Airspy R2 + Spyverter R2 questions


Normand Fortin
 

Hi everyone, my 1st post, quick intro, i've been scanning for 30+ years,
SDR"ing" for the last 3 years, with several nooelec dongles including
v3. I jumped in the Airspy / spyverter wagon couple weeks ago with the
R2 versions. So far the Space WX has been rocking since then (East
Canada often covered in auroral spwx lately) so i haven't had a chance
to give it a good test although i received good bits from time to time.
I'm using a long wire 30' connected to a Miracle whip antenna
preselector that was working awesome in any previous setup, but the spys
are so sensitive i might have to rethink it.

But first, questions:

  1 - The airspy unit gets warmer while in use and this is expected, the
Spyverter remains room temp, i was expecting it to warm up as well, is
that normal?  (bias Tee is on and i do receive stuff, not much more than
nooelec v3)
2- I started as suggested with linearity gain but does somebody has a
"recipe" with free gains control i tried several with mitigated success
til now ?
3- Is there a decimation sweetspot that yield better isolation of faint
signals?
4- I will have a hamitup noise source handy soon, is there some
reference signal specs i can use to test and make sure my Airspy / SV
combo is up to what it should be?

To further clean up rx, i will use a cavity / fm trap as i can see some
overloading and also make a copper box for antenna connection.

The spy's are a different beast, and although a read a lot on it, i'd
like some inputs, including your current rx performance in the actual
sun condition.

I follow closely Simon HF+ testing as well (really promising), so if
somebody has some figures for R2 versions, i could rule out the
defective unit possibility (although least probable but this is the 1
check to be done before blaming it on SPWX / location)

Thanks

Norm
Monitoring waves from Quebec, Canada


David Eckhardt
 

The AirSpy has an internal heater to stabilize the LO reference.  It normally runs above room temperature.

However, it is designed to operate in open air at room temperature.  We are using an AirSpy as the receiver (after a lot of low-noise gain and filtering) for our hydrogen line receiver at 1.420 GHz (radio astronomy) at the Little Thompson Observatory <starkids.org>.  In an attempt to stabilize the gain over temperature changes, we have tried embedding it in both warm and cool environments.  It does not like either.  Too cold or too warm, and we loose the USB link and have to restart SDR# after it warms/cools to room temperature.  However, it is normal for it to run warm to the touch. 

As far a gain settings go, increase the overall gain in either 'Linear' or 'Sensitivity' modes to the extent where you see the 'grass' increase about 3 to 5 dB above that where the gain is set to minimum.  That adjustment should be made with the antenna connected.  Mine usually comes in around 15 to 17.  Any more gain will spoil dynamic range and open the system to IM products and unwanted mixing of stronger signals.

Yes, if you have 'strong' FM BC'ers in your local area, you will need an FM SBF.  I don't have the problem above the FM band, but below it is a minor annoyance.

I can't speak to decimation as I seldom use it.  However, I've read that the best method to reduce displayed bandwidth is to use decimation instead of decreasing the span by other means.  It is a powerful tool available in the digital world that just can't be implemented with the older superhetrodyne technology.  'OLDER SUPERHETRODYNE" technology?  Man, I thought I'd never see that in my lifetime.  But, here I am.  

Dave - WØLEV

On Fri, Sep 29, 2017 at 8:24 AM, Normand Fortin <normand_fortin@...> wrote:
Hi everyone, my 1st post, quick intro, i've been scanning for 30+ years,
SDR"ing" for the last 3 years, with several nooelec dongles including
v3. I jumped in the Airspy / spyverter wagon couple weeks ago with the
R2 versions. So far the Space WX has been rocking since then (East
Canada often covered in auroral spwx lately) so i haven't had a chance
to give it a good test although i received good bits from time to time.
I'm using a long wire 30' connected to a Miracle whip antenna
preselector that was working awesome in any previous setup, but the spys
are so sensitive i might have to rethink it.

But first, questions:

  1 - The airspy unit gets warmer while in use and this is expected, the
Spyverter remains room temp, i was expecting it to warm up as well, is
that normal?  (bias Tee is on and i do receive stuff, not much more than
nooelec v3)
2- I started as suggested with linearity gain but does somebody has a
"recipe" with free gains control i tried several with mitigated success
til now ?
3- Is there a decimation sweetspot that yield better isolation of faint
signals?
4- I will have a hamitup noise source handy soon, is there some
reference signal specs i can use to test and make sure my Airspy / SV
combo is up to what it should be?

To further clean up rx, i will use a cavity / fm trap as i can see some
overloading and also make a copper box for antenna connection.

The spy's are a different beast, and although a read a lot on it, i'd
like some inputs, including your current rx performance in the actual
sun condition.

I follow closely Simon HF+ testing as well (really promising), so if
somebody has some figures for R2 versions, i could rule out the
defective unit possibility (although least probable but this is the 1
check to be done before blaming it on SPWX / location)

Thanks

Norm
Monitoring waves from Quebec, Canada




--
Dave - WØLEV
Just Let Darwin Work


Daniel Fox
 

How are you logging data from your radio telescope?  I’ve been hoping for some time that there will be an upgrade to the astrospy software that would periodically log the averaged spectrum to a csv file.

 

Dan – KF9ET

 

From: main@airspy.groups.io [mailto:main@airspy.groups.io] On Behalf Of David Eckhardt
Sent: Friday, September 29, 2017 1:07 PM
To: main@airspy.groups.io
Subject: Re: [airspy] Airspy R2 + Spyverter R2 questions

 

The AirSpy has an internal heater to stabilize the LO reference.  It normally runs above room temperature.

 

However, it is designed to operate in open air at room temperature.  We are using an AirSpy as the receiver (after a lot of low-noise gain and filtering) for our hydrogen line receiver at 1.420 GHz (radio astronomy) at the Little Thompson Observatory <starkids.org>.  In an attempt to stabilize the gain over temperature changes, we have tried embedding it in both warm and cool environments.  It does not like either.  Too cold or too warm, and we loose the USB link and have to restart SDR# after it warms/cools to room temperature.  However, it is normal for it to run warm to the touch. 

