airspy@groups.io | Messages

Re: AstroSpy #1420mhz #21cm #radioastronomy

Marcus D. Leech

#31067

On 06/09/2019 01:55 PM, David Eckhardt wrote:

1) What is the aperture of your horn?

2) How much gain do you have after the two LNA4ALL preamps?

3) What is the loss of your BPF for 1420?

4) What is you detection bandwidth?

5) What is the loss of your coaxial cable(s)?

The reason for all the questions is based on our experience with a 14-foot off-boresite fed dish reflector as an antenna, a full-wave loop antenna element placed 1/4-wavelength

in front of a splash plate. That is fed to (all Minicircuits) a 0.5 dB NF 23 dB gain preamp. That feeds a 1 GHz HPF to eliminate (mostly, but not completely) a near-by cell tower

installation (grrrr....). The HPF feeds another preamp of the same ilk. Then some 70-feet of low loss rigid coaxial cable into the 'warm room' where we have installed

roughly another 40 dB of gain. Inside, we have also installed 3 dB attenuators between active stages for impedance stabilization and gain vs. SWR stabilization.

That finally feeds an AirSpy SDR. The system operates under SDR#. Our noise temperature is nominally 100 to 120 K, established (somewhat painstakingly) by several different and independent

methods (not all 'calibrated' noise sources exhibit consistency in the third decimal place!!). Installation of the 1 GHz filter to get rid of a very dirty cell tower

installation is responsible for half the noise temperature...... As you are aware, the H1 emission can be up to 500 to 750 kHz wide. You are detecting only a small

amount of the power of the H1 emission with the SDR#-limited available max bandwidth.

I'm very confused by your bandwidth comments here. I don't know much about SDR#, but if it shows a couple of MHz around the notional
line frequency of 1420.40575MHz, and allows deep integration, then you've covered essentially ALL of the hydrogen line doppler range within
the galaxy.

The next reasonable "target" for an amateur setup is the emissions from our sister galaxy, Andromeda, which are up-shifted to around 1422.5MHz
or so due to blue shift (Andromeda is hurtling towards us). Very long integration times would be required, due to having to deal with
inter-galactic, rather than inter-stellar, distances.

Here at CCERA, we operate a 21cm spectrometer, using AirSpy receivers on a 1.8m dish. Our final bandwidth is about 2MHz, which allows us
to "see" features at +/- 170km/sec from the rest frequency. Our software is Gnu Radio based, rather than based on AstroSpy or SDR#.

I'll likely do a write-up sometime soon.

Re: AstroSpy #1420mhz #21cm #radioastronomy

Marcus D. Leech

#31066

On 06/09/2019 02:42 AM, erbe.joshua@... wrote:

I have the Airspy Mini and I have built a horn antenna, I'm using 2 LNA4ALLs and a 1420-1470 MHz bandpass filter in between them. I think I have picked up the hydrogen emission signal. I would like to know more about Astro Spy software. Specifically, what is it doing? What does the the integration time do? Does the program average the signal strength over the time indicated by the Integration time box?

That hump is likely the hydrogen line signal.

What size is your horn antenna?

NRAO has a fairly full collection of tutorials on basic radio astronomy, including discussions of integration time. Also, www.radio-astronomy.org.

https://science.nrao.edu/opportunities/courses/era

https://www.cv.nrao.edu/course/astr534/Radiometers.html

But integration of noisy signals is not a strictly-radio-astronomy thing. Used all over the place in science and communications. Based on the
statistical distribution of random noise, the SNR improves roughly with the square-root of the number of samples taken, which equates directly
to how long you are integrating for, and the bandwidth you're integrating over.

Tmin ~= sqrt(Bw*Tau)

Where Tmin is the minimal change in noise temperature you can detect, Bw is the observing bandwidth, in Hz, and Tau is the integration time,
in seconds.

What this means is that for weaker spectral components, you have to integrate for a longer time period to "expose" them than for stronger/brighter
spectral components.

I went to the Airspy website to see if I could email them directly but it seems like this is the place to contact Airspy so I would like to hear from the company directly but if anyone else has experience with this program or knows what it does, I would love to hear your thoughts. Thanks.

