Happy

[Paul Maxan (microp11)]

Hi All,

Happy to have found this group. My name is Paul Maxan, I live in Prince Edward Island, Canada, and as of 2 days ago I was able to capture the Hydrogen line with an off-the-shelf setup. I am so happy. My system is not yet calibrated in any way, and I am not very sure that I interpret correctly what I believe I see. I will attach a small video file, an excel speadsheet with selected data, and a sample of averaged values.

My current setup is as follows:
- Nooelec antenna (the one in the GOES Weather Satellite RTL-SDR Bundle ~15deg +/- 7.5deg), looking straight up
- Nooelec SAWbird+ H1 on bias-t (at the antenna)
- 10m RG58
- RTL-SDR Blog V3 R860 (R820T2)
- SDR# + IF-Average plugin
- Stellarium
- Chronolapse (capture screenshots)
- ffmpeg (make movie from screenshots)
- MS Excel

I have recorded data over 24h+ in 10mins intervals, each sample integrated over 500s. The attached speadsheet has 25h of data, one column per hour. I have percentage normalized the data and calculated the doppler shift. Not very precise as I was more interested to get the sign for the doppler and the range close to papers and images I found, which it did.

I am still all over the place, would like to try to understand the system and calibrate it, or at least understand what I am doing. For example, while I understand "cold" and "hot" I still cannot currently wrap my mind in moving from signal power to Kelvins. Then... trying to get my system through a noise calculator app and see if theory matches reality. So much fun! Or automate the capturing...

I have a motorised 2.5m dish that I can control with Stellarium and at some point I would like to move my experiments there. Maybe by next summer?! Not before I understand what I am doing using the current setup.

Thank you. Happy!

Cheers,

Paul

[Alex P]

Hello Paul,

Welcome to the Group !

You have all the right equipment and software 

Excel is optimal for comparing data and refining your system.

3 years into this, I still use Excel for reviewing the data.

Consider some of these videos ..

https://www.youtube.com/channel/UC-SzptAQZ-20c9CkRb9ZPxw/videos

and specifically :

https://www.youtube.com/watch?v=C6NCefVxNL8

Looking forward to seeing your results.

Best Regards,

Alex KK4VB

[b alex pettit jr]

Noise Temperature etc.

This is an Excellent Reference for Microwave Info

Microwaves101 | Noise Temperature

Microwaves101 | Noise Temperature Microwaves101 | Noise Temperature

[Paul Maxan (microp11)]

Hi all,

This is the data I collected at the time of the measurement a couple of days ago. Please see attached.

Recorded over 24h+ in 10mins intervals, each sample integrated over 500s. The attached speadsheet has 25h of data, one column per hour. I have percentage normalized the data and I believe I have calculated the doppler shift correctly.

I think it would be interesting to refere to this in the future, hopefully with a better understanding.

Cheers,

Paul

[Captain Anne Flint]

Welcome Paul! Please send photos of your setup. Wende 

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<data.xlsx><0637.jpg>

[b alex pettit jr]

Hello Paul,

I converted col J of Your Data  to dB ref to Cold Sky  ( as in my plots )

FYI, this shows my Very first data to that obtained 1 year later ..

 

Alex

[b alex pettit jr]

I also purchased the 1.7G GOES antenna ..

There are problems with the 1.7G feed ... #1 the dipole is positioned incorrectly  for 1.42G

This compares its normal 38 cm distance to the dish with shortening it to 35cm

 I have spent hundreds of hours reading, testing, documenting,  adjusting .. 

each improvement may be only a few 10ths of a dB, but they Add Up !

[Andrew Thornett]

Nooelec do now sell a 1.4GHz tuned antenna

Andy

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Sent: Thursday, November 23, 2023 9:03:15 PM
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Subject: Re: [SARA] Re: Happy

 

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[Andrew Thornett]

......it saves all those hours of adjustment

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[Paul Maxan (microp11)]

Thank you so much, this is very useful as I can now verify my own calculations.