 

As far a gain settings go, increase the overall gain in either 'Linear' or 'Sensitivity' modes to the extent where you see the 'grass' increase about 3 to 5 dB above that where the gain is set to minimum.  That adjustment should be made with the antenna connected.  Mine usually comes in around 15 to 17.  Any more gain will spoil dynamic range and open the system to IM products and unwanted mixing of stronger signals.

 

Yes, if you have 'strong' FM BC'ers in your local area, you will need an FM SBF.  I don't have the problem above the FM band, but below it is a minor annoyance.

 

I can't speak to decimation as I seldom use it.  However, I've read that the best method to reduce displayed bandwidth is to use decimation instead of decreasing the span by other means.  It is a powerful tool available in the digital world that just can't be implemented with the older superhetrodyne technology.  'OLDER SUPERHETRODYNE" technology?  Man, I thought I'd never see that in my lifetime.  But, here I am.  

 

Dave - WØLEV

 

On Fri, Sep 29, 2017 at 8:24 AM, Normand Fortin <normand_fortin@...> wrote:

Hi everyone, my 1st post, quick intro, i've been scanning for 30+ years,
SDR"ing" for the last 3 years, with several nooelec dongles including
v3. I jumped in the Airspy / spyverter wagon couple weeks ago with the
R2 versions. So far the Space WX has been rocking since then (East
Canada often covered in auroral spwx lately) so i haven't had a chance
to give it a good test although i received good bits from time to time.
I'm using a long wire 30' connected to a Miracle whip antenna
preselector that was working awesome in any previous setup, but the spys
are so sensitive i might have to rethink it.

But first, questions:

  1 - The airspy unit gets warmer while in use and this is expected, the
Spyverter remains room temp, i was expecting it to warm up as well, is
that normal?  (bias Tee is on and i do receive stuff, not much more than
nooelec v3)
2- I started as suggested with linearity gain but does somebody has a
"recipe" with free gains control i tried several with mitigated success
til now ?
3- Is there a decimation sweetspot that yield better isolation of faint
signals?
4- I will have a hamitup noise source handy soon, is there some
reference signal specs i can use to test and make sure my Airspy / SV
combo is up to what it should be?

To further clean up rx, i will use a cavity / fm trap as i can see some
overloading and also make a copper box for antenna connection.

The spy's are a different beast, and although a read a lot on it, i'd
like some inputs, including your current rx performance in the actual
sun condition.

I follow closely Simon HF+ testing as well (really promising), so if
somebody has some figures for R2 versions, i could rule out the
defective unit possibility (although least probable but this is the 1
check to be done before blaming it on SPWX / location)

Thanks

Norm
Monitoring waves from Quebec, Canada




--

Dave - WØLEV

Just Let Darwin Work


Marcus D. Leech <mleech@...>
 

I've never seen USB-link issues with the AirSpy, even in an uncooled laboratory environment inside a hot enclosure.

I don't think the AirSpy has a heater in it--just a TCXO, which is NOT the same as an OCXO, which *IS* controlled with a heater with a closed-loop sensor.

You might find my "Differential Radiometry" paper useful for dealing with gain stability.

http://www.sbrac.org/files/DTP_RX.pdf

You can never really gain stabilize low-noise receivers enough to "reach" the theoretical limits of your dish, so you need something more clever.  Granted, some set-ups do better than others, but at the end of the day, "smart" techniques like Dicke switching and differential radiometry need to be considred.

 

 

 

On 2017-09-29 13:07, David Eckhardt wrote:

The AirSpy has an internal heater to stabilize the LO reference.  It normally runs above room temperature.
 
However, it is designed to operate in open air at room temperature.  We are using an AirSpy as the receiver (after a lot of low-noise gain and filtering) for our hydrogen line receiver at 1.420 GHz (radio astronomy) at the Little Thompson Observatory <starkids.org>.  In an attempt to stabilize the gain over temperature changes, we have tried embedding it in both warm and cool environments.  It does not like either.  Too cold or too warm, and we loose the USB link and have to restart SDR# after it warms/cools to room temperature.  However, it is normal for it to run warm to the touch. 
 
As far a gain settings go, increase the overall gain in either 'Linear' or 'Sensitivity' modes to the extent where you see the 'grass' increase about 3 to 5 dB above that where the gain is set to minimum.  That adjustment should be made with the antenna connected.  Mine usually comes in around 15 to 17.  Any more gain will spoil dynamic range and open the system to IM products and unwanted mixing of stronger signals.
 
Yes, if you have 'strong' FM BC'ers in your local area, you will need an FM SBF.  I don't have the problem above the FM band, but below it is a minor annoyance.
 
I can't speak to decimation as I seldom use it.  However, I've read that the best method to reduce displayed bandwidth is to use decimation instead of decreasing the span by other means.  It is a powerful tool available in the digital world that just can't be implemented with the older superhetrodyne technology.  'OLDER SUPERHETRODYNE" technology?  Man, I thought I'd never see that in my lifetime.  But, here I am.  
 
Dave - WØLEV

On Fri, Sep 29, 2017 at 8:24 AM, Normand Fortin <normand_fortin@...> wrote:
Hi everyone, my 1st post, quick intro, i've been scanning for 30+ years,
SDR"ing" for the last 3 years, with several nooelec dongles including
v3. I jumped in the Airspy / spyverter wagon couple weeks ago with the
R2 versions. So far the Space WX has been rocking since then (East
Canada often covered in auroral spwx lately) so i haven't had a chance
to give it a good test although i received good bits from time to time.
I'm using a long wire 30' connected to a Miracle whip antenna
preselector that was working awesome in any previous setup, but the spys
are so sensitive i might have to rethink it.

But first, questions:

  1 - The airspy unit gets warmer while in use and this is expected, the
Spyverter remains room temp, i was expecting it to warm up as well, is
that normal?  (bias Tee is on and i do receive stuff, not much more than
nooelec v3)
2- I started as suggested with linearity gain but does somebody has a
"recipe" with free gains control i tried several with mitigated success
til now ?
3- Is there a decimation sweetspot that yield better isolation of faint
signals?
4- I will have a hamitup noise source handy soon, is there some
reference signal specs i can use to test and make sure my Airspy / SV
combo is up to what it should be?