Re: AstroSpy #1420mhz #21cm #radioastronomy

David Eckhardt

#31065

1) What is the aperture of your horn?

2) How much gain do you have after the two LNA4ALL preamps?

3) What is the loss of your BPF for 1420?

4) What is you detection bandwidth?

5) What is the loss of your coaxial cable(s)?

The reason for all the questions is based on our experience with a 14-foot off-boresite fed dish reflector as an antenna, a full-wave loop antenna element placed 1/4-wavelength

in front of a splash plate. That is fed to (all Minicircuits) a 0.5 dB NF 23 dB gain preamp. That feeds a 1 GHz HPF to eliminate (mostly, but not completely) a near-by cell tower

installation (grrrr....). The HPF feeds another preamp of the same ilk. Then some 70-feet of low loss rigid coaxial cable into the 'warm room' where we have installed

roughly another 40 dB of gain. Inside, we have also installed 3 dB attenuators between active stages for impedance stabilization and gain vs. SWR stabilization.

That finally feeds an AirSpy SDR. The system operates under SDR#. Our noise temperature is nominally 100 to 120 K, established (somewhat painstakingly) by several different and independent

methods (not all 'calibrated' noise sources exhibit consistency in the third decimal place!!). Installation of the 1 GHz filter to get rid of a very dirty cell tower

installation is responsible for half the noise temperature...... As you are aware, the H1 emission can be up to 500 to 750 kHz wide. You are detecting only a small

amount of the power of the H1 emission with the SDR#-limited available max bandwidth.

With this system, we are easily able to detect the H1 line with the antenna drift scanned across SDR-A* or the center of the galaxy on the SDR# RF display with no additional processing.

We are also able to detect some structure in the target rather than just a 'blob'. However, until recent installation of a hack from Russian SW, we were limited to the

bandwidths allowable with SDR#. That had severely limited our detection threshold of the H1 emission as most of the power from the target emission was not being

gathered for analysis. With 15 or 30 kHz bandwidths under SDR#, it took post-detection processing to bring out the H1 line. With the hack which allows roughly 0.5 MHz of bandwidth the H1 line

is easily visible on both the spectrum and waterfall display under SDR#. Another check of your system is that you should 'see' the LO roughly 10 MHz below (in our case)

the H1 emission. We do not use AstroSpy, but, rather, the full 10 MHz (to view the LO), and 2 MHz to yield display of the H1 line on the spectrum and waterfall. The reason for

that is AstroSpy does not allow for AirSpy parameter adjustments as does the 'normal' operation of the SDR under SDR#.

Your trace looks much like you have detected the H1 emission, but many variables need to be considered before one can nail it. I've given you our experiences gained over

some three years operation of our H1 'scope. Hopefully, it bounds you detection threshold. A good 1420 MHz low-level signal source is highly usable. I'll attach

a write-up of a source I did and is published in the SARA Journal (Society of Amateur Radio Astronomers) a couple of years ago. The comb generator output in

the attachment should not be connected to any efficient antenna it is highly likely to cause interference, but is a highly useful tool in setting up an H1 radio telescope.

See the attachment.

This installation is part of the offerings at the Little Thompson Observatory on the high school grounds in Berthoud, Colorado. It is offered as an educational tool for the school,

the community along the Front Range, and physics department and is totally supported technically by us volunteers and is a completely volunteer organization. You can

access us at <starkids.org>. We also annually work with a small group of STEM students on projects associated with radio astronomy. The observatory also offers

18" and 24" optical telescopes for the school and once a month to the public on "Public Star Nights". We also offer at no charge 'special events' of scientific interest to the

community on a request basis.

Dave - WØLEV

Volunteer: Little Thompson Observatory

<starkids.org>

Virus-free. www.avast.com

Show quoted text

On Sun, Jun 9, 2019 at 10:34 AM <erbe.joshua@...> wrote:

I have the Airspy Mini and I have built a horn antenna, I'm using 2 LNA4ALLs and a 1420-1470 MHz bandpass filter in between them. I think I have picked up the hydrogen emission signal. I would like to know more about Astro Spy software. Specifically, what is it doing? What does the the integration time do? Does the program average the signal strength over the time indicated by the Integration time box?

