Radiation Storm Lets You Listen Long-Distance

bubblegoose writes: "There is a large radiation storm in progress caused by a solar flare on the backside of the Sun. Here's a story from Spaceweather. It has a pretty cool effect on radio signals. I was picking up a 6000 Watt North Carolina FM station from near Philly." Bubblegoose also brings you this link to dxing.com, a site all about listening in when freak atmospheric conditions create unusual RF propagation patterns.

Comments

If you think this is cool, check out Ham radio

[moebius_4d]

If you want to learn more about ionospheric skip, sporadic-E, transmission by meteor scatter (literally bouncing signals off meteors), moonbounce, and other neat ways to communicate long distances by radio, check out Amateur Radio (often called ham radio). One good place to start learning more is at the American Radio Relay League, www.arrl.org. There's a lot of amateur radio stuff on the web.

Honestly, you can buy or build an inexpensive radio and antenna for peanuts. Some kit radio projects like the "tuna tin" radio can be built in 15 minutes!

While you do need a license, the technician class exam is so easy most slashdotters should be able to pass with no studying. The FCC mandates a fixed question pool from which the questions will be drawn, and these are available on-line. (So are practice tests.) So if you just like to get perfect scores, read all the questions first! :)
And the exam fee is also mandated by the FCC, currently $10.00, so basically this is very easy to get into.

I hope that a lot of people here are intrigued by the fascinating world of long-distance radio wave propagation. From simple chatting with people in your local area, to talking to Africa and even Antarctica, radio is the only communication system that covers the globe.

Also there's the exciting world of amateur satellites, satellite designed, built, and launched by amateur volunteers and funds. These are another great way for a low-power station to communicate DX (long distance) without much special equipment.

I guess I don't need to add how pleased I am to see radio wave propagation stories on /. :)

See you on the air!

Any CB/Ham operator knows it's called...

[Anonymous Coward]

Skip

short rambling on Natural Radio

[Anonymous Coward]

Eh.. i shouldn't do this, but.. What the hell.

While screwing up human-created radio patterns is an interesting effect, if the idea of listening to sound generated entirely by natural phenomena emitting radio waves interests you, there is a pretty good writing --> at this url <--, at the everything2 entry for "natural radio". The important thing about this site is that it contains a URL at the end containing recordings of the noise parsed by humans from natural radio. Turns out Mother Nature can create ambient about as evocative as anything we could ever replicate using our primitive tape recording systems..

If anyone else has some related links, btw, (and if y'all feel like it, we could maybe let this thread spiral way offtopic and maybe throw in a couple links regarding Oval, Pole, Farmers Manual or Disc or japanese noise groups, "Numbers Stations", etc..) could you post them as a reply to this?

In specific: The recent (excellent imho) issue of Wire with the cover story on nondeterministic music (or maybe it was the Urb where they interview richie hawtin.. can't remember. whatever.) They had a URL for some page at NASA in which they have sound files up containing natural radio emissions picked up by satellites *orbiting mars*.. with the source of the emissions being martian atmospheric phenomena. Freaky stuff, but it sounded really cool. unfortunately, i have lost that link. anyone have it?

Trop vs skip

[n3hat]

Long distance vhf reception may be the result of ionospheric conditions (sporadic E skip, e.g.). A more common cause in my experience is tropospheric ducting ("trop"). Trop creates a waveguide in the atmosphere. It is often caused by a temperature inversion.
Although the speed of light is nearly as fast in air as it is in a vacuum, it does differ slightly. And it is lower in dense, cool air than in thin, warm air. In other words, the refractive index of cool air is higher that of warm air. The signals are bent back to earth when they hit a discontinuity in the refractive index caused by a layer of warm air overlaying a region of cool air. Inversion layers commonly form on cool, clear nights. So you will often hear anomalous FM reception in the morning -- distant stations heard between local stations, or even interfering with weak locals.
A Yahoo search on "temerature inversion radio propagation" will enlighten the curious - this is one result. Or run to the library and look in "The Radio Amateur's Handbook".

javaradio

[awptic]

www.javaradio.com has links to several shortwave receivers around the world connected to the internet. The lag between the audio and the controls is horrible, if you can bare with that it can be quite interesting.

'Frequency'

[Chmarr]

As an aside, the particular effect was one of the key 'reason for being' points of the movie Frequency.

You can go click the link for a summary of the movie. Fairly decent flick, got too wrapped up in funny timetravellish things, and how the radios magically did not need the TX buttons pushed anymore was particually annoying.

Re:'Frequency'

[jnik]

As an aside, the particular effect was one of the key 'reason for being' points of the movie Frequency.
Actually no. What's happening now is standard ionospheric skip, just on higher-than usual frequencies becuase of higher ionization levels. "Frequency" was about Long Delayed Echoes, where you'll pick up a transmission from years or even decades ago. LDE's still aren't fully explained; the difficulty of course is that in order to pick up a ten-year old signal you need either some sort of store-resend mechanism (aliens on the moon!) or the signal needs to travel a distance the same as to Proxima and back. And still be audible.

AM != FM

[ebh]

It's nothing special to have AM broadcasts travel long distances at night--it's an inherent property of that frequency range. You'll sometimes hear about "50,000 watt clear channel" stations. For each AM broadcast frequency, one station in the US has permission to crank up their transmitter to 50KW, and every other station on that frequency in the country either has to drastically lower their power or go off the air altogether, hence the existence of dawn-to-disk AM stations. (I remember one AM station that broadcast road conditions for all major US Interstates, since they knew that their signal could be heard all over North America at that time of night.)

"Skip" (explained in other posts) is common in the HP range (3-30MHz), but much less so in the VHF range (30-300MHz). HF's skip characteristics are varied depending on frequency, but fairly predictable. Hams talk of "maximum usable frequency" (MUF), which deals with the less-predictable frequencies in the upper parts of HF and lower parts of VHF. It is significant to hams when the MUF tops 50MHz, because that allows skip traffic over 6 meters (50-54MHz-so THAT's what happened to channel 1!), which most of the time is restricted to line-of-sight.

On rare occasions, such as during this radiation storm, the MUF can go past 150MHz, allowing skip for FM broadcast, 2-meter (144-148MHz) ham, and many of the VHF broadcast TV channels.

It can be loads of fun seeing what all you can pick up on your FM radio which this happens.

Not the Sun at all

[Anonymous Coward]

The solar flare had nothing to do with this. What you are hearing is tropospheric ducting. Being a ham, the 2m and 70cm bands have had tropo the past two days because of the warm days and cool nights. I live near Philly and have been working stations further south then I do most of the time because of this. It has been very strong. This site dxing.com explains what tropo and Sporadic-E are. Tropo has nothing to do with the sun but Sporadic-E does. The distance between Philly and NC is kinda short for Sporadic-E. Also Sporadic-E doesn't last for long periods of time.