To further clean up rx, i will use a cavity / fm trap as i can see some
overloading and also make a copper box for antenna connection.

The spy's are a different beast, and although a read a lot on it, i'd
like some inputs, including your current rx performance in the actual
sun condition.

I follow closely Simon HF+ testing as well (really promising), so if
somebody has some figures for R2 versions, i could rule out the
defective unit possibility (although least probable but this is the 1
check to be done before blaming it on SPWX / location)

Thanks

Norm
Monitoring waves from Quebec, Canada

 

 

 




--
Dave - WØLEV
Just Let Darwin Work


David Eckhardt
 

I wish we all could record I/Q data even though the files would be huge.  But MS has put a limit on file size.  Gotta do Linux. 

We decode in AM at 32 kHz.  That's the widest bandwidth available for any amplitude-sensitive demod mode.  I'd like to demod the entire 100 MHz bandwidth of the water, but can't.  SpectrumSpy can easily display the whole water hole, but no like to demod modes from SpectrumSpy.

We feed the demodulated AM to Radio SkyPipe through VB Cable.  VB Cable is freeware and is a virtual audio cable that bridges from the USB interface of the AirSpy to audio just as though you were connected to the sound card directly (well, almost - watch dynamic range in VB Cable). 

AstroSpy is just SpectrumSpy taylored for the water hole frequency and 1.420405751 GHz, specifically.  I do wish they'd have a line to the demod modes from that application, but so far, notta. 

Our signal track is:

1)  5 sq meter dish
2)  1 GHz HPF
3)  LNA
4)  BPF (water hole)
5)  LNA
6)  Bias TEE
6)  75-feet of 1/2-inch solid shield coax
7)  Bias TEE
8)  LNA (feed gain isn't quite enough)
9)  AirSpy
10)  VB Cable (PC)
11)  Radio SkyPipe (PC based chart recorder)

Forgot the feed and I'm not going to renumber.  It's a single circular feet 1/4-wavelength from a large splash plate.  We might do a dipole feed at some time in the future.

Radio SkyPipe, with other very useful information and applications,  can be downloaded at:


The RSP data can be read into an EXCEL file, but that's another volunteer as I'm not a digital type.

Dave Eckhardt - WØLEV
Volunteer:  Little Thompson Observatory
                <starkids.org>  

On Fri, Sep 29, 2017 at 11:17 AM, Daniel Fox <foxd@...> wrote:

How are you logging data from your radio telescope?  I’ve been hoping for some time that there will be an upgrade to the astrospy software that would periodically log the averaged spectrum to a csv file.

 

Dan – KF9ET

 

From: main@airspy.groups.io [mailto:main@airspy.groups.io] On Behalf Of David Eckhardt
Sent: Friday, September 29, 2017 1:07 PM
To: main@airspy.groups.io
Subject: Re: [airspy] Airspy R2 + Spyverter R2 questions

 

The AirSpy has an internal heater to stabilize the LO reference.  It normally runs above room temperature.

 

However, it is designed to operate in open air at room temperature.  We are using an AirSpy as the receiver (after a lot of low-noise gain and filtering) for our hydrogen line receiver at 1.420 GHz (radio astronomy) at the Little Thompson Observatory <starkids.org>.  In an attempt to stabilize the gain over temperature changes, we have tried embedding it in both warm and cool environments.  It does not like either.  Too cold or too warm, and we loose the USB link and have to restart SDR# after it warms/cools to room temperature.  However, it is normal for it to run warm to the touch. 

 

As far a gain settings go, increase the overall gain in either 'Linear' or 'Sensitivity' modes to the extent where you see the 'grass' increase about 3 to 5 dB above that where the gain is set to minimum.  That adjustment should be made with the antenna connected.  Mine usually comes in around 15 to 17.  Any more gain will spoil dynamic range and open the system to IM products and unwanted mixing of stronger signals.

 

Yes, if you have 'strong' FM BC'ers in your local area, you will need an FM SBF.  I don't have the problem above the FM band, but below it is a minor annoyance.

 

I can't speak to decimation as I seldom use it.  However, I've read that the best method to reduce displayed bandwidth is to use decimation instead of decreasing the span by other means.  It is a powerful tool available in the digital world that just can't be implemented with the older superhetrodyne technology.  'OLDER SUPERHETRODYNE" technology?  Man, I thought I'd never see that in my lifetime.  But, here I am.  

 

Dave - WØLEV

 

On Fri, Sep 29, 2017 at 8:24 AM, Normand Fortin <normand_fortin@...> wrote:

Hi everyone, my 1st post, quick intro, i've been scanning for 30+ years,
SDR"ing" for the last 3 years, with several nooelec dongles including
v3. I jumped in the Airspy / spyverter wagon couple weeks ago with the
R2 versions. So far the Space WX has been rocking since then (East
Canada often covered in auroral spwx lately) so i haven't had a chance
to give it a good test although i received good bits from time to time.
I'm using a long wire 30' connected to a Miracle whip antenna
preselector that was working awesome in any previous setup, but the spys
are so sensitive i might have to rethink it.

But first, questions:

  1 - The airspy unit gets warmer while in use and this is expected, the
Spyverter remains room temp, i was expecting it to warm up as well, is
that normal?  (bias Tee is on and i do receive stuff, not much more than
nooelec v3)
2- I started as suggested with linearity gain but does somebody has a
"recipe" with free gains control i tried several with mitigated success
til now ?
3- Is there a decimation sweetspot that yield better isolation of faint
signals?
4- I will have a hamitup noise source handy soon, is there some
reference signal specs i can use to test and make sure my Airspy / SV
combo is up to what it should be?

To further clean up rx, i will use a cavity / fm trap as i can see some
overloading and also make a copper box for antenna connection.

The spy's are a different beast, and although a read a lot on it, i'd
like some inputs, including your current rx performance in the actual
sun condition.