I went to the Airspy website to see if I could email them directly but it seems like this is the place to contact Airspy so I would like to hear from the company directly but if anyone else has experience with this program or knows what it does, I would love to hear your thoughts. Thanks.

--

Dave - WØLEV

Just Let Darwin Work

Just Think

A COMB GENERATOR - 20 MAY 2016 - NO ANT GAIN.docx

AstroSpy #1420mhz #21cm #radioastronomy

erbe.joshua@...

#31064

I have the Airspy Mini and I have built a horn antenna, I'm using 2 LNA4ALLs and a 1420-1470 MHz bandpass filter in between them. I think I have picked up the hydrogen emission signal. I would like to know more about Astro Spy software. Specifically, what is it doing? What does the the integration time do? Does the program average the signal strength over the time indicated by the Integration time box?

I went to the Airspy website to see if I could email them directly but it seems like this is the place to contact Airspy so I would like to hear from the company directly but if anyone else has experience with this program or knows what it does, I would love to hear your thoughts. Thanks.

Re: Astrospy

erbe.joshua@...

#31063

I realize you posted this over 2 years ago but I'm doing some radio astronomy with Astro Spy and a small homebuilt horn antenna. I would love to compare your screen shots with mine if you still have them somewhere!

Re: Help HF+ install

py3ol - Alan

#31062
Edited

Yes, I installed a new version of the OS in both 32bits and 64 bit of the W10. 
Also tested with W7 32bits. Configuration USB 480M in bios setup.
 Other USB2 and USB3 cables tested as well. 
Tested pci_e express USB3. Hf + firmware update works fine

I'm getting help from Prog and Itead.com

Alan - py3ol

Re: Help HF+ install

PMM

#31061

Have you tried removing Motherboard drivers and re-installing latest version on the manufacturers website. Also is your MB bios up-to date? What are the USB settings used in bios at boot up.

Show quoted text

On Tue, 4 Jun 2019, 22:38 h. garcia, <pu3hag.l@...> wrote:

Allan,

send me a private email in so we can arrange a TeamViewer session. I had no trouble connecting the other model AirSpy R2.

While testing with PY3JR and some old hardware, we found the USB port was critical. On 2 PCs tested, we had to try all available USB ports until we found one that worked. Unsure if it was oxidation or current limits.

On the other hand, test I made with modern laptops (2017 or newer) running Win10 went 100% flawlessly, in all ports, all times.

pu3hag ponto L arroba gmail ponto com

73,
pu3hag

On Tue, Jun 4, 2019, 16:52 prog <info@...> wrote:
On Tue, Jun 4, 2019 at 09:51 PM, py3ol wrote:

But another test and outher computer will tested next days. After, i call itead.com
Add me in cc: info at airspy dot com. Thanks!

Re: Help HF+ install

py3ol - Alan

#31060

Thanks huelber for help me and help by teamviewer.. Dear Prog is help me and i contact support itead.com... thanks !

Re: Looking for a Signal Strength plug in for SDR#

Edward MacDonald

#31059

I will see what I can do for you.

Show quoted text

On Tue, Jun 4, 2019, 3:37 AM z_mark via Groups.Io, <zmark98=yahoo.com@groups.io> wrote:

Hello Edward,
if possible, perhaps something like RSSI or "dBmLogger".

Re: Help HF+ install

h. garcia

#31058

Allan,

send me a private email in so we can arrange a TeamViewer session. I had no trouble connecting the other model AirSpy R2.

While testing with PY3JR and some old hardware, we found the USB port was critical. On 2 PCs tested, we had to try all available USB ports until we found one that worked. Unsure if it was oxidation or current limits.

On the other hand, test I made with modern laptops (2017 or newer) running Win10 went 100% flawlessly, in all ports, all times.

pu3hag ponto L arroba gmail ponto com

73,

pu3hag

Show quoted text

On Tue, Jun 4, 2019, 16:52 prog <info@...> wrote:

On Tue, Jun 4, 2019 at 09:51 PM, py3ol wrote:

But another test and outher computer will tested next days. After, i call itead.com
Add me in cc: info at airspy dot com. Thanks!

