[HN Gopher] Digital Telecommunication in HF band - WWWAN - World...
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Digital Telecommunication in HF band - WWWAN - World-Wide Wireless
Area Network
Author : pabs3
Score : 58 points
Date : 2024-05-05 02:52 UTC (20 hours ago)
(HTM) web link (pretalx.sysmocom.de)
(TXT) w3m dump (pretalx.sysmocom.de)
| KaiserPro wrote:
| Related but not quite the same: http://www.dxcluster.org/
|
| Dxcluster used to use a lot of radio links to disseminate data.
| However fixed internet lines have become much cheaper, so there
| isn't the need to have massive HF antenna to create relay link
| any more.
| runlaszlorun wrote:
| > so there isn't the need to have massive HF antenna to create
| relay link any more.
|
| HF is having quite a resurgance among various militaries.
| blantonl wrote:
| I'm not sure why this was downvoted. The author is correct.
|
| Given that space communications and the militarization of
| space is becoming more and more prevalent, we are on the cusp
| of seeing some military actions in space that could render a
| few defense agencies impotent with regards to C3.
| greenish_shores wrote:
| "Multimedia"? Over HF where one "cell" (using the WWAN
| nomenclature) may have several tens kbps of total (uplink and/or
| downlink) throughput at most? (see Shannon-Hartley theorem, which
| is distinct from Shannon-Nyquist sampling theorem) But for emails
| and the rest of proposed use, sure.
|
| Also, OsmoDevCon is iirc invite-only, making linking to its
| schedule on a public forum mostly pointless (visit #osmocom on
| Libera for more info; disclaimer: I wasn't invited, either).
| Unless, of course, a recording would be added (which it probably
| will), but it's not true yet (as the event didn't took place
| yet?)
| lxgr wrote:
| If you consider SSB voice one medium, and CW morse code
| another, HF has been multimedia for more than a century :)
| nrdgrrrl wrote:
| There's also SSTV. Surely images, voice and text counts as
| multi-media?
| DeathArrow wrote:
| What HF means in this context? A few GHz? Also, for long range I
| thought the longer the wave length is, the better.
| SigmundA wrote:
| https://en.wikipedia.org/wiki/High_frequency
| macnetic wrote:
| HF is 3 MHz to 30 MHz. Yes it does not make much sense, the
| term is ancient.
| nativeit wrote:
| I mean, any higher and I'll have to start thinking about
| printed circuit boards, shielded wires, and non-coat-hanger-
| based antennas...frankly if 30,000 kilocycles can't get the
| job done, I'll just have to light the thing on fire and use
| it to make smoke signals.
|
| Best regards, 50 years ago
| xattt wrote:
| 640 K[Hz] ought to be enough for anybody.
| 1992spacemovie wrote:
| If you did a modicum of reading it makes sense.
| yau8edq12i wrote:
| Ancient? The HF band is still very much in use... Modern
| developments have not changed the fundamental properties of
| RF propagation. UHF ("a few GHz") can only be propagated in
| line of sight reliably. HF can literally travel around the
| world.
| lxgr wrote:
| GP called the term ancient, not the band itself, and I find
| it hard to disagree with that.
|
| Calling something "high", "fast", or "new" is rarely a
| naming decision that'll stand the test of time, but given
| that there were already LF and MF below it, it did make
| sense at the time. Who could have predicted we'd go up all
| the way into visible light with our RF communications?
|
| The only thing on a lower frequency used daily by most
| people would be contactless payment cards and maybe NFC at
| around 13 MHz.
| yau8edq12i wrote:
| Millimeter wavelength RF was already studied in the 19th
| century... The RF communication band you're talking about
| is smack dab in a band already defined in the original
| 1937 document.
|
| Honestly the naming scheme makes sense to me. The
| spectrum is divided into 12 bands of equal (log) size, up
| to a frequency where we don't know whether such waves
| will _ever_ be reliably generated at room temperature
| without breaking the laws of physics. Then these bands
| are consistently named from "extremely low" to
| "extremely high", with an extra annoying band at the top.
| Really, it could be worse.
| zamadatix wrote:
| I agree it could be worse but the idea it's really any
| good seems more like us being used to it than anything
| else. It's a stupid naming scheme. For a log scale I
| would really have been happier with everyone using band
| numbers or something rather than explaining "super high
| frequency" is higher than "Ultra high frequency" and,
| despite the terms, that's probably where most typical
| radio device use cases are these days.
| lxgr wrote:
| Fortunately we have not just one but two competing band
| designators - IEEE (widely in use in e.g. satellite
| communication; L-band, Ku-band, Ka-band etc. come from
| that nomenclature) and EU/NATO (which seems somewhat
| obsolete) :)
|
| In addition to that, hams (in study materials and exams)
| use wavelengths, which is always "fun" to convert from/to
| frequencies.
| cycomanic wrote:
| I'm not sure I understand. In 1937 we already knew that
| light and RF are both part of the EM spectrum so I don't
| know what you mean by generating waves that break the
| laws of physics (we have and had absolutely no issues
| generating waves with 100s of THz frequency). As a
| physicist coming from the optics I find naming in RF
| often quite puzzling, e.g. why do we call it microwave,
| while wavelengths are all longer that millimeters?
| yau8edq12i wrote:
| > we have and had absolutely no issues generating waves
| with 100s of THz frequency
|
| In a way suitable for even medium range RF communication?
| No. That's what I mean. The required power would be
| insanely high. So high that it's not achievable without
| some breakthrough. I didn't literally mean "break the
| laws of physics", because that's something we obviously
| cannot do.
| cameldrv wrote:
| UHF can be used with troposcatter techniques. Before
| satellites this was somewhat popular. It seems to be having
| a little bit of a comeback as well as you can get hundreds
| of miles of propagation fairly reliably and since it's
| higher frequency you can get a pretty wide bandwidth.
| Something that can fit on a small trailer can send hundreds
| of megabits hundreds of miles.
| lxgr wrote:
| Even today, it still is higher than low and medium frequency
| :)
| mannyv wrote:
| How is this different from what the ham radio guys have? They
| were doing ip over ham in the 90s, i think, which is more
| performant than uucp for sure.
| ale42 wrote:
| Not very different I think... on the air it's the same: they're
| using VARA, which has been introduced by a ham radio guy
| (https://rosmodem.wordpress.com/), and is widely used by ham
| radio operators.
|
| I'm a bit annoyed by the closed and Windows-only nature of VARA
| (see also discussion https://old.reddit.com/r/amateurradio/comm
| ents/12d2s3e/would...), but well, it works well as far as I've
| heard.
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