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Dual Receiver Tricks

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Dick Dickinson

Dual Receiver Tricks

A late model SDR Receiver (only) is said to have a soon to be released
software update. I've seen a demonstration whereby using 2 antennas and a
computer device, the unit will be able (to some degree?) determine signal
direction.

Does Elecraft have plans to develop K4D software with such capabilities or
sanction 3rd party development of such? Will there be other software /
firmware development to come with the K4D beyond that of a dual receiver
K3/s?

Lastly, beyond control and perhaps IF output, will the K4 receiver(s) be
able to interface with external 'computers?' (No, I'm not sure what I mean
by that!)

Kindly,

Dick - KA5KKT

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David Gilbert

Re: Dual Receiver Tricks

Over the past few years I have twice requested Elecraft include
something like that as a software modification, but nobody (either at
Elecraft or here on the list) seems interested in the least. Since phase
is preserved during down conversion in a superhet circuit the software
crunching could even be done at audio ... it isn't required to be done
at RF. It doesn't require the K4 either ... the K3 and K3s with the new
synths also make it feasible.

In addition to simply determining signal direction, the software would
potentially be able to equalize volume from the two receivers (generally
required since typically two different antennas would be used) and then
add or subtract the two signals to peak a desired signal or null an
unwanted one. The equalization could be done in software while the
phase shifting would be manual and require a repurposing of a knob. DX
Engineering sells a stand alone unit for over $700 that performs these
same functions at RF, while a software mod could do the same for free
(to us ... obviously it would take a commitment of coding resources from
Elecraft).

Elecraft has already said that they would at some indeterminate time in
the future consider sanctioning well-chosen and trusted third party
software developers for ancillary applications for the K4, but I'd like
to see this capability for my K3 as well.

As an aside, it would theoretically be possible to investigate arrival
angles using two horizontally polarized antennas placed one above the
other a known distance apart. At the least it might even allow a user
to discriminate between two interfering signals from the same azimuth
but arriving at different vertical angles.

73,
Dave AB7E

On 6/25/2019 8:14 AM, Dick Dickinson wrote:

> A late model SDR Receiver (only) is said to have a soon to be released
> software update. I've seen a demonstration whereby using 2 antennas and a
> computer device, the unit will be able (to some degree?) determine signal
> direction.
>
>
>
> Does Elecraft have plans to develop K4D software with such capabilities or
> sanction 3rd party development of such? Will there be other software /
> firmware development to come with the K4D beyond that of a dual receiver
> K3/s?
>
>
>
> Lastly, beyond control and perhaps IF output, will the K4 receiver(s) be
> able to interface with external 'computers?' (No, I'm not sure what I mean
> by that!)
>
>
>
>
>
> Kindly,
>
> Dick - KA5KKT
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Bill K9YEQ

Re: Dual Receiver Tricks

Dave, the two receivers fed from two antennas give you what you are looking for at rf level. It works super well. On upper bands I have used SteppIR short vert with dipole. My experience has been excellent vs single antenna.

Bill
920-421-1172

________________________________
From: [hidden email] <[hidden email]> on behalf of David Gilbert <[hidden email]>
Sent: Tuesday, June 25, 2019 7:07:55 PM
To: [hidden email]
Subject: Re: [Elecraft] Dual Receiver Tricks

Over the past few years I have twice requested Elecraft include
something like that as a software modification, but nobody (either at
Elecraft or here on the list) seems interested in the least. Since phase
is preserved during down conversion in a superhet circuit the software
crunching could even be done at audio ... it isn't required to be done
at RF. It doesn't require the K4 either ... the K3 and K3s with the new
synths also make it feasible.

In addition to simply determining signal direction, the software would
potentially be able to equalize volume from the two receivers (generally
required since typically two different antennas would be used) and then
add or subtract the two signals to peak a desired signal or null an
unwanted one. The equalization could be done in software while the
phase shifting would be manual and require a repurposing of a knob. DX
Engineering sells a stand alone unit for over $700 that performs these
same functions at RF, while a software mod could do the same for free
(to us ... obviously it would take a commitment of coding resources from
Elecraft).

Elecraft has already said that they would at some indeterminate time in
the future consider sanctioning well-chosen and trusted third party
software developers for ancillary applications for the K4, but I'd like
to see this capability for my K3 as well.

As an aside, it would theoretically be possible to investigate arrival
angles using two horizontally polarized antennas placed one above the
other a known distance apart. At the least it might even allow a user
to discriminate between two interfering signals from the same azimuth
but arriving at different vertical angles.