I follow closely Simon HF+ testing as well (really promising), so if
somebody has some figures for R2 versions, i could rule out the
defective unit possibility (although least probable but this is the 1
check to be done before blaming it on SPWX / location)

Thanks

Norm
Monitoring waves from Quebec, Canada




--

Dave - WØLEV

Just Let Darwin Work




--
Dave - WØLEV
Just Let Darwin Work


Marcus D. Leech <mleech@...>
 

If you move to Linux, consider doing a Gnu Radio install, then you can use my spectro_radiometer application, which does both spectral and detected-power logging.  It will also do interferometry and differential radiometry.

 

 

 

On 2017-09-29 14:43, David Eckhardt wrote:

I wish we all could record I/Q data even though the files would be huge.  But MS has put a limit on file size.  Gotta do Linux. 
 
We decode in AM at 32 kHz.  That's the widest bandwidth available for any amplitude-sensitive demod mode.  I'd like to demod the entire 100 MHz bandwidth of the water, but can't.  SpectrumSpy can easily display the whole water hole, but no like to demod modes from SpectrumSpy.
 
We feed the demodulated AM to Radio SkyPipe through VB Cable.  VB Cable is freeware and is a virtual audio cable that bridges from the USB interface of the AirSpy to audio just as though you were connected to the sound card directly (well, almost - watch dynamic range in VB Cable). 
 
AstroSpy is just SpectrumSpy taylored for the water hole frequency and 1.420405751 GHz, specifically.  I do wish they'd have a line to the demod modes from that application, but so far, notta. 
 
Our signal track is:
 
1)  5 sq meter dish
2)  1 GHz HPF
3)  LNA
4)  BPF (water hole)
5)  LNA
6)  Bias TEE
6)  75-feet of 1/2-inch solid shield coax
7)  Bias TEE
8)  LNA (feed gain isn't quite enough)
9)  AirSpy
10)  VB Cable (PC)
11)  Radio SkyPipe (PC based chart recorder)
 
Forgot the feed and I'm not going to renumber.  It's a single circular feet 1/4-wavelength from a large splash plate.  We might do a dipole feed at some time in the future.
 
Radio SkyPipe, with other very useful information and applications,  can be downloaded at:
 
 
The RSP data can be read into an EXCEL file, but that's another volunteer as I'm not a digital type.
 
Dave Eckhardt - WØLEV
Volunteer:  Little Thompson Observatory
                <starkids.org>  

On Fri, Sep 29, 2017 at 11:17 AM, Daniel Fox <foxd@...> wrote:

How are you logging data from your radio telescope?  I've been hoping for some time that there will be an upgrade to the astrospy software that would periodically log the averaged spectrum to a csv file.

 

Dan – KF9ET

 

From: main@airspy.groups.io [mailto:main@airspy.groups.io] On Behalf Of David Eckhardt
Sent: Friday, September 29, 2017 1:07 PM
To: main@airspy.groups.io
Subject: Re: [airspy] Airspy R2 + Spyverter R2 questions

 

The AirSpy has an internal heater to stabilize the LO reference.  It normally runs above room temperature.

 

However, it is designed to operate in open air at room temperature.  We are using an AirSpy as the receiver (after a lot of low-noise gain and filtering) for our hydrogen line receiver at 1.420 GHz (radio astronomy) at the Little Thompson Observatory <starkids.org>.  In an attempt to stabilize the gain over temperature changes, we have tried embedding it in both warm and cool environments.  It does not like either.  Too cold or too warm, and we loose the USB link and have to restart SDR# after it warms/cools to room temperature.  However, it is normal for it to run warm to the touch. 

 

As far a gain settings go, increase the overall gain in either 'Linear' or 'Sensitivity' modes to the extent where you see the 'grass' increase about 3 to 5 dB above that where the gain is set to minimum.  That adjustment should be made with the antenna connected.  Mine usually comes in around 15 to 17.  Any more gain will spoil dynamic range and open the system to IM products and unwanted mixing of stronger signals.

 

Yes, if you have 'strong' FM BC'ers in your local area, you will need an FM SBF.  I don't have the problem above the FM band, but below it is a minor annoyance.

 

I can't speak to decimation as I seldom use it.  However, I've read that the best method to reduce displayed bandwidth is to use decimation instead of decreasing the span by other means.  It is a powerful tool available in the digital world that just can't be implemented with the older superhetrodyne technology.  'OLDER SUPERHETRODYNE" technology?  Man, I thought I'd never see that in my lifetime.  But, here I am.  

 

Dave - WØLEV

 

On Fri, Sep 29, 2017 at 8:24 AM, Normand Fortin <normand_fortin@...> wrote:

Hi everyone, my 1st post, quick intro, i've been scanning for 30+ years,
SDR"ing" for the last 3 years, with several nooelec dongles including
v3. I jumped in the Airspy / spyverter wagon couple weeks ago with the
R2 versions. So far the Space WX has been rocking since then (East
Canada often covered in auroral spwx lately) so i haven't had a chance
to give it a good test although i received good bits from time to time.
I'm using a long wire 30' connected to a Miracle whip antenna
preselector that was working awesome in any previous setup, but the spys
are so sensitive i might have to rethink it.

But first, questions:

  1 - The airspy unit gets warmer while in use and this is expected, the
Spyverter remains room temp, i was expecting it to warm up as well, is
that normal?  (bias Tee is on and i do receive stuff, not much more than
nooelec v3)
2- I started as suggested with linearity gain but does somebody has a
"recipe" with free gains control i tried several with mitigated success
til now ?
3- Is there a decimation sweetspot that yield better isolation of faint
signals?
4- I will have a hamitup noise source handy soon, is there some
reference signal specs i can use to test and make sure my Airspy / SV
combo is up to what it should be?

To further clean up rx, i will use a cavity / fm trap as i can see some
overloading and also make a copper box for antenna connection.

The spy's are a different beast, and although a read a lot on it, i'd
like some inputs, including your current rx performance in the actual
sun condition.

