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New LoRa RF distance record

thethingsnetwork.org

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Re: New LoRa RF distance record

#121

Post by blantonl »

nickcw wrote: post #43

LoRa runs in the 868 MHz band (in Europe) - a frequency range known for being line of sight only as the ionosphere doesn't reflect radio waves of that high frequency. However sometimes you can get Troposheric propagation on these high frequency bands. This used to be common when I was a teenager living in the south of England in Kent and we could occasionally receive racy TV channels from Europe. https://en.wikipedia…

Just to expand upon this, tropospheric propagation happens typically where there is a temperature inversion, meaning, air near the surface is cooler than higher up in altitude. That warmer air aloft acts as a layer that radio waves bounce off of.

Re: New LoRa RF distance record

#122

Post by jacquesm »

throwbadubadu wrote: post #106
jacquesm wrote: post #57

Earlier quoted context omitted.

HN is weird in that there is a format for that, which, as a relatively new entrant you may not be aware of, but that's what 'Show HN' is for, so that you know that whoever is posting something is associated with the article. Otherwise you will get to the point where HN is just another advertising medium, only with the ads not labelled as ads.

Is that written somewhere? Maybe just different understandings and expectations.. but for me "Show HN" is about here is my work/project I'm proud of, want to share with the rest of the world, want to have it discussed. For a normal news, even if you are the author of submitting, not sure if that's necessary. "Show HN" is imo not the anti-astroturfing disclosure, and for my expectations I would actually be a bit surpr…

Yes, that's written somewhere but I'm not going to quite from private correspondence. I was recently corrected when I mentioned that Show HN is for projects rather than for companies and apparently it is for companies as well. As you can see by clicking the 'Show' link at the top of the page.

Re: New LoRa RF distance record

#123

Post by gh02t »

wienke wrote: post #111
catbert69 wrote: post #49

Earlier quoted context omitted.

You can get a LoRa transmitter/receiver for like $5 and setup your own network. Documentation and datasheets are freely available. They are really not printing money with that technology. There isn't any opensource modulation scheme that comes even close to LoRa.

So it takes more than 5 dollars. You also need a gateway but you can get these for 99 dollars. Still this technology has a very low barrier to entry for such a long range and low power capability.

For people reading this since I'm certain wienke knows this, you can also do point to point or mesh LoRA between cheap devices (e.g. Meshtastic). You don't necessarily need a multi-channel gateway, depends on what you want to do.

Re: New LoRa RF distance record

#124

Post by femto »

wienke wrote: post #107
mk_stjames wrote: post #77

There is never any mention of bitrate when talking about LoRa. It's infuriating from someone on the outside. From what I gather, the map says a "SF:12" which means a spread factor of 12, at a bandwidth of 125khz. With a code rate of '1' according to https://www.rfwireless-world.com/calculators/LoRa-Data-Rate-... this means about 292 bits-per-second transmission rate for the packet. But I'm unsure if this is correct.…

Good point. We'll add that to the next post if there is a new record. Also what can be confusing is that the business viable part is even much smaller than the technical viable part. The low power operations is really only at lower SF7 or SF8. And we push our partners and ecosystem to keep the payload as small as possible as every byte counts. It is a completely different way of thinking than WiFi or cellular. Yet I…

> It is a completely different way of thinking...

On that point, have you looked at Myriota's research? (https://myriota.com/) In developing their system they went right back to the fundamentals and reworked everything around the idea of short messages. For example, an implicit assumption in the Shannon bound is that the message length is long, so they figured out that their short message system doesn't obey the Shannon bound and designed the coding and so on accordingly. It's fascinating stuff if you're into information theory.

Re: New LoRa RF distance record

#125

Post by drmpeg »

wl wrote: post #82
H8crilA wrote: post #54

Earlier quoted context omitted.

It can bounce off of meteor trails or the moon. It's been done many times in the ham community. Signals do bounce off of aircraft too, there are even passive military radars that track airborne objects using DVB-T or other strong signal reflections. It could be used if the conditions are just right. All of this has really nothing to do with LoRa and everything to do with physical properties of the emissions (frequenc…

The path loss for moonbounce is approximately 390 dB. You're not doing that by accident. In addition to using weak signal modes, you'll need directional antennas and lots of power to overcome that.

It's not that high. You have to use the radar equation with the moon being a very lossy but huge target cross section. The path loss at 432 MHz and average moon distance of 384,400 km is 261.6 dB.

Re: New LoRa RF distance record

#126

Post by KWxIUElW8Xt0tD9 »

dopidopHN wrote: post #103
albertzeyer wrote: post #90

So I know LoRA: Low-Rank Adaptation of Large Language Models and Using LoRA for Efficient Stable Diffusion Fine-Tuning. But from the text, I don't think this is about it? It seems it's this: https://en.wikipedia.org/wiki/LoRa

Correct. It’s a low bandwidth/ long distance RF protocol over specifics bands. It’s also kinda proprietary.

check out ham radio WSPR for an indication of the sorts of things that can be done

Re: New LoRa RF distance record

#129

Post by westmeal »

dopidopHN wrote: post #103
albertzeyer wrote: post #90

So I know LoRA: Low-Rank Adaptation of Large Language Models and Using LoRA for Efficient Stable Diffusion Fine-Tuning. But from the text, I don't think this is about it? It seems it's this: https://en.wikipedia.org/wiki/LoRa

Correct. It’s a low bandwidth/ long distance RF protocol over specifics bands. It’s also kinda proprietary.

Not super familiar with LoRa, can you explain what makes it properietary? Is it the protocol?

Re: New LoRa RF distance record

#130

Post by jacquesm »

westmeal wrote: post #129
dopidopHN wrote: post #103

Earlier quoted context omitted.

Correct. It’s a low bandwidth/ long distance RF protocol over specifics bands. It’s also kinda proprietary.

Not super familiar with LoRa, can you explain what makes it properietary? Is it the protocol?

They've taken out a bunch of patents for instance:

https://patents.google.com/patent/US20160094269A1/en

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