[b alex pettit jr]

Agreed, the 1.42GHz would have performed much better, but :

Its probably not worth the $$ to purchase another Dipole based feed as they still pick up excessive ground noise.

The next step is a Loop_Feed  &  easy to fab.  Due to the close coupling of the LNA to Loop, This is an efficient design.

=============================================================================

On Thursday, November 23, 2023 at 04:23:37 PM EST, 'Andrew Thornett' via Society of Amateur Radio Astronomers <sara...@googlegroups.com> wrote:

......it saves all those hours of adjustment

[Paul Maxan (microp11)]

Thank you Alex,  this is really nice to know. Much appreciated. Will let you know what the difference is once I get to make this change, as I will.

I understand what Andrew T. mentions below, the off-the-shelf being tuned for GOES.

[b alex pettit jr]

Paul, I did not check  your velocity conversion . the formula is in my presentation ....

( and here )

FYI, you might consider 'standardizing' on 4 minute ( 1 degree in RA drift ) data scans . and 512 channels is quite sufficient to resolve the velocity spectrum.

See this post

 

Alex

=================================================================

[b alex pettit jr]

" % in POWER "

Paul I'm not sure how you converted the IF_Ave data, but the saved amplitude units are Linear not Power units.

Meaning the conversion equation is 20 * LOG10( value ) and if you did not take that into account, I calculated the data Incorrectly,

and the plot Correctly Converted to dB re Cold Sky would actually be  2x higher (  & more reasonable )

[Paul Maxan (microp11)]

Thank you, I understand my confusion regarding linear vs. power. Will take time to clear things in my mind.

This below I found very helpful for me on understanding the measurement of a signal power in dB:

 https://greatscottgadgets.com/sdr/3/

[b alex pettit jr]

I verified the proper equation by inserting calibrated attenuators and recording the result ..

The "Learning Opportunities" associated with Radio Astronomy are Huge ....

Alex

[Paul Maxan (microp11)]

These are the pictures, just a stock Nooelec antenna (the one in the GOES Weather Satellite RTL-SDR Bundle).

The support was changed long time ago to allow for a more precise positioning while I was using it on GOES.

There is a Nooelec SAWbird+ H1 on bias-t in the red enclosure I found on Amazon. The enclosure is not UV resistant, however it did very well over one winter. I just replaced it with a new one for the new winter.

The enclosure is transparent enough to be able to see at night the LED from the amplifier.

[Marcus D. Leech]

On 22/11/2023 22:51, 'Paul Maxan (microp11)' via Society of Amateur

Paul:

If you ever find yourself in the Ottawa area, let me know, and I can
give you a tour of our observatory.

Cheers
Marcus
http://www.ccera.ca

[Captain Anne Flint]

Thanks, nice looking setup - Wende 

<antenna.JPG>

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[Paul Maxan (microp11)]

Hi All,

I have received a 1.4G boom from Nooelec, called Inmarsat boom. I am attaching a comparative picture to the similar one from Nooelec for 1.7G that comes with GOES.

I will hopefully be able to set some comparative tests, this coming weekend.

Cheers,

Paul

[b alex pettit jr]

Hello Paul,

And for comparison, here are photos of the 1.7G and 2.4G boom&feeds.

Alex

[Andrew Thornett]

Yes that is the same one they send with the 1.4GHz mesh dish. The dosh in that kit is also slightly larger than the one in 1.7GHz kit but I doubt that matters too much.

How much did they charge you for 1.4GHz boom and waveguide?

Andy

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Subject: Re: [SARA] Re: Happy

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[Paul Maxan (microp11)]

Hi Andy,

I got the 1.4Ghz boom as part of a kit so I don't have a price.

I am not sure if Nooelec sells it separately, however it would be worth asking for sure. I will ask as well.

Cheers,

Paul

[Paul Maxan (microp11)]

I will measure the 1.4GHz boom as well, although it would make sense that the dipole (or whatever is inside the black box) is different too, as it is larger than the 1.7Ghz one.