I follow closely Simon HF+ testing as well (really promising), so if
somebody has some figures for R2 versions, i could rule out the
defective unit possibility (although least probable but this is the 1
check to be done before blaming it on SPWX / location)

Thanks

Norm
Monitoring waves from Quebec, Canada




--

Dave - WØLEV

Just Let Darwin Work

 

 

 

 




--
Dave - WØLEV
Just Let Darwin Work


David Eckhardt
 

Marcus, Terry and I have talked seriously about Dicke switching, but our present setup is barely beyond 'first light'.  I have used Dicke switching (just because I could) in my EME efforts long ago in Albuquerque.  It is probably the easiest, but we have other issues at present as we're not even sure we have placed the feed at the focus of our off-center fed dish.  It's a WIP - Work in Progress.

It with the optical resources of the observatory are offered to the students of Berthoud HS.  Of course, they see the big dish and want to do astronomy projects with the radio astronomy resources we have recently added.  So, the WIP is a balance between the student's needs and our technical engineering, some of which we involve the students.    

Interferometry has also been considered, but that requires a whole second setup.  Thanks for the link to Differential Radiiometry.  VERY INTERESTING!

Dave Eckhardt - WØLEV
Volunteer: Little Thompson Observatory
               <starkids.org>  

On Fri, Sep 29, 2017 at 11:55 AM, Marcus D. Leech <mleech@...> wrote:

I've never seen USB-link issues with the AirSpy, even in an uncooled laboratory environment inside a hot enclosure.

I don't think the AirSpy has a heater in it--just a TCXO, which is NOT the same as an OCXO, which *IS* controlled with a heater with a closed-loop sensor.

You might find my "Differential Radiometry" paper useful for dealing with gain stability.

http://www.sbrac.org/files/DTP_RX.pdf

You can never really gain stabilize low-noise receivers enough to "reach" the theoretical limits of your dish, so you need something more clever.  Granted, some set-ups do better than others, but at the end of the day, "smart" techniques like Dicke switching and differential radiometry need to be considred.

 

 

 

On 2017-09-29 13:07, David Eckhardt wrote:

The AirSpy has an internal heater to stabilize the LO reference.  It normally runs above room temperature.
 
However, it is designed to operate in open air at room temperature.  We are using an AirSpy as the receiver (after a lot of low-noise gain and filtering) for our hydrogen line receiver at 1.420 GHz (radio astronomy) at the Little Thompson Observatory <starkids.org>.  In an attempt to stabilize the gain over temperature changes, we have tried embedding it in both warm and cool environments.  It does not like either.  Too cold or too warm, and we loose the USB link and have to restart SDR# after it warms/cools to room temperature.  However, it is normal for it to run warm to the touch. 
 
As far a gain settings go, increase the overall gain in either 'Linear' or 'Sensitivity' modes to the extent where you see the 'grass' increase about 3 to 5 dB above that where the gain is set to minimum.  That adjustment should be made with the antenna connected.  Mine usually comes in around 15 to 17.  Any more gain will spoil dynamic range and open the system to IM products and unwanted mixing of stronger signals.
 
Yes, if you have 'strong' FM BC'ers in your local area, you will need an FM SBF.  I don't have the problem above the FM band, but below it is a minor annoyance.
 
I can't speak to decimation as I seldom use it.  However, I've read that the best method to reduce displayed bandwidth is to use decimation instead of decreasing the span by other means.  It is a powerful tool available in the digital world that just can't be implemented with the older superhetrodyne technology.  'OLDER SUPERHETRODYNE" technology?  Man, I thought I'd never see that in my lifetime.  But, here I am.  
 
Dave - WØLEV

On Fri, Sep 29, 2017 at 8:24 AM, Normand Fortin <normand_fortin@...> wrote:
Hi everyone, my 1st post, quick intro, i've been scanning for 30+ years,
SDR"ing" for the last 3 years, with several nooelec dongles including
v3. I jumped in the Airspy / spyverter wagon couple weeks ago with the
R2 versions. So far the Space WX has been rocking since then (East
Canada often covered in auroral spwx lately) so i haven't had a chance
to give it a good test although i received good bits from time to time.
I'm using a long wire 30' connected to a Miracle whip antenna
preselector that was working awesome in any previous setup, but the spys
are so sensitive i might have to rethink it.

But first, questions:

  1 - The airspy unit gets warmer while in use and this is expected, the
Spyverter remains room temp, i was expecting it to warm up as well, is
that normal?  (bias Tee is on and i do receive stuff, not much more than
nooelec v3)
2- I started as suggested with linearity gain but does somebody has a
"recipe" with free gains control i tried several with mitigated success
til now ?
3- Is there a decimation sweetspot that yield better isolation of faint
signals?
4- I will have a hamitup noise source handy soon, is there some
reference signal specs i can use to test and make sure my Airspy / SV
combo is up to what it should be?

To further clean up rx, i will use a cavity / fm trap as i can see some
overloading and also make a copper box for antenna connection.

The spy's are a different beast, and although a read a lot on it, i'd
like some inputs, including your current rx performance in the actual
sun condition.

I follow closely Simon HF+ testing as well (really promising), so if
somebody has some figures for R2 versions, i could rule out the
defective unit possibility (although least probable but this is the 1
check to be done before blaming it on SPWX / location)

Thanks

Norm
Monitoring waves from Quebec, Canada

 

 

 




--
Dave - WØLEV
Just Let Darwin Work




--
Dave - WØLEV
Just Let Darwin Work


Marcus D. Leech <mleech@...>
 

On 09/29/2017 02:43 PM, David Eckhardt wrote:
I wish we all could record I/Q data even though the files would be huge.  But MS has put a limit on file size.  Gotta do Linux. 

We decode in AM at 32 kHz.  That's the widest bandwidth available for any amplitude-sensitive demod mode.  I'd like to demod the entire 100 MHz bandwidth of the water, but can't.  SpectrumSpy can easily display the whole water hole, but no like to demod modes from SpectrumSpy.

We feed the demodulated AM to Radio SkyPipe through VB Cable.  VB Cable is freeware and is a virtual audio cable that bridges from the USB interface of the AirSpy to audio just as though you were connected to the sound card directly (well, almost - watch dynamic range in VB Cable). 

AstroSpy is just SpectrumSpy taylored for the water hole frequency and 1.420405751 GHz, specifically.  I do wish they'd have a line to the demod modes from that application, but so far, notta. 

