3 ms·

Early long distance communication often depended upon wavelengths suitable for ionospheric propagation, signals have been bounced off the moon, and (if I recall

by II2II 2y ago

Early long distance communication often depended upon wavelengths suitable for ionospheric propagation, signals have been bounced off the moon, and (if I recall correctly) the earliest experiments in communications involved large reflective balloons. Even though none of those are repeaters, the idea of using space to communicate over the horizon was something considered early on.

peter_d_sherman 2y ago
Now that I think about it, I wonder if it would be possible to use a second radio signal as a repeater, that is, bounce/reflect a radio signal off of another radio signal in other words bounce a wave off of another wave (in space)...? While in all likelihood such a thing is not possible (although, I'm the last guy on Earth who would say that!), it would be kind of cool to envision a kind of Sci-Fi future where such a thing could be possible... Perhaps more research in this area is needed... remember that a long time ago it was believed that Electricity and Magnetism were not related in any way, and it (apparently!) took Hans Christian Oersted (via electrical wire near compass needle) in 1820 (or thereabouts!) to show the scientific community that they were in fact related! In fact, I'd even go a step further... I wouldn't want to just bounce electromagnetic radiation off of other electromagnetic radiation (although, that would be interesting enough, to be sure!) -- I'd even go so far as to say I'd be extremely curious if electromagnetic radiation could speed up, slow down, redirect, cancel and/or possibly reverse the direction of other electromagnetic radiation... See, if we could accomplish some or even all of that... then we'd be at or close to living in a Star Trek-like future universe! Which would be... cool! Ah, the future possibilities! :-)
- mystified5016 2y ago
  What you're talking about, roughly, is called beamforming. Pretty much all modern high-speed radio communication works this way. Essentially, by transmitting your signals through multiple antenna, you can create interference patterns which can collimate and amplify the original signal and point it in one specific direction. This involves a lot of calculations that must happen extremely quickly, so it hasn't been possible until relatively recently. As to modulating the speed and direction of a signal coming from an external transmitter this way, probably not. I'm not good with the math involved here, but I don't think there's any way to reflect radio like this. We can reflect radio with special materials and geometries, but not through wave interference. I'm not aware of any mechanism which can slow down the propagation velocity of a wave other than through interaction with a physical medium. If you really wanted to, you could amplify an external signal by broadcasting an exactly equal signal, which sounds suspiciously like a simple repeater. Canceling a signal is more difficult, conceptually it's the same problem as noise canceling in your headphones: you have to produce a wave exactly opposite to the incoming signal. In practice this is difficult to do for anything other than continuous noise like engine sounds. It doesn't work well for rapidly changing signals like voices or digital radio signals.
  - peter_d_sherman 2y ago
    Agreed, we have beamforming. Beamforming, to recap, uses multiple radio transmitters acting in a coordinated fashion, along with specific fast calculations -- to modify the conditions of the combined radio wave at a specfic point (or points) of space... So agreed, we have beamforming. Now with respect to the various arrays of antennas acting in a coordinated fashion, aka "phased arrays" / "phased array antennas" -- if I think about say, a Starlink Dish -- I think about a whole series of antenna circuits -- on a 2D flat plane: https://www.google.com/search?tbm=isch&q=starlink+dish+teardown https://www.google.com/search?tbm=isch&q=starlink+dish+teard... This seems very similar to The University Of Alaska's HAARP: https://www.google.com/search?tbm=isch&q=haarp https://www.google.com/search?tbm=isch&q=haarp https://en.wikipedia.org/wiki/High-frequency_Active_Auroral_Research_Program https://en.wikipedia.org/wiki/High-frequency_Active_Auroral_... https://haarp.gi.alaska.edu/ https://haarp.gi.alaska.edu/ But... that's not my point! See, these (basically 2D X x Y grid) designs for beamforming radio transmitters are great and all, but I'd be immensely curious if there weren't some interesting 3D antenna geometries that could be couldn't be coupled with beamforming technologies... for example, what happens if someone were to make a 3D phi-spiral phased array transmitting (or receiving?) antenna array? Some 3D version of something like: https://www.google.com/search?tbm=isch&q=phi+spiral https://www.google.com/search?tbm=isch&q=phi+spiral Or potentially like: https://cosmometry.net/phi-double-spiral-field-patterning#:~:text=Cross%2Dsection%20of%20a%20Torus https://cosmometry.net/phi-double-spiral-field-patterning#:~... Or perhaps like: https://www.facebook.com/photo.php?fbid=230792927111973&id=106168786241055&set=a.112729698918297 https://www.facebook.com/photo.php?fbid=230792927111973&id=1... Or even something like: https://www.youtube.com/playlist?list=PLTS3UsPvxuStfe0VI3M1SleaNnHt4R8tv https://www.youtube.com/playlist?list=PLTS3UsPvxuStfe0VI3M1S... You know, get something like that working with some Tesla Coils (https://www.google.com/search?tbm=isch&q=tesla+coil https://www.google.com/search?tbm=isch&q=tesla+coil https://en.wikipedia.org/wiki/Tesla_coil https://en.wikipedia.org/wiki/Tesla_coil) and see what happens! In other words, perhaps there may be more possibilities to explore here... But yes, agreed, we have beamforming!

