3 ms·

Also, I’m not sure if people are aware of the number of radio systems that enable their smartphones. NFC (eg. Apple Pay) is a radio, range a few cm. Bluetooth

by Isamu 3y ago

Also, I’m not sure if people are aware of the number of radio systems that enable their smartphones. NFC (eg. Apple Pay) is a radio, range a few cm. Bluetooth is a radio, a few meters. WiFi is several radio systems, range tens of meters. Cell phone is several radio systems, range up to kilometers. GPS (and rival systems) range up to thousands of kilometers.

IndrekR 3y ago
NFC is not really a radio. Basically it uses a loosely copled transformer. Works much closer than 1 wavelength and only magnetic field matters.
- fourier54 3y ago
  100%. Every time I read the term "antenna" when referring to the coil used for NFC/RFID I suffer inside...
- Isamu 3y ago
  Good point, NFC is described as operating in a particular RF band but not through radio waves: > As with proximity card technology, NFC uses inductive coupling between two nearby loop antennas effectively forming an air-core transformer. Because the distances involved are tiny compared to the wavelength of electromagnetic radiation (radio waves) of that frequency (about 22 metres), the interaction is described as near field. An alternating magnetic field is the main coupling factor and almost no power is radiated in the form of radio waves (which are electromagnetic waves, also involving an oscillating electric field); that minimises interference between such devices and any radio communications at the same frequency or with other NFC devices much beyond its intended range. NFC operates within the globally available and unlicensed radio frequency ISM band of 13.56 MHz. Most of the RF energy is concentrated in the ±7 kHz bandwidth allocated for that band, but the emission's spectral width can be as wide as 1.8 MHz[57] in order to support high data rates. https://en.m.wikipedia.org/wiki/Near-field_communication https://en.m.wikipedia.org/wiki/Near-field_communication
dTal 3y ago
...and yet, efficiently transferring a 1kb file between two physically adjacent smartphones remains an apparently unsolved problem.
- pests 3y ago
  AirDrop it?
  - dTal 3y ago
    I'm sure that works beautifully, unless one or both parties happen to be running the most popular mobile OS in the world, Android. That 'AirDrop' even exists as a proprietary technology really proves the point.
    - ianburrell 3y ago
      On Android, use Android Quick Share which uses Google Nearby. It works very similarly to Air Drop including support for UWB. There are lots of things where Apple and Google have solutions that don't work together.

by Isamu 3y ago

IndrekR 3y ago

NFC is not really a radio. Basically it uses a loosely copled transformer. Works much closer than 1 wavelength and only magnetic field matters.

fourier54 3y ago
100%. Every time I read the term "antenna" when referring to the coil used for NFC/RFID I suffer inside...
Isamu 3y ago
Good point, NFC is described as operating in a particular RF band but not through radio waves: > As with proximity card technology, NFC uses inductive coupling between two nearby loop antennas effectively forming an air-core transformer. Because the distances involved are tiny compared to the wavelength of electromagnetic radiation (radio waves) of that frequency (about 22 metres), the interaction is described as near field. An alternating magnetic field is the main coupling factor and almost no power is radiated in the form of radio waves (which are electromagnetic waves, also involving an oscillating electric field); that minimises interference between such devices and any radio communications at the same frequency or with other NFC devices much beyond its intended range. NFC operates within the globally available and unlicensed radio frequency ISM band of 13.56 MHz. Most of the RF energy is concentrated in the ±7 kHz bandwidth allocated for that band, but the emission's spectral width can be as wide as 1.8 MHz[57] in order to support high data rates. https://en.m.wikipedia.org/wiki/Near-field_communication https://en.m.wikipedia.org/wiki/Near-field_communication

dTal 3y ago

...and yet, efficiently transferring a 1kb file between two physically adjacent smartphones remains an apparently unsolved problem.

pests 3y ago
AirDrop it?
- dTal 3y ago
  I'm sure that works beautifully, unless one or both parties happen to be running the most popular mobile OS in the world, Android. That 'AirDrop' even exists as a proprietary technology really proves the point.
  - ianburrell 3y ago
    On Android, use Android Quick Share which uses Google Nearby. It works very similarly to Air Drop including support for UWB. There are lots of things where Apple and Google have solutions that don't work together.