<p>Partial answer:</p>
<blockquote>
<p>I imagine this array would have very high resolution due to the large number of large and small baselines</p>
</blockquote>
<p>and</p>
<blockquote>
<p>I expect time synchronization would be an issue, but perhaps they could find a clever way to synchronize.</p>
</blockquote>
<p>The 1 meter dishes are small and so for the dish to have any relevance to the project the wavelength has to be a lot smaller.</p>
<p>To do <em>interferometry</em> your synchronization will have to be extremely good; a 3 cm wavelength would be 10 GHz and the period is 0.1 nanosecond. You'll need to have all kinds of expensive and sophisticated electronics to maintain a stable and drift-free timebase at that level of accuracy.</p>
<p>You might be able to leverage your long baselines but fairly wide fields of view for these small dishes by using <em>timing</em> somehow. If you had ten distant dishes each pointed in 50 different directions and there was a sudden event, you might be able to localize it by arrival time differences, a bit like how lightning detectors work.</p>
<p>I don't know anything about it, but there is also something called <a href="https://en.wikipedia.org/wiki/Intensity_interferometer" rel="nofollow noreferrer">intensity interferometry</a> but it's not clear if that's actually helpful at all. See <a href="https://en.wikipedia.org/wiki/Hanbury_Brown_and_Twiss_effect" rel="nofollow noreferrer">Hanbury Brown and Twiss effect</a> and (paywalled) R. Hanbury Brown, R.Q. Twiss (1954) <a href="https://www.tandfonline.com/doi/abs/10.1080/14786440708520475" rel="nofollow noreferrer">LXXIV. A new type of interferometer for use in radio astronomy</a></p>
<blockquote>
<p>A new type of interferometer for measuring the diameter of discrete radio sources is described and its mathematical theory is given. The principle of the instrument is based upon the correlation between the rectified outputs of two independent receivers at each end of a baseline, and it is shown that the cross-correlation coefficient between these outputs is proportional to the square of the amplitude of the Fourier transform of the intensity distribution across the source. The analysis shows that it should be possible to operate the new instrument with extremely long baselines and that it should be almost unaffected by ionospheric irregularities.</p>
</blockquote>
<p>See <a href="https://books.google.com/books?id=jWIe46x13p0C&amp;printsec=frontcover&amp;dq=A+Personal+Story+of+the+Early+Days+of+Radar,+Radio+Astronomy+and+Quantum+Optics&amp;hl=en&amp;sa=X" rel="nofollow noreferrer">Boffin : a personal story of the early days of radar, radio astronomy and quantum optics</a></p>
<p>See also Dainis Dravens' 2010 <a href="http://home.thep.lu.se/%7Eanders/ATP_slides/100526-BosonInterferometry.pdf" rel="nofollow noreferrer">BOSON INTERFEROMETRY From astronomy to particle physics, and back</a> especially the radio part.</p>
<p>Only somewhat related, with some discussion of the effect before going on to discuss the optical implementation (but using electronic correlation): <a href="https://arxiv.org/abs/1607.03490" rel="nofollow noreferrer">Intensity interferometry: Optical imaging with kilometer baselines</a></p>
<p>I wrote a related answer here: <a href="https://astronomy.stackexchange.com/a/42131/7982">https://astronomy.stackexchange.com/a/42131/7982</a></p>

CC BY-SA 4.0
2021-05-01T15:07:16.513Z
2021-05-01T16:21:22.833Z
2021-05-01T16:21:22.833Z
uhoh
<p>Suppose an astronomer gave a 1 m radio dish to 500 people scattered over the face of the Earth and connected them to the internet. The people are directed to set their radio antennae up in their backyard per given instructions. The astronomer would then control the array of radio antennae remotely via the internet.</p>
<p><strong>Could such an array of radio dishes be used to do <em>any</em> kind of meaningful astronomical interferometry? If so, what kind? If not, why not?</strong></p>
<p>I fully expect that the radio dishes wouldn’t hold a candle to the sensitivity other radio dish networks (EVT, VLA, EVLA, etc.) due to the tiny dish size. I expect time synchronization would be an issue, but perhaps they could find a clever way to synchronize. I imagine this array would have very high resolution due to the large number of large and small baselines — extended further by the Earth’s rotation. Between low dish sensitivity, large numbers of dishes and a huge baseline count, I’m curious what such a network could be capable of.</p>

CC BY-SA 4.0
2021-04-28T05:28:43.250Z
different but related: [Open source library to calculate image from signals of a distributed set of radio dishes?](https://astronomy.stackexchange.com/q/42127/7982) and [Recommend a radio calibration target for amateur radio telescope](https://astronomy.stackexchange.com/q/41906/7982) and [Can one build a distributed radio telescope?](https://astronomy.stackexchange.com/q/42042/7982) and [What radio frequency ranges are most beneficial for astronomy?](https://astronomy.stackexchange.com/q/43508/7982)
uhoh
CC BY-SA 4.0
2021-04-28T07:17:00.780Z
Very interesting question indeed, could have been my brain child :-)  Here another related question: [Requirements to resolve position of Jovian Whistlers up to magnitude of Red Spot with amateur radio equipment?](https://astronomy.stackexchange.com/q/43560/37191)
B--rian
<observational-astronomy><radio-astronomy><radio-telescope><interferometry>
What could a cloud of mini radio dishes see?
jvriesem
# What could a cloud of mini radio dishes see?

(Asked by: username_0 on 2021-04-28)

Suppose an astronomer gave a 1 m radio dish to 500 people scattered over the face of the Earth and connected them to the internet. The people are directed to set their radio antennae up in their backyard per given instructions. The astronomer would then control the array of radio antennae remotely via the internet.

**Could such an array of radio dishes be used to do *any* kind of meaningful astronomical interferometry? If so, what kind? If not, why not?**

I fully expect that the radio dishes wouldn’t hold a candle to the sensitivity other radio dish networks (EVT, VLA, EVLA, etc.) due to the tiny dish size. I expect time synchronization would be an issue, but perhaps they could find a clever way to synchronize. I imagine this array would have very high resolution due to the large number of large and small baselines — extended further by the Earth’s rotation. Between low dish sensitivity, large numbers of dishes and a huge baseline count, I’m curious what such a network could be capable of.

**Tags:** observational-astronomy, radio-astronomy, radio-telescope, interferometry
> **Comments:**
> **username_1**: different but related: [Open source library to calculate image from signals of a distributed set of radio dishes?](https://astronomy.stackexchange.com/q/42127/7982) and [Recommend a radio calibration target for amateur radio telescope](https://astronomy.stackexchange.com/q/41906/7982) and [Can one build a distributed radio telescope?](https://astronomy.stackexchange.com/q/42042/7982) and [What radio frequency ranges are most beneficial for astronomy?](https://astronomy.stackexchange.com/q/43508/7982)  
> **username_2**: Very interesting question indeed, could have been my brain child :-)  Here another related question: [Requirements to resolve position of Jovian Whistlers up to magnitude of Red Spot with amateur radio equipment?](https://astronomy.stackexchange.com/q/43560/37191)  

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## 1 answers

### Answer by username_1 on 2021-05-01. Score: 4 | Accepted answer

Partial answer:

> I imagine this array would have very high resolution due to the large number of large and small baselines

and

> I expect time synchronization would be an issue, but perhaps they could find a clever way to synchronize.

The 1 meter dishes are small and so for the dish to have any relevance to the project the wavelength has to be a lot smaller.

To do *interferometry* your synchronization will have to be extremely good; a 3 cm wavelength would be 10 GHz and the period is 0.1 nanosecond. You'll need to have all kinds of expensive and sophisticated electronics to maintain a stable and drift-free timebase at that level of accuracy.

You might be able to leverage your long baselines but fairly wide fields of view for these small dishes by using *timing* somehow. If you had ten distant dishes each pointed in 50 different directions and there was a sudden event, you might be able to localize it by arrival time differences, a bit like how lightning detectors work.

I don't know anything about it, but there is also something called [intensity interferometry](https://en.wikipedia.org/wiki/Intensity_interferometer) but it's not clear if that's actually helpful at all. See [Hanbury Brown and Twiss effect](https://en.wikipedia.org/wiki/Hanbury_Brown_and_Twiss_effect) and (paywalled) R. Hanbury Brown, R.Q. Twiss (1954) [LXXIV. A new type of interferometer for use in radio astronomy](https://www.tandfonline.com/doi/abs/10.1080/14786440708520475)

> A new type of interferometer for measuring the diameter of discrete radio sources is described and its mathematical theory is given. The principle of the instrument is based upon the correlation between the rectified outputs of two independent receivers at each end of a baseline, and it is shown that the cross-correlation coefficient between these outputs is proportional to the square of the amplitude of the Fourier transform of the intensity distribution across the source. The analysis shows that it should be possible to operate the new instrument with extremely long baselines and that it should be almost unaffected by ionospheric irregularities.

See [Boffin : a personal story of the early days of radar, radio astronomy and quantum optics](https://books.google.com/books?id=jWIe46x13p0C&printsec=frontcover&dq=A+Personal+Story+of+the+Early+Days+of+Radar,+Radio+Astronomy+and+Quantum+Optics&hl=en&sa=X)

See also Dainis Dravens' 2010 [BOSON INTERFEROMETRY From astronomy to particle physics, and back](http://home.thep.lu.se/%7Eanders/ATP_slides/100526-BosonInterferometry.pdf) especially the radio part.

Only somewhat related, with some discussion of the effect before going on to discuss the optical implementation (but using electronic correlation): [Intensity interferometry: Optical imaging with kilometer baselines](https://arxiv.org/abs/1607.03490)

I wrote a related answer here: <https://astronomy.stackexchange.com/a/42131/7982>


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