outputs
of the two receivers into a single electrical channel. Two reasons.
First, as Bob has noted, the ear/brain is really good at choosing
signals presented to two ears -- that's how we hear directionality, and
it's how stereo works. Indeed, stereo works on the TIME difference of
the sound reaching the two ears. Second, if the travel times to the two
antennas are sufficiently different, the AUDIO signals can be enough
different in phase and equal in amplitude that they cancel in the
electrical channel. When the electrical signals are directed separately
to L and R loudspeakers, there is relatively little cancellation, and
there is none in headphones with one radio per ear.

I've summarized this from the result of decades of experience with sound
systems, an extensive study of phychoacoustics (the science of how
humans hear), as well as from 60 years in ham radio.

73, Jim K9YC

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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Jim Brown-10

Re: Diversity Reception

On Mon,8/3/2015 8:41 PM, Edward R Cole wrote:
> However it is not always bad for the two diversity channels to be
> combined for best signal. The example is digital signals which the
> human brain cannot process. The example was given of using two
> antennas of differing polarity for HF.

Combining, yes -- into different inputs of the analysis system. Again,
when signals combine IN THE SAME SIGNAL CHANNEL (emphasis added)
differences in the time/phase response of the two signal paths can cause
destructive interference which degrades decoding.

OTOH, in a sophisticated decoding system, there's certainly nothing
wrong with bring both signals in on separate inputs, then combining
them, or choosing the best signal, or even processing the signals to
enhance readability. But ONLY combining them on a single electrical
channel is a bad idea.

One of my neighbors (near Santa Cruz) has a VERY interesting UHF
repeater system. It's multi-site(five sites going on six),voted (meaning
that the RX with the best signal is transmitted), and simulcast (all
sites transmit at the same time). To make this work, Bboth audio and RF
are synchronized to the Hz using a GPS reference and some really
innovative use of low cost audio and networking gear. If you're
interested, look at wb6ece.org, especially the Technical Info page,
where there's video and audio of a talk that KA6SQG did at Pacificon
about his system (WB6ECE is his dad's call). The audio is not well
recorded, so you'll need headphones for good copy.

73, Jim K9YC
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Vic Rosenthal

Re: Diversity Reception

I use diversity (vertically and horizontally polarized antennas) on CW a
lot, and there's more to it than just selecting the louder signal. I
can't put my finger on the precise mechanism, but it seems that CW
characters are less prone to being damaged by bursts of QRN in diversity
mode.

73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/

On 4 Aug 2015 07:32, Jim Brown wrote:

> On Mon,8/3/2015 8:41 PM, Edward R Cole wrote:
>> However it is not always bad for the two diversity channels to be
>> combined for best signal. The example is digital signals which the
>> human brain cannot process. The example was given of using two
>> antennas of differing polarity for HF.
>
> Combining, yes -- into different inputs of the analysis system. Again,
> when signals combine IN THE SAME SIGNAL CHANNEL (emphasis added)
> differences in the time/phase response of the two signal paths can cause
> destructive interference which degrades decoding.
>
> OTOH, in a sophisticated decoding system, there's certainly nothing
> wrong with bring both signals in on separate inputs, then combining
> them, or choosing the best signal, or even processing the signals to
> enhance readability. But ONLY combining them on a single electrical
> channel is a bad idea.
>
> One of my neighbors (near Santa Cruz) has a VERY interesting UHF
> repeater system. It's multi-site(five sites going on six),voted (meaning
> that the RX with the best signal is transmitted), and simulcast (all
> sites transmit at the same time). To make this work, Bboth audio and RF
> are synchronized to the Hz using a GPS reference and some really
> innovative use of low cost audio and networking gear. If you're
> interested, look at wb6ece.org, especially the Technical Info page,
> where there's video and audio of a talk that KA6SQG did at Pacificon
> about his system (WB6ECE is his dad's call). The audio is not well
> recorded, so you'll need headphones for good copy.
>
> 73, Jim K9YC
> ______________________________________________________________
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Arie Kleingeld PA3A-2

Re: Linked VFO's -- usage?

