[Flexradio] Diversity Reception for Flex 5000 owners

[Bob McGwier]

Eric and I have begun adding the diversity reception capability to the
Flex 5000. It will work for those 5000's which have the RX2 installed.
In my diversity branch, one can find the enabled code. It is VERY
rough but as you can tell from Lee's blog:

http://w9oy-sdr.blogspot.com/

the software antenna diversity can be used for signal enhancement by
increased gain or by noise source nulling.

It is rough to use and must be done manually for now.

If you start running the code

svn co
svn://206.216.146.154/svn/repos_sdr_windows/PowerSDR/branches/n4hy/diversity/bin/Release

you will be able to type ctrl-alt-D and bring up the form that you can
see on Lee's blog. With RX1 and RX2 hooked to separate antennas, you
"tune the array" using the right hand side of the DSP form.

When you bring it up, and you have set RX1 and RX2 to the same mode and
filter size, you click "sync" and then enable. This does several
things. It locks the two VFO's together in hardware and then enable
does it in software as well.

You then play with mag, angle, and gain to optimize the signal you are
wishing to listen to. This is pretty rough, but it does work. This
will be automated for HF Shortwave folks in SAM-Diversity as soon as
possible to do automated signal combining and as we learn from that, we
will add additional capabilities. After this is completely vetted and
made easier to use, it will be added to the main stream.

THANK YOU to Lee for doing this blog entry and adding the mp3's showing
the effects.

Bob

[Frank Brickle]

FWIW there is an article by Victor K1LT for QEX about work with this same
technique, using multiple SoftRocks and Linux DttSP. Victor has been
developing his own software for phased combining of multiple antenna inputs
for a couple of years now, with considerable success, as related in the
article.

73
Frank
AB2KT

Eric and I have begun adding the diversity reception capability to the Flex
5000...

[Bob McGwier]

Post by Frank Brickle
FWIW there is an article by Victor K1LT for QEX about work with this same
technique, using multiple SoftRocks and Linux DttSP. Victor has been
developing his own software for phased combining of multiple antenna inputs
for a couple of years now, with considerable success, as related in the
article.
73
Frank
AB2KT

Eric and I have begun adding the diversity reception capability to the Flex
5000...

I saw that work written up in QEX. I don't know what he did with Linux
DttSP but to do it right several things need synchronization.

In the current code implementation I needed to barrier across threads

1) to get the software oscillators to line up and shared across the
receivers
2) to do the processing down to just before the agc
and finally
3) to have the combined output appear before the threads are released to
wait on new samples.

I will do what is necessary in my branches and you can then help me do
it the way you want it done from there.

Bob

[Jim Barber]

Not being familiar with the architecture or sources, would there be any
value in developing a 2-input, LMS-style noise reduction scheme using
the same antenna for both receivers and a small frequency offset? (RX2
would be tuned to an unoccupied "noise" frequency as close as possible
to the "active" RX1 operating frequency)

That technique has been successfully used elsewhere and has the
advantage of adaptively canceling any static or long-term difference in
"phase" between the signals. (primarily group delay in this case?). The
obvious disadvantage is having to choose a suitable noise frequency on a
busy band, assuming one is available.

Thoughts?

Thanks,
Jim Barber, N7CXI

Post by Bob McGwier
Eric and I have begun adding the diversity reception capability to the
Flex 5000. It will work for those 5000's which have the RX2
installed. In my diversity branch, one can find the enabled code.
http://w9oy-sdr.blogspot.com/
the software antenna diversity can be used for signal enhancement by
increased gain or by noise source nulling.
It is rough to use and must be done manually for now.
If you start running the code
svn co
svn://206.216.146.154/svn/repos_sdr_windows/PowerSDR/branches/n4hy/diversity/bin/Release
you will be able to type ctrl-alt-D and bring up the form that you can
see on Lee's blog. With RX1 and RX2 hooked to separate antennas, you
"tune the array" using the right hand side of the DSP form.
When you bring it up, and you have set RX1 and RX2 to the same mode
and filter size, you click "sync" and then enable. This does several
things. It locks the two VFO's together in hardware and then enable
does it in software as well.
You then play with mag, angle, and gain to optimize the signal you are
wishing to listen to. This is pretty rough, but it does work. This
will be automated for HF Shortwave folks in SAM-Diversity as soon as
possible to do automated signal combining and as we learn from that,
we will add additional capabilities. After this is completely vetted
and made easier to use, it will be added to the main stream.
THANK YOU to Lee for doing this blog entry and adding the mp3's
showing the effects.
Bob

[Bob McGwier]

Jim:

We can do this right now with a software receiver. We need to make the
oscillators coherent in the same way we have done (in software). So
this will be usable by SDR-1000 and Flex3000 owners. Good idea.

