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New LoRa RF distance record

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Re: New LoRa RF distance record

#131

Post by abwizz »

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.…

fwiw lora is meant for extreme low-bw applications, like a few key-value pairs per hour.

maybe not mentioning the bitrate discourages misappropriation?

Re: New LoRa RF distance record

#133

Post by BenjiWiebe »

drmpeg wrote: post #125
wl wrote: post #82

Earlier quoted context omitted.

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.

It's still not going to happen accidentally.

Re: New LoRa RF distance record

#134

Post by BenjiWiebe »

KWxIUElW8Xt0tD9 wrote: post #126
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.

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

WSPR is very different than LoRa. WSPR is usually used at HF, and has very low bandwidth. LoRa is used at UHF frequencies, and has very wide bandwidth, as it's a spread spectrum modulation scheme.

There's more differences but those are the ones relevant to this discussion.

Re: New LoRa RF distance record

#135

Post by Saris »

martin_a wrote: post #6

Yeah... But WiFi doesn't work when I'm sitting on the toilet two rooms down the corridor. Crazy times. No, to be honest: Very impressive. It's kind of a "dream" of me, to bring Internet to the river/picknick area two kilometers away from me. LoRa would probably be the way to go, will have to look further into that.

The difference is the 160bps they have with this isn't going to be too much fun for web browsing!

Re: New LoRa RF distance record

#136

Post by Saris »

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.

You only need a gateway for LoRaWAN, you can do point to point or mesh LoRa without a gateway.

Re: New LoRa RF distance record

#137

Post by whizzter »

jacquesm wrote: post #32
SahAssar wrote: post #23

Earlier quoted context omitted.

Posting ones own content is not astroturfing unless they try to hide that it was them.

The submitter is a low karma anonymous account that just so happens to match the last name of the CEO of the company, so it isn't disclosed. Also this shot up on the 'new' page suggesting more than one company vote, this isn't the first time this happens with that particular domain either. Similar stuff is happening on Wikipedia, read the talk page there (and the LoRa page) to see what I'm getting at.

If he had used another "anonymous" name I might've agree that it could border astro-turfing but if your handled matches your last-name it's probably more of an over-eager CEO that thinks the world revolves around his ideas and interests (Being the company at the moment), so I'd rather put it in the spammy-behaviour box (But that seems accepted to a certain extent here still for obvious reasons).

Re: New LoRa RF distance record

#138

Post by extraduder_ire »

drmpeg wrote: post #125
wl wrote: post #82

Earlier quoted context omitted.

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.

Would it be closer to the other value if you factored in the atmosphere, and whatever else is in the way?

As an aside, would radio via the moon ever be practical? Without pumping out so much transmit power that you pick up the signal anyway, without pointing a receiver at the moon. I think it would be neat, if only for the sake of novelty.

Re: New LoRa RF distance record

#139

Post by throwbadubadu »

jacquesm wrote: post #122
throwbadubadu wrote: post #106

Earlier quoted context omitted.

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.

First sentence

> Show HN is for something you've made that other people can play with. HN users can try it out, give you feedback, and ask questions in the thread

Feels like it fits exactly my understanding? Not company vs person/project, but press release/announcement vs something to play with, something easily accessible and tryable, detailed?? And it goes much further that it must be something like this.. and no mention at all that this is the necessary disclosure if this is your article, newsletter or similar.... this one here definitely not a "Show HN"!

Re: New LoRa RF distance record

#140

Post by drmpeg »

extraduder_ire wrote: post #138
drmpeg wrote: post #125

Earlier quoted context omitted.

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.

Would it be closer to the other value if you factored in the atmosphere, and whatever else is in the way? As an aside, would radio via the moon ever be practical? Without pumping out so much transmit power that you pick up the signal anyway, without pointing a receiver at the moon. I think it would be neat, if only for the sake of novelty.

No, there's very little loss from the atmosphere at 432 MHz. The 390 dB figure is a misunderstanding of how the path loss is calculated. The poster "wl" took the one way path loss (195 dB) and doubled it. But the moon is a huge reflector and provides "gain".

Here's a C program with the correct equation.

  #include 
  #include 
  #include 

  int main(int argc, char **argv)
  {
    double  d, f, lambda, loss;

    if (argc != 3) {
      fprintf(stderr, "usage: moon  \n");
      exit(-1);
    }

    d = atof(argv[1]) * 1000.0;
    f = atof(argv[2]);

    lambda = 299792458.0 / (f * 1000000.0);
    loss = (0.065 * (1.738e6 * 1.738e6) * (lambda * lambda)) / (631.65468167 * (d * d * d * d));
    printf("EME path loss = %f dB\n", 10 * log10(loss));
    return 0;
  }
1.738e6 is the radius of the moon in meters and 0.065 is the reflection efficiency.

Satellites make moonbounce impracticable.

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