In reply to this post by Don Wilhelm-4

Don,

I know what diversity is Don, and I use it as you describe.
It just happens that I sometimes need to concentrate on one channel only
to make the QSO. That's where the A-A en b-b come into play. After
finishing and logging the QSO, I switch the K3 back into A-b with one
simple keystroke F9.

73
Arie

Don Wilhelm schreef op 3-8-2015 om 17:05:

> 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.
>>
>
>

Arie Kleingeld PA3A-2

Re: Linked VFO's -- usage?

In reply to this post by Guy Olinger K2AV

Thanks for your support Guy.
I have addressed this subject several times in the past (with no
success). I often use diversity in contests (ever since I have my K3,
which carries #1255).

Now that the K3 runs the diversity form one VFO and the problem of the
filter offsets seems to be solved, this is the last thing to improve.

73
Arie PA3A

Guy Olinger K2AV schreef op 3-8-2015 om 23:29:

Arie Kleingeld PA3A-2

Re: Diversity Reception

In reply to this post by Bob McGraw - K4TAX

Bob,

This is how I often use the diversity of my K3 (it has the sub RX, and
similar filters in Man and Sub RX)
- on 20m: one 3-el beam to NW on Main and a 5-el mono to NE on Sub
- on 160m: vertical on Main and receive 4-square on Sub
- on 40m: 3 el beam on Main, vertical on Sub
(It depends a bit on the antennas I can use at that time.)
If there's a weak station on one ear that I want to work, and loud
signals come battering on my other ear, I'd like to concentrate on one
channel to make it easier. Than I switch the audio to the channel I
want. After finishing the QSO I switch back to diversity.

Yes, the antenna's are not more than 50m apart but they have a totally
different receive pattern. I remember that during a DXpedition I was
working with a beam and had a vertical on the other RX. The guys I heard
on the vertical were copyable very well on the vertical. On the beam
they were buried under the pile-up in the beam direction.

Diversity is such a nice feature of the k3.

73
Arie

Bob McGraw - K4TAX schreef op 3-8-2015 om 22:31:
>
>
> >>> 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. <<<
> 73 Bob, K4TAX

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Edward R Cole

Re: Diversity Reception

In reply to this post by Bob McGraw - K4TAX

Inserted comments, below:
----------
Date: Mon, 3 Aug 2015 21:32:33 -0700
From: Jim Brown <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] Diversity Reception
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=windows-1252; format=flowed

On Mon,8/3/2015 8:41 PM, Edward R Cole wrote:
> However it is not always bad for the two diversity channels to be
> combined for best signal. The example is digital signals which the
> human brain cannot process. The example was given of using two
> antennas of differing polarity for HF.

Combining, yes -- into different inputs of the analysis system. Again,
when signals combine IN THE SAME SIGNAL CHANNEL (emphasis added)
differences in the time/phase response of the two signal paths can cause
destructive interference which degrades decoding.

# Yes, simple combining of RF signal would result in such effects.

OTOH, in a sophisticated decoding system, there's certainly nothing
wrong with bring both signals in on separate inputs, then combining
them, or choosing the best signal, or even processing the signals to
enhance readability. But ONLY combining them on a single electrical
channel is a bad idea.

# Our dual-pol adaptive eme system is done in digital domain with DSP
where channel amplitude and phase angle can be separated for
re-combination using sw which accomplishes vector addition of the
signal to produce display of polarity angle and constructive addition
of signals. Both Linrad and MAP65 can perform these computations.

One of my neighbors (near Santa Cruz) has a VERY interesting UHF
repeater system. It's multi-site(five sites going on six),voted (meaning
that the RX with the best signal is transmitted), and simulcast (all
sites transmit at the same time). To make this work, Bboth audio and RF
are synchronized to the Hz using a GPS reference and some really
innovative use of low cost audio and networking gear. If you're
interested, look at wb6ece.org, especially the Technical Info page,
where there's video and audio of a talk that KA6SQG did at Pacificon
about his system (WB6ECE is his dad's call). The audio is not well
recorded, so you'll need headphones for good copy.

73, Jim K9YC

# My only exposure was with Motorola voting systems for commercial FM
2-way communications. I did not do much with such here in AK. I
believe one ham 2m repeating system used a couple voted satellite
receivers. Occasionally they would hunt a little causing a chopped signal.

73, Ed

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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