I do not agree that the algorithm you suggest is the correct one but it
will be the first one because it is easy. It will be applicable to HF
broadcast very quickly.

The algorithms based on MUSIC and ESPRIT are better suited, especially
to the typical amateur installation where the elements are not identical
and not spaced the correct distance apart.

http://eprints.eemcs.utwente.nl/15144/01/final_report_Jasper_Vrielink.pdf

http://www.springerlink.com/content/y8001q047g520398/

These algorithms allow for much more than two elements and are pretty
efficient when only two elements are involved.

My work partners and I are running a phased array with SDR design
contract with a well known (not Flex) SDR hardware manufacturer and
these algorithms will be part of the adaptive phased array work that
must be done. Again, open source will benefit all.

Happy Cinco de Mayo to all!

http://twitpic.com/4mqnv

We are about to embark on some SERIOUS adaptive algorithm development
with DttSP, Flex, Gnuradio, etc. all involved. All of us will benefit.

Post by Jim Barber
Not being familiar with the architecture or sources, would there be
any value in developing a 2-input, LMS-style noise reduction scheme
using the same antenna for both receivers and a small frequency
offset? (RX2 would be tuned to an unoccupied "noise" frequency as
close as possible to the "active" RX1 operating frequency)
That technique has been successfully used elsewhere and has the
advantage of adaptively canceling any static or long-term difference
in "phase" between the signals. (primarily group delay in this case?).
The obvious disadvantage is having to choose a suitable noise
frequency on a busy band, assuming one is available.
Thoughts?
Thanks,
Jim Barber, N7CXI

[Jim Barber]

Thanks for the reply, Bob.

I have no axe to grind with regard to any particular algorithm, but I
did want to make sure what I thought would be the simplest/most common
case would be covered; IE one antenna available and the desire for the
most effective noise reduction/cancellation. Having done that, I'll
retract my nose and let you guys get back to your (excellent) work.

Thanks & 73,
Jim Barber, N7CXI

Post by Bob McGwier
We can do this right now with a software receiver. We need to make
the oscillators coherent in the same way we have done (in software).
So this will be usable by SDR-1000 and Flex3000 owners. Good idea.
I do not agree that the algorithm you suggest is the correct one but
it will be the first one because it is easy. It will be applicable to
HF broadcast very quickly.
The algorithms based on MUSIC and ESPRIT are better suited, especially
to the typical amateur installation where the elements are not
identical and not spaced the correct distance apart.
http://eprints.eemcs.utwente.nl/15144/01/final_report_Jasper_Vrielink.pdf
http://www.springerlink.com/content/y8001q047g520398/
These algorithms allow for much more than two elements and are pretty
efficient when only two elements are involved.
My work partners and I are running a phased array with SDR design
contract with a well known (not Flex) SDR hardware manufacturer and
these algorithms will be part of the adaptive phased array work that
must be done. Again, open source will benefit all.
Happy Cinco de Mayo to all!
http://twitpic.com/4mqnv
We are about to embark on some SERIOUS adaptive algorithm development
with DttSP, Flex, Gnuradio, etc. all involved. All of us will benefit.

Post by Jim Barber
Not being familiar with the architecture or sources, would there be
any value in developing a 2-input, LMS-style noise reduction scheme
using the same antenna for both receivers and a small frequency
offset? (RX2 would be tuned to an unoccupied "noise" frequency as
close as possible to the "active" RX1 operating frequency)
That technique has been successfully used elsewhere and has the
advantage of adaptively canceling any static or long-term difference
in "phase" between the signals. (primarily group delay in this
case?). The obvious disadvantage is having to choose a suitable noise
frequency on a busy band, assuming one is available.
Thoughts?
Thanks,
Jim Barber, N7CXI

[Bob McGwier]

You idea is a good one. Period. That is all you should take away from
my remarks. I had not even begun to think of doing coherent processing
with the software receivers except to suck off interfering sidebands
from other signals in our passband. Thank you. John lovingly calls it
the Bob Sucker. DUMB. ;-).

