5 ms·

"Listening to all the radio at once" is mathematically, physically, and technically impossible to do as stated on a continuous spectrum. If you have an continu

"Listening to all the radio at once" is mathematically, physically, and technically impossible to do as stated on a continuous spectrum. If you have an continuous and uncountable number of possible broadcast frequencies (even in a finite range) and each has a finite bandwidth, you need an infinite amount of bandwidth. Another way to think about it is to ask how you demodulate any given broadcast given the carrier frequency. Then when you have to allow for any other broadcast at any other frequency and then claim you can separate them with a single device and no other information. If they're not well separated in frequency, cooperatively encoded so they are separable, or possibly doing something clever with directional waves, etc you will never be able to extract both signals separately. I'm guessing this is just effectively another software radio that will let you demodulate a countable number of sufficiently separated signals. A far cry from "all the radio".

H8crilA 2y ago
You wrote a lot of words to "explain" that this sort of a circuit is supposedly impossible (no filters here, except for inherent limitations of components): Antenna->Amplify->Rectify->Headphones It's a classic circuit, and yes it works. Given enough power it can be even replaced with a smoking hot dog (yes, a sausage), for example when directly touching the TX antenna.
- fc417fc802 2y ago
  [dead]
- thenthenthen 2y ago
  It’s a classic yeah! [edit] The fact this works is because of the lack of filters or tuned circuits, its basically an amplified diode (you can even do without out it tbh) But small correction, in this case it seems to be: Antenna > Rectify > Amp > Headphones Right? Ofc you can add more - rf or audio - amps between the antenna and headphones. But yeah. The lm386 is pretty interesting for this use, try it out, you will surprised what you will hear (from a mess of all nearby stations all mixed together to em emitting devices in your location and possibly ghosts (:p).
- drpossum 2y ago
  Sure didn't and this is probably the fundamental misunderstanding the author had too. You can receive all the frequencies (this is easy and what you and the author are claiming is all you need to do). You cannot listen to all of them at once as the title suggests because it is impossible to demodulate it for all frequencies at once. Nuance and understanding are important before you credulously say "well they say they built it so what they say must be true"
  - jasonjayr 2y ago
    I'm just starting to really dig into learning radio and what not, but if it's tuned to a band where AM modulation is the norm, then wouldn't it work? The transmitters that push the amplitude above the noise floor(or squelch) will produce an audible frequency simply but pushing enough power at the human-perceptible frequency?
    - BenjiWiebe 2y ago
      Well if you had enough different stations, you'd get white noise. I guess if you just listen to white noise you could say you're listening to everything at once. The radio stations will interfere with each other. The more stations, the more interference.
dtgriscom 2y ago
You can "listen to" an orchestra without being able to discern each violin. You can "listen to" the wind in the trees without hearing a single leaf tapping against a branch. There's no suggestion that the user would be able to understand every single AM broadcast; it's just a way to get a sense of the "oeuvre" of the entire (covered) radio band.

H8crilA 2y ago

You wrote a lot of words to "explain" that this sort of a circuit is supposedly impossible (no filters here, except for inherent limitations of components): Antenna->Amplify->Rectify->Headphones It's a classic circuit, and yes it works. Given enough power it can be even replaced with a smoking hot dog (yes, a sausage), for example when directly touching the TX antenna.

fc417fc802 2y ago
[dead]
thenthenthen 2y ago
It’s a classic yeah! [edit] The fact this works is because of the lack of filters or tuned circuits, its basically an amplified diode (you can even do without out it tbh) But small correction, in this case it seems to be: Antenna > Rectify > Amp > Headphones Right? Ofc you can add more - rf or audio - amps between the antenna and headphones. But yeah. The lm386 is pretty interesting for this use, try it out, you will surprised what you will hear (from a mess of all nearby stations all mixed together to em emitting devices in your location and possibly ghosts (:p).
drpossum 2y ago
Sure didn't and this is probably the fundamental misunderstanding the author had too. You can receive all the frequencies (this is easy and what you and the author are claiming is all you need to do). You cannot listen to all of them at once as the title suggests because it is impossible to demodulate it for all frequencies at once. Nuance and understanding are important before you credulously say "well they say they built it so what they say must be true"
- jasonjayr 2y ago
  I'm just starting to really dig into learning radio and what not, but if it's tuned to a band where AM modulation is the norm, then wouldn't it work? The transmitters that push the amplitude above the noise floor(or squelch) will produce an audible frequency simply but pushing enough power at the human-perceptible frequency?
  - BenjiWiebe 2y ago
    Well if you had enough different stations, you'd get white noise. I guess if you just listen to white noise you could say you're listening to everything at once. The radio stations will interfere with each other. The more stations, the more interference.

dtgriscom 2y ago

You can "listen to" an orchestra without being able to discern each violin. You can "listen to" the wind in the trees without hearing a single leaf tapping against a branch. There's no suggestion that the user would be able to understand every single AM broadcast; it's just a way to get a sense of the "oeuvre" of the entire (covered) radio band.