LoRaWAN packet received at record distance of 702 km(thethingsnetwork.org)
thethingsnetwork.org
LoRaWAN packet received at record distance of 702 km
https://www.thethingsnetwork.org/article/ground-breaking-world-record-lorawan-packet-received-at-702-km-436-miles-distance
52 comments
The 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.
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.
take a look at https://en.wikipedia.org/wiki/QRP_operation - there's an entire community dedicated to this pursuit. Also take a look at https://en.wikipedia.org/wiki/LowFER - you can even use 160-190 kHz under FCC part 15 in the US.
The data rates would be very low, but for experimental purposes it's viable. The cool thing is there's a ton of simple circuits you can build on your own that other enthusiasts have put online.
The requirement for a small antenna is hard to accommodate, but a lot of people find creative ways to deploy something with a low profile.
I also think the idea of using drones for microwave links has some potential - haven't seen much on that yet but I'm sure people are doing it.
The data rates would be very low, but for experimental purposes it's viable. The cool thing is there's a ton of simple circuits you can build on your own that other enthusiasts have put online.
The requirement for a small antenna is hard to accommodate, but a lot of people find creative ways to deploy something with a low profile.
I also think the idea of using drones for microwave links has some potential - haven't seen much on that yet but I'm sure people are doing it.
What you are describing there is basically longwave AM radio broadcasting. Large transmitter, small transistor radio receiver.
Low speed data can be and is sent using such transmitters, it is done by phase modulating the carrier. The data can be used to switch electrical appliances on and off.
https://en.wikipedia.org/wiki/Radio_teleswitch
https://en.wikipedia.org/wiki/Droitwich_Transmitting_Station
Droitwich puts out 500kW and reception range is on the order of 1000km.
Low speed data can be and is sent using such transmitters, it is done by phase modulating the carrier. The data can be used to switch electrical appliances on and off.
https://en.wikipedia.org/wiki/Radio_teleswitch
https://en.wikipedia.org/wiki/Droitwich_Transmitting_Station
Droitwich puts out 500kW and reception range is on the order of 1000km.
Right, but that's only one direction. I thought I put it in my comment, but I'm only curious about bidirectional stuff. The best path forward here seems to be WSPR- like stuff, but that requires larger transmitters on the order of tens of meters.
That's the problem, an asymmetry in transceiver size does not really lend itself to bidirectional unless its relatively short distances like cellular phone networks.
To game the unlimited base station rule in these criteria: you could use an EMP weapon type of transmitter. Apparently you can get tens of terawatts with flux-compression generator + vircator/reditron systems, or more with nuclear devices. The pulses are quite short so I'm not sure how the transmitted payload would be encoded, but I'm sure a RF engineer could tell you.
You could use magnetic loop antenna for transmitting. They're pretty small but only work at once very specific frequency.
Take a look at the various amateur radio HF digital modes like JT65 and WSPR.
Iridium SBD?
Wow. 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.
Ho 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-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.
The catch is, thanks to Shannon of course, bandwidth. WSPR will do something like 1.46 baud. That and the 13 meter long antenna.
Bah! Try 20,896,392,102 kilometers, using 35-year old technology https://voyager.jpl.nasa.gov/mission/status/
To be fair, they use dish antennas on both ends. Otherwise that feat would be ludicruosly impossible.
Try hundreds of meters deep in seawater, all around the earth:
https://en.wikipedia.org/wiki/Communication_with_submarines#...
Bandwidth is even worse though (<<1 baud), and don't start on antenna length.
https://en.wikipedia.org/wiki/Communication_with_submarines#...
Bandwidth is even worse though (<<1 baud), and don't start on antenna length.
How about while drilling 1000s of meters underground? How do you transmit data back to the surface? This is a problem faced by oil drilling and exploration companies, and they have a solution for it. Take a guess what it is...
Mud modulation.
Basically, while drilling, mud is pumped down the drill string and back out for cooling and cleaning purposes.
Some genius at one of the major oil drilling companies (maybe Schlumberger?) came up with the crazy idea of modulating the mud pressure to transmit information into the depths of the earth. You can control the drill bit speed, angle of drilling, and monitor all sorts of diagnostics over a mud-based communication channel. The bandwidth is decent (think: dial-up), especially when the drilling tools use an efficient modulation scheme.
It's amazing stuff to see first-hand.
Mud modulation.
Basically, while drilling, mud is pumped down the drill string and back out for cooling and cleaning purposes.
Some genius at one of the major oil drilling companies (maybe Schlumberger?) came up with the crazy idea of modulating the mud pressure to transmit information into the depths of the earth. You can control the drill bit speed, angle of drilling, and monitor all sorts of diagnostics over a mud-based communication channel. The bandwidth is decent (think: dial-up), especially when the drilling tools use an efficient modulation scheme.
It's amazing stuff to see first-hand.
Oh 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).
>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).
Radio 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.
I looked into this "earth mode" radio recently and even tried it out in my backyard without too much success. My question is, does the FCC have jurisdiction over this? Seems like it's not really radio so much as making a circuit using the earth as the conductor.
If the FCC doesn't regulate this could you use this for metro mesh networks? Of course I assume you'd have to be rigorous about avoiding leakage.
https://en.wikipedia.org/wiki/Communication_with_submarines#...
> "This article needs additional citations for verification."
> "This article needs additional citations for verification."
Agreed, it's not the distance on itself that is impressive, but the fact that it is achieved with very small off-the-shelf hardware, a short piece of wire as antenna, license-exempt ISM band, on a freely available IoT data network that you even can extend by placing a gateway yourself!
Good 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/
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/
You 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/
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/
Yeah, 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.
Using 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.
We were transmitting at 3 watt using a small Yaesu hand-held connected to a micro-controller.
[deleted]
Could this be replicated on an imaginary pure flat land ?
On 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.
Motorola (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.
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.
I 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.
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.
From a balloon in almost 40km altitude. Still impressive but nowhere as impressive as I read this headline. I thought this was ground to ground...
Ground-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.
There 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/
The longest one with a photograph is 443km (275mi).
The longest one with a photograph is 443km (275mi).
Comments like this are why I still read hacker news.
IIRC the above link was the frontpage not that long ago. Very interesting
Indeed, 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.
That’s great. I am wondering what was the throughput at that distance...
It's LoRa, so probably 50-ish byte packet transmitted at 800-ish bits per second.
Yes, we reached this 700+ km gateway at SF9 (1758 bps) and SF11 (537 bps).
How many channels does LoRa have?
It 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)
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)
This is the most "out there" thread, involving emerging technology, that I've seen on HN in a while.
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?