Re: AstroSpy #radioastronomy #21cm #1420mhz

Marcus D. Leech
 

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.

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