Re: Help HF+ install

prog

#31057

On Tue, Jun 4, 2019 at 09:51 PM, py3ol wrote:

But another test and outher computer will tested next days. After, i call itead.com

Add me in cc: info at airspy dot com. Thanks!

Re: Help HF+ install

py3ol - Alan

#31056

Yes.

But another test and outher computer will tested next days. After, i call itead.com

Thanks

Alan

Re: Help HF+ install

prog

#31055

On Tue, Jun 4, 2019 at 09:27 PM, py3ol wrote:

Any help ?

If nothing works, contact your retailer for return, diagnostics and repair/replacement.
This is just a mailing list for general discussion.

Re: Help HF+ install

py3ol - Alan

#31054

Hi prog

Its is real. MB asus Maximus formula +Intel Q6600 quad core +4gb. USB2.0. Test W7 32 and w10 32 + 64 bits. I have test with pcie USB 3.0 and same result. Also test anothere MB Asus P5K Premium + W7 32. No used VM. Test with another cable USB. All is same results. Used sdr-iq test on all usb port and is ok ! But is fine upgrade firmware, no problem.

Sdr-iq start.. led is blue... but no receiver.

Any help ?

Very thanks

Alan - py3ol

South Brazil

Re: Looking for a Signal Strength plug in for SDR#

z_mark

#31053

Hello Edward,
if possible, perhaps something like RSSI or "dBmLogger".

Re: Help HF+ install

prog

#31052

On Tue, Jun 4, 2019 at 08:12 AM, py3ol wrote:

i use win 10 32bits

Is this a VM or the real hardware? Try a different PC (not a VM) with all the Windows updates installed.

Re: Help HF+ install

py3ol - Alan

#31051

Hi prog

Update 2.1.0 BB is ok. Now.. i use win 10 32bits and usb2.0

Re: Airspy HF+ calibration instructions

Airspy US

#31050

We just averaged the units we took to the Dayton Hamvention (easy since they were all documented
together) and found the average was 2032, but anywhere from 2000 to 2500 is a good starting point.

This batch does seem to be a little lower than past units and I believe we recommended 2500 in the past.

One tip we use is that before zooming in, we note if the carrier is higher or lower than the expected frequency (or watch if zooming makes it go high or low) then we just use the buttons. You can tell when the carrier is getting close. Well, you can after doing several units. You get a feel for when the carrier is getting close by watching the "noise floor".

Perhaps Youssef can add an 'auto' button to adjust to the highest carrier in the range for a quicker adjustment. That won't always be the one you want, but many times it will be the one you want - especially in a closed environment (not over-the-air). Then the fine tuning can occur.

---------
Airspy.US
Your USA source for quality SDR products!
www.Airspy.US

NOTE! This email address is not routinely monitored.
If you have an issue, please contact us at airspy@airspy.us

Show quoted text

On 6/3/2019 10:52 AM, David J Taylor via Groups.Io wrote:
From: Airspy US via Groups.Io

Why the test settings? Just use the up-down arrows until the carrier is
centered. If it's low, use the down arrow. If it's high, use the up
arrow. (we know - counter to what is intuitive, but you're changing the
correction factor where a high carrier needs a larger factor set)

Also in the USA the best over-the-air sources are ATSC TV pilot
carriers. They are on very odd and
specific frequencies, but will be much more accurate than FM Broadcast,
NOAA, or similar transmitter.

Of course GPSDO would be the recommended source. For the Americas, we
would recommend the following source (US):
<<https://v3.airspy.us/product/lb-gpsdo-mini/>;>

Those who purchased their HF+ from us can also email for the value
originally used. This will not account for aging, but should get the
casual user very close with no need for over-the-air sources or any
sources for that matter.

As always, look at the value BEFORE updating the SW and write that value
down somewhere.
=========================================

Somehow I preferred to use numbers rather than buttons.  Typically I'm finding values around 2500, and that's perhaps a good starting point, but thanks for pointing out the buttons.  I use those for the final adjustments. Finding an accurate frequency reference is indeed an issue, and the mini GPSDO is a most handy instrument to have around.

Agreed to note the value!

