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Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

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Re: Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

#21

Post by cycomanic »

yau8edq12i wrote: post #17
lxgr wrote: post #15

Earlier quoted context omitted.

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…

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…

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?

Re: Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

#22

Post by [deleted] »

greenish_shores wrote: post #3

"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 fo…

[deleted]

Re: Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

#23

Post by [deleted] »

cycomanic wrote: post #21
yau8edq12i wrote: post #17

Earlier quoted context omitted.

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…

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 m…

[deleted]

Re: Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

#24

Post by yau8edq12i »

cycomanic wrote: post #21
yau8edq12i wrote: post #17

Earlier quoted context omitted.

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…

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 m…

> 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.

Re: Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

#25

Post by ale42 »

mannyv wrote: post #19

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.

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/comments/12d2s3e/would...), but well, it works well as far as I've heard.

Re: Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

#27

Post by cameldrv »

yau8edq12i wrote: post #12
macnetic wrote: post #6

Earlier quoted context omitted.

HF is 3 MHz to 30 MHz. Yes it does not make much sense, the term is ancient.

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.

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.

Re: Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

#28

Post by guenthert »

nrdgrrrl wrote: post #16
lxgr wrote: post #13

Earlier quoted context omitted.

If you consider SSB voice one medium, and CW morse code another, HF has been multimedia for more than a century :)

There's also SSTV. Surely images, voice and text counts as multi-media?

Uh, I didn't know SSTV had been used since the Apollo moon landings.

But what is it actually used for today? Or is it rather one of those we do, because we can?

Re: Digital Telecommunication in HF band - WWWAN - World-Wide Wireless Area Network

#29

Post by cycomanic »

yau8edq12i wrote: post #24
cycomanic wrote: post #21

Earlier quoted context omitted.

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 m…

> 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.

What do you mean? We routinely do satellite communications with free space optics, and fibre comms which at the backbone of all modern comms uses light around 193 THz.
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