Our signal track is:

1)  5 sq meter dish
2)  1 GHz HPF
3)  LNA
4)  BPF (water hole)
5)  LNA
6)  Bias TEE
6)  75-feet of 1/2-inch solid shield coax
7)  Bias TEE
8)  LNA (feed gain isn't quite enough)
9)  AirSpy
10)  VB Cable (PC)
11)  Radio SkyPipe (PC based chart recorder)

Forgot the feed and I'm not going to renumber.  It's a single circular feet 1/4-wavelength from a large splash plate.  We might do a dipole feed at some time in the future.

Radio SkyPipe, with other very useful information and applications,  can be downloaded at:


The RSP data can be read into an EXCEL file, but that's another volunteer as I'm not a digital type.

Dave Eckhardt - WØLEV
Volunteer:  Little Thompson Observatory
                <starkids.org>  

Not sure how close to "civilization" your observatory is, but you might benefit from a 1/4-wave shorted-stub on the input to your LNA, which will provide
  a sloppy-bandpass response, rather than a high-pass response--and they're very low-loss, and as a side-effect provide ESD protection for your LNAs.

Also, you'd mentioned offset-fed dishes?  They need to be fed with a higher-gain feed in order to reduce spillover issues--because they are generally
  higher-F/D than prime-focus dishes in the same size range.  A cylindrical waveguide feed with an expander cone on it is relatively easy to make,
  and produces a narrower illumination angle.





David Eckhardt
 

We have a very nasty cell tower installation that dictated the 1 H GHz HPF.  I did a survey from one of our optical domes and a calibrated horn.  All the garbage from that tower is even producing bad noise IN the water hole.  Personally, I'd like to exercise my 12-gauge........ 

One of our members was first to come up with the feed we are using.  For a volunteer organization, we can't turn down anything! 

Terry and I have looked at spill over.  If anything we are under illuminated, but one thing at a time.  We really don't see much ground 'heat'.  We have recently come up with a method to determine the proper position for focus, but due to weather and travel, that hasn't been instituted, yet.

Your interesting paper on the Dicke interferometer and the idea of two antennas placed far apart as a function of wavelength tweaks my interest here at home (where is it MUCH quieter, RF wise).  I have two matched 5-element Yagis designed for the low end of our 70-cm band.  I had one in service last year on 431 MHz (408 now supports an unlicensed digital 'repeater' in my area - future 12-gauge target??  Maybe its gone as I haven't checked recently).  I can certainly set those up several wavelengths apart.  I'm tempted to add a 180-degree phasing line as well to one of the antennas.  Even with a single Yagi, I was able to clearly detect CYA A and CASS A on a drift scan on a good night.  I'm itching to try it with two properly phased but separated antennas as the article describes.  That idea has been brewing since I did the single antenna.   

Dave Eckhardt - WØLEV
Volunteer:  Little Thompson Observatory 

On Fri, Sep 29, 2017 at 3:50 PM, Marcus D. Leech <mleech@...> wrote:
On 09/29/2017 02:43 PM, David Eckhardt wrote:
I wish we all could record I/Q data even though the files would be huge.  But MS has put a limit on file size.  Gotta do Linux. 

We decode in AM at 32 kHz.  That's the widest bandwidth available for any amplitude-sensitive demod mode.  I'd like to demod the entire 100 MHz bandwidth of the water, but can't.  SpectrumSpy can easily display the whole water hole, but no like to demod modes from SpectrumSpy.

We feed the demodulated AM to Radio SkyPipe through VB Cable.  VB Cable is freeware and is a virtual audio cable that bridges from the USB interface of the AirSpy to audio just as though you were connected to the sound card directly (well, almost - watch dynamic range in VB Cable). 

AstroSpy is just SpectrumSpy taylored for the water hole frequency and 1.420405751 GHz, specifically.  I do wish they'd have a line to the demod modes from that application, but so far, notta. 

Our signal track is:

1)  5 sq meter dish
2)  1 GHz HPF
3)  LNA
4)  BPF (water hole)
5)  LNA
6)  Bias TEE
6)  75-feet of 1/2-inch solid shield coax
7)  Bias TEE
8)  LNA (feed gain isn't quite enough)
9)  AirSpy
10)  VB Cable (PC)
11)  Radio SkyPipe (PC based chart recorder)

Forgot the feed and I'm not going to renumber.  It's a single circular feet 1/4-wavelength from a large splash plate.  We might do a dipole feed at some time in the future.

Radio SkyPipe, with other very useful information and applications,  can be downloaded at:


The RSP data can be read into an EXCEL file, but that's another volunteer as I'm not a digital type.

Dave Eckhardt - WØLEV
Volunteer:  Little Thompson Observatory
                <starkids.org>  

Not sure how close to "civilization" your observatory is, but you might benefit from a 1/4-wave shorted-stub on the input to your LNA, which will provide
  a sloppy-bandpass response, rather than a high-pass response--and they're very low-loss, and as a side-effect provide ESD protection for your LNAs.

Also, you'd mentioned offset-fed dishes?  They need to be fed with a higher-gain feed in order to reduce spillover issues--because they are generally
  higher-F/D than prime-focus dishes in the same size range.  A cylindrical waveguide feed with an expander cone on it is relatively easy to make,
  and produces a narrower illumination angle.







--
Dave - WØLEV
Just Let Darwin Work


Alberto I2PHD
 

On 9/29/2017 8:43 PM, David Eckhardt wrote:

I wish we all could record I/Q data even though the files would be huge.  But MS has put a limit on file size.  Gotta do Linux. 

Are you perhaps still using FAT32 formatting on your disks ? FAT32 has a 4GB limit. NTFS does not have it.

--
73 Alberto I2PHD
Credo Ut Intelligam



Marcus D. Leech <mleech@...>
 

On 09/29/2017 06:15 PM, David Eckhardt wrote:
We have a very nasty cell tower installation that dictated the 1 H GHz HPF.  I did a survey from one of our optical domes and a calibrated horn.  All the garbage from that tower is even producing bad noise IN the water hole.  Personally, I'd like to exercise my 12-gauge........ 

