8 ms·
LoRaWAN packet received at record distance of 702 km
- vvanders 9y agoGood stuff, HAAT(height above average terrain) always makes a big difference. I regularly see APRS packets of 120mi+, although probably at a lot more power. The current record seems to be near ~2,000 mile[1] bounced from the ISS. [1] - http://qrznow.com/new-iss-packet-distance-record-claimed/ http://qrznow.com/new-iss-packet-distance-record-claimed/
- deleted 9y ago[deleted]
- X-Istence 9y agoUsing ARPS when I helped launch a weather balloon while in college, we were recorded by a station in Las Vegas. We launched south of Phoenix so at least 300 miles. We were transmitting at 3 watt using a small Yaesu hand-held connected to a micro-controller.
- gravypod 9y agoYou can also go very long distances if you use forward-error-correcting protocols like JT9 or WSPR. WSPRNet[0] is a network of WSPR transceivers that use milliwatts to communicate across the world. It's just.... very slow. Edit: And this is very frequency dependent. [0] - http://wsprnet.org/drupal/ http://wsprnet.org/drupal/
- vvanders 9y agoYeah, I've been wanting to try JT9 but haven't picked up a HF radio yet. Some of the moon bounce stuff is just incredible.
- egeekuk 9y agoMight just be me, but I read this as ~2 kilometers, rather than the intended ~2,000 miles.
- agumonkey 9y agoCould this be replicated on an imaginary pure flat land ?
- kbumsik 9y agoThat’s great. I am wondering what was the throughput at that distance...
- dfox 9y agoIt's LoRa, so probably 50-ish byte packet transmitted at 800-ish bits per second.
- ju-st 9y agoHow many channels does LoRa have?
- dfox 9y agoIt is variable-bandwith spread spectrum modulation, so talking about discrete channels does not make that much sense. But each of frequency bands it operates in is notionally divided into 9-11 uplink and downlink channels. The modulation scheme is essentially FM with a twist: high bitrate mode is essentially straight FSK and lower rate modes are FM modulated with sawtooth, which is or is not inverted in each period depending on the transmitted bit. The idea is essentially same as various QRP modes involving painting images on waterfall diagram. (Full gateway nodes receive full band and can track ~50 transmitting nodes at once)
- tikwidd 9y agoDo you think it would be possible to build an IPFS network over LoRaWAN?
- api 9y agoSure but it would be slower than moles' asses in January.
- telkamp 9y agoYes, we reached this 700+ km gateway at SF9 (1758 bps) and SF11 (537 bps).
- Animats 9y agoWow. Both the receiving and transmitting antennas were omnidirectional. There's no problem doing this with a dish pointed at a dish, but that low power without directional antennas is impressive.
- sbierwagen 9y agoHo ho, is nothing! Try 7,869km, transmitting at 10 milliwatts. The transmitter? A couple passives attached to a GPIO pin on a raspberry pi: https://gerolfziegenhain.wordpress.com/2013/04/13/raspi-as-wspr-transmitter/ https://gerolfziegenhain.wordpress.com/2013/04/13/raspi-as-w... The catch is, thanks to Shannon of course, bandwidth. WSPR will do something like 1.46 baud. That and the 13 meter long antenna.
- revelation 9y agoTry hundreds of meters deep in seawater, all around the earth: https://en.wikipedia.org/wiki/Communication_with_submarines#Extremely_low_frequency https://en.wikipedia.org/wiki/Communication_with_submarines#... Bandwidth is even worse though (<<1 baud), and don't start on antenna length.
- wlesieutre 9y agoOh my. You're not kidding about that. >Instead, one has to find an area with very low ground conductivity (a requirement opposite to usual radio transmitter sites), bury two huge electrodes in the ground at different sites, and then feed lines to them from a station in the middle, in the form of wires on poles. Although other separations are possible, the distance used by the ZEVS transmitter located near Murmansk is 60 kilometers. As the ground conductivity is poor, the current between the electrodes will penetrate deep into the Earth, essentially using a large part of the globe as an antenna. The antenna length in Republic, Michigan, was approximately 52 kilometers (32 mi).
- Animats 9y agoRadio through the ground was used by radio hams during WWII, because ham radio though the air was prohibited during the war. People would drive two stakes into the ground about 50 feet apart and talk cross-town.
- aw3c2 9y agoFrom a balloon in almost 40km altitude. Still impressive but nowhere as impressive as I read this headline. I thought this was ground to ground...
- vvanders 9y agoGround-to-ground is limited by the curvature of the earth(unless you're bouncing things off the atmosphere like with HF radio). Generally even with a repeater on a mountain nearby the best you can expect is ~100mi.
- jws 9y agoThere are many spots on the Earth with longer LoS views. Here is an interesting list along with photographs people have made of them: https://beyondhorizons.eu/lines-of-sight/ https://beyondhorizons.eu/lines-of-sight/ The longest one with a photograph is 443km (275mi).
