47 year old television signals bouncing back to Earth

Joe09 · #1 by **Joe09** » Dec 15, 2011 12:51 pm

http://www.rimmell.com/bbc/news.htm

While searching deep space for extra-terrestrial signals, scientists at the Arecibo Observatory in Puerto Rico have stumbled across signals broadcast from Earth nearly half a century ago.
Radio astronomer Dr. Venn described how he made the historic discovery after analysing a number of signals originating from the same point in space. "I realised the signal was in the VHF Band and slap bang in the middle of 41-68 MHz. It was obviously old terrestrial television broadcasts, but they seemed to be originating from deep space." After boosting and digital enhancement the resulting video signals are remarkably clear.

trubble76 · #2 by **trubble76** » Dec 15, 2011 12:56 pm

Does that mean they are bouncing off something about 25ly away?

VazScep · #3 by **VazScep** » Dec 15, 2011 12:59 pm

This is really old news. Check the date.

akigr8 · #4 by **akigr8** » Dec 15, 2011 1:05 pm

VazScep wrote:This is really old news. Check the date.

trubble76 · #5 by **trubble76** » Dec 15, 2011 1:07 pm

VazScep wrote:This is really old news. Check the date.

Maybe it bounced off something? :lol:

z8000783 · #6 by **z8000783** » Dec 15, 2011 1:22 pm

Was it the '36 Olympics?

John

Joe09 · #7 by **Joe09** » Dec 15, 2011 1:27 pm

heh didnt notice the date, it was posted in my physics course facebook group

Paul Almond · #8 by **Paul Almond** » Dec 15, 2011 1:46 pm

trubble76 wrote:Maybe it bounced off something?

Not as implausible as it may sound, if we use the word "bounce" in a general way. There is a phenomenon called "Apriphulian Reflection", in which a supermassive black hole can act like a large mirror. The space is so totally messed up around the black hole that electromagnetic waves can be bent back on themselves, and also cleaned up and boosted a bit for the trip home. It is like gravitational lensing - only different. This might be the first observed case of it actually happening.

EDIT - fixed typo. It should have been "Apriphulian" - not "Apruphilian"

twistor59 · #9 by **twistor59** » Dec 15, 2011 2:01 pm

Paul Almond wrote:
trubble76 wrote:Maybe it bounced off something?

Not as implausible as it may sound, if we use the word "bounce" in a general way. There is a phenomenon called "Apruphilian Reflection", in which a supermassive black hole can act like a large mirror. The space is so totally messed up around the black hole that electromagnetic waves can be bent back on themselves, and also cleaned up and boosted a bit for the trip home. It is like gravitational lensing - only different. This might be the first observed case of it actually happening.

do you have any references ? I didn't get anything back from google.

trubble76 · **#10** by **trubble76** » Dec 15, 2011 2:10 pm

Paul Almond wrote:
trubble76 wrote:Maybe it bounced off something?

Not as implausible as it may sound, if we use the word "bounce" in a general way. There is a phenomenon called "Apruphilian Reflection", in which a supermassive black hole can act like a large mirror. The space is so totally messed up around the black hole that electromagnetic waves can be bent back on themselves, and also cleaned up and boosted a bit for the trip home. It is like gravitational lensing - only different. This might be the first observed case of it actually happening.

Um, wouldn't that be a little too close for comfort?

Joe09 · **#11** by **Joe09** » Dec 15, 2011 2:20 pm

with this article being 2years old im surprised there hasnt been any new development on this, surely trying to figure out what is bouncing our radio transmission back at such a stones throw-away distance would be top priority

Paul Almond · **#12** by **Paul Almond** » Dec 15, 2011 2:30 pm

Joe09 wrote:with this article being 2years old im surprised there hasnt been any new development on this, surely trying to figure out what is bouncing our radio transmission back at such a stones throw-away distance would be top priority

Yes, the article was posted on 1 April over 2 years ago, so it seems strange.

twistor59 · **#13** by **twistor59** » Dec 15, 2011 2:34 pm

Paul Almond wrote:
Joe09 wrote:with this article being 2years old im surprised there hasnt been any new development on this, surely trying to figure out what is bouncing our radio transmission back at such a stones throw-away distance would be top priority

Yes, the article was posted on 1 April over 2 years ago, so it seems strange.