Cheers,
David

Re: Airspy HF+ calibration instructions

David J Taylor

#31049

From: Airspy US via Groups.Io

Why the test settings? Just use the up-down arrows until the carrier is
centered. If it's low, use the down arrow. If it's high, use the up
arrow. (we know - counter to what is intuitive, but you're changing the
correction factor where a high carrier needs a larger factor set)

Also in the USA the best over-the-air sources are ATSC TV pilot
carriers. They are on very odd and
specific frequencies, but will be much more accurate than FM Broadcast,
NOAA, or similar transmitter.

Of course GPSDO would be the recommended source. For the Americas, we
would recommend the following source (US):
<<https://v3.airspy.us/product/lb-gpsdo-mini/>;>

Those who purchased their HF+ from us can also email for the value
originally used. This will not account for aging, but should get the
casual user very close with no need for over-the-air sources or any
sources for that matter.

As always, look at the value BEFORE updating the SW and write that value
down somewhere.
=========================================

Somehow I preferred to use numbers rather than buttons.  Typically I'm finding values around 2500, and that's perhaps a good starting point, but thanks for pointing out the buttons.  I use those for the final adjustments. Finding an accurate frequency reference is indeed an issue, and the mini GPSDO is a most handy instrument to have around.

Agreed to note the value!

Cheers,
David
-- 
SatSignal Software - Quality software for you
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv

Re: Airspy HF+ calibration instructions

Airspy US

#31048

Why the test settings? Just use the up-down arrows until the carrier is centered. If it's low, use the down arrow. If it's high, use the up arrow. (we know - counter to what is intuitive, but you're changing the correction factor where a high carrier needs a larger factor set)

Also in the USA the best over-the-air sources are ATSC TV pilot carriers. They are on very odd and
specific frequencies, but will be much more accurate than FM Broadcast, NOAA, or similar transmitter.

Of course GPSDO would be the recommended source. For the Americas, we would recommend the following source (US): <<https://v3.airspy.us/product/lb-gpsdo-mini/>;>

Those who purchased their HF+ from us can also email for the value originally used. This will not account for aging, but should get the casual user very close with no need for over-the-air sources or any sources for that matter.

As always, look at the value BEFORE updating the SW and write that value down somewhere.

---------
Airspy.US
Your USA source for quality SDR products!
www.Airspy.US

NOTE! This email address is not routinely monitored.
If you have an issue, please contact us at airspy@airspy.us

Show quoted text

On 6/3/2019 10:27 AM, David J Taylor via Groups.Io wrote:
I updated my notes when I recalibrated my Airspy HF+ after the 2.1.0 firmware update.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1. Download the latest SDR#. Set the airspyhf.debug flag to "1".
  Edit SDRSharp.exe.config, changing the value from "0" to "1":

      <add key="airspyhf.debug" value="1" />

2. Connect the unit and get it working with the latest SDR# and
  let it warm up for 10-15 minutes receiving signals.

3. Find yourself a precise and accurate frequency source, at as
  high a frequency as possible (I used 250 MHz). I suggest a GPS
  disciplined oscillator (GPSDO), but failing that a reliable
  broadcast station. The higher frequency you use the more accurate
  the result can be. Possibly a talk or classical music FM station
  (from the BBC) but be wary of deliberate frequency offsets.

 http://www.leobodnar.com/shop/index.php?main_page=product_info&;products_id=301 

4. Tune to the standard frequency source, and zoom in so that you
  can see the carrier alone. It may be helpful to have the Zoom FFT,
  Enable IF checked.

5. If the carrier is offset by more than 0.5 ppm, enter a non-zero
  value in the CLK (PPB) field (e.g. 1000) and press Flash. Does the
  display show the carrier being closer to the selected frequency?
  If not, try -1000 and press Flash again. Repeat until the frequency
  is spot-on.

6. Stop reception in SDR#, finally press Flash once again.

7. Stop SDR#. Unplug the HF+, wait a few seconds and reconnect it.

On restarting, you should find the calibration spot-on.  This has
stored the calibration in the device, not in the SDR# settings,
so the device should be fine on any other PC or software. You
should be able to get within 0.1 ppm, so about 1/10 Hz at medium
wave frequencies, but at those levels remember that varying ambient
temperatures will affect the calibration.

David Taylor
2019-Jun-03
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I hope that's useful, but please notify me of any corrections or suggestions.

Cheers,
David