Bob

Post by Jim Barber
Thanks for the reply, Bob.
I have no axe to grind with regard to any particular algorithm, but I
did want to make sure what I thought would be the simplest/most common
case would be covered; IE one antenna available and the desire for the
most effective noise reduction/cancellation. Having done that, I'll
retract my nose and let you guys get back to your (excellent) work.
Thanks & 73,
Jim Barber, N7CXI

Post by Bob McGwier
We can do this right now with a software receiver. We need to make
the oscillators coherent in the same way we have done (in software).
So this will be usable by SDR-1000 and Flex3000 owners. Good idea.
I do not agree that the algorithm you suggest is the correct one but
it will be the first one because it is easy. It will be applicable to
HF broadcast very quickly.
The algorithms based on MUSIC and ESPRIT are better suited,
especially to the typical amateur installation where the elements are
not identical and not spaced the correct distance apart.
http://eprints.eemcs.utwente.nl/15144/01/final_report_Jasper_Vrielink.pdf
http://www.springerlink.com/content/y8001q047g520398/
These algorithms allow for much more than two elements and are pretty
efficient when only two elements are involved.
My work partners and I are running a phased array with SDR design
contract with a well known (not Flex) SDR hardware manufacturer and
these algorithms will be part of the adaptive phased array work that
must be done. Again, open source will benefit all.
Happy Cinco de Mayo to all!
http://twitpic.com/4mqnv
We are about to embark on some SERIOUS adaptive algorithm development
with DttSP, Flex, Gnuradio, etc. all involved. All of us will benefit.

Post by Jim Barber
Not being familiar with the architecture or sources, would there be
any value in developing a 2-input, LMS-style noise reduction scheme
using the same antenna for both receivers and a small frequency
offset? (RX2 would be tuned to an unoccupied "noise" frequency as
close as possible to the "active" RX1 operating frequency)
That technique has been successfully used elsewhere and has the
advantage of adaptively canceling any static or long-term difference
in "phase" between the signals. (primarily group delay in this
case?). The obvious disadvantage is having to choose a suitable
noise frequency on a busy band, assuming one is available.
Thoughts?
Thanks,
Jim Barber, N7CXI

[Lee A Crocker]

I made a few more clips. The effect can be spectactular or very subtle. In 40-E I found on static the source is sort of from a quadrant and so the notching is very broad. None the less I could get about 3dB of noise reduction. In 40-F the SWBC is dramatic. The station was very weak. If this had been a CW station it would have been Q5. Finally in 40-G the AM BC station is about 4 miles north of my house and extremely strong. The effect is amazing!! (and the tuning is critical)

As to the static canceling question, you have no real need of using the second receiver, just make another watch receiver and use the in-band noise you already have contained in the 192khz base band. I expect this test by Bob is the first step toward that goal. Once that is accomplished it will be the gorilla of "next killer apps!!!"

73 W9OY

w9oy-sdr.blogspot.com

[Bob McGwier]

Post by Lee A Crocker
I made a few more clips. The effect can be spectactular or very subtle. In 40-E I found on static the source is sort of from a quadrant and so the notching is very broad. None the less I could get about 3dB of noise reduction. In 40-F the SWBC is dramatic. The station was very weak. If this had been a CW station it would have been Q5. Finally in 40-G the AM BC station is about 4 miles north of my house and extremely strong. The effect is amazing!! (and the tuning is critical)
As to the static canceling question, you have no real need of using the second receiver, just make another watch receiver and use the in-band noise you already have contained in the 192khz base band. I expect this test by Bob is the first step toward that goal. Once that is accomplished it will be the gorilla of "next killer apps!!!"
73 W9OY
w9oy-sdr.blogspot.com
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Thanks for all of the work and the feedback from all including Jim
Barber, N7CXI . We made the steps in the controls too large. On point
sources that are narrowband for real, it will be fairly sensitive control.

Now that this technique is included in the code, and after we start
doing multirate sampling techniques this week, a pretty thorough
cleaning and optimization will need to be done with all of your inputs.
A raft of adaptive signal processing things are on Eric's board for both
the receiver and the transmitter. Each and everyone of them will be a
significant improvement in radio for us and separate these offerings as
SDR's from traditional radios even more.

This will be crystallized/finalized in DttSP 3 in cgran as Frank makes
it fit the overall architecture.