- DanWaterworth 9y agoComments like this are why I still read hacker news.
- mhh__ 9y agoIIRC the above link was the frontpage not that long ago. Very interesting
- telkamp 9y agoIndeed, this was pure line-of-sight, as the gateway was within the radio horizon of the balloon. Ground to ground would be more impressive, we have already seen ground distances with LoRaWAN of 320+ km due to atmospheric ducting. We'll look for more data and do a post about that later.
- owenversteeg 9y agoSo, this raises a question I've been meaning to ask for a while. Let's say you want to transmit a very small amount of information over a very long distance (say 80 bytes over a minimum distance of hundreds to thousands of kilometers.) What options are there that are relatively small-sized? Let's say maximum receiver size is roughly 10cm by 10cm, and power consumption can't be over 10 watts, but the "base station" can be as large and powerful as you want. [edit] cause this is getting some upvotes, here's some thinking I was doing: you can't go through the ground (unless you're at ultra low frequencies and those need antennas measured in tens of kilometers long). So you pretty much have to bounce stuff off the atmosphere, right? When you see stuff like this [0], with thousands of kilometers of range, I imagine that's what happening. Especially as that's 10MHz, which is 30 meters wavelength, which bounces off the atmosphere pretty well IIRC. The only thing with that is that the powers are incredibly low and the antennas are huge. What if you increased the power but decreased the antenna size, for example a 10cm x 10cm antenna with 10W? 100W? 1kW? Would transmissions across thousands of kilometers still be possible?
- pmorici 9y agoIridium SBD?
- LeoPanthera 9y agoYou could use magnetic loop antenna for transmitting. They're pretty small but only work at once very specific frequency.
- tlrobinson 9y agoTake a look at the various amateur radio HF digital modes like JT65 and WSPR.
- jdietrich 9y agoThe Shannon-Hartley theorem is your friend. The theoretical maximum data rate of a channel is the product of bandwidth and SNR. With a sufficiently low data rate and/or a sufficiently wide bandwidth, we can effectively communicate at well below the noise floor. There are many propagation modes to choose from. HF frequencies (~3MHz to ~30MHz) will propagate via the skywave mode, bouncing off charged layers in the ionosphere. By using codings with extremely low data rates (JT65, QRSS), amateurs routinely make contacts over thousands of miles on a fraction of a watt. Unfortunately, this mode relies on sunspot activity and we're currently at a minimum in the solar cycle. Frequencies below 3MHz will diffract around obstacles and follow the curvature of earth; unfortunately an efficient antenna at these wavelengths is enormously long, so a small system would have absolutely vast antenna losses. NVIS propatation is usable between about 3 and 8MHz, although you're limited to about 600km in a single hop. Multi-hop propagation is possible, although the path loss increases exponentially. Satellite is the other obvious propagation mode and is surprisingly accessible to amateurs. Solutions to the Shannon-Hartley equation that involve very wide bandwidths are sadly underexplored by the amateur community, because of an FCC requirement to use the narrowest possible bandwidth and the relatively meagre frequency allocations available to amateur operators. The extraordinarily wide bandwidth of a modern direct-conversion transceiver offers some tantalising possibilities.
- qwerty_asdf 9y agoThis is the most "out there" thread, involving emerging technology, that I've seen on HN in a while.
- api 9y agoOn the higher speed front: has anyone looked into 802.11ah (900mhz wifi) or any of the smart "TV white space" stuff? It's standardized but I can't find any hardware on the market. There is a company near us (Irvine, CA) that apparently has an 802.11ah chipset but no cards or USB versions and emails go strangely unanswered. Found them since they had a press release about hitting like a few tens of megabits at over a kilometer on very low power and a small omnidirectional antenna.
- jlgaddis 9y agoMotorola (Canopy) used to make a bunch of 900 MHz (ISM) radios that were popular with WISPs. They weren't technically Wi-Fi but a proprietary protocol. I can't recall if Ubiquiti ever had any 900 MHz radios or not but they have plenty in the 2.4/5 GHz (unlicensed) bands as well as the 3.65 GHz (licensed) bands that would probably serve your needs for cheap. Unfortunately, the 900 MHz band is getting quite crowded these days, leading to lots of interference and reduced "throughput". Mimosa is another (younger) company making similar gear that's relatively cheap with good bang for the buck. A place I do some work for has several 15-20 mile links (6/11 GHz) pushing ~500 Mbps although those are much more expensive.
- superkuh 9y agoI run two ubiquiti nanostation M900 at home on a 10m pole and in my car through the sunroof for a mobile data link. Both use custom made omnidirectional antenna. Because my area is very hilly it's super intermittent but when it does work it's fast. The ethernet bridge in the car is shared to devices with either ethernet to the switch or 2.4GHz wifi with a tiny openwrt router. As with all VHF and higher data comms what matters most is antenna height and line of sight. I can get 3km fine up on a big hill or lose signal only 300m away from home in other directions.