4 ms·

This site is a bit scarce on details. There's more details and some photos here: https://de.wikipedia.org/wiki/Cave-Link https://de.wikipedia.org/wiki/Cave-Link

This site is a bit scarce on details. There's more details and some photos here: https://de.wikipedia.org/wiki/Cave-Link https://de.wikipedia.org/wiki/Cave-Link http://www.hoehlenverein-blaubeuren.de/index.php/cavelink-telemetriesystem http://www.hoehlenverein-blaubeuren.de/index.php/cavelink-te... (Use Google Translate)

dll 5y ago
I wonder how the licensing issue referenced in the Wikipedia article is handled in the UK. I imagine Ofcom will have had to approve and license these installations, or will they have made these exempt (I can't find any evidence of this)?
- detaro 5y ago
  as far as I know similar general licensing exists for such purposes. Lots of inductive applications need it.
- gnfargbl 5y ago
  I can't see these devices specifically mentioned in https://www.ofcom.org.uk/__data/assets/pdf_file/0028/84970/ir-2030.pdf https://www.ofcom.org.uk/__data/assets/pdf_file/0028/84970/i..., though the frequency range they operate in (20-140kHz) is allowed to be used by induction loop type applications, at a suitably low power.
  - ale42 5y ago
    ... but the cave link uses relatively high power levels (20-30 Watts if I remember correctly)
    - lazide 5y ago
      Inductive stove tops are also In the KW range
goodpoint 5y ago
I'm really surprised ELF are not commonly used for this. Even a simple single-frequency CW transmitter for emergencies. I wonder if audio frequencies below 20KHz can be used to make a cheaper system.
- ttyprintk 5y ago
  At the extremity of that band, fewer nations have constructed transmitters than have nuclear weaponry. You can combine acoustic with radio in TARF (yes, really).
  - goodpoint 5y ago
    I meant acoustic frequencies in ELF, not using sound... but TARF looks amazing.
  - ale42 5y ago
    see e.g. https://www.mit.edu/~fadel/papers/TARF-paper.pdf https://www.mit.edu/~fadel/papers/TARF-paper.pdf for those who didn't hear about TARF (translational acoustic-RF communication)
meibo 5y ago
Something that is mentioned here and not on the main page: the devices form a mesh network and can relay messages between each other. Seems strange, feels like a pretty big selling point.

dll 5y ago

I wonder how the licensing issue referenced in the Wikipedia article is handled in the UK. I imagine Ofcom will have had to approve and license these installations, or will they have made these exempt (I can't find any evidence of this)?

detaro 5y ago
as far as I know similar general licensing exists for such purposes. Lots of inductive applications need it.
gnfargbl 5y ago
I can't see these devices specifically mentioned in https://www.ofcom.org.uk/__data/assets/pdf_file/0028/84970/ir-2030.pdf https://www.ofcom.org.uk/__data/assets/pdf_file/0028/84970/i..., though the frequency range they operate in (20-140kHz) is allowed to be used by induction loop type applications, at a suitably low power.
- ale42 5y ago
  ... but the cave link uses relatively high power levels (20-30 Watts if I remember correctly)
  - lazide 5y ago
    Inductive stove tops are also In the KW range

goodpoint 5y ago

I'm really surprised ELF are not commonly used for this. Even a simple single-frequency CW transmitter for emergencies. I wonder if audio frequencies below 20KHz can be used to make a cheaper system.

ttyprintk 5y ago
At the extremity of that band, fewer nations have constructed transmitters than have nuclear weaponry. You can combine acoustic with radio in TARF (yes, really).
- goodpoint 5y ago
  I meant acoustic frequencies in ELF, not using sound... but TARF looks amazing.
- ale42 5y ago
  see e.g. https://www.mit.edu/~fadel/papers/TARF-paper.pdf https://www.mit.edu/~fadel/papers/TARF-paper.pdf for those who didn't hear about TARF (translational acoustic-RF communication)

meibo 5y ago

Something that is mentioned here and not on the main page: the devices form a mesh network and can relay messages between each other. Seems strange, feels like a pretty big selling point.