One of our members was first to come up with the feed we are using.  For a volunteer organization, we can't turn down anything! 

Terry and I have looked at spill over.  If anything we are under illuminated, but one thing at a time.  We really don't see much ground 'heat'.  We have recently come up with a method to determine the proper position for focus, but due to weather and travel, that hasn't been instituted, yet.

Your interesting paper on the Dicke interferometer and the idea of two antennas placed far apart as a function of wavelength tweaks my interest here at home (where is it MUCH quieter, RF wise).  I have two matched 5-element Yagis designed for the low end of our 70-cm band.  I had one in service last year on 431 MHz (408 now supports an unlicensed digital 'repeater' in my area - future 12-gauge target??  Maybe its gone as I haven't checked recently).  I can certainly set those up several wavelengths apart.  I'm tempted to add a 180-degree phasing line as well to one of the antennas.  Even with a single Yagi, I was able to clearly detect CYA A and CASS A on a drift scan on a good night.  I'm itching to try it with two properly phased but separated antennas as the article describes.  That idea has been brewing since I did the single antenna.   

Dave Eckhardt - WØLEV
Volunteer:  Little Thompson Observatory 

The CCERA interferometer operates at 611MHz, with simple HDTV antenna at each end--each "station" is 2 X 8-Bay HDTV antenna connected together
  in-phase, then LNA/filter, and then to a USRP B210 where we do single-lag correlation on the signals.

A differential interferometer is the poor-cousin to that.



David Eckhardt
 

Yes, I we are using FAT32 formatting.  Thanks for the tip!!

Dave

On Fri, Sep 29, 2017 at 4:19 PM, Alberto I2PHD <i2phd@...> wrote:
On 9/29/2017 8:43 PM, David Eckhardt wrote:

I wish we all could record I/Q data even though the files would be huge.  But MS has put a limit on file size.  Gotta do Linux. 

Are you perhaps still using FAT32 formatting on your disks ? FAT32 has a 4GB limit. NTFS does not have it.

--
73 Alberto I2PHD
Credo Ut Intelligam





--
Dave - WØLEV
Just Let Darwin Work


Siegfried Jackstien
 

imagime if we could sync the iq data (via internet) of e few hundred dishes (imagine a cloud of receivers spread over the whole earth ...each one with a 6 foot or bigger dish)

that would make a nice setup

dg9bfc sigi


Am 29.09.2017 um 22:15 schrieb David Eckhardt:

We have a very nasty cell tower installation that dictated the 1 H GHz HPF.  I did a survey from one of our optical domes and a calibrated horn.  All the garbage from that tower is even producing bad noise IN the water hole.  Personally, I'd like to exercise my 12-gauge........ 

One of our members was first to come up with the feed we are using.  For a volunteer organization, we can't turn down anything! 

Terry and I have looked at spill over.  If anything we are under illuminated, but one thing at a time.  We really don't see much ground 'heat'.  We have recently come up with a method to determine the proper position for focus, but due to weather and travel, that hasn't been instituted, yet.

Your interesting paper on the Dicke interferometer and the idea of two antennas placed far apart as a function of wavelength tweaks my interest here at home (where is it MUCH quieter, RF wise).  I have two matched 5-element Yagis designed for the low end of our 70-cm band.  I had one in service last year on 431 MHz (408 now supports an unlicensed digital 'repeater' in my area - future 12-gauge target??  Maybe its gone as I haven't checked recently).  I can certainly set those up several wavelengths apart.  I'm tempted to add a 180-degree phasing line as well to one of the antennas.  Even with a single Yagi, I was able to clearly detect CYA A and CASS A on a drift scan on a good night.  I'm itching to try it with two properly phased but separated antennas as the article describes.  That idea has been brewing since I did the single antenna.   

Dave Eckhardt - WØLEV
Volunteer:  Little Thompson Observatory 

On Fri, Sep 29, 2017 at 3:50 PM, Marcus D. Leech <mleech@...> wrote:
On 09/29/2017 02:43 PM, David Eckhardt wrote:
I wish we all could record I/Q data even though the files would be huge.  But MS has put a limit on file size.  Gotta do Linux. 

We decode in AM at 32 kHz.  That's the widest bandwidth available for any amplitude-sensitive demod mode.  I'd like to demod the entire 100 MHz bandwidth of the water, but can't.  SpectrumSpy can easily display the whole water hole, but no like to demod modes from SpectrumSpy.

We feed the demodulated AM to Radio SkyPipe through VB Cable.  VB Cable is freeware and is a virtual audio cable that bridges from the USB interface of the AirSpy to audio just as though you were connected to the sound card directly (well, almost - watch dynamic range in VB Cable). 

AstroSpy is just SpectrumSpy taylored for the water hole frequency and 1.420405751 GHz, specifically.  I do wish they'd have a line to the demod modes from that application, but so far, notta. 

Our signal track is:

1)  5 sq meter dish
2)  1 GHz HPF
3)  LNA
4)  BPF (water hole)
5)  LNA
6)  Bias TEE
6)  75-feet of 1/2-inch solid shield coax
7)  Bias TEE
8)  LNA (feed gain isn't quite enough)
9)  AirSpy
10)  VB Cable (PC)
11)  Radio SkyPipe (PC based chart recorder)

Forgot the feed and I'm not going to renumber.  It's a single circular feet 1/4-wavelength from a large splash plate.  We might do a dipole feed at some time in the future.

Radio SkyPipe, with other very useful information and applications,  can be downloaded at:


The RSP data can be read into an EXCEL file, but that's another volunteer as I'm not a digital type.

Dave Eckhardt - WØLEV
Volunteer:  Little Thompson Observatory
                <starkids.org>  

Not sure how close to "civilization" your observatory is, but you might benefit from a 1/4-wave shorted-stub on the input to your LNA, which will provide
  a sloppy-bandpass response, rather than a high-pass response--and they're very low-loss, and as a side-effect provide ESD protection for your LNAs.