[Paul Maxan (microp11)]

Hi All,

A bit closer to cleaning up my signals:  https://x.com/microp11sat/status/1738314140198875212?s=20

This is the pre-processed one (in blue) and the processed one (in orange): https://x.com/microp11sat/status/1738313588689805795?s=20.

Captured with the 1.7G boom on the Nooelec antenna, same as the original test, except using https://wvurail.org/dspira-lessons/ DSPIRA instead of SDR# and plugins.

I did not move yet to the 1.4G boom as I was more interested in cleaning what I have received already.

The system is still not calibrated, I hope that the distinction can be made by looking at the signal itself (I would expect more definition I guess) using a better calibrated antenna.

Cheers,

Paul

[b alex pettit jr]

Hello Paul,

Excellent Data !

While comparing configurations, you want to keep the data in power or convert to dB ref to Cold Sky.

Pick some convenient reference RA/Dec and use the difference between Cold Sky & Max Signal as an indicator of performance.

( signal strength )

 

You can also calculate RMS Noise vs Pk Signal

Alex

[Andrew Thornett]

That's excellent and shows the 1.7GHz boom can still very effectively.be used to collect hydrogen data sp perhaps the 1.4GHz boom on Nooelwc mesh antenna really isnt necessary,  especially as it costs lot more.

I wonder - does this reflect other people's experience? How important is it to tune the antenna close to 1.4GHz rather then 1.7GHz, eg with horn antenna or corner antennae or yagis or other dishes?

Andy

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Subject: Re: [SARA] Re: Happy

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[b alex pettit jr]

They are identically priced.

[Andrew Thornett]

That is interesting means the 1.7GHz has gone up in price I bought mine for £31 and then £100 for the 1.4GHz version - although admittedly I hadn't looked at Amazon for 1.7GHz version since. 

Wind has blown over 1.4GHz mesh twice in recent storm and wide guide looking rather bent! Hopefully I can straighten it out........

Andy 

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[Paul Maxan (microp11)]

Hi Alex,

Thank you!

I have added a quick RMS calculation and a max peak to peak on the max point only at this time: 
https://x.com/microp11sat/status/1738610892810420396?s=20

Once I collect enough data I will do comparisons.

I think based on curves lso i can identif

Also attached is one minute of averages that can be used to play with calculations and assumptions as they are at this moment in time. Following the spririt of "real" programmers, not much commenting of the code file. Will improve... perhaps...

The time is in UTC and can be corroborated with Stellarium or similar for 180 azimuth, 90 elevation, at:

N 46*23'34.08"

W 63*16'12.36"

Cheers,

Paul

[Paul Maxan (microp11)]

... I think based on curves l can also identify a patch of cold sky to have a power reading in K at that point.

[b alex pettit jr]

Hello Paul,

You need to Verify is amplitude Units.. are they Power or Linear ?

The way I tested the IF_Ave *.txt saved files  was to insert a calibration attenuator in the RF path 

and verify the change represented the atten as marked on the unit...

Example : an Atten marked  " 6 dB " 

will  Halve the value of Linear amplitude data

and Quarter the value for Power scaled data

Alex

[Paul Maxan (microp11)]

Added the 1.4-1.7G Nooelec boom dimensions as well. This is the one that comes with the Inmarsat package from Nooelec.

[Andrew Thornett]

How much did it cost to buy the 1.4GHz boom from Nooelec alone to upgrade the 1.7GHz mesh to 1.4GHz?

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Subject: Re: [SARA] Re: Happy

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[Paul Maxan (microp11)]

Hi All,

I did not buy the 1.4G boom alone. Not sure if Nooelec sells it alone. I have mentioned in the past that I would ask. I just did not have the chance yet.

There is however a significant improvement in signal quality if using the 1.4G boom vs. the 1.7G one:

https://x.com/microp11sat/status/1740020720321884564?s=20

Still unsure of the vertical scale units, however the difference (ppmax - rms noise) is definitely larger using the Inmarsat boom: 18 vs. 13.