Bob

[Bob McGwier]

Wow is right. It is hard to understand just how impressive 40F really
is. 40G sounds the most impressive but to the trained ear and tools, 40
F is amazing. The Flex 5000 is utterly coherent through the
oscillators. It is two different DDS's that are synchronized by a built
in system which Gerald made sure was supported. As soon as we made the
software oscillators coherent (identical in fact) and then applied a
phase and amplitude modification (scalar) to one of them for phasing,
we get a phase stable system.

I was expecting it to work but I had no idea it would be this impressive.

More things like this are to follow.

Frank mentioned one person who had done some phasing experiments. I
would also like to mention Alex Shovkoplyas, VE3NEA who has done a
really neat version. I intend to steal his user interface idea
completely. It makes both mathematical and user sense.

Bob

Post by Lee A Crocker
I made a few more clips. The effect can be spectactular or very subtle. In 40-E I found on static the source is sort of from a quadrant and so the notching is very broad. None the less I could get about 3dB of noise reduction. In 40-F the SWBC is dramatic. The station was very weak. If this had been a CW station it would have been Q5. Finally in 40-G the AM BC station is about 4 miles north of my house and extremely strong. The effect is amazing!! (and the tuning is critical)
As to the static canceling question, you have no real need of using the second receiver, just make another watch receiver and use the in-band noise you already have contained in the 192khz base band. I expect this test by Bob is the first step toward that goal. Once that is accomplished it will be the gorilla of "next killer apps!!!"
73 W9OY
w9oy-sdr.blogspot.com
_______________________________________________
FlexRadio Systems Mailing List
FlexRadio at flex-radio.biz
http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/
Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/

[Dennis Petrich]

I would upgrade to a Flex5000 just to get Diversity....

Keep up the great work guys.

73, Dennis, k0eoo


----- Original Message -----
From: "Bob McGwier" <rwmcgwier at gmail.com>
To: "Lee A Crocker" <lee_crocker at yahoo.com>
Cc: "Flexradio" <FlexRadio at flex-radio.biz>
Sent: Tuesday, May 05, 2009 6:58 PM
Subject: Re: [Flexradio] Diversity Reception for Flex 5000 owners

Wow is right. It is hard to understand just how impressive 40F really is.
40G sounds the most impressive but to the trained ear and tools, 40 F is
amazing. The Flex 5000 is utterly coherent through the oscillators. It
is two different DDS's that are synchronized by a built in system which
Gerald made sure was supported. As soon as we made the software
oscillators coherent (identical in fact) and then applied a phase and
amplitude modification (scalar) to one of them for phasing, we get a
phase stable system.
I was expecting it to work but I had no idea it would be this impressive.
More things like this are to follow.
Frank mentioned one person who had done some phasing experiments. I would
also like to mention Alex Shovkoplyas, VE3NEA who has done a really neat
version. I intend to steal his user interface idea completely. It makes
both mathematical and user sense.
Bob

Post by Lee A Crocker
I made a few more clips. The effect can be spectactular or very subtle.
In 40-E I found on static the source is sort of from a quadrant and so
the notching is very broad. None the less I could get about 3dB of noise
reduction. In 40-F the SWBC is dramatic. The station was very weak. If
this had been a CW station it would have been Q5. Finally in 40-G the AM
BC station is about 4 miles north of my house and extremely strong. The
effect is amazing!! (and the tuning is critical)
As to the static canceling question, you have no real need of using the
second receiver, just make another watch receiver and use the in-band
noise you already have contained in the 192khz base band. I expect this
test by Bob is the first step toward that goal. Once that is
accomplished it will be the gorilla of "next killer apps!!!"
73 W9OY
w9oy-sdr.blogspot.com
_______________________________________________
FlexRadio Systems Mailing List
FlexRadio at flex-radio.biz
http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/
http://www.flex-radio.com/

--
(Co)Author: DttSP, Quiktrak, PowerSDR, GnuRadio Member: ARRL, AMSAT,
AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
"You don't need to see the whole staircase, just
take the first step.", MLK.
Twitter:rwmcgwier
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[Phil Harman]

Post by Bob McGwier
Frank mentioned one person who had done some phasing experiments. I
would also like to mention Alex Shovkoplyas, VE3NEA who has done a
really neat version. I intend to steal his user interface idea
completely. It makes both mathematical and user sense.
Bob

I had the good fortune to do some Beta testing of Alex's diversity
software. I built a pair of 40m Softrocks and ran then off the same local
oscillator.