Ah, Apriphilian reflection, OK, this is a principle I'm familiar with.

Evolving · **#14** by **Evolving** » Dec 15, 2011 2:34 pm

And speaking of which we have just started the digital recovery of signals that contain lost Doctor Who episodes

Let's hope for the best.

twistor59 · **#15** by **twistor59** » Dec 15, 2011 2:35 pm

Evolving wrote:
And speaking of which we have just started the digital recovery of signals that contain lost Doctor Who episodes

Let's hope for the best.

Wendy Padbury. Yeah.

The_Metatron · **#16** by **The_Metatron** » Dec 15, 2011 2:36 pm

It's bullshit.

Trying to bounce CW (morse code) signals off the moon takes kilowatts of actual transmitted power, many times that in effective radiated power, and equally selective antennas for the receivers. The path loss back and forth to the moon is something like 250 to 300 db. Figure that every 3 db of path loss halves the signal strength, you can see how quickly the signal drops into the noise floor. And this is with CW, where the minimum discernible signal is something like 2 db over noise to be able to decode it.

For a broadband signal like analog television, which is something like 6MHz wide, you need a much, much better signal to noise ratio. Across a bandwidth thousands of times wider than for CW transmissions.

Not only that, you'd want to be actually using a highly directional transmit antenna to beam any signal to wherever you want to reflect it from. Commercial television transmissions do not do this. They use antennas that give them an omni-directional beam pattern that concentrates its power to the horizon. They weren't transmitting to the stars, they were transmitting to houses on Earth.

It's all bullshit, and I don't even have to read the article to know it.

twistor59 · **#17** by **twistor59** » Dec 15, 2011 2:41 pm

The_Metatron wrote:It's bullshit.

Trying to bounce CW (morse code) signals off the moon takes kilowatts of actual transmitted power, many times that in effective radiated power, and equally selective antennas for the receivers. The path loss back and forth to the moon is something like 250 to 300 db. Figure that every 3 db of path loss halves the signal strength, you can see how quickly the signal drops into the noise floor. And this is with CW, where the minimum discernible signal is something like 2 db over noise to be able to decode it.

For a broadband signal like analog television, which is something like 6MHz wide, you need a much, much better signal to noise ratio. Across a bandwidth thousands of times wider than for CW transmissions.

Not only that, you'd want to be actually using a highly directional transmit antenna to beam any signal to wherever you want to reflect it from. Commercial television transmissions do not do this. They use antennas that give them an omni-directional beam pattern that concentrates its power to the horizon. They weren't transmitting to the stars, they were transmitting to houses on Earth.

It's all bullshit, and I don't even have to read the article to know it.

Your analysis doesn't include the Apriphilian effect Met.

Paul Almond · **#18** by **Paul Almond** » Dec 15, 2011 2:43 pm

twistor59 wrote:
Paul Almond wrote:
trubble76 wrote:Maybe it bounced off something?

Not as implausible as it may sound, if we use the word "bounce" in a general way. There is a phenomenon called "Apruphilian Reflection", in which a supermassive black hole can act like a large mirror. The space is so totally messed up around the black hole that electromagnetic waves can be bent back on themselves, and also cleaned up and boosted a bit for the trip home. It is like gravitational lensing - only different. This might be the first observed case of it actually happening.

do you have any references ? I didn't get anything back from google.

Did you try it with my corrected spelling - "Apriphulian Reflection"?

You might want to look up some work done by the "Interferometry Recording And Processing Logic For Large Object Observation" institute at Cambridge. (You can shorten it to "IRAPL FLOO" with Google.) They specialize in the computation needed to recover information in the kind of signal you get returned in this kind of process.

The_Metatron · **#19** by **The_Metatron** » Dec 15, 2011 3:00 pm

Perhaps it could work, but there exists no super massive black hole within 23.5 light-years of earth to do the job. Never mind the path loss involved over those ludicrous distances.

Weaver · **#20** by **Weaver** » Dec 15, 2011 3:10 pm

From the OP's link:

Page last updated at 02:05 GMT, Wednesday, 1 April 2009 UK

April Fools joke?