73,
Dave AB7E

On 6/25/2019 8:14 AM, Dick Dickinson wrote:

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David Gilbert

Re: Dual Receiver Tricks

Not sure what you are describing. If you mean two antennas feeding two
receivers at RF for diversity reception, yes ... that works well but is
not the same thing at all. Your brain is doing some spatial processing,
but it doesn't peak or null. It also, as is apparent from the antennas
you cite, compensates for polarization changes that would otherwise
cause fading ... but it isn't peak/null.

If instead you are talking about being able to adjust phase and adding
or subtracting the result, that can be done at RF but it definitely
requires additional hardware. You can't get there with just the K3 or
K4 as is.

And none of what you describe would give you a numerical azimuth (or
elevation) indication as the original post described.

Dave AB7E

On 6/25/2019 6:19 PM, Bill Johnson wrote:

> Dave, the two receivers fed from two antennas give you what you are
> looking for at rf level. It works super well. On upper bands I have
> used SteppIR short vert with dipole. My experience has been
> excellent vs single antenna.
>
> Bill
> 920-421-1172
>
> ------------------------------------------------------------------------
> *From:* [hidden email]
> <[hidden email]> on behalf of David Gilbert
> <[hidden email]>
> *Sent:* Tuesday, June 25, 2019 7:07:55 PM
> *To:* [hidden email]
> *Subject:* Re: [Elecraft] Dual Receiver Tricks
>
> Over the past few years I have twice requested Elecraft include
> something like that as a software modification, but nobody (either at
> Elecraft or here on the list) seems interested in the least. Since phase
> is preserved during down conversion in a superhet circuit the software
> crunching could even be done at audio ... it isn't required to be done
> at RF. It doesn't require the K4 either ... the K3 and K3s with the new
> synths also make it feasible.
>
> In addition to simply determining signal direction, the software would
> potentially be able to equalize volume from the two receivers (generally
> required since typically two different antennas would be used) and then
> add or subtract the two signals to peak a desired signal or null an
> unwanted one. The equalization could be done in software while the
> phase shifting would be manual and require a repurposing of a knob. DX
> Engineering sells a stand alone unit for over $700 that performs these
> same functions at RF, while a software mod could do the same for free
> (to us ... obviously it would take a commitment of coding resources from
> Elecraft).
>
> Elecraft has already said that they would at some indeterminate time in
> the future consider sanctioning well-chosen and trusted third party
> software developers for ancillary applications for the K4, but I'd like
> to see this capability for my K3 as well.
>
> As an aside, it would theoretically be possible to investigate arrival
> angles using two horizontally polarized antennas placed one above the
> other a known distance apart. At the least it might even allow a user
> to discriminate between two interfering signals from the same azimuth
> but arriving at different vertical angles.
>
> 73,
> Dave AB7E
>
>
> On 6/25/2019 8:14 AM, Dick Dickinson wrote:
> > A late model SDR Receiver (only) is said to have a soon to be released
> > software update. I've seen a demonstration whereby using 2 antennas
> and a
> > computer device, the unit will be able (to some degree?) determine
> signal
> > direction.
> >
> >
> >
> > Does Elecraft have plans to develop K4D software with such
> capabilities or
> > sanction 3rd party development of such? Will there be other software /
> > firmware development to come with the K4D beyond that of a dual receiver
> > K3/s?
> >
> >
> >
> > Lastly, beyond control and perhaps IF output, will the K4 receiver(s) be
> > able to interface with external 'computers?' (No, I'm not sure what
> I mean
> > by that!)
> >
> >
> >
> >
> >
> > Kindly,
> >
> > Dick - KA5KKT
> >
> >
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
> >
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Bill K9YEQ

Re: Dual Receiver Tricks

You are correct, I didn't acknowledge peak - null situations. I generally thought this was also done using antennas, which was perhaps your point which I had no interest.

Bill
920-421-1172

________________________________
From: David Gilbert <[hidden email]>
Sent: Tuesday, June 25, 2019 8:36:44 PM
To: Bill Johnson; [hidden email]
Subject: Re: [Elecraft] Dual Receiver Tricks

Not sure what you are describing. If you mean two antennas feeding two receivers at RF for diversity reception, yes ... that works well but is not the same thing at all. Your brain is doing some spatial processing, but it doesn't peak or null. It also, as is apparent from the antennas you cite, compensates for polarization changes that would otherwise cause fading ... but it isn't peak/null.

If instead you are talking about being able to adjust phase and adding or subtracting the result, that can be done at RF but it definitely requires additional hardware. You can't get there with just the K3 or K4 as is.

And none of what you describe would give you a numerical azimuth (or elevation) indication as the original post described.

