The Hydrogen Line in Radio Astronomy

[@rossburns5604]

Fantastic explanation of the Hydrogen line. Really liked that. It makes detecting the spectral line even more exciting now that I know that it’s a super slow spin flip, but there’s just an absurd amount of Hydrogen atoms around that it is actually observable. Mind-blowing

[@bonsaisonixnet]

Seriously good video and explanation of the hydrogen 21 cm line. Thank you!

[@Jamessheffield11]

Dang, left us on a cliffhanger! Looking forward to the next episode!

[@smithja6]

Thanks for posting! I'm a science teacher just learning more about radio Astronomy. I've got some students who will really dig what you are working on.

[@2jpu524]

Please note, you don't need a sound-card, or an audio input jack as the interface is USB. Also, I'd recommend getting an RTL-SDR dongle that uses an TCXO local oscillator,(this is a big deal as the oscillators can drift with temperature and loose sensitivity as it gets warmer) or the AirSpy that increase the bit-depth from 8 bits to 12, etc.. Another useful thing to add is a "cavity filter" which blocks all other radio interference sources to minimize out-of-band interference and has exceptional stop-band attenuation. There are plans on how to make these on the web as well. You will see a huge difference in the sensitivity. Also, please get the lowest "noise-figure" and highest gain "low noise amplifier" you can get. If you're feeling even more adventuresome, you can pull out the horizontal and vertical polarizations, as galactic sources often have distinctive polarizations, but this requires an additional radio (or channel), LNA, etc..

[@Bart_noplease]

This is just fantastic. Exactly what I was looking for. I’m in astrophotography for just over the year now with my 80mm scope and all the gizmos attached. I was looking to get into radio astronomy with DIY project. I can’t wait to build one of my own. Thank you for creating this channel !!!

[@leohorishny9561]

Jeez, are you a physics teacher? 'Coz you should be, this is an amazing, clear explanation of the concepts involved!👏👏👏

[@ayurash]

Clear and loud! I like your projects and how you teach. Thank you!

[@patrickyeo2016]

excellent video man! Kudos to you!

[@halevidiomas5429]

Wow! Thank you so much for making this resource available!

[@piotrekpolak1122]

Very interesting video. Please keep up the good work!

[@paxsevenfour]

This is a great introductory video on this topic! Nice work 👍🏻

[@cpkukay02]

This is absolutely fantastic

[@jfluh9]

Thank you so much for making this video!

[@fosteral1957]

Very well done. Thank you.

[@Daljit779]

Very good Explanation Sir, Pls tell me books or resources or KZbin videos where I can learn this stuff more about theory part of it more .

[@Kyle-xt8ip]

Great video sir

[@FanaticalRK]

So much passion in this video

[@chanduarya6563]

A very good video sir Iam too interested in Radio astronomy and some day want to build a radio telescope Iam seeing this video for the first time and little bit late I hope you achieve a high degree of practice in Radio astronomy and some day amateur telescope like yours may catch a glimpse of far away universe and black holes at the centres of many galaxies just as today's event horizon telescope does

[@stargazer7644]

3:24 An SDR software defined radio receiver has nothing to do with the computer's sound card. The RF detection and audio processing is all done in software. The soundcard is only needed to play the audio the software has detected.

[@petevenuti7355]

Back in the 80's and early to mid 90's, before USB and SDRs, the sound card was very important and how data was collected for both radio astronomy and hams . Maybe that's what he was thinking of. The Atari 400 computer was especially popular back then because of the quality and ease of programming of it's sound chip relative to system price and it's data recorder used ordinary audio tapes too! (Before hard drives were smaller than your desk drawer and affordable)

[@stargazer7644]

@@petevenuti7355I'm sure what he was thinking about were the various soundcard modes still used in ham radio today such as FT8, Q65 (and the rest of the WSJT-X suite) and the older modes like PSK31, RTTY, AMTOR, etc (FLDigi as an example). But those don't have anything in particular to do with SDRs. We didn't really have soundcards on 8 bit computers in the 80s. Many had sound generating chips of various abilities, but most couldn't record and playback audio (with a very few exceptions). While there was certainly some specialized software for doing things like CW or RTTY back then, the soundcard modes didn't really become a thing until the 00s quite a while after soundcards appeared in PCs. It had to wait until processors were powerful enough to handle the CPU intensive real-time DSP those modes require.

[@petevenuti7355]

@@stargazer7644 the 80' didn't have much, and yes the Atari didn't natively support audio in. 8-bit audio is only 255 levels of intensity and when sampled at hundreds of hz , but if you made 4 different TTL level meters filtering for 4 different frequencies... oh nevermind, it sucked.... But there was plenty of stuff in the 90's, I still have a few ISA m-audio cards (if you ran os\2 you could use 4 cards at once, that's 8 44khz channels or 4 88khz channels, still can't see why anyone would ever need more .. There were a bunch of digital audio data transmission by hams in the 90's. It started well before the 2000's Anyway, I was really just reminiscing about how they used Atari 400's for SETI. Amazing how much was done with those old 8-bit machines...

[@moritzheintze7615]

1:45 - Pyramidal horn antennas have gotten into dis-use not only by radio astronomers but also everywhere else in radio communication. Including radio amateurs. The reason is, although they are easy to design and build, the performance is rather poor for the amount of material used. Actually a cheap Wifi Yagi will beat the big horn shown here hands down. Even better is a small horn + old satellite dish. Probably a dish will allow to locate the milky way with good accuracy, givern its gain.

[@bajasandor7826]

Excellent video, thank for sharing the good quality information. I'm pretty new in radioastronomy, and I considered a very, very interesting branch. I have some questions too about building a homemade rediotelescope: what is the minimum size of the dish? (I like to build it using a parabolic antenna), and I have to use a SDR too to see on a computer monitor? (or a spectrum analiser is useful too??), and the last, if is good to use a low noise amplifier too ? Thanks for you help. Have nice day!

[@julioc.7760]

Wow the guy rocks!, excellent video thanks (out of my league construction though...)

[@ronsindric4241]

GREAT POST ! Wish you would share your WEB sources for the plans for the antenna parts as well as other sources for radioastronomy hardware and software. If you had a couple of dozen small radiotelescopes and synchronized them using the time standard from. WWV would it be possible to Create a WEB Based VLA to allow members to do RADIOINTERFEROMETRY?

[@BlueCordVideo]

I had shared these in response to another comment, but it was buried a bit. The plans are at lweb.cfa.harvard.edu/~npatel/hornAntennaAASposterPDF2.pdf. As for interferometry, the Society of Amateur Radio Astronomers had an article in a recent issue of their journal about doing that.

[@joelbergeron3515]

wow! Does the size of the horn matter? Is bigger better?

[@BlueCordVideo]

The size of the horn does matter, and in general, bigger is better. However, what is more important is the ratio of different parts of the horn. The purpose of the horn is to gradually change the impedance so it matches the impedance of the waveguide, and the size of the waveguide is determined by the frequency you want to detect.

[@cinescopefilms]

Excellent!

[@stanhopkins6959]

Very fine introduction to the hobby! Have you found research projects using your data and perhaps data publicly avaliable produced by professional radio telescopes. Unfortunately my lot is heavily wooded.

[@petevenuti7355]

For those comments about sound card requirement, Back in the 80's and early to mid 90's, before USB and SDRs, the sound card was very important to and how data was collected for both radio astronomy and hams . Maybe that's what he was thinking of. The Atari 400 computer was popular back then for this purpose (more for SETI then Ham's) because of the quality and ease of programming of it's sound chip relative to system price and it's data recorder used ordinary audio tapes too! (Before hard drives were smaller than your desk drawer and affordable)

[@gabrielaochoamagana2331]

Terminal on the waveguide that measures the electric plane. How are the calculations? Is half the wavelength or any half multiple of it?

[@scientensity]

How can i learn software like AIPS, CASA, IDL

[@pri5469]

Why parabolic antenna is preferred over elliptical antenna?? For astronomy

[@alo1236546]

I hope i can hear God through radio someday

[@petevenuti7355]

It there a way to cause the spin flip? Or do you need a magnet bigger than an MRI?

[@qzorn4440]

wow! So in the very beginning of the 1st hydrogen atoms I guess there was no flipping unto millions of year later? 😎 Thank you very much. Brilliant video. Now I can start making plans to make my first radio telescope and figure out how to use it. Can you use an optical telescope to help point the wave guide?

[@CherryBoyReloaded]

Well done...

[@bencordell1965]

Can you transmit on the hydrogen line frequency?

[@rajaking1505]

What are the connector used for this radio telescope (like example n type connector)?????.... And how many connector I need in each type to make this radio telescope..

[@BlueCordVideo]

The connector on the waveguide is an N-type. This is stepped down to an SMA connector, which is what both the LNA and SDR use. The SDR is this connected to the Raspberry Pi via USB.

[@surasobservation]

thanks a lot

[@seanoneill2098]

Thank you.

[@thingslookingatthingseyebo4319]

where can i find the blueprints for the horn?

[@pri5469]

Sir, I am using old computer.. It is not compatible with sdr software... So I am trying to buy new laptop, which able to support sdr softwares... Can you give any suggestion(recommend) for laptop which in affordable rate... A cheapest laptop.

[@TheRichieEffect]

Do you have the specifications for your horn Radio-telescope? I teach in second level and would like to do similar with my students

[@BlueCordVideo]

Here are the instructions I used as a starting point: lweb.cfa.harvard.edu/~npatel/hornAntennaAASposterPDF2.pdf.

[@bradleywong8719]

good

[@mubeenmdmubeen5107]

Send to back in time sengal possible

[@SentientArtist]

Watched

[@ghostedyoutuber263]

Loose the carbs, get some exercise.