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We demonstrated simultaneous reception of neighboring channels with strong isolation between them." This enabled the researchers to monitor numerous radio chann

We demonstrated simultaneous reception of neighboring channels with strong isolation between them." This enabled the researchers to monitor numerous radio channels at once, instead of tuning into them individually. Can anyone elaborate on this? How does a single receiver produce multiple concurrent outputs, and how are they isolated in this context?

amelius 8mo ago
I have no clue, but I would guess that they do not have a single atom but rather an entire crystal of them.
jacquesm 8mo ago
Because all of the signals are superimposed. So if your receiver isn't selective it will show all of them at once and if you then demodulate selective parts of the spectrum by filtering you can isolate the signals individually. Think of any antenna: it is just a rod or a coil, it may have a specific frequency that it particularly likes because that is a nice fraction of its wavelength or close to its own resonance frequency, but that doesn't mean it isn't going to receive all the other signals to greater or lesser extent as well. The ratio between that one that it likes and the rest is called selectivity. The lower the selectivity the more evenly you will receive all signals at the same time. Usually receivers have a tuned front-end to get as much of the signal you want and to repress the rest as much as possible but that is optional, you can have a wideband front end just the same.
richk449 8mo ago
Unlike conventional cars that require expensive safety systems such as air bags and seat belts, the mover3000's top speed of one mile per hour makes it intrinsically safe.
sidewndr46 8mo ago
If you're just looking for the modern explanation of how an SDR works: an SDR just measures electrical current flow over time. If you graph current over time as detected it usually just looks like a bunch of signals all superimposed upon each other. A signal like "f = asin(x) + bsin(y) + c*sin(z)" if all the transmitters were just transmitting pure carriers with no modulation. Somewhere in the SDR, electrical current flow becomes a number using analog to digital conversion on the order of 7-12 bits in most SDRs. At that point you apply something like a FFT and then the time domain signal becomes a frequency domain signal, which can separate out different carriers.

amelius 8mo ago

I have no clue, but I would guess that they do not have a single atom but rather an entire crystal of them.

jacquesm 8mo ago

Because all of the signals are superimposed. So if your receiver isn't selective it will show all of them at once and if you then demodulate selective parts of the spectrum by filtering you can isolate the signals individually. Think of any antenna: it is just a rod or a coil, it may have a specific frequency that it particularly likes because that is a nice fraction of its wavelength or close to its own resonance frequency, but that doesn't mean it isn't going to receive all the other signals to greater or lesser extent as well. The ratio between that one that it likes and the rest is called selectivity. The lower the selectivity the more evenly you will receive all signals at the same time. Usually receivers have a tuned front-end to get as much of the signal you want and to repress the rest as much as possible but that is optional, you can have a wideband front end just the same.

richk449 8mo ago

Unlike conventional cars that require expensive safety systems such as air bags and seat belts, the mover3000's top speed of one mile per hour makes it intrinsically safe.

sidewndr46 8mo ago

If you're just looking for the modern explanation of how an SDR works: an SDR just measures electrical current flow over time. If you graph current over time as detected it usually just looks like a bunch of signals all superimposed upon each other. A signal like "f = asin(x) + bsin(y) + c*sin(z)" if all the transmitters were just transmitting pure carriers with no modulation. Somewhere in the SDR, electrical current flow becomes a number using analog to digital conversion on the order of 7-12 bits in most SDRs. At that point you apply something like a FFT and then the time domain signal becomes a frequency domain signal, which can separate out different carriers.