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There's a lot of cool radio-related things our smartphones could do but probably never will for regulatory/political/commercial reasons like you note. My pet i
by retrac 1y ago
There's a lot of cool radio-related things our smartphones could do but probably never will for regulatory/political/commercial reasons like you note.
My pet idea is to make some use of longwave! You know those time signals broadcast around 60 kHz? They cover thousands of kilometres from one transmitter. At 60 kHz the wavelength is 5 kilometres long and the RF tends to diffract around objects like mountains, buildings, etc. that get in the way. Longwave tends to penetrate underground, and through Faraday cages meant for short wavelengths.
Those time signals broadcast, in effect, 1 bit per second. The receiver is dead simple electronically and requires almost no energy to run. What if we broadcast a more modern error-corrected data stream? Every device could be supplied with a receive-only stream of a few hundred bits a second of whatever. I admit it's a solution somewhat in search of a problem. Weather updates? Emergency alerts?
- implements 1y ago> My pet idea is to make some use of longwave! […] At 60 kHz the wavelength is 5 kilometres long … Dim memory from my Ham Radio days that you’d need an antenna length of 1/4 the wavelength, which wouldn’t be very convenient for portable devices, unfortunately.
- lxgr 1y agoOnly for most efficient transmission. Reception just scales with antenna size, so as long as your transmitter is powerful enough in terms of effectively radiated power, you can make the receiver arbitrarily small. Many wristwatches are capable of receiving these LF time beacons, despite usually having antennas more compact than several kilometers.
- sidewndr46 1y agoThe 1/4 wavelength is derived from the half-wave dipole. It's not necessary to have an antenna that is 1/4 wavelength. It'll probably perform better if it is closer to that size, but it isn't required.
- lxgr 1y agoSome countries already do this! For example, the German LF time signal, DCF77, dedicates some of its "spare bits" to broadcast civil protection and weather forecast information, the latter of which many simple LCD "home weather station" thermometers can receive and decode. GNSS (navigation satellite systems like GPS or Galileo) are also an obvious candidate for this, given that essentially all phones already can receive their signals.
- tatjam 1y agoGalileo already has search and rescue (SAR) and emergency functions (EWSS)! GPS is trickier, as it's still sort of a millitary-first platform.