Also I have ordered a set of Nooelec attenuators ( https://www.amazon.ca/dp/B07YYMT65T?psc=1&ref=ppx_yo2ov_dt_b_product_details) and I am going to follow up on another excellent suggestion from Alex (thank you so much!) to define my vertical scale.

Cheers,

Paul

[Paul Maxan (microp11)]

Hi all,

Just to let you know, I have asked Nooelec engineering if they would be selling the 1.4G boom independently. I have received an answer today.

The answer was affirmative: "the boom will be sold as a standalone product on our website in the coming weeks". 

Cheers,

Paul

[Paul Maxan (microp11)]

Hi all,

Nooelec is now selling the booms as stand-alonr products: this is the 1.4G boom: https://www.nooelec.com/store/hydrogen-boom.html

Cheers,

Paul

[b alex pettit jr]

Paul,

Have you taken any data with this antenna & can you post results if so ?

Alex

[Paul Maxan (microp11)]

Hi Alex,

I am still struggling with calibrating the receiver chain.

I am using: https://github.com/WVURAIL/gr-radio_astro for the capturing of the data and calibration.

Based on the documentation I found at: https://github.com/WVURAIL/lightwork/tree/master/memos I am starting to understand what I am seeing in terms of my setup.

The system:

Nooelec grid antenna w/ 1.4G boom + Nooelec H1 LNA (the very first model they sold) + 10m LMR400 + Airspy (the first model) + 50 Ohm resistor in a SMA package.

gnuradio running NsfIntegrate100, gain1=gain2=22.0 gain3=0, cf=1421MHz, bw=10MHz, n_ave=572 =~2mins

Following the noise temperature measurement as described by this document (https://github.com/WVURAIL/lightwork/blob/master/memos/LightWork0030-r1-ATaleOfThreeLNAs.pdf and calibration notes as in https://github.com/WVURAIL/lightwork/blob/master/memos/LightWorkMemo028-r7-NoiseTemp.pdf), I got:

With the entire chain minus the antenna (cold measurement):

K Max 297

K Min 135

K Median 168.2

dB Max 12.575

dB Min 5.734

dB Median 7.985

Intensity counts Max 18.079

Intensity counts Min 3.568

Intensity Median 6.299

With the entire chain including the 1.4G boom connected:

K Max 858.5

K Min 143.1

K Median 183.6

dB Max 17.619

dB Min 6.114

dB Median 8.150

Intensity counts Max 49.832

Intensity counts Min 4.284

Intensity Median 6.578

The documentation says the the medians are the values most indicative of the system performance and 183.6 seems to be a relatively good value:

I do not have screenshots of the signal while in dB mode and calibrated, however if I run a quick graph on raw data, I am getting this:

and the signal is clearly visible.

There are still inconsistencies in calibrating and cleaning up the signal for RFI took me a long time, but it looks I am making some progress.

Hope this helps a bit with your question. Unfinished stuff here lots.

I can already run graphs that display data in K or dB, just not very consistent yet.

Once I am sure I can repeat the calibration steps, and data is being displayed in dB or K, I can then run comparisons. Hopefully soon.

Cheers,

Paul

[Alex P]

Hello Paul,

        A Recommendation for  system performance measurement / comparison,

1) correct for system background  .. use a 50 ohm load into the LNA, measure the spectrum and use it as a correction factor

meaning the spectrum should be a flat line with no H data.

2)  measure some reference point in the MW  . I use Dec+40 RA20:30 as it is a bright area in Cygnus.

3) convert to dB  

            ( One Time : with any signal into the LNA: use an atten prior to the SDR to verify dB change = dB marked on atten )

4) Normalize all data to Cold_Sky  Plot Data

5) Recording Earth_Sky measurements is also useful

You can build up a library of systems/changes as a reference OR even use them to compare with other's systems

Alex

[b alex pettit jr]

FYI : That data is from 5 minute averages   no added  ' smoothing, post filtering, or 'Cleaning'  '.

You do NOT want to do that in order to See the noise floor

Alex