Also, you'd mentioned offset-fed dishes?  They need to be fed with a higher-gain feed in order to reduce spillover issues--because they are generally
  higher-F/D than prime-focus dishes in the same size range.  A cylindrical waveguide feed with an expander cone on it is relatively easy to make,
  and produces a narrower illumination angle.







--
Dave - WØLEV
Just Let Darwin Work


jdow
 

Sigi, I have a notion how it could be accomplished via post processing.

This would require a high quality GPS time receiver and GPS synchronization of the signals. This would allow recordings which could be lined up with each other in time fairly easily, especially if you use some automation to achieve the synch. This would give you an ad hoc synthetic aperture antenna if the GPS coordinates were also in each recording's metadata. AirSpy's ability to be phase locked to a precision reference is a key ingredient.

Do remember that for best decimation gain you do need an intentional spurious signal within the AirSpy bandwidth. As long as you're aimed at a region with a relatively strong source near the points of interest you should be able to achieve the precision time coordination you'd need for accurate phase alignment.

{^_^} Joanne

On 2017-09-30 02:50, Siegfried Jackstien wrote:
imagime if we could sync the iq data (via internet) of e few hundred dishes (imagine a cloud of receivers spread over the whole earth ...each one with a 6 foot or bigger dish)
that would make a nice setup
dg9bfc sigi
Am 29.09.2017 um 22:15 schrieb David Eckhardt:
We have a very nasty cell tower installation that dictated the 1 H GHz HPF.  I did a survey from one of our optical domes and a calibrated horn.  All the garbage from that tower is even producing bad noise IN the water hole. Personally, I'd like to exercise my 12-gauge........

One of our members was first to come up with the feed we are using.  For a volunteer organization, we can't turn down anything!

Terry and I have looked at spill over.  If anything we are under illuminated, but one thing at a time.  We really don't see much ground 'heat'.  We have recently come up with a method to determine the proper position for focus, but due to weather and travel, that hasn't been instituted, yet.

Your interesting paper on the Dicke interferometer and the idea of two antennas placed far apart as a function of wavelength tweaks my interest here at home (where is it MUCH quieter, RF wise).  I have two matched 5-element Yagis designed for the low end of our 70-cm band.  I had one in service last year on 431 MHz (408 now supports an unlicensed digital 'repeater' in my area - future 12-gauge target??  Maybe its gone as I haven't checked recently).  I can certainly set those up several wavelengths apart.  I'm tempted to add a 180-degree phasing line as well to one of the antennas.  Even with a single Yagi, I was able to clearly detect CYA A and CASS A on a drift scan on a good night.  I'm itching to try it with two properly phased but separated antennas as the article describes.  That idea has been brewing since I did the single antenna.

Dave Eckhardt - WØLEV
Volunteer: Little Thompson Observatory

On Fri, Sep 29, 2017 at 3:50 PM, Marcus D. Leech <mleech@ripnet.com <mailto:mleech@ripnet.com>> wrote:

On 09/29/2017 02:43 PM, David Eckhardt wrote:
I wish we all could record I/Q data even though the files would be huge. But MS has put a limit on file size.  Gotta do Linux.

We decode in AM at 32 kHz.  That's the widest bandwidth available for any
amplitude-sensitive demod mode.  I'd like to demod the entire 100 MHz
bandwidth of the water, but can't. SpectrumSpy can easily display the
whole water hole, but no like to demod modes from SpectrumSpy.

We feed the demodulated AM to Radio SkyPipe through VB Cable.  VB Cable
is freeware and is a virtual audio cable that bridges from the USB
interface of the AirSpy to audio just as though you were connected to the
sound card directly (well, almost - watch dynamic range in VB Cable).

AstroSpy is just SpectrumSpy taylored for the water hole frequency and
1.420405751 GHz, specifically.  I do wish they'd have a line to the demod
modes from that application, but so far, notta.

Our signal track is:

1) 5 sq meter dish
2) 1 GHz HPF
3) LNA
4) BPF (water hole)
5) LNA
6) Bias TEE
6) 75-feet of 1/2-inch solid shield coax
7) Bias TEE
8) LNA (feed gain isn't quite enough)
9) AirSpy
10) VB Cable (PC)
11) Radio SkyPipe (PC based chart recorder)

Forgot the feed and I'm not going to renumber.  It's a single circular
feet 1/4-wavelength from a large splash plate.  We might do a dipole feed
at some time in the future.

Radio SkyPipe, with other very useful information and applications,  can
be downloaded at:

http://radiosky.com/skypipeishere.html
<http://radiosky.com/skypipeishere.html>

The RSP data can be read into an EXCEL file, but that's another volunteer
as I'm not a digital type.

Dave Eckhardt - WØLEV
Volunteer: Little Thompson Observatory
              <starkids.org <http://starkids.org>>
Not sure how close to "civilization" your observatory is, but you might
benefit from a 1/4-wave shorted-stub on the input to your LNA, which will
provide
  a sloppy-bandpass response, rather than a high-pass response--and
they're very low-loss, and as a side-effect provide ESD protection for
your LNAs.

Also, you'd mentioned offset-fed dishes?  They need to be fed with a
higher-gain feed in order to reduce spillover issues--because they are
generally
  higher-F/D than prime-focus dishes in the same size range.  A
cylindrical waveguide feed with an expander cone on it is relatively easy
to make,
  and produces a narrower illumination angle.







--
*Dave - WØLEV
*
*/Just Let Darwin Work/*


Greg Ella
 

There is a guy in Germany right now doing something similar to locate transmitters using multilateration.  See this link here: http://www.panoradio-sdr.de/tdoa-transmitter-localization-with-rtl-sdrs/

He uses cheap RTL-SDR dongles and Raspberry Pi computers.  No GPS timing and no locked local oscillators.  He tunes all the receivers to a common transmitter (DAB), starts capturing data, and shifts to the signal of interest seamlessly with modified driver code.  Then he sorts everything out in MatLab post processing.

We could do something similar out here in Northern Colorado.  Stations in Cheyenne, Berthoud, Parker and Fort Morgan could all see the same DTV signal from Lookout Mountain to capture sync data.  Of course, we would use GPS locked Airspy receivers.

Greg Ella
AD0JP