Hot News! NASA published an article about "Simple"! HERE

Welcome to the Fringe Dwellers "Simple" radio astronomy site. This site is mostly about constructing low frequency, cross-correlating, meridian transit radio interferometers and about doing radio astronomy with them.

Such an instrument has two radio receivers, fed by individual antennas. The antennas are spaced some "baseline" distance apart. The two receivers run coherently, meaning that not only do they work at roughly the same frequency, they are precisely phase-locked together. This involves having the two receivers share a common local oscillator (LO). We use a normal stereo soundcard (and some purpose made software) to read the audio output of the two receivers. The baseline distance determines the resolution of an interferometer, so even simple equipment can be used to build high resolution radio telescopes. Interferometers also have other useful properties.

"Fringe pattern" produced by the active sun, over a day.

Background

Working mostly after-hours, the first "Simple Interferometer" of this design was developed by David Brodrick, Tim Kennedy, Steven Tingay and Daron Brooke of the CSIRO Australia Telescope National Facility (ATNF). The idea was to introduce people to radio interferometery without them having to spend mega bucks. Our original 20MHz Simple Interferometer has been operating since late 2001 at the ATNF's Compact Array site near Narrabri, NSW, Australia (~ 150E/30S). A few radio observatories now share the same design.

As of 2004 I (David) have been enrolled in a research masters degree with Dr. Steve Tingay of Swinburne University and Dr. Mark Wieringa and Dr. Michael Dahlem of the ATNF. My masters involves doing science with these low frequency interferometers, using data from the original "Simple" at Narrabri, Dr Michael Dahlem's "simpleton" interometer, and some of the other interferometers. It is a great opportunity for me to study radio astronomy with professional radio astronomers while also further developing the "Simple Interferometer" idea so that it can be shared with interested university groups and amateur and professional radio astronomers.

"Simple" consists of two little silver RadioJove receivers and an old Linux PC

After Tim and I gave a few public talks about "Simple" in 2002/2003 we caught the attention of Steve Heaton who put most of the original effort into developing and hosting this website and really encouraged us to try to spread the word about our interferometer project. Together we set up a Yahoo email list where there is sometimes interesting discussions about building simple interferometers - worth considering if you are seriously interested.

2004 was a great year with Dusty Samouce (USA), Michael Dahlem (also with ATNF Narrabri) and Brett Dawson at the ATNF's Parkes Observatory (~300 km south of Narrabri) setting up simple 20MHz interferometers. However it looks like 2005 might be a highlight year for the project (for me personally) with the first real results of my masters work coming through, being a publication using some very nice Simple data to estimate the true size of the largest ever recorded solar flare, a flare so large that even the GOES satellites, the work horses of solar X-ray photometry, were overloaded. I will post more details about this soon.

Listen to the sky,
As it crackles and it pops,
what does it all mean?
Rose 2005

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