Dave AB7E

On 6/25/2019 6:19 PM, Bill Johnson wrote:
Dave, the two receivers fed from two antennas give you what you are looking for at rf level. It works super well. On upper bands I have used SteppIR short vert with dipole. My experience has been excellent vs single antenna.

Bill
920-421-1172

________________________________
From: [hidden email]<mailto:[hidden email]> <[hidden email]><mailto:[hidden email]> on behalf of David Gilbert <[hidden email]><mailto:[hidden email]>
Sent: Tuesday, June 25, 2019 7:07:55 PM
To: [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] Dual Receiver Tricks

Over the past few years I have twice requested Elecraft include
something like that as a software modification, but nobody (either at
Elecraft or here on the list) seems interested in the least. Since phase
is preserved during down conversion in a superhet circuit the software
crunching could even be done at audio ... it isn't required to be done
at RF. It doesn't require the K4 either ... the K3 and K3s with the new
synths also make it feasible.

In addition to simply determining signal direction, the software would
potentially be able to equalize volume from the two receivers (generally
required since typically two different antennas would be used) and then
add or subtract the two signals to peak a desired signal or null an
unwanted one. The equalization could be done in software while the
phase shifting would be manual and require a repurposing of a knob. DX
Engineering sells a stand alone unit for over $700 that performs these
same functions at RF, while a software mod could do the same for free
(to us ... obviously it would take a commitment of coding resources from
Elecraft).

Elecraft has already said that they would at some indeterminate time in
the future consider sanctioning well-chosen and trusted third party
software developers for ancillary applications for the K4, but I'd like
to see this capability for my K3 as well.

As an aside, it would theoretically be possible to investigate arrival
angles using two horizontally polarized antennas placed one above the
other a known distance apart. At the least it might even allow a user
to discriminate between two interfering signals from the same azimuth
but arriving at different vertical angles.

73,
Dave AB7E

On 6/25/2019 8:14 AM, Dick Dickinson wrote:

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Bob McGraw - K4TAX

Re: Dual Receiver Tricks

Some years ago when operating HF packet in S. FL., I built an antenna
switching arrangement which would take the error signal from my PK-232,
count the errors and at some point switch to the other antenna.   One
antenna was an 80M inverted V, the other was a Butternut vertical
mounted over a salt water tidal canal. I generally found when the
signal faded, thus more errors, on one antenna the signal was stronger
on the other.   The system switched antennas during the receive cycle.
    I also incorporated a power control system which looked at each
packet acknowledgement and would reduce TX power a small amount. After
a number N of missed acknowledgements it would increase power in small
amounts.    It was nice to have a radio which I could control power by
applying a few volts to the ALC input.

The aluminum Butternut vertical over tidal salt water presented one
issue, which was the SWR changed multiple times per day as the tide
cycle rise and fall. The SWR change wasn't a lot but clearly noticeable
a 3' to 5' tide change. In effect the ground moved up and down,
regardless of the amount of copper buried in the canal bottom.   I guess
that stuff is still there as we moved away and left it in the canal.
Oh, the Butternut is now located in my shop, clean and ready to install
again.   It has only been there 23 years and I still plan to get around
to it.........one of these days.

The things hams won't try and do.

73

Bob, K4TAX

On 6/25/2019 9:31 PM, Bill Johnson wrote:

> You are correct, I didn't acknowledge peak - null situations. I generally thought this was also done using antennas, which was perhaps your point which I had no interest.
>
> Bill
> 920-421-1172
>
> ________________________________
> From: David Gilbert <[hidden email]>
> Sent: Tuesday, June 25, 2019 8:36:44 PM
> To: Bill Johnson; [hidden email]
> Subject: Re: [Elecraft] Dual Receiver Tricks
>
>
>
> Not sure what you are describing. If you mean two antennas feeding two receivers at RF for diversity reception, yes ... that works well but is not the same thing at all. Your brain is doing some spatial processing, but it doesn't peak or null. It also, as is apparent from the antennas you cite, compensates for polarization changes that would otherwise cause fading ... but it isn't peak/null.
>
> If instead you are talking about being able to adjust phase and adding or subtracting the result, that can be done at RF but it definitely requires additional hardware. You can't get there with just the K3 or K4 as is.
>
> And none of what you describe would give you a numerical azimuth (or elevation) indication as the original post described.
>
> Dave AB7E
>
>
> On 6/25/2019 6:19 PM, Bill Johnson wrote:
> Dave, the two receivers fed from two antennas give you what you are looking for at rf level. It works super well. On upper bands I have used SteppIR short vert with dipole. My experience has been excellent vs single antenna.
>
> Bill
> 920-421-1172
>
> ________________________________
> From: [hidden email]<mailto:[hidden email]> <[hidden email]><mailto:[hidden email]> on behalf of David Gilbert <[hidden email]><mailto:[hidden email]>
> Sent: Tuesday, June 25, 2019 7:07:55 PM
> To: [hidden email]<mailto:[hidden email]>
> Subject: Re: [Elecraft] Dual Receiver Tricks
>
>
> Over the past few years I have twice requested Elecraft include
> something like that as a software modification, but nobody (either at
> Elecraft or here on the list) seems interested in the least. Since phase
> is preserved during down conversion in a superhet circuit the software
> crunching could even be done at audio ... it isn't required to be done
> at RF. It doesn't require the K4 either ... the K3 and K3s with the new
> synths also make it feasible.
>
> In addition to simply determining signal direction, the software would
> potentially be able to equalize volume from the two receivers (generally
> required since typically two different antennas would be used) and then
> add or subtract the two signals to peak a desired signal or null an
> unwanted one. The equalization could be done in software while the
> phase shifting would be manual and require a repurposing of a knob. DX
> Engineering sells a stand alone unit for over $700 that performs these
> same functions at RF, while a software mod could do the same for free
> (to us ... obviously it would take a commitment of coding resources from
> Elecraft).
>
> Elecraft has already said that they would at some indeterminate time in
> the future consider sanctioning well-chosen and trusted third party
> software developers for ancillary applications for the K4, but I'd like
> to see this capability for my K3 as well.
>
> As an aside, it would theoretically be possible to investigate arrival
> angles using two horizontally polarized antennas placed one above the
> other a known distance apart. At the least it might even allow a user
> to discriminate between two interfering signals from the same azimuth
> but arriving at different vertical angles.
>
> 73,
> Dave AB7E
>
>
> On 6/25/2019 8:14 AM, Dick Dickinson wrote:
>> A late model SDR Receiver (only) is said to have a soon to be released
>> software update. I've seen a demonstration whereby using 2 antennas and a
>> computer device, the unit will be able (to some degree?) determine signal
>> direction.
>>
>>
>>
>> Does Elecraft have plans to develop K4D software with such capabilities or
>> sanction 3rd party development of such? Will there be other software /
>> firmware development to come with the K4D beyond that of a dual receiver
>> K3/s?
>>
>>
>>
>> Lastly, beyond control and perhaps IF output, will the K4 receiver(s) be
>> able to interface with external 'computers?' (No, I'm not sure what I mean
>> by that!)
>>
>>
>>
>>
>>
>> Kindly,
>>
>> Dick - KA5KKT
>>
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]<mailto:[hidden email]>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]<mailto:[hidden email]>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Edward R Cole

Re: Dual Receiver Tricks

In reply to this post by Dick Dickinson

Dave AB7E,

I have been doing something similar with my K3 with subRx:

I feed signals from two antenna that are orthogonally polarized (one
is horz and other is Vert polarity, both pointed in the same
direction and essentially in-phase).
I use the eme sw MAP-65 to process the output of both Rx and it
resolves the angle of polarization and maxes signal strength in
alignment with the actual angle of polarity. There is another sw
called Linrad that can do that for two signals (written in Linux).
http://www.sm5bsz.com/linuxdsp/linrad.htm

MAP-65 is authored by Joe Taylor - K1JT who also created FT8 and
FT4. You might contact Joe about your ideas and maybe he would be
interested in creating the sw you want??

73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[hidden email]

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Jim Brown-10

Re: Dual Receiver Tricks

Some words are being misunderstood and mis-used.

Polarization describes the geometric orientation of the antenna and the
resulting EM field. Polarity is the positive or negative going sense of
voltage or current in a circuit (what for decades we mistakenly called
"in phase/out of phase). Polarity has two values, positive or reverse.
We change the polarity by turning the wires over in a circuit.

Phase is a continuously valued function and is measured in degrees or
radians. The phase relationship between two signals has meaning only for
sine waves of the same frequency. The phase relationship between
antennas is a function of the distance between them, the frequency of
each signal they transmit or receive. Further, this phase relationship
is different for every angle from which a signal arrives or to which it
is transmitted. The phase relationship also includes the electrical
lengths of the transmission lines involved, and, of course, the
difference in phase increases in proportion to the frequency of the signal.

There's a tutorial discussion of these concepts in
http://k9yc.com/VE3DO.pdf in the context of how the DX Engineering NCC-1
and NCC-2 work to steer the directivity of two spaced antennas. The same
laws of physics are at play in this discussion.

73, Jim K9YC

On 6/26/2019 9:20 PM, Edward R Cole wrote:
> I feed signals from two antenna that are orthogonally polarized (one
> is horz and other is Vert polarity, both pointed in the same direction
> and essentially in-phase).
> I use the eme sw MAP-65 to process the output of both Rx and it
> resolves the angle of polarization and maxes signal strength in
> alignment with the actual angle of polarity.

______________________________________________________________
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David Gilbert

Re: Dual Receiver Tricks

I agree that Ed misused the term "polarity" at the end of his post, but
I'm pretty sure it was a slip of the pen (keyboard) because he has been
doing this stuff for a long time. I'm pretty certain he meant
"polarization". I know he has done some work (and written about it)
using cross polarized antennas (orthogonal and spaced a bit apart fore
and aft relative to the arriving signal) to measure both the degree and
direction of ellipsoid arriving signals, and I remember that he took
great pains to account for differences in the feedline delays.

When he's simply looking for the tilt angle and not the handedness of
the ellipse, as he states below the two orthogonal antennas are in the
same plane ... but if the arriving signal is circularly polarized the
phase will indeed appear to be different between the two antennas. If
the arriving signal isn't particularly circular but simply has a
polarization tilt, the phase difference would be small and the
differences in amplitude would indicate the angle of tilt.

Be sure to correct me if I'm wrong here, Ed. I'm doing my best to
visualize this stuff.

I think Ed is telling me in in his post below the name of some software
that allows him to compare the two signals, and presumably that is the
case for both amplitude which he is using to get the tilt angle, and for
phase, which I want to use to get arrival angle using two horizontal
antennas one above the other or azimuth using two vertical antennas
spaced laterally. It will be interesting to see if that does the job.

As I once posted in the past, I have previously fed the audio from both
K3 receivers while tuned to the same frequency in diversity mode ...
with the signals coming from two different antennas, one above the other
by a known distance ... into the sound card of my computer running a
simple dual trace audio oscilloscope application. By triggering on one
of the signals while looking at the delay in the other signal I could
get an approximate indication of the change in arrival angle over time,
so I know the concept is valid. To get a clean reading I used some 40m
AM broadcast carriers during periods when there was no modulation, such
as between programs. The angle changed 10 to 15 degrees in fractions of
a second, and if had been able to accurately know the delay difference
between the two feedlines I would have been able to calculate the
absolute arrival angles instead of just the changes.

To be honest, the software necessary to do all of this should be fairly
straightforward. I'm just not knowledgeable enough to code it myself.
From my perspective it should also be possible to do it inside the K3,
K3s, or K4, but if that doesn't happen (and it appears that it won't)
I'll try to figure out how to do it with a separate application.

As you say, all of this can be accomplished at RF as is done with the DX
Engineering boxes ... but it can be done more simply at audio via
software (at least for receive) since phase is preserved upon down
converting.

73,
Dave AB7E

On 6/26/2019 10:11 PM, Jim Brown wrote:

> Some words are being misunderstood and mis-used.
>
> Polarization describes the geometric orientation of the antenna and
> the resulting EM field. Polarity is the positive or negative going
> sense of voltage or current in a circuit (what for decades we
> mistakenly called "in phase/out of phase). Polarity has two values,
> positive or reverse. We change the polarity by turning the wires over
> in a circuit.
>
> Phase is a continuously valued function and is measured in degrees or
> radians. The phase relationship between two signals has meaning only
> for sine waves of the same frequency. The phase relationship between
> antennas is a function of the distance between them, the frequency of
> each signal they transmit or receive. Further, this phase relationship
> is different for every angle from which a signal arrives or to which
> it is transmitted. The phase relationship also includes the electrical
> lengths of the transmission lines involved, and, of course, the
> difference in phase increases in proportion to the frequency of the
> signal.
>
> There's a tutorial discussion of these concepts in
> http://k9yc.com/VE3DO.pdf in the context of how the DX Engineering
> NCC-1 and NCC-2 work to steer the directivity of two spaced antennas.
> The same laws of physics are at play in this discussion.
>
> 73, Jim K9YC
>
> On 6/26/2019 9:20 PM, Edward R Cole wrote:
>> I feed signals from two antenna that are orthogonally polarized (one
>> is horz and other is Vert polarity, both pointed in the same
>> direction and essentially in-phase).
>> I use the eme sw MAP-65 to process the output of both Rx and it
>> resolves the angle of polarization and maxes signal strength in
>> alignment with the actual angle of polarity.
>
>
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