Comment by modeless
22 days ago
Walkie talkies as licensed today wouldn't because they are required by law to use exclusively stone-age radio technology. But modern unlicensed radio technology is incredibly good at sharing scarce 2.4 Ghz spectrum. Sometimes devices do interfere with each other, but they remain useful and they are far better at sharing than any expert would have predicted years ago. Let the radio engineers try.
It is not as easy as you think.
RF attenuation is proportional to frequency and at 2.4 GHz, it is very high. Also, the distance over which one could communicate depends on antenna height, so if both parties are at ground level, it is not feasible over a few hundred meters unless both are in wide open space.
Source: ham operator who has played with long distance device to device communication without using a repeater.
> RF attenuation is proportional to frequency and at 2.4 GHz, it is very high.
Through building materials, foliage etc, but not in free space/line-of-sight.
> Also, the distance over which one could communicate depends on antenna height, so if both parties are at ground level, it is not feasible over a few hundred meters unless both are in wide open space.
Isn't it just the opposite? Antenna height is only the limiting factor with line-of-sight, otherwise NLOS considerations like attenuation by building materials, multipath propagation etc. start to matter much more. Modern radio standards are extremely good at that.
Of course line-of-sight usually remains the ceiling, since there usually isn't much in the sky to helpfully reflect signals back down, at least with mobile transmitter compatible transmission levels (i.e. excluding shortwave).
> Through building materials, foliage etc, but not in free space/line-of-sight.
Yeah. Even in free space. For example, attenuation at 1 km for 144 MHz (ham VHF band) is about -76 dB while for 2.4 GHz, it is about -100 dB. That 24 dB drop could mean, the signal is below the noise floor of your receiver unless you increase the RF power output which means more battery drain.
For example, BT audio gets cut just moving to the next room despite the RF power of BT transmitters being ~ 5mW( 7 dBm ) and at 10m, the attenuation is -60 dB(just free space loss which is ideal condition), so 53 dBm (7-60) at the receiver is usually sufficient, yet they struggle.
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This is great on paper until some jackass wants to access their home NAS over the public frequency range so they can watch anime all day at their desk, which only works when they use multiple channels at once.
There are tons of cool things society could enjoy if it wasn't for a small handful of shameless actors.