by II2II 2y ago

peter_d_sherman 2y ago

Now that I think about it, I wonder if it would be possible to use a second radio signal as a repeater, that is, bounce/reflect a radio signal off of another radio signal in other words bounce a wave off of another wave (in space)...? While in all likelihood such a thing is not possible (although, I'm the last guy on Earth who would say that!), it would be kind of cool to envision a kind of Sci-Fi future where such a thing could be possible... Perhaps more research in this area is needed... remember that a long time ago it was believed that Electricity and Magnetism were not related in any way, and it (apparently!) took Hans Christian Oersted (via electrical wire near compass needle) in 1820 (or thereabouts!) to show the scientific community that they were in fact related! In fact, I'd even go a step further... I wouldn't want to just bounce electromagnetic radiation off of other electromagnetic radiation (although, that would be interesting enough, to be sure!) -- I'd even go so far as to say I'd be extremely curious if electromagnetic radiation could speed up, slow down, redirect, cancel and/or possibly reverse the direction of other electromagnetic radiation... See, if we could accomplish some or even all of that... then we'd be at or close to living in a Star Trek-like future universe! Which would be... cool! Ah, the future possibilities! :-)

mystified5016 2y ago
What you're talking about, roughly, is called beamforming. Pretty much all modern high-speed radio communication works this way. Essentially, by transmitting your signals through multiple antenna, you can create interference patterns which can collimate and amplify the original signal and point it in one specific direction. This involves a lot of calculations that must happen extremely quickly, so it hasn't been possible until relatively recently. As to modulating the speed and direction of a signal coming from an external transmitter this way, probably not. I'm not good with the math involved here, but I don't think there's any way to reflect radio like this. We can reflect radio with special materials and geometries, but not through wave interference. I'm not aware of any mechanism which can slow down the propagation velocity of a wave other than through interaction with a physical medium. If you really wanted to, you could amplify an external signal by broadcasting an exactly equal signal, which sounds suspiciously like a simple repeater. Canceling a signal is more difficult, conceptually it's the same problem as noise canceling in your headphones: you have to produce a wave exactly opposite to the incoming signal. In practice this is difficult to do for anything other than continuous noise like engine sounds. It doesn't work well for rapidly changing signals like voices or digital radio signals.
- peter_d_sherman 2y ago
  Agreed, we have beamforming. Beamforming, to recap, uses multiple radio transmitters acting in a coordinated fashion, along with specific fast calculations -- to modify the conditions of the combined radio wave at a specfic point (or points) of space... So agreed, we have beamforming. Now with respect to the various arrays of antennas acting in a coordinated fashion, aka "phased arrays" / "phased array antennas" -- if I think about say, a Starlink Dish -- I think about a whole series of antenna circuits -- on a 2D flat plane: https://www.google.com/search?tbm=isch&q=starlink+dish+teardown https://www.google.com/search?tbm=isch&q=starlink+dish+teard... This seems very similar to The University Of Alaska's HAARP: https://www.google.com/search?tbm=isch&q=haarp https://www.google.com/search?tbm=isch&q=haarp https://en.wikipedia.org/wiki/High-frequency_Active_Auroral_Research_Program https://en.wikipedia.org/wiki/High-frequency_Active_Auroral_... https://haarp.gi.alaska.edu/ https://haarp.gi.alaska.edu/ But... that's not my point! See, these (basically 2D X x Y grid) designs for beamforming radio transmitters are great and all, but I'd be immensely curious if there weren't some interesting 3D antenna geometries that could be couldn't be coupled with beamforming technologies... for example, what happens if someone were to make a 3D phi-spiral phased array transmitting (or receiving?) antenna array? Some 3D version of something like: https://www.google.com/search?tbm=isch&q=phi+spiral https://www.google.com/search?tbm=isch&q=phi+spiral Or potentially like: https://cosmometry.net/phi-double-spiral-field-patterning#:~:text=Cross%2Dsection%20of%20a%20Torus https://cosmometry.net/phi-double-spiral-field-patterning#:~... Or perhaps like: https://www.facebook.com/photo.php?fbid=230792927111973&id=106168786241055&set=a.112729698918297 https://www.facebook.com/photo.php?fbid=230792927111973&id=1... Or even something like: https://www.youtube.com/playlist?list=PLTS3UsPvxuStfe0VI3M1SleaNnHt4R8tv https://www.youtube.com/playlist?list=PLTS3UsPvxuStfe0VI3M1S... You know, get something like that working with some Tesla Coils (https://www.google.com/search?tbm=isch&q=tesla+coil https://www.google.com/search?tbm=isch&q=tesla+coil https://en.wikipedia.org/wiki/Tesla_coil https://en.wikipedia.org/wiki/Tesla_coil) and see what happens! In other words, perhaps there may be more possibilities to explore here... But yes, agreed, we have beamforming!