The Astronomical Impacts of the Digital Transition
12 June 2009 | By mike-kgmi in UncategorizedAfter much delay and self-generated media hype, the FCC is officially putting the ax to analog television signals in the U.S. starting today, June 12th, making your old TV with the rabbit ears officially useless. Our analog AM and FM radio signals are next up on the chopping block. The Digital Audio Broadcast (DAB) Transition hopes to make your radio receiver obsolete as well, although the FCC currently says it “will not establish a deadline for radio stations to convert to digital broadcasting.”
The reason for the transition is because they say non-directional high-powered signals like traditional TV and radio are wasteful of the electromagnetic spectrum, and could instead be used for low-power transmissions such as cell-phones and wireless internet. But according to the Fermi paradox, the transition away from analog communication could cost us a chance of making contact with other intelligent life. High-powered wasteful radio signals like KGMI’s can be heard across the universe, so that means all the horrible-sounding broadcasts I made as an intern are still out there somewhere! But even if an advanced alien civilization does exist light years away, if our species is any indication they would have already gone through their own digital transition. So we may never hear them, and now they will probably never hear us.
13 June 2009 | BarnCat Said:
To help support your inalienable right to watch television, the U.S. government is offering a converter box coupon program. All U.S. households will be eligible to request up to two coupons (available in limited quantities), worth $40 each, to be used toward the purchase of up to two converter boxes.
Hope this helps folks enable themselves to “Dig-It-All”! Big relief on the Radio Tip though, if I didn’t have Cable, I’d be listening to alot more AM/FM! {It’d be just like MTV way back when the popular Music video channel actually played Music!}
10 July 2009 | ffoulkes Said:
It’s a nice thought, achieving a form of immortality (as an earthling), or detecting alien races via leaked transmissions.
Like sailing on the solar winds…
I have to confess I would find watching the alien game-shows interesting. Or their equivalent of ‘Fear Factor’, maybe. “Flarg, you must now consume an entire Denebian slime devil in the larval stage…”
I don’t know if I’d want aliens observing or even detecting us by our transmissions. What if they’d consider them like a mosquito does carbon dioxide? “Oh, look, there’s food over there on that planet.” Something like the spores from Invasion of the Body Snatchers, or the Thing? We could handle the James Arness/Thing I’m sure, but I don’t know about the one in the Kurt Russell version. Or an Independence Day scenario, that’d be bad. They might not have an Achilles heel, making the common cold or chicken pox our protectors as they often show in fiction. Considering the nature of Nature, it might be best as a planet to play it low-key in the first place…
I do hate to deflate your Sagan-esque bubble a bit, honestly I do, but our more primitive transmissions wouldn’t be detectable for very far.
First, not much if any AM leaks into space anyway. The waves bounce off the ionosphere and the ground, and wrap around the surface of the earth. On a clear night, someone here might be able to pick up a station in Colorado or California; I believe this was useful to ships and subs in WWII because they could triangulate their positions easily out at sea. FM and TV have to be line-of-sight for earthly receivers like rabbit ears because they will punch through the atmosphere and not wrap around the planet.
In their paper, ‘How far away could we detect radio transmissions?’(1) , Al Aburto and David Woolley based their calculations (table one) on a receiver being about the size of our largest, at Arecibo, Puerto Rico, which is 305 meters, or a little over a thousand feet, and they show, if the atmospheric barrier to AM waves could be ignored, they would only reach out to about .007 Astronomical Units (an AU being the approximate distance from the earth to the Sun, about 93 million miles), or about three times the distance to the moon.
FM radio makes it out to about 5.4 AU, which is a little farther than the distance from the Sun to Jupiter.
UHF television pictures get out to about 2.5 AU, which is about 150% of the size of Mars’ orbit. If earth and Mars were on opposite sides of the sun in their orbits, with a 1000ft radio telescope, Martians could just barely get a picture transmitted from earth. The carrier would be detectable for a thousand times that distance, about a third of a light year, though I don’t know if it would be recognizable by aliens as being of artificial origin, and it’s still more than ten times that far to the closest star.
However, as an optimistic Louis Scheffer points out in ‘Aliens can watch ‘I Love Lucy” (2) , the range could be extended by improving the sensitivity of the receiver, through size increase, advanced signal processing, use of gravitational lenses, etc. A receiver a thousand kilometers on a side, with a surface area about twenty million times that of the Arecibo telescope, for example, would be able to pick up a TV picture from over ten light years away, and that’s into the range of “interstellar”.
Communication would be possible, but it’d probably have to involve a much more dedicated effort.
1. http://stason.org/TULARC/science-engineering/astronomy/100-How-far-away-could-we-detect-radio-transmissions.html
2. http://contactincontext.org/cic/v2i1/lucy.pdf , or http://74.125.95.132/search?q=cache:2Bfy4ZT4ZmkJ:contactincontext.org/cic/v2i1/lucy.pdf+aliens+can+watch+i+love+lucy&cd=1&hl=en&ct=clnk&gl=us