As Bob says, Alex's user interface is just teriffic and I'm pleased that
Bob is going down the same UI path.

My results of using the system was inconclusive. What I found was that
strong local signals could be nulled completely. However, on DX stations
it was very difficult to get any form of null or enhancement. When you
looked at the direction the signals where coming from on the UI it was
quite common to see massive, and rapid, angular changes.

This may have been a quirk of the 40m band at night but it will be very
interesting to see how others find the effectiveness of diversity
reception on 40m.


73's Phil....VK6APH

[Mike Naruta]

Perhaps what we need is adaptive diversity reception.

:)

Post by Phil Harman
My results of using the system was inconclusive. What I found was that
strong local signals could be nulled completely. However, on DX stations
it was very difficult to get any form of null or enhancement. When you
looked at the direction the signals where coming from on the UI it was
quite common to see massive, and rapid, angular changes.
This may have been a quirk of the 40m band at night but it will be very
interesting to see how others find the effectiveness of diversity
reception on 40m.
73's Phil....VK6APH

[Lee A Crocker]

My impression is you need more than a single pair of antenna choices.

I spent a lot of time trying to seperate WWVH and WWVB from FL using 2 verticals that were endfire to the E/W. I think something like a triangle feeding 2 els against one, or 3 x 2el pairs may be a better topology

73 W9OY






________________________________
From: Phil Harman <phil at pharman.org>
To: Bob McGwier <rwmcgwier at gmail.com>
Cc: Lee A Crocker <lee_crocker at yahoo.com>; Flexradio <flexradio at flex-radio.biz>
Sent: Tuesday, May 5, 2009 9:02:44 PM
Subject: Re: [Flexradio] Diversity Reception for Flex 5000 owners

Post by Bob McGwier
Frank mentioned one person who had done some phasing experiments. I
would also like to mention Alex Shovkoplyas, VE3NEA who has done a
really neat version. I intend to steal his user interface idea
completely. It makes both mathematical and user sense.
Bob

I had the good fortune to do some Beta testing of Alex's diversity
software. I built a pair of 40m Softrocks and ran then off the same local
oscillator.

As Bob says, Alex's user interface is just teriffic and I'm pleased that
Bob is going down the same UI path.

My results of using the system was inconclusive. What I found was that
strong local signals could be nulled completely. However, on DX stations
it was very difficult to get any form of null or enhancement. When you
looked at the direction the signals where coming from on the UI it was
quite common to see massive, and rapid, angular changes.

This may have been a quirk of the 40m band at night but it will be very
interesting to see how others find the effectiveness of diversity
reception on 40m.


73's Phil....VK6APH

[radioart]

Back when I was in the Navy we would setup three different types of diversity reception for news broadcasts. Phase (spacing between antennas) diversity, frequency diversity and polarization diversity... Usually one or the other would give us the best SNR.

And thats all I remember....

73's

Dennis Petrich
Amateur Radio Station K0EOO
Lakeville Minnesota USA
k0eoo at arrl.net
952-898-1082

----- Original Message -----
From: "Lee A Crocker" <lee_crocker at yahoo.com>
To: phil at pharman.org, "Bob McGwier" <rwmcgwier at gmail.com>
Cc: "Flexradio" <flexradio at flex-radio.biz>
Sent: Tuesday, May 5, 2009 8:32:59 PM GMT -06:00 US/Canada Central
Subject: Re: [Flexradio] Diversity Reception for Flex 5000 owners

My impression is you need more than a single pair of antenna choices.

I spent a lot of time trying to seperate WWVH and WWVB from FL using 2 verticals that were endfire to the E/W. I think something like a triangle feeding 2 els against one, or 3 x 2el pairs may be a better topology

73 W9OY






________________________________
From: Phil Harman <phil at pharman.org>
To: Bob McGwier <rwmcgwier at gmail.com>
Cc: Lee A Crocker <lee_crocker at yahoo.com>; Flexradio <flexradio at flex-radio.biz>
Sent: Tuesday, May 5, 2009 9:02:44 PM
Subject: Re: [Flexradio] Diversity Reception for Flex 5000 owners

Post by Bob McGwier
Frank mentioned one person who had done some phasing experiments. I
would also like to mention Alex Shovkoplyas, VE3NEA who has done a
really neat version. I intend to steal his user interface idea
completely. It makes both mathematical and user sense.
Bob

I had the good fortune to do some Beta testing of Alex's diversity
software. I built a pair of 40m Softrocks and ran then off the same local
oscillator.

As Bob says, Alex's user interface is just teriffic and I'm pleased that
Bob is going down the same UI path.

My results of using the system was inconclusive. What I found was that
strong local signals could be nulled completely. However, on DX stations
it was very difficult to get any form of null or enhancement. When you
looked at the direction the signals where coming from on the UI it was
quite common to see massive, and rapid, angular changes.

This may have been a quirk of the 40m band at night but it will be very
interesting to see how others find the effectiveness of diversity
reception on 40m.


73's Phil....VK6APH



_______________________________________________
FlexRadio Systems Mailing List
FlexRadio at flex-radio.biz
http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/
Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/

[radioart]

Bob, how would this work with the SDR-1000 and Flex3000 considering they only have one RX? Are you using the Multi-Rx capability in PowerSDR and them applying the ESPRIT algorithms from the paper you referenced in this email??

73,

Dennis Petrich
Amateur Radio Station K0EOO
Lakeville Minnesota USA
k0eoo at arrl.net
952-898-1082

----- Original Message -----
From: "Bob McGwier" <rwmcgwier at gmail.com>
To: audioguy at charter.net
Cc: "FLEX USERS" <flexradio at flex-radio.biz>
Sent: Tuesday, May 5, 2009 7:39:01 PM GMT -06:00 US/Canada Central
Subject: Re: [Flexradio] Diversity Reception for Flex 5000 owners

Jim:

We can do this right now with a software receiver. We need to make the
oscillators coherent in the same way we have done (in software). So
this will be usable by SDR-1000 and Flex3000 owners. Good idea.

I do not agree that the algorithm you suggest is the correct one but it
will be the first one because it is easy. It will be applicable to HF
broadcast very quickly.

The algorithms based on MUSIC and ESPRIT are better suited, especially
to the typical amateur installation where the elements are not identical
and not spaced the correct distance apart.

http://eprints.eemcs.utwente.nl/15144/01/final_report_Jasper_Vrielink.pdf

http://www.springerlink.com/content/y8001q047g520398/

These algorithms allow for much more than two elements and are pretty
efficient when only two elements are involved.

My work partners and I are running a phased array with SDR design
contract with a well known (not Flex) SDR hardware manufacturer and
these algorithms will be part of the adaptive phased array work that
must be done. Again, open source will benefit all.

Happy Cinco de Mayo to all!

http://twitpic.com/4mqnv

We are about to embark on some SERIOUS adaptive algorithm development
with DttSP, Flex, Gnuradio, etc. all involved. All of us will benefit.

Post by Jim Barber
Not being familiar with the architecture or sources, would there be
any value in developing a 2-input, LMS-style noise reduction scheme
using the same antenna for both receivers and a small frequency
offset? (RX2 would be tuned to an unoccupied "noise" frequency as
close as possible to the "active" RX1 operating frequency)
That technique has been successfully used elsewhere and has the
advantage of adaptively canceling any static or long-term difference
in "phase" between the signals. (primarily group delay in this case?).
The obvious disadvantage is having to choose a suitable noise
frequency on a busy band, assuming one is available.
Thoughts?
Thanks,
Jim Barber, N7CXI

--
(Co)Author: DttSP, Quiktrak, PowerSDR, GnuRadio
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
"You don't need to see the whole staircase, just
take the first step.", MLK.
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[Bob McGwier]

Post by radioart
Bob, how would this work with the SDR-1000 and Flex3000 considering they only have one RX? Are you using the Multi-Rx capability in PowerSDR and them applying the ESPRIT algorithms from the paper you referenced in this email??
73,
Dennis Petrich
Amateur Radio Station K0EOO
Lakeville Minnesota USA
k0eoo at arrl.net
952-898-1082

Yes, but it will not be to do diversity combing on the same transmitted
signal from independent receive paths. It will be do other enhancements
that can be made by understanding the ENVIRONMENT AROUND the signal of
interest. Also the SDR-1000 and the Flex 3000 are BOTH capable of
supporting frequency diversity reception and frequency diversity path
transmission BECAUSE of their wider IF paths that sustain large dynamic
range as are other SDR offerings in the ham community now.

Bob