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Showing posts with label RF propagation. Show all posts
Showing posts with label RF propagation. Show all posts

Sunday, March 28, 2010

Dark Flow and a Soft Radio Network


To the dark matter and dark energy mysteries, we can now add dark flow...

NASA’s Sasha Kashlinsky discovered a twenty degree patch of sky between Centaurus and Vela to which 700 X-ray clusters are being pulled at 611 miles per second. The significance of this is that it contradicts predictions that large-scale motion should show no preferred direction and that the motions should decrease at ever increasing distances. Kashlinsky posits that the source of the pull is "outside the currently observable universe".

I mention this because this gives us a patch of sky to which we can point our software-defined radios and perhaps observe something interesting.


The limitation is that our radios have to either be space-borne or in the Southern Hemisphere to get in on the action. Also this "dark flow' patch occurs out of the range of the Ukrainian radio telescope data visualized in a previous post:


It is my hope to create a network of Orbs - Soft Radios that can cooperate to locate celestial signals. Orbs are wide-band radios that downlink to the web using TCP/IP 802.11 protocols. Orbs talk to each other to using ham, astronomy, and ISM bands in real time. Their locations in space time is computed using GPS-disciplined internal oscillators.


Sunday, September 13, 2009

Hamtrak - Excerpt from Work In Progress


Added the ability to annotate RF sources streamed from data capture.

Wednesday, April 09, 2008

Antenna Gain


Gain patterns can be drawn for microphones, radio antennas and light reflecting from surfaces. They are both informative and beautiful.
The following images show the gain of a certain "wideband" herringbone antenna as frequency increases. Gain is simply the sensitivity of the antenna to a signal in a given direction.

When you tune a radio, you are selecting which frequency you want to listen to. But your antenna has to be cooperating by being sensitive to both the frequency of that station, its location, and how the signal bounces off the sky, land, water, trees, mountains and buildings.

So to begin we tune to 1.0 megahertz on our radio dial. In the pictures that follow we will increase the frequency on our radio dial by a factor of ten with each click. That makes for pretty big jumps. I hope to animate the in-between's soon. There are
so many variables one must decide what to show first. In the meantime here is a keyframe warm-up starting at the promised 1 MHz. Captions are below the images.

You Say Tomato
1 MHz - Radially symmetric pattern, more gain at top than bottom.

I Say Potato

10 MHz -More gain at the ends than the middle.


The Edges of Lambda

100 MHz -Nature is more beautiful than I can imagine.



Butterfly Spectacular

1000 MHz -Think about this next time you tune a radio.

The last picture is around the frequency of cellphones and some cordless phones. But their antennas actually have blobby radiation patterns like